Unfortunately one late night when tired I hooked one up without a crossover...man, I've only done that a couple times in 40 years of hobby at least. That one is marked with blue tape on the back.
No longer have original boxes so will use some for Dayton tweeters.

$85 shipped conus in USPS flat rate box.

Thanks, Don

All unused. Shipped usps flat rate to usa lower 48.

SOLD. SEOS-8. Pair. Black. $60 shipped. (= 20 each + 20 shipping).

One pair left! WG-300. Black. $60 shipped.

This is the best way I've learned to ship being on the west coast, otherwise prices climb quickly going east...unfortunately shipping has gone up a lot.

Thanks, Don

Hey all... I just bought a lot of over 20,000 1 watt carbon comp resistors. Most values between 5.6 ohms and 22 meg. I'm thinking $5 for 10, $10 for 25, assorted values OK, plus postage. Open to offers on larger quantity. And half price on values over 1 meg.

All NOS, unbent leads. Some are shiny tin and others are more oxidized. Unknown manufacturers and age.

I checked a few dozen random samples and all but one were within tolerance. Surprising number were within 1%. I can select or match for an extra $0.50 per resistor if needed.
Here's a list:

I've designed this ugly monstrosity. I call it The Off Axis. It uses 9 https://www.parts-express.com/pedocs/specs/297-2164--tebm65c20f-4-spec-sheet.pdf and 1 https://www.parts-express.com/pedocs/specs/Spec Sheets/292-816--grs-8sw-4he-spec-sheet.pdf

Tell me, do you think this abomination would have too many canceling waves and sound like poop, or would it be awesome paired with a KABD4100 for full room filling action?

I wanted this to be one of the first products I highlight in my new forum. This amp started as a GB in this thread.

TPA3255 Reference Design Class D Amp GB

There was a second GB here:

XRK RTR TPA3255 Reference class D Amp GB2

What can I say, this is a superb sounding amp. Quiet, powerful, dynamic, non fatiguing, low distortion.

JPS64 created a masterpiece with his signature symmetry, via stitched ground planes, and ultra short high current traces. The board is 2mm thick, 2oz copper, ENIG finish. Assembled in California using premium genuine Mouser-sourced BOM. Each amp is individually tested on an Audio Precision test stand at the factory and then sound quality tested by myself before shipping.

Many people have assembled this amp into a nice chassis and everyone loves the sound. With the right PSU, the amp has the distinction of being the quietest amp I have built. You cannot tell it is on with ear pressed to the speaker cone. Just silence.

I hope folks will share their builds here. Or feel free to ask technical questions.

Redjr made on of the nicest implementations. More here.



Vunce made an awesome build with a linear PSU with an LT4320 Ideal bridge rectifier amp on a plank here:


For best results, this amp should be paired with the BTSB balanced buffer which provides selectable gains (0dB/6dB/14dB/20dB) SE or Bal input and SE and Bal output. Since the TPA3255 with PFFB only has 15dB gain, it needs a preamp with about 14dB of gain in order to play music to its maximum levels. The BTSB is a superb preamp design by Jhofland. It started as a GB in this thread. Here is the panel mount version of the BTSB:


Those of you who know me, know that I hate casework (chassis building). This most of my amps are “plank” amps. Amps on a plank of wood. Only the most special and deserving of amps get a chassis. Well this amp is one of those amps. More to come...

Edit Jan 31, 2023: video on how to setup and connect your amp module for the first time.

Hello everyone,


I’m new here and excited to join this community! I have a question regarding a speaker driver I own, and I’d appreciate your expertise. I have an Alpair 11 MS Gen 2 driver, but I’m facing some challenges:

1. Availability and Identification: This driver seems to be quite rare. I can’t find it easily online, and there’s no barcode or serial number on the unit. However, I have photos to share (I’ll attach them below). Can anyone confirm if this is indeed an Alpair 11 MS Gen 2, and when it might have been released? Mark Audio’s official site doesn’t provide much detail on this specific variant.
2. Mono System Setup: Since finding a matching pair is difficult, I’m considering using it in a mono configuration. I have an Aiyima T9 Pro tube amplifier (stereo, 2 x 38W @ 8 ohm). How can I safely set up a mono system with this single driver? Any advice on wiring (e.g., combining channels, adding resistors) or cabinet design (e.g., Transmission Line like Larissa TML) would be greatly appreciated.
3. Finding a Pair: If possible, I’d love to find another Alpair 11 MS Gen 2 to create a stereo setup. Are there any suggestions on where to look (e.g., second-hand markets like eBay, or direct from Mark Audio)? Alternatively, would pairing it with a similar model (e.g., Alpair 11 MS or MS Gold) work, considering technical compatibility?

I’ve attached photos of the driver for reference. Any help or insights would be fantastic—thank you in advance!


Best regards,

Hey friends,

I'm really trying to download a couple of PDF manuals for the Sansui CA-303 from HiFiEngine, but as many of you know, new registrations are currently closed 🙁

Would anyone with an active account be kind enough to help me download these two files?

They’re located here (you may need to copy-paste the link):
👉 https://www.hifiengine.com/manual_library/sansui/ca-303.shtml

What I’m looking for:

• Instruction/Owners Manual (Japanese) – Uploaded by HiFi1991
• Quick Start Guide (Japanese) – Also from HiFi1991

I'd really appreciate the help – thanks a lot in advance!

I'm in search of a decent 8" midbass driver. Needs to do mid-90s dB/2.83v and handle the 300 - 900 hz range with ease, preferably 4 ohm impedance.

The main issue I'm running into looking for a suitable driver is sufficient xmax along with efficiency. The driver will need to handle some decent power without turning into mush with loud transients. Obviously it will need to be some sort of pro audio driver given the application. Low distortion is a must.

Drivers like the Audax PR170MO don't have enough xmax to play louder without using steeper HP filter slopes. Levels I expect are 110 dB peaks in the specified range.

My other favorite B&C 8NDL51 isn't quite efficient enough and isn't available in 4 ohms. The 8PS21 has the same issue.

The 8PE21 is efficient enough as an 8 ohm driver, but not enough xmax to deal with a 300 hz 2nd order HP at higher output levels.

I've toyed around with the idea of using 2 drivers, but this will result in weird vertical dispersion issues.

Any suggestions?

Good day guys I’m having problem trying to identify this Zener (DZ3 silkscreen) on this amp. It’s cathode is on 12v and is in series with a regular diode (prob 4148) that it’s cathode is on the gate feed to the resistors for power supply, it’s marking is Z39 part number, that’s all that is on the casing.

I am about to pull the trigger on a pair of Mark Audio Alpair 10.3 drivers. The two finalists are 1) The Pensil 10.3 and 2) the Eland. Much of this is dictated by the small footprint (consequently the appropriate Frugal horn is NOT on the table)
This is the Pensil
http://frugal-phile.com/boxlib/pensils/Pensil103-plan-300114.pdf
And this is the Eland
https://www.diyaudio.com/community/...audio-fostex-tb-dayton-seas-etc.323051/page-3

Both of these are MLTLs (although I am an old guy and would simply call them Bass Reflex since neither has any sort of tapered line behind the driver)

The highlights are the Eland has a CSA of about 40 sq in and a volume of 1450 cu in. The Pensil is a few inches taller and has a CSA 2.5 times larger and a volume that is 2.9 times larger. The Fb on the Eland is 40 Hz and a F6 of 32 Hz (this is more than adequate since they will be near a wall / corner). I did not find the comparable specs on the Pensil. Since the Pensil is larger my assumption that there will be adequate bass.

Both seem like easy builds. The recommended bracing in the Eland is simpler and only calls for felt lining on the walls. The bracing on the Pensil is more elaborate but achievable and the the cabinet calls for stuffing (fluffy) only.

Here is my confusion. Both designs were done by Scott ( I saw no others mentioned so I hope I did not slight anyone), but I get the impression that many Pensils (10.3 version) have been made. The Eland, however, is not widely discussed. Was it a prototype that was never fine-tuned or was it overtaken by the favorable success of the Pensil? I am only guessing.

Big question: given the geometry of the boxes (mostly overall size) are different, so has anyone listened / measured both and what was the outcome.

Just as an aside. I noticed the Sibelius by Pearl (similar driver and similar size) has enjoyed some enthusiasm (certainly in the cosmetics category). But it appears to have a tapered line behind the driver ( although the advertising refers to it as "a front loaded "V" shaped horn"). Intriguing and fun to think about, but it would tax my limited knowledge trying to mimic that alignment.

Thanks in advance for any knowledge and feedback that you can provide

Greetings from a music lover!

My home office (24' x 18’) doubles as my personal audio listening area . A repurposed Denon 3803 AVR hides under my desk, driving either my 300 ohm phones or my main 2.1-channel rig. The Denon utilizes BB PCM-1791 (DS) DACs, 2 per channel operating in differential mode. I hang on to this equipment because I have not yet discovered any other solution offering me more audible goodness.

The 2.1 Denon front end feeds an ADCOM GFA-5802 (MOSFET aficionado) fronting Usher BE-718 'Tiny Dancer' bookshelfs (nominally 8 ohm but with complex impedance), supplemented by a Definitive PF-15 acoustic-suspension sub (internal amplification removed, now driven by an external mono Outlaw Model 200). Likely not the sharpest/fastest response in bass speakers, its usable attribute for me is that it goes down low and accurate. I keep a lid on the power, so it doesn’t provide big thumping, but rather musically some very low harmonics reinforcing the 40Hz bottom of the bookshelf speakers, to the point that I can just feel the extended bass.

The BE-718s stand on top of a 28" high heavy bookcase, their upward-angled facia aimed toward me as near-field monitors, 6' from me and 6' apart, occupying just 1/4 of the total room space. Every home audio space presents many audio compromises; but this small system overcomes them nicely to my ear.

My choices of audio equipment emanate from my audio taste: natural instrumental/vocal sound, absent harshness/shrillness/glaze, airy open sound/stage, always smoothly musical even when prompted to slam if the composer demands. I enjoy the bass/rhythm lines as fundamental to appreciation (when I attempt composition, I start with these). Yet I am not a head banger; for me, loud is the enemy of music except perhaps for short passages for contrast/emphasis. Listening to an entire hour’s worth of LOUD music fatigues me. Fortunately the loudness wars that produced popular CDs with no headroom are a bad memory. My equipment may seem overpowered, but it enables soft playing to remain in a critically low distortion band of the amp/speker combo where authority and reveal are maximized..

My audio hobby started when I was in my mid-20s. This experience was realized in three periods: the Servo Statik I (single guy searching for truth while exploring limits); the Magneplanar (minimal WAF inputs); the BE-718 (WAF emphasizes hear, not see). I never considered myself to have golden ears, so never toyed with valve amplification or 'high end' wires. I jumped into CDs as soon they appeared, digitizing any of my vinyl greats that did not make it to CD. I relegate vinyl and valves to the past and enjoy my Redbook streamers thru MOSFETs. My library of streamers includes 1100 albums stored on a Mac Mini's SSD in Apple lossless .m4a files.

(Help. I just couldn't resist another experiment in sound perfection, so bought a Fiio K11 R2R DAC; I hope it will control treble better than sigma-delta types, so as not to spotlight some unwanted brightness around the speaker's 2kHz crossover; also to further enhance the amp's musicality. I will feed its analog output into the Denon's L/R/Sub external analog inputs, which supports 2.1 channel analog pre-outs with bass management support. I will post how I like the result. I considered the BB PCM-1704, an R2R DAC with great respect in audio circles, but it is an obsolete part and I have not found a used application that’s not several times more costly than the K11 R2R.)

My handle hints at my aversion to working on great equipment. I have ruined more than I have enhanced. I did build a car audio amp from parts found on the Internet and it worked great for under $40 and drove two pairs of 4 ohm, 4" speakers. But even then, it was a messy effort. I rest my case.

Our 77” Samsung OLED lives in the living area accompanied by its own matched Samsung bluetooth surround separates. Works great for movies. No interest in modifying anything there. All content streamed via wireless.

Hi All,

I have a spare ERMSDCV2 Low Noise Amplifier + RMS to DC (log/lin) PCB for sale.

Price: 19 € + shipping

If interested please PM. Thank you.

Regards,
VS

I have four old turntables, Kenwood KD-990, Dual CS-521, Dual 1219 and Pro-ject Genie. My amp is Kenwood KA-8100. My speakers are finnish Gradient 1.3. Nice to be here!

Hi all,

I wanted to use a Bourns 91 series dual conductive plastic pot in my project, but KiCAD does not include a compatible footprint, so I had to design my own. This is literally the first KiCAD footprint I have ever made.

Did I do a good job, what do you think? I tried to mimic the included footprints (e.g. for Alps RK163) as much as possible.

This is the original mechanical drawing from the datasheet:



And this is my footprint:



I used KiCAD's positioning tools to reference all pads and silkscreen to the origin point. The pads are 2mm in diameter with 0.85mm holes. My concern is that the holes might be a bit too tight to accommodate manufacturing tolerances...

I've just discovered I have Misophonia It's pretty common, I'm relieved to know; supposedly something like 1 in 5 have it, so I guess many members of DIYAudio might also suffer this ailment. To save you looking the word up to find out what it means, it is the hate or disgust of certain sounds, especially eating noises. It was triggered again yesterday so I did some Googling on it and pleased to find out I'm not the only one. I was also thinking that our passion of loving music and purity of sound could even mean we have a bigger proportion than average. I list the ones that make me explode with anger and makes me want to scream SHUT that ****ing noise. I find it hard to really give them any order of intensity of the annoyance ...They really are nearly all the same to me. So, I start with the most recent one:
1) People scraping out plastic/paper yogurt pots when they're nearly empty. That little tap-tapping sound as they search around and around with the spoon, looking for the very last molecule of it, makes me go nuts!
2) People who have transistor radios on at work in the office, on the beach or a neighbour in the garden, nearly all are tuned to utter modern pathetic crap pop music. It's even worse when I can only just hear it too. Maybe if it was blaring out loudly, I could stand it more? ...Hmmmm maybe not!
3) People whispering on TV or radio ads or films. That breathy-over-loud- unnatural sound makes me want to scream. You know the type.... you can actually hear the lips moving...UGGGGH!
4) More commonly, people who smack their lips when they eat, I guess this must be very common with people.
5). Oh yes, just thought of another one....In the UK it has now become trendy to miss out the letter T when pronouncing any word that contains it midway in the word... This insults me so much in that the utter, shear, low-life, ignorance of the person speaking has actually entered my brain via my ears!

Anyway, I would love to know what other sounds get people angry to the point of rage. It could be quite funny, I think.

Hi All,

I have a set of "nx-amp v2.0 + PSU" and "kx-amplifier + PSU" boards for sale

Price: 19 €/set + shipping. Offers accepted.

If interested please PM. Thank you.

Regards,
VS

Hi All,

I have two spare Walt Jung Super (Diamond) Buffer with LN regulator Boards PCBs for sale.

Price: 11 € + shipping

If interested please PM. Thank you.

Regards,
VS

I'm looking for a used speaker to buy. Beyma SM112N. I prefer Europe to save on shipping costs and waiting times.

TU-8850SE KT170 SEP AMP 16W X 2​

Available in September 15, 2023

$1,185 with stock OPT​

$1,750 with Lundahl LL3727/90ma​

​

Audio Note Tantalum Resistor set is available 26 x 2 pcs = $286 singnal path only ​

I am trying to design a baffle step compensation network for the woofers in my system. The calculations require the speaker Re, the DC resistance of the speaker voice coil. The published specs say this value is 6.7 ohms. My multimeter, with zeroed leads resistance, says the value is 6 .7 ohms. But my Dayton Audio DATS3 gave me a value of 8.98 ohms. They can't both be right, and using the different Re for the calculations gives me different values for the resistance and inductance of the circuit and for a zobel circuit across the woofer. Why am I getting different numbers, and which Re should I use?

Here is the link to the updated NX2-Amplifier documentation at hifisonix.com https://www.hifisonix.com/articles/power-amplifiers/hifisonix-nx2-amplifier/

I will post a few decent photographs in the next few days, plus my listening impressions.

Click here to order two off amplifier module PCBs

Click here to order a PSU+inrush controller PCB

I used the Speaker Protection PCB on my build

The Hifisonix Universal Chassis uses the Modushop Mini Dissipante. Gianluca at Modushop can pre-drill and mill the chassis for a small additional fee - just send him the zip file attached below.

Here are the final measured specifications (23rd June 2025).

I’m finishing putting together a Hagerman Clarinet preamp that I was lucky enough to find a pcb for. It’s going in a wood case with an aluminum top plate, a rear aluminum plate bolted to the outside, and an aluminum plate inset inside the front to mount the controls to. Which plate would be the best to tie safety earth to? I plan on running short pieces heavy awg wire between the plates and bolts securely. The original design had a ground jack on the rear plate that Jim had the safety ground and a single pcb ground going to in an all metal chassis, fwiw. I could sure use some help to make this as safe as possible.

As a result of my list there’s already 10 pairs on their way to Austria.

More on the shelves.

R

I picked up a Victor A-X900 (JVC A-X900B) a few days ago, however its right side isn't functioning. The biassing IC (Super-A VC50022-2) appears to be burned out or damaged as of right now. I can't find a reliable place to get this IC. I tried using an equivalent circuit diagram that I found in another JVC schematic. which is not properly working! from my limited or lack of knowledge, I can't detected the problem. I've shared the detailed schematic.

It would be greatly appreciated if you could give me some advice on how to resolve this issue.

Thanks

Today I bought 🙂 (pics are not mine)

Harman Kardon Citation 11


Yamaha B-2


Nakamichi 480


Philips CD-104


Yamaha CT-610


Philips CDR-765


CEC DD-8200 with Shure V15 type IV


Grundig Fine Arts T-903 MKII


Next 😀

Oops! Almost forgot yesterdays goodie 🙂

Recently recapped my dh-220. on the left channel was able to set the bias current to 275ma and dc offset to 0V with no problems.
However, on the right channel, I cnat get more the 60ma on the bias. I check P2 and it seems fine. Resistance goes up to 1K.
So I started checking the other resistors in that network. R22 and R23 both measure to spec. R38 isn't the 28K resistor called for in the parts list, but is 17.4k. This is the same in both channels, however in the right channel, it measures at 17.1K (on the left it measured to spec).

So, I'm thinking I should replace that resistor. 300 ohms is almost 30% of the range of P2.

But, I thought I'd check in here first to see what the resident Hafler experts thought ;-)

Note all measurements where done with components in the board.

Thanks,
James

The DIY ACA mini (Amp Camp Amp mini) is in the process of shipping to
the Burning Amp Festival lottery winners and a few of the helpers and
associates.

I am pleased to present the DIY ACA mini article here (in two parts as it
exceeds the size limit of the forum).

There has been at least one addition to the design since BAF, and here's
your chance to look at it again and in more detail.

I am hoping that 6L6 will provide us with one of his usual exemplary build
guides, and I anticipate more general availability of this piece in the
future, as it was intended as a low cost, easily accessed project.



----
See Also:

• ACA Mini Bill of Materials V1.1 (currently used in the ACA Mini completion kit)
• Note about how to bend the trimpot leads in the current batch of completion kits

I bought these untested as spares at auction but are now surplus to requirements. They came without speaker terminals and bass drivers but I have fitted the correct ones alongside fitting a pair of alternative Volt bass drivers that I had in stock.

They have the Fountek Neo CD2.0 ribbon tweeters & Volt BM220.1 mid-bass drivers (instead of the BM220.8 or BM222.8), the BM220.1s are an older model and did have silver metal grilles installed which I have removed. I have re-attached the surround on one as the glue had failed but all repaired and tested working as they should.

The cabinets are well made, pretty heavy too but just finished in stained MDF so could do with a colour of your choice or veneering.

Come with the grilles and some speaker spikes too.

Looking for £175

Collection from Faringdon, Oxfordshire (UK).

Can potentially split if anyone wants the components seperate rather than the cabinets.

Hello EL34 Baby Huey builders,

As suggested by SCD in the following thread : http://www.diyaudio.com/forums/tubes-valves/72536-el84-amp-baby-huey-217.html#post5533779 I am starting a new thread specially dedicated to the building of Baby Huey amplifier based on my PCB which has been produced in more than 330 pieces and is still requested by many tube amplifier fans in a possible future Group Buy 4 : http://www.diyaudio.com/forums/group-buys/312869-gb-baby-huey-pcb-42.html 🙂

I will put in this thread all the information available about the assembly of the EL34 Baby Huey amplifier and some of the auxiliary board that I have used or designed to add some features to the amplifier. I must tell you that I am not in professional amplifier business, this is just a time consuming hobby for me and, as you will see, English is not my first language and I have sometimes difficulties to explain things correctly, sorry for that but at least you will understand easily schematics, pictures, B.O.M., etc... 😀

History

All that started about two years ago when I read the http://www.diyaudio.com/forums/tubes-valves/72536-el84-amp-baby-huey-217.html#post5533779 post from "gingertube" ! As I was interested by the shunt feedback concept that I didn't know I wanted to test it and decided to build the simplest version with two PCL86 tubes. Since I am very bad in point to point wiring, I made a small PCB. This amplifier was so good that I decided to continue my quest and, since the ECL86 or PCL86 were unfortunately no more produced, I made a second PCB for the EL84 version which needed a third tube, a 12AX7 (ECC83) for the input stage and added MOSFET with current source to drive the output tubes. This amplifier was very good and I was very satisfied by the MOSFET driver stage, but I was also a little bit frustrated by the limitation in power, about 12 W, and the fact that I could not use different power tubes...

To solve this problem, I made an identical version but with octal socket to accept many compatible tubes from the 6V6 to the KT88 and the EL34 Baby Huey was born ! Following the presentation of this solution on the diyaudio forum some members asked me if I could sell the PCB, I had never done this before but since the moderator move this discussion to the Group Buy forum I have received several request and started a GB1 with a target of 50 boards but finally closed it with 80 PCB ordered 🙂 I had to send them Worldwide and to learn how to make PayPal invoice... Later others readers asked me for more board and I offered a second and "last" GB2 which finished with 120 boards ordered !!!

Later, since there was still a strong demand, I asked Prasi, to whom I have bought a CRC power supply PCB, if he would accept to manage a third GB and he kindly accepted 🙂 He also suggested to make 2.4 mm boards for better rigidity. Now 120 more boards have been ordered and are in production and there is already 20 PCB's in waiting list for a possible GB4 ?

Documentation

In this first post I will enclose some of the latest documents available for building the EL34 Baby Huey and I will add more in next posts depending of your questions.

You will find the updated BOM in the GB letter, the latest schematics, some building recommendations, how to connect and to adjust the amplifier and several pictures showing the PCB assembled on top side (big components go on bottom side), a 6CA7 board fully assembled in test and finally the EL34 Baby Huey in its enclosure nearly finished (two vu-meters are still missing).

More pictures and data will come from all the people who have built this nice small amplifier. It is a very nice project for those who have never made and listen a tube amplifier, but remember there is some lethal high voltage (up to 500 V) and you should be very careful when you work on it

Have a nice time building the EL34 Baby Huey...

Best regards,
Marc

hello i have 6 modules first one M from lazy cat and 6 micro audio smsp 600 watt 60volt

they were designed for those modules.

i was using them with an active speaker

i have heatsinks and metal plates i am willing to give for free if somebody wants to buy all off them to go active
but they are heavy and shipping will be costly.

i would like 600 euro for all or 3 set of 2 modules and 2 smps for 200 euro each set.

the modules are 2 version 1.4 and the other 4 version 1.2.

these are still the best amps i have ever heard with second the hypex nc 400 and third the fusion fa 253.

i am located in greece so europe would be easier for shipping.

no signal, bridge.


5hz.


100hz.


2khz.

10khz.



20klhz.


50khz.


100khz.

300khz.

senoidal 20khz.


the preamplifier.

1.177 / 5.000


Hello, first of all I want to make it clear that, as almost everyone knows, Chinese advertisements and clones often do not even look like what they advertise. In this case, I want to make known what I consider a bargain. Leaving aside the title we have a preamplifier that I consider excellent, at a ridiculous price of 10$ with shipping (at least to Spain), small size (easy to connect if you want an integrated amplifier), you only need a 15-0-15 v. transformer, or a switched source for example of equal value for another 7$, it has its regulators, with its capacitors that really work very well, at the input it has an OP JRC-5532D, then BC550 and BC560, everything quite normal, I ordered 2 units, assembled it and passed it through the oscilloscope, the result is excellent (in my opinion and the price) I put captures of up to 400khz in square wave, the sine wave logically better, it responds from 5hz without problems, I have tried other clones and other originals that I have, and this one on paper gives better measurements, something that measures well can't sound bad. The sound, the little I have tried so far, is quite good, better than the Denon 1500pra that I have.
and other clones except the PASS 1.7, for me it is better for more detail, dynamics and width, but for the price it is gold, now here come the more technical forum members (I am not) who could suggest improvements, for the already excellent preamp, I attach captures from the oscilloscope, greetings.

Hello everyone. I found a pair of unmolested Mark IIIs and my plan is to keep the original circuit and just modernize components (resistors, caps, selenium rectifier to a diode).

It has been few years since I did this with two Stereo 70s. I'm looking for feedback on a few items. I don't want to create a huge debate about original circuit and improved circuits or this cap brand / that cap brand.

Questions:

1. Diodes across rectifier tube. Yes / No These will not be used daily and I did not do this on my ST70s.
2. Feedback wiring. Leave as is or tap from the 4 ohm wire since I will be using the 4 ohm connection with my speakers
3. Adding 100ohm 1/4 watt resistors (or was it 10 ohm) to the output tubes (pin 4) to the transformer. I know in the past, this was talked about as simple protection.

I did change the AC input wiring so the switch and fuse were on the hot wire to make it a bit more safe. Also, I have a CL-80 ready on the input to lower the line voltage a bit.

Thanks in advance.

Several people built this and reported it works well and has very good sound.
For information please see here.
Please PM me with a sensible offer.

In recent years, since Toshiba has stopped production of their low noise JFETs, there have been a lot of discussion about possible alternatives to replace them,
and what penalties there might be :
https://www.diyaudio.com/forums/pass-labs/142769-b1-jfet-alternatives-list.html
https://www.diyaudio.com/forums/pass-labs/317563-replacement-toshiba-2sk170-2sj74.html

The most recent discussion is probably the source follower used in the LX Mini Active Crossover.
Following the discussions there, we decided to put some substance behind that discussion.
https://www.diyaudio.com/forums/pass-labs/324747-lx-mini-crossover-article-6.html#post5501795

With the help of Jan Didden, we obtained access to an Audio Precision 2722 Distortion Analyser for half a day.
A small test setup was prepared to test various (Toshiba low noise) N-JFETs in a source follower buffer circuit.
The circuit consisted of 2x 9V alkaline batteries as power supply.
This was further filtered by 4mH Fastron inductors, followered by Panasonic FC 120μF capacitors.
Each of the N-JFET pairs used in the testing was matched to <10μA in Idss.
The output was loaded by a 10k ohm Vishay S102 bulk foil resistor.

The JFETs tested were
a. 2SK170BL at 8.2mA Idss
b. 2SK117BL at 7.5mA Idss
c. 2SK209GR at 3.8mA Idss

Single-ended input signal was 1Vrms and 2Vrms at 1kHz from the AP built-in waveform generator.
The results can be summarised.

DUT 1Vrms __H2 __H3__ 2Vrms H2 __H3
2SK170BL -102dB -104dB -96dB -92dB
2SK117BL -99dB -100dB -93dB -89dB
2SK209GR -92dB -107dB -86dB -97dB


As can be seen, there is very little performance difference between 2SK170 and 2SK117 (= 2SK209 in SMD) at the same Idss; on average about 3dB.
Halving the Idss push up the second harmonics by so 6dB, in return for 7dB lower third harmonics. The latter result (with the low H3) was rather unexpected and interesting.


Patrick
.

This regulator has good qualities due to much gain.
Problem I have is how to compensate it.
How do you recommend?

Hi All,

I have a stock of new transistores for sale bought from Mouser and Farnell some years ago:

0 x KSA1220AY (Fairchild/On Semi)
0 x KSC2690AY (Fairchild/On Semi)

160 V / 1.2 A / 20 W / TO-126 / (highest grade hFE = 160-360).

Price per pair with a minimum qty of 20 pieces: 1.5 Euros/pair + Shipping.

Matching available. Please PM.

Regards,
VS

A rare opportunity

I have a few modules left over from when I sold my SA-01 and MA-01 amplifiers which are from the NC***MP range of Ncore modules from Hypex.

I have these modules, all unused.

1 x NC250 MP - £175 - Datasheet - this is a single channel 250W module
1 x NC500 MP - £280 - Datasheet this is a single channel 500W module
1 x NC122 MP - £220 - Datasheet - this is a 2 channel 125W module
2 x NCSA500MP - £200 each - Datasheet - these are 2 channel 400W + 100W modules designed primarily for active speaker projects
3 x NC100HF - £50 each - Datasheet - These are single channel 100W modules designed to daisy chain from the main NCxxxMP modules above to drive tweeters in active applications. One of them is missing the cable set but I will either find it, or show you where to get one.
2 x MP-DSP main - £50 each - these are the DSP boards used in the Hypex Fusion DSP plate amps. You could build your own fusion amp using the NCxxxMP amp modules
1 x MP-DSP DigIn - £50 - this is the optical, coax and AES/EBU input board for the above MP-DSP

If you want all of them you can have them for £1000. I will also include the handy little evaluation board I have which lets you test the modules easily.

UK based postage will be £9 via UPS - happy to ship elsewhere at cost though.

Hello DiyAudio community,

TL;DR: This is a USB transport for audio output (up to 8ch) and input (2ch for now) and user device control (e.g., DSP management) from PC (MacOS/Linux/Windows) thru I2C/GPIO. Including bootloader for remote firmware update, flexible device configuration, HID interface, multiple audio output options, integration with SigmaStudio (simultanious audio playback and ADAU DSP configuration). Compact module available in USB-C and USB-B versions, isolated or non-isolated.

Latest docs, config tool, link to buy:
http://york.eclipsevl.org/

So, the story started when I needed a USB transport for audio output and another channel for device control, such as for managing DSP.

Last time, I solved this problem using a USB hub and a USB to Serial converter. This way, I assembled the required interface from 4 chips:
https://www.diyaudio.com/community/threads/audio-transport-module-york.406025/
(first post)

I tried to combine everything into one XMOS chip. This was also a working solution, but there was a big problem with the availability of the chips, especially in the desired package.

Thus, developing the transport on the pic32mz seemed the most logical to me. The first prototype module was based on Dortonyan’s project from Vegalab: in terms of circuitry, it almost completely repeated the original project and was designed for two-channel audio output, plus a serial interface. During testing of the firmware based on the original source code, several problems were identified when working in different OSs. The serial port was also not fully implemented.
I posted my version of the firmware with fixes in the original thread and on GitHub: https://github.com/eclipsevl/york_pic32mz_uac2_osfw/

After that, I continued working on the functions I needed. The following features were implemented:

1. Bootloader. Necessary for firmware updates via USB, without a programmer.
2. Flexible device configuration using a PC utility (which is also used for firmware updates).
3. HID interface for transmitting service information and device configuration. Initially, I planned to use the serial port, but HID is much more suitable.
4. Serial interface, which can be optionally enabled.
5. Various additional audio output options: s/pdif, 8-channel TDM, dual i2s (for using some DACs channel-by-channel in mono mode). Recently I also added support for old dacs with clock/data/latch interface. I.e. direct connection to dac ICs such as AD1862/PCM1702 etc is also possible without glue logic.
6. Various clocking options: module oscillators, external clock (slave mode), internal PLL clocking.
7. I2C port and library for integration with SigmaStudio: for simultaneous audio input/output and DSP ADAU programming.
This last feature is currently a unique combination and fits well into DSP projects: https://www.diyaudio.com/community/threads/freedsp-octavia.393804/page-18#post-7625685

The configuration and firmware update utility looks like this:

Device name and PID/VID settings


Audio interface settings:


Input of up to 2 PCM channels, up to 192kHz (384kHz with external clocking at 1024fs)
Output of 2 PCM channels, up to 192kHz
(384kHz with external clocking)
Output of 8 channels in TDM8 mode (up to 96kHz, clocked by PLL)
Output of 8 channels in 2xI2S mode
Output of 2 S/PDIF channels, up to 192kHz clocked by PLL



And of course, in the simplest version, this module can work similarly to any USB interface, in slave or master mode.
DSD has not been tested yet.


Photo of the module, second version.

The additional 4-pin connector can be configured as i2c/uart/gpio, and is also used for forced entry into the bootloader (in case of unsuccessful software update).



Available in two versions: USB-C and USB-B. The transport itself is quite compact: it fits into an area of about 2x2 cm - which is important for integration into other devices.
So I'm working on a smaller PCB with same functionality.

Later I'm going to release a software library to basically enable anyone to create their own app for PC to control custom devices: toggle GPIO of USB module/send I2C transactions.


The module is available with USB-B or USB-C, the price is 49 Euro.
For purchase PM me. Also available on Tindie:
Multichannel USB UAC2+HID+CDC interface York

I'm open for requests for additional features but whether it is going to be added to the firmware depends on hardware limitations and time required to implement it.

Latest version of config tool:
https://york.eclipsevl.org/york_config_tool.zip

P.S. Huge thanks to:
1. Alexey (Dortonyan) for publishing the project. His work laid the foundation, and without it, this project would never happen.
2. Beta testers of the first version: @CyberPit, @Ludilu

UPD Oct 28th 2024:
Documentation draft attached

UPD Feb 17th 2025:
Latest docs, config tool, link to buy:
http://york.eclipsevl.org/

looking over photos of DIY projects on the net, and hearing the many stories about hum, makes me want to offer some observations that might help amateur builders.


Understanding the problem of tube heaters and hum is the first step toward ensuring your wiring job will be good enough to give happy results (no hum).

(1) The heater supply is usually A.C. (alternating current), a 50 or 60 cycle voltage taken from a winding off of the power-supply transformer. As such, it is usually more or less a sine-curve (but often with additional components, harmonics), but can actually appear as gross as a sawtooth depending upon the quality of your line voltage.

(2) For hi-fi and musical applications, the heater lines unfortunately provide a way in for noise from the mains (random hash, transients), and also radio frequency noise (RF), because the wires can also act as antennae, picking up noise from nearby motors and other equipment.

(3) So even if you don't convert your Alternating Current (A.C.) power to Direct Current (D.C.), you will still want to have some filtering and protection from line and radio noise.

(4) Also, if you don't convert to D.C., the 60 cycle A.C. hum will leak into other nearby circuits through the electromagnetic field coming off the heater wires, unless you take some precautions.

(5) As well, noise from other parts of the amp (the High Voltage HV supply, the screen supply and bias supplies) can also pick up and inject noise back into the heater lines.

(6) Many people don't bother to convert A.C. to D.C. for the heaters, and so other methods must be applied to minimize hum and noise. This is sometimes a cheaper solution.

In any case, hum and noise remains a problem with amplifier circuits, so basic strategies should be used.

Regardless of whether or not you convert A.C. to D.C. (removing most of the hum), the Mains coming into the amp should be filtered and/or isolated from line noise. This can be done with a basic capacitor network on the lines.
It can be built into the line plug:


-----------------------------------------------------
Next, comes the layout of the heater wiring itself.

(1) The A.C. supply wires are twisted together, to collapse and minimize the field around each. At the same time as current flows in one direction on one line, it is returning in the opposite direction on the other line, and the two fields interact and cancel each other out.



(2) But there is ANOTHER reason why the wires are twisted together, which is often forgotten or neglected: It also stiffens the delivery system and minimizes movement of the wires. What movement? Any motion in a wire carrying current, or in a magnetic field generates a signal, or creates a coupling field. The motion can be very small, almost invisible, as in a guitar or violin string. It will still be very significant here.



The practice of twisting wires is also done to greatly stiffen them, minimizing motion and coupling fields.

(3) This is also the reason why SOLID wire (such as 18 to 14 gauge) should be used for heater leads. In fact, any and all electrical activity has an impact on all metal in the area, and in case you haven't guessed it, will also cause physical forces of motion on the wires. Here we DON'T want flexibility, but rather stiffness.

If you doubt this, or think it is insignificant,
try loosening the bracing bolts on your power transformer,
and listening to the horrible vibrating rattles as the E-I sections bounce around.

(4) Getting back to the theory behind twisting the wires, We want to recognise also that the number of twists is also strongly related to the DISTANCE to the next object that might pick up the signal, by the Inverse Square Law:

Quote:
"The circuit is essentially a coreless electromagnet with only a single turn of wire. By twisting the wires, we produce many small electromagnets, instead of one large one. Furthermore, these many small magnets are pointing in alternating directions. If we were very close to one of these magnets, we could still detect it, but once we are a small distance away, the adjacent opposing magnets will cancel it out (figure 3)."




Thus we want as many twists as possible (per inch), to minimize the proximity effect to other nearby objects.

On the other hand, if you twist the wires too tight, you can also short them or break them or weaken them to the point where they generate resistance and heat unevenly, so there is a limit to how much you can coil / twist the wires before you risk damaging them.

Now we are ready to understand why many seemingly good efforts at heater-wire dressing fail.

The hum is directly related to distance:

(1) The most sensitive components are the ones closest to the heater wire. That would be the area right around the socket! This is typically where the twisting-dressing technique is done the most poorly and sloppily!

(2) Wires at a right-angle to the heater-wire are the least sensitive to hum. Often wires and components are laid out badly in regard to this obvious issue: orientation.

(3) Other components may or may not be more or less sensitive to heater hum depending on orientation. THERE ARE NO general rules for this. For instance, its a bit tricky to orient a coil (or a cap!) for minimum hum, because it has a 3-dimensional field! Some components will be sensitive in ANY orientation, and must be shielded.

Hello, not sure if this is the correct forum category for this, but I am sort of looking for some parts, the parts in question being cabinet kits 🙂

A little bit more info:

I have been inspired by the Boominator design and what to do my own speaker, the problem is that I live in an apartment and I don't have the tools nor time to build my own enclosure, hence I am looking for EU based suppliers that provide cabinet kits, full kits or kits that can be assembled with minimal tools (I can use a screwdriver/glue/electric drill 🙂).

I was thinking first of making 2 woofer 2' speaker design, or a 2x4' one with a piezo tweeter (or one without a tweeter at first). My plan is to eventually make a 2x6.5' design with a piezo tweeter with high efficiency, like the Boominator, but I am currently far off from that.

So if anybody knows of a place to get cheap cabinet kit or even a place that can build a cabinet for you from schematics is highly appreciated. I can source the actual speakers locally, but I just need an enclosure to fit them in. Doesn't need to be HiFi, just need to be cheap and hopefully have decent sound.

I forgot to mention that 3D printed enclosure schematics are also an option since I have access to a 3D printing service, but I am not sure how they sound compared to MDF.

Is TRIPATH Class "T" Performance Outdated - Or Not?

Way back in the dark ages, I bought one of those cheap-azz Sonic Impact, battery-powered Tripath 2024 amps at the dare of a friend. He told me get ready to be humbled. WELL! I was pretty blown away from the unexpected, good sound that it produced. And I'm a guy that listens to some rather fine, single-ended tube amplifiers.

I purchased three very high-quality, Tripath kits from the now-defunct company "41 Hz" in Sweden: a 20 watt per channel, a 100 w/pc and a 4-channel amp for HT use. I built the 20 watt (TA2020 chip) amp about 12 years ago, and am still reasonably impressed with it's natural, very single-ended "tube-like" quality. The Tripath patents specifically addressed sound quality, in particular the clipping characteristics - to make their chips sound like typical "Class A" circuitry. Have you read their patents? Pretty brilliant, actually...

Fast forward to now. Of course, Tripath is sadly out of business and very few of their chips or amp boards are left in the marketplace. But I've still got two more 41Hz, Tripath amp kits left to build, and a bunch of spare Tripath chips in case I lose one to a failure.

Curious, I came on here to see what the latest and greatest in Class D technology is. Of course, nobody discusses Tripath anymore because the product is basically unavailable. I do see the primary hot tickets are Hypex modules (relatively expensive, I think) and the TPA3116D2 and its many variants. My personal experience with them is zero. Never heard one.

My question regards a few posts that have trashed the Tripath sonic performance as being vastly inferior to the latest and greatest Class D. Knowing human nature, I always wonder if this is just confirmation bias at work, and whether or not the Tripath bashers have actually owned a well-executed example of the Tripath technology? Other people simply parrot what others have said. So...is the Tripath now a truly outdated technology, with relatively inferior performance?

Before I delve into building yet even more possibly "outdated" Tripath amplifiers - is there anybody out there who owns a Tripath, plus one or both of the other technologies (Hypex or TPA3116) - and is willing to offer up an honest, unbiased description of the relative differences in sound quality?

My own suspicions lead me to believe that any possible improvements in the later Class D technologies will be subtle at best. When I have compared the little Tripath 2020 amp to numerous very high quality, "audiophile approved" amplifiers...it always held it's head up. It might sound different, yes...but vastly inferior? No way.

Can I please get some opinions based on actual listening experience?

Many thanks!

The WBT connectors here are recommended in the build of the Aegis tube head amp.

https://partsconnexion.com/products/wbt-0210-cums-rca-female-jack

Anyone have experience with these connectors ? Are they worth it ? It seems many very expensive amps just use cheap Rean connectors so are those basically sonically as good ?

I recently picked up a Thomann FIR DSP408 speaker management system as an upgrade from my Dayton Audio DSP408. It’s an absolute beast of a unit: 96kz sampling, XLR ins and outs and no noise at all whatsoever in the signal. However, because it’s designed for PA reinforcement in questionable conditions, presumably loaded into racks with amps and little ventilation, it has a fan that runs all of the time. That’s a bonus for pro audio, but for home use, it’s a deal breaker that defeats the low noise floor of the signal.

So, for home use with constant 70° ambient temperatures and adequate ventilation, is there any reason to have the fan running at all? Are there aftermarket fan controls that I could use to slow the fan to a whisper? The T. Racks otherwise works very well and is about a third the price of comparable units, I just can’t tolerate the fan noise.

I have 2 KABD 4100 amps running cascaded in a 3 way config. Basically a mtmsw since my floor speakers are MTM and I'm trying to power the sub as well. I'd rather run the sub from a standalone monoblock amp that I already have. Is there a way to get low output feed coming from the KABD that I can run to my amp for my sub? I guess it would technically be a sub-out. If so, could you breakdown the wiring of it for me. Or better yet, is there a way to run 3 of these amps cascaded? I bought these amps mainly to run digital crossovers. I'm just not a fan of designing then redesigning passive crossovers. The last time I had 2 redesigns which was not cheap and I still wasn't happy with them

now have NEW
SJEP120R125 30pcs
SJEP120R063 34PCS
SEJP120R063C2 5PCS
SJDP120R085 15pcs

Hello, diyAudio
I'm an embedded electronics engineer who has been devoted to researching and developing products and projects related to Bluetooth chips/modules, voice chips/modules. Looking forward to exchanging ideas and making progress together with you all.


Junluan Tsui

I want an order address for showed cinch female connectors in special outline, i. e. with additional solder lead for GND connection - go to the attachement (top view of a class-A unity gain preamp based on Andrea Ciuffoli's Power Follower).

The used cinch connectors are from WBT (early 80's) and from this company no longer available since a long time.

Thank you for advices.

Update: WBT tells me by phone, that the follow jacks are the successors:
https://wbt.de/produkte/a/detailansicht/Artikel/nextgentm-cinchbuchse-signature.html
go also to the attachments and to
https://web.archive.org/web/2017031...ailansicht/Artikel/topline-cinchbuchse-1.html
or
https://wbt.de/produkte/a/detailansicht/Artikel/topline-cinchbuchse-1.html
currently overview from WBT
https://wbt.de/english/products/a/kategorien/p/rca-sockets.html

P.S.: this currently offers of RCA/Cinch jacks close to WBT I have just found (July, 18 2023) :

SINNOXX® CB-201 RHODIUM (dead, ask for successor)
https://www.dienadel.de/sinnoxx-cb-201-rhodium-cincheinbaubuchse/a-353632238/
Clear Components PREMIUM RCA CHASIS - RHODINIERT
https://www.clear-components.de/cinch-einbau-auswahl/cinch-einbau-rhodium-groß/
Eichmann, FC-TC07 (discontinued)
https://www.vhaudio.com/eti-fr-tc07-rca-socket.html
https://www.audiophonics.fr/en/rca-...-mount-rca-tellurium-copper-pair-p-11934.html
https://www.hificollective.co.uk/phono_sockets/eichmann-phonopod-female-sockets.html
KLEI (Keith Louis Enterprises & Innovations, successor Eichmann)
1/KLEI™Classic Harmony RCA Socket
CMC-805-2.5F/816-U/826AG (please note: there are many counterfeits)
http://www.hifizubehoer24.de/Cinch-Einbaubuchsen
http://www.audio-cmc.com/rca-jacks/rca-jacks-p_17.html
http://www.audio-cmc.com/rca-jacks/rca-jacks-p_29.html
http://www.audio-cmc.com/rca-jacks/rca-jacks-p_30.html
CONNEX-75120
ConneX Connector RCA Female Jacks Tiffany Style
https://partsconnexion.com/product_images/downloads/CONNEX-75120.pdf
FURUTECH FP-908
https://www.furutech.com/2013/01/27/1837/
https://www.justhifi.de/furutech-fp-908-rca-buchsen-4325
https://www.audiophonics.fr/en/rca-...ets-gold-plated-pure-copper-pair-p-10418.html
CARDAS GRFA
https://www.cardas.com/rca-females
Cardas GRFA L Cincheinbaubuchse
Don-Audio no Type/Model Naming
https://www.don-audio.com/RCA-Cinch-High-End-PCB-Panel-Jack-Gold-red

I built an amplifier using several TDA7293 chips connected in parallel to make good use of my extra stock. The result honestly surprised even me!

I added a buffer stage at the input using opamps like the OPA1641, OPA1655, or OPA627, because I'm using an ALPS RK27 potentiometer for volume control directly at the output of a NOS DAC.

If you prefer, you can easily disable the buffer. Simply remove the opamp and short pins 2 and 3 of the socket.
In this case, R2 should be 47K, and you should remove both C23 and R1.
If you would like to keep an RC-filtered input instead, use R1 = 100Ω and C23 = 100pF.

Now, I’m excited to share some measurements with you!


EPIC W



1W Measurement (2x42VDC)



Output Noise (input shorted)



Schematic



Positive Regulator



Negative Regulator

So I have a Sonos Arc that is not fully working. Here is a short backstory. This unit was not producing sound even everything else seem to be working, I've decided to try to repair it myself. After disassembly, on the PSU/Amp board I found few blown capacitors and some dead DAC chips, I have replaced everything that looked suspicious and the unit started to produce sound, unfortunately it resets the volume to 15% all the time, as I read this indicates a fault somewhere in Amp circuit. As I don't have access to any documentation or spare parts, I don't think it's possible to repair for me. I'm not interested in paying someone to repair it either, I'd much rather turn it in some sort of DIY solution.

What I'm looking for is some kind of electronics project that would be able to drive speakers that left from arc. Ideally to be able to preserve surround and eARC connectivity, but that is optional.
I've tried looking for some ready solutions on the internet, but frankly, felt overwhelmed as I don't have knowledge on audio equipment, but willing to learn it.
Can anyone recommend anything for this use case?

Hello fellow audiophiles,

I have been building my own speakers and modifying them for many years. The goal is to achieve the most natural sound quality possible, so that the playback is indistinguishable from an unplugged live performance. A loudspeaker should not have its own sound; after all, it is not a musical instrument but a device meant solely for reproduction. One of the most challenging aspects of designing a good loudspeaker is undoubtedly creating an effective crossover filter. It involves not only calculating the perfect values of the components but also making the right component choices.

Over the past years, I have extensively experimented with capacitors, always trying to use the best possible ones. However, high-quality capacitors are quite expensive, and sometimes it's not feasible to use them due to their high cost. I always use film capacitors based on polypropylene in my designs, as electrolytic capacitors are a no-go for speaker crossovers, at least for me. For low frequencies, you often need capacitors with high values, especially in a three-way system like mine. The midrange driver starts around 60Hz, and I let the woofer roll off around 50Hz to avoid interference frequencies. Using really good film capacitors in this scenario can quickly become quite expensive.

In my design, the midrange driver covers a frequency range from 60Hz to 5KHz. It's a very wide range, but the advantage is that almost all critical frequencies are handled by the same speaker driver, eliminating any crossover interference within this range. For the midrange driver, I need a series capacitor of 100uF, which is quite a high value that can't easily be filled with super expensive capacitors if you don't want to spend a fortune.

Until now, I have used a combination of Jantzen Audio Superior-Z and Jantzen Audio Silver-Z, along with bypassing them with Cornell Dubilier 940C 3000V capacitors. This setup already cost me over €450 per midrange driver. Although I'd like to use even better capacitors, options like Alumen-Z would cost around €1000 per midrange driver, which is not doable for me. Therefore, I was thrilled when I came across the brand WEET on an audio forum on the internet. I checked the capacitors they offer and directly contacted Fay through www.musicaps.com. She was very friendly and professional, addressing all my inquiries excellently. Eventually, I chose 20 pieces of 10uF WEET WMH Aluminium capacitors, and we agreed on a price that was feasible for me.


I then spent two days building my two crossover filters on wooden panels, which I mounted on vibration dampers, externally on the back of the speakers.





After completing the setup, I began listening to the speakers. I know that capacitors, and every conductor in general, even a simple copper wire, as well as all the new sockets, plugs, and not to forget the 0.47mH Litz coil placed in series with the capacitors, need a minimum of 150 hours of playtime before they start sounding as they should. Often, the sound quality reaches only 80% to 90% of its potential during that time, depending on the materials used. For instance, Teflon capacitors require half a century of "breaking in," and silver conductors also need several weeks to reach their full potential. However, I started by playing track no. 2 from the IsoTek Full System Enhancer & Rejuvenation Disc, which is a half-hour long track. I knew there would be quite a noticeable difference after playing this track once only. After 30 minutes, I played a piece of music and started listening.

Right from the first notes from my speakers, I was pleasantly surprised! It already sounded significantly better than what I was accustomed to! Over the following week, I let the speakers play continuously at a low volume. During the night and when I was away from home, I used the IsoTek CD, and when I returned from work, I played music. Every day, I heard improvements, and I must admit that I experienced goosebumps several times while listening. These WEET WMH capacitors achieve an unbelievable high sound quality: the openness, depth, and width of the soundstage, the pinpoint precision, and the realism with which the music is reproduced are of such high quality that at times, I genuinely feel like the musicians are performing in my living room. I have never been a huge fan of live recordings; somehow, I found them less natural and was more drawn to studio recordings. However, that has changed completely now! Every live recording I've heard so far has astonished me; the realism is unlike anything I've ever heard before, even with very exotic speakers and expensive sound systems. I can only use superlatives to describe the experience, and that's precisely how I perceive it. Not just me, but all my audiophile friends who come to my place regularly to listen, while enjoying some drinks and snacks, were amazed as well. The most memorable compliment came from one of these friends who said before leaving: "Thank you, Alex." I asked, "Why?" And he replied with a smiling but serious face, "Now I won't be able to listen to my own setup at home for at least a week because it sounds like an old-fashioned transistor radio compared to this."

I've never received a better compliment, and at the end of this rather lengthy review, I want to pass on the same great compliment to WEET and thank them for all the beauty these capacitors will bring me in the coming years!


The WEET WMH capacitors are not just very good; they are a MUST for anyone who needs higher value in capacitance range and wants to build or modify a relatively affordable crossover filter in such a way that there is no doubt about achieving a realistic reproduction. With the WMH capacitors, you can be certain that at least capacitor quality won't be the limiting factor!



Best regards,

Alex

Bought to experiment with and no longer required.

There's a thread about these boards here:


Requires a +5v and +12 to 15v supply. I used a silentswitcher, which was perfect for the job. I swapped the included 22uf output tants for vishay bc122 solid aluminium 33uf, just because I like these as coupling caps in other builds. There's plenty of pad options on the board to try other cap types. I only had a single 2 and 3 way block to hand, hence why they are mismatched.

£50 posted in uk, international postage at cost.

I am considering assembling this 2E26 amp, what is your opinion on it:

https://www.r-type.org/articles/art-271.htm

I'm from Poland and while I don't have experience with audio equipment, I do have experience with electronics repair. I've joined mainly for interesting DIY projects to do.
The first that I'm looking to is to repurpose speakers from a dead Sonos Arc, into some kind of working setup for TV

Hi all

I use a miniDSP in an AV setup and run 5 subs. All 7.1 channels are fed in to drive the subs (the output is sub only so all channels except LFE are fed direct as well so no DSP on anything other than subs)

My question is about the relatively low levels of signal in and the best way to manage trim and the 10db difference between the LFE and mains

I have simply cut all the 7 channels on the way in by 10db or near and then all the subs are aligned to work as a group and I add the missing bass to each channel

I now realise that the level when playing loud (105db peaks on music more on film) is only 190mV when feeding in 1V to a channel ( I know CD is circa 2V on peaks but used 1V to see what's going on) so my thinking is perhaps better to boost the LFE not cut the input to the 7 channels or everything happening in the DSP is at a lower voltage and possibly SNR ?

Any thoughts

I am here to get more Info about modifications of blu-ray player. I have Panasonic UB9000 with ESS chip and Rattlebyte multiregion mod bought in UK from TPS. I like it, it allow me to use external subtitles and I can watch special features on discs from KL (USA) without any problems. I wish I could get the sound quality on the next level as I would like to play more Dolby Atmos and 5.1 Audio Blu-rays. Anyone have tried to upgrade the player with mods from Coris or another sources like oppomod or Authentic Cinema?

Good afternoon. After ordering a qcc5125 + es9038q2m + NE5532 board on aliexpress, a problem arose. In general, the board gives me good enough sound for me, but there is a nuance. After I stop the sound from Spotify, there is silence. There is no sound in games, no sound in Discord either. I saw that this is a problem with the firmware of the Bluetooth module itself. Can I reflash it? I'm not a handyman, but I don't have very deep knowledge of electronics. Is there any way to fix it? I'd be very grateful if someone could throw a link to the instructions or write how to fix it.


Module: link

Hello. Is it possible to make a BBC dip adjuster and shelving adjuster for the high range. Like Tannoy have? My ears are very sensitive in the 2000Hz range. And I now use Shiit Loki equalizer. I tilt down 2000Hz about 3dB and shelves the up from 6000Hz about 1-2dB.
Is it possible to do this in the crossover?

Hi all,

Planning to drop my newly acquired (for a great price!!! &BEAUTIFUL!!!) F10 Neo V1 (Fs 30 Hz, Qts 0.50) into a 12.5 W × 15 D × 43 H″ birch tower (net ≈ 103 L).
I want to aim for 30 Hz reach but keep the driver’s mid/treble magic.

Because of the size constrains, I wonder what's a proven build that could help me get there. I've done so much research I am now actually lost: folds, back loaded horns, MLTL, TQWT, tuned precision port - different lengths.... etc etc.

A USSR speaker being restored.
Fascinating drivers & crossover > I think the cap's are even oil-filled.
Interesting to watch.
Login to view embedded media

Some of you folks have seen this schematic which I’ve attached a few times.
I believe I’ve corrected the mistakes and hope to start building.

But aside from what errors you might uncover I have a question about grounding as pertains to the three ICs (MC33171N [spec sheet also attached]).

But first the purpose of the device:

• Produce a center channel (mono) output
• Produce an output consisting of what is unique to each of the channels of the stereo signal
  and
• Produce an output consisting of what is common to each of the channels of the stereo signal

In none of the ICs is there a direct grounding. Rather, connection to ground is made through a resistor.
Does this seem right?

I started ordering parts 10 1/2 years and 2 houses ago. Now it's mostly mounted on a chunk of 3/16ths aluminum.

Jan 12AT7
Russian 7198 equivalents
Coke bottle 5U4
Hammond 272.....EX?
Hammond 20H choke
Trancendar OPTs. 5k:8Ohm

Next step is a plywood cradle for it to sit on during the build.

I'm going to do some sort of fancy wood frame upon completion.

I'm mounting the power cord and fuse on the base. I'll move the switch there if it seems to be a noise issue.

Ignore the plugs next to the power tubes. I realized I was probably going to burn myself using the volume knob and power switch. Makes for a sub-optimal listening experience. Live and learn. This is my first tube/valve chassis.

Hopefully people posting will guilt me into continuing progress!

Stay safe.

A preamp is usually a combination of a couple of sections, a gain section and a control section to connect audio components to the amplifier. Try finding a very good controller for the preamp, there just aren’t many available. This project is a control system for a Preamp. It does away with knobs and potentiometers in favor of digitally controlled relays and not much else in the signal path to add noise to the audio signal.The parts that the audio signal pass through are chosen for best sound quality without breaking the bank. You have the option of replacing the volume resistors with Caddock if you so wish but the Dale/Vishay resistors used were chosen for very high-quality sound, that is, they do not add much in the way of distortions to the audio signal. All parts add or subtract something from the audio signal so picking a component that minimizes it is the quest.

At minimum, the control of the audio system includes the volume, up and down, input selection, and it would be nice to be able to mute the sound without having to turn the volume down then having to turn it up to the perfect level you had it before.

I started this project when a friend who has an audiophile company wanted to add a preamp to his affordable audio line; he already has a great no holds barred, cost is what it is, line of very high-end products. He is a great analogue guy but he had a digital volume, input selection, and mute circuit control board that had some issues so being a digital guy in my past jobs I looked at the problems to see what could be done.

The control board was stereo single ended unit but could do balanced audio with a second add on board making the setup a little costly but not outrageous, it had a couple 7-segment LED readouts for volume and input, and it came with an infrared remote. It used an R2R resistor ladder (if you don’t know what that is then search it on the net, the design is interesting) for the volume level control with 6 bits from an 8051 microprocessor controlling relays for 64 volume steps. The resistors were metal film but not audiophile quality so the sound quality at lower volumes suffered just a bit, and when muted you could still hear a tiny bit of signal coming through the speakers. I wanted to look at the code in the processor and see if it could be modified for how it controlled the input, volume and mute relays. First problem was having to buy a fixture to read and program the 8051 on-chip memory. The chip is so old that finding drivers and a programming environment to work in for it was next to impossible. I could use a new, smaller, more powerful microprocessor and design a new board around it but I didn’t like the idea of a megahertz clock signal for the processor anywhere near an audio circuit. Later I had an email conversation with Jan Didden about some of the new processors and that they could go to sleep, shutting down the oscillator, then wake up when a button was pushed. I started thinking about if I could design a board using discrete logic chips to do all the same things, with better sound quality, and at an equal or lower cost than the current board. Even a slightly higher cost would be acceptable if it had superior sound.

All the input switching, volume control and muting could be done with switches and pots but sonically good volume pots for balanced circuits with really good channel tracking, and motorized for remote control, are expensive and can become noisier as they age, and it is just not an elegant solution. I looked around at what had already been done on the market and I own a Nelson Pass Aleph P preamp which had very neutral sound so I decided to go with a similar design for the control board, but where Pass Labs used a microprocessor I would use discrete digital chips. The idea behind using discrete digital chips is: no programming required, easy to trouble shoot, and no digital electrical switching noise to affect the sound when the control buttons are not being pushed. Any onboard oscillators could be isolated from the audio side of the board and decoupled to prevent noise in the audio.

In all designs there are decisions to be made and this one included several but one was the question of where along the signal path to put the attenuator, before the preamp gain circuit or after. I have seen it both ways and seen arguments for both. Putting the attenuator after the preamp moves any items that might add noise until after the amplification so you don’t amplify the noise, the down side is the output resistance to the amplifier will vary with the volume setting. After looking at the thermal noise specs of resistors used in audiophile designs I decided it was a very small concern. Another downside was the power dissipation in the resistors at the output side, audio signal already amplified now needing attenuation, but the voltages and currents are small so that doesn’t pose a real problem. Putting the volume control before the preamp meant having the preamp gain buffer closer to the output and able to drive interconnect cables better, so that is how this board is designed. This control board is for fully balanced audio, input to output, for four of the six inputs. It can be used single ended for all inputs by connecting the negative input to ground input pin. The two inputs which are single ended can be modified on the board to full balanced with four cuts and direct wiring as they are only single ended by a ground line added to one side of the relay.

I began with the volume control section. The first design decision is how many bit, four bits is easy to display but only gives 16 volume level steps, too few, eight bits give 256 volume level steps, more bits is not as easy to implement for displaying the volume level but gives sub-DB per step, so eight bits were chosen.You need one button for Up and one for Down, which needs to be de-bounced. You wouldn’t want to have to push the button 256 times to go from zero to full volume so a helper circuit needs to be added. And finally, you need to step up to 256 and stop so you don’t roll over back to zero, and on the down side you need to stop at zero and not roll over to 256 which could be jarring and potentially destructive to your speakers.

The Input selection circuit was next. How many inputs do you need? I chose to have six inputs controlled by one button, again de-bounced, and scroll one to six and rollover to one again.

It would also be nice to have a mute button so you can silence the system instantly for a phone call, or whatever, and be able to un-mute to the same volume. I like to disconnect the volume control section from the gain section and ground the input to the gain section for absolute quiet while muted.

And finally, a remote control would be extremely nice. Never having worked with infrared or RF transmitter/receivers I studied advantages and disadvantages of each and since it is an indoors system where most audio systems are used, and a short distance, infrared is much simpler and cheaper. With four different signals, volume up and down, mute, and input selection, an encoder and decoder chip set would be necessary. So much for the design decisions, on to the actual design.

Main Board:
The main board contains the power supply for the control circuitry which consisting of a double primary and double secondary winding transformer, T1. The double primary windings can be paralleled for 115v or used in series for 230v, set with the switch S2 (you can use jumpers if you like to save a dollar). The secondaries are in parallel for the higher current output. The AC voltage and current is rectified by a bridge rectifier, D1, and fed through a fuse to the fixed voltage three pin 5.0 volt regulator, U1. There is a current storage capacitor before the regulator, C1, and one after, C2.

There is a reset controller, U9, that reads the voltage at startup and sends a reset pulse out when the voltage has reached the operating point so the board comes up in a known state: the volume at zero, no input selected and the mute not active. The output pulse of the reset controller is sent through two inverter gates, U12, in series so a positive and a negative going pulse can be directed to the chips which need to be reset with the appropriate polarity pulse.

There is an oscillator made with a 555 timer chip, U5, running at 15 Hz, its output is ANDed by U2 with the volume up and down signals to step the volume up or down while holding a button down on the remote or display board. There is a third input to the AND gates, U2, for the volume up/down inputs which is from the enable/inhibit (E/I) circuit created with U10, U11, U13, and U4, and reads the eight output lines from the 2 counters, U6 and U7. When the output from the two counters reaches maximum volume, 255, the output of the E/I chips is ANDed by U13 and inverted to proper polarity by U4, goes low to the Up AND gate so it will not accept any more input and thus not roll over from maximum to zero. Likewise, when the two counters reach zero the output of the E/I chips, U10 ANDed by U13 and inverted to proper polarity by U4 goes low to the Down AND gate, U2, so it will not accept any more input and not roll over from zero to maximum.

The output from the volume counters is fed to the volume display control circuit, U14 and U18, and the output lines from the counters also drive a transistor per line to turn on a relay to control the volume resistors. The resistors that pass the audio signal were chosen after reading an article in Linear Audio showing the distortion levels in different types of resistors. The Dale/Vishay RN60D resistors were listened to and then used in the design. There are four of each value and are matched to better than 1%.

The volume display control circuit is made up of U12, U14, U15, U16, and U18. Two gates of U12 form an astable oscillator which clocks the counter U14 and the display counters on the display board at 5 kHz, C5 provides the oscillator with a tank and R3 sets the speed of oscillation. U15 and U16 are two 4-bit comparators, ganged to form an 8-bit comparator. This compares the output of the binary counter U14 with the binary output taken from the volume counters U6 and U7. When the comparator inputs are equal, pin 6 of U15 goes high, triggering the monostable U18, which outputs a brief pulse to the latch control line that goes to the display counters on the display board. When the counter U14 reaches a value of 256, the link between pins 11 and 12 resets the chip and sends the reset pulse to the display counters on the display board also.

The input selection signal from the display board is inverted by U4 to drive the counter input of U8s clock; one press of the input selection button clocks the counter up by one. The three output lines are in BCD, and go to a BCD decoder U17, a high current device, which is capable of driving the input selection relays directly. The outputs from the counter are ANDed together so when all three are high, a seven, it outputs a pulse which is inverted by a U4 gate to the correct polarity to clock the Load input of the input selection counter whose inputs are set to load a one. The outputs from the counter also go to the display to be decoded to show the input selected. So, the input counter starts at zero at power up, counts up to 6 and resets to 1 in a loop of 1 to 6 back to 1.

The mute control signal from the display board sets and resets a flip flop, U3, whose output goes to the mute control relay to mute the audio and the output of the flip flop also goes back to the display board to turn on and off the mute LED.

Display Board:
The display board has an infrared photo receiver, PH1, operating at 950nm and 38 kHz modulated signals, capacitor C1 makes sure the receiver has very clean power. It demodulates the signal back to the code sent by the remote, but it is inverted so it is sent to an inverter, U1, then to the decoder chip, U2, which decodes the pulse train input which then raises one of its four output lines for the code received. The outputs are for volume up and down, input selection and mute control. The decoder output is ORed with the user push buttons by U3.The input from the user buttons are “debounced” by a network between the push button and the OR gate. The input to the inverter, more gates of U1, are held high by a pull up resistor, and charges the capacitor, which keeps the inverter output low. When a button is pushed the capacitor is discharged through the resistor in parallel with the diode, when voltage reaches a low enough level the inverter switches to a high output. When the button is released the capacitor is recharged quickly through the diode in parallel with the resistor, at a high enough voltage level the inverter switches to a low output. The inverter is a Schmidt trigger type so it cleans up the input wave form from the user. These control signals go across the ribbon cable to the main control board.

The display board also receives control signals from the main control board over the ribbon cable.

The mute control signal turns on and off the transistor, Q1, which drives the red LED D5, R9 limits the current to the base of the transistor and R10 limits the current to the LED, increasing the value of R10 will reduce the brightness of the LED.

The three control signals for the Input control are BCD, Binary Coded Decimal, and are fed to U4 which decodes the BCD in to signals to drive a 7 segment LED display directly through current limiting resistors (U4 requires a common anode 7 segment LED).

The volume display is driven by three control signals: a 9 kHz clock signal, a latch signal, and a reset signal. The counter/display driver chips, U5 – U7, each drive a 7 segment LED display directly through current limiting resistors (U5 –U7 requires a common cathode 7 segment LED). The counters are daisy chained so that the first counter U7, or ones place digit driver, is fed the 9 kHz signal to its clock input, when it reached its maximum count it outputs a clock pulse from its carry output to U6 clock input, when U6 reaches maximum count it outputs a clock pulse from its carry output to U5 clock input. The count of the counter is not displayed until the latch control signal on each counter is pulsed by the common latch signal, the counter then outputs the decoded count to drive the LED segments. When the maximum count is reached the reset line is pulsed by the main board resetting the count to zero. The latch signal refreshes the display approximately 9 times per second. Whatever count is latched remains on the display.

Prototyping designs:
For a visual display of the volume level I started with eight LEDs, five green, two yellow and 1 red LED in a line to display the volume as binary data, it looked neat to an engineer but not really good for a consumer product so seven segment LED displays were chosen, and to display 256 requires three. To drive the display for eight bits would require a dedicated circuit as only 4 bit display drivers existed. I looked around for an idea on the web and found a circuit that looked interesting and when tried it worked but required some debugging. (This is a more detailed explanation of the info above). The circuit, most of it on the main board, uses two 4 bit comparators, U15 and U16, tied to the outputs of the counters, U6 and U7, and compares with the output from another free running counter, U14, driven by a nine kilohertz oscillator, U12, which would update the display 9 times per second and which also clocks the counter/display driverchips, U5 – U7, on the display board. When the counter output, U14, matches the volume control output, U6 and U7, it triggers a mono-stable one-shot, U18, which pulses and latches the count on the display drivers, U5 – U7, on the display board. It worked but the display would flicker at certain volume counts due to a race condition between the volume output lines and the free running counter, one moment it would display one number below the volume number and the next moment the actual number. A different resistor value on the mono-stable one-shot pullup resistor, R4, was needed to makethe circuit more stable, then on the second revision a capacitor, C7, to ground on the one-shot input circuit was needed to stretch the latch pulse long enough to stop the flickering.

The Input selection circuit was next. It also would use a binary up/down counter, U8, but only one button input to count up 1 through 6, when it hits 7 an AND gate enables and resets the counter, which is set to load a one into the register so it starts at one again. The output from the counter goes to a Binary to Decimal Decoder, BCD, U7 on the main board, which drives the input relays directly, (hicurrent output). The lines from the counter also go to the display driver and another seven segment LED display.

The mute circuit uses a flip-flop, U3, that toggle between on and off to drive a relay that disconnects the volume section from the preamp and grounds the input to the preamp to remove any possible noise on the output. It also drives an LED as a visual display.

All was coming together but testing showed an issue with the circuit coming up in random states on power up so a reset chip, U9, that sends out a reset pulse at power on is used to reset everything to a known state.

The last thing needed was to design a remote control. Linx Technologies makes a couple of sets of encoders and decoders chips as well as RF remotes in key FOB cases and RF receivers but after pricing RF antennas and cables I decided on infrared as the way to go, read less expensive. For a receiver I tried a phototransistor but ended up with a TSOP 38 kHz IR receiver and since it was most sensitive at 940 nm wavelength an IR LED was chosen at that wavelength for the transmitter but the output of the encoder had to be modulated with a 7555 timer to the 38-kHz carrier frequency so the IR receiver could pick it up. Since I had never worked with IR LEDs I did a lot of testing but I am still not 100% positive that I am not overdriving the transistor driving the IR LED. Different TSOP IR receivers were tried as they have automatic gain control, AGC, built into make them less sensitive to a noisy environment such as strong fluorescent lighting, but too much gain control and you can lose data so an AGC2 chip worked best in testing. The receivers are also made for short burst data and long burst. The output of the encoder could be considered long burst so that left two part number options in the TSOP receiver and either worked well.

The power supply for the controls needed to be 5 volts for the logic chips and relays. After estimating the worst-case current for all the chips and relays it might need 3 amps so I found a 6.3 volt transformer with 5 amps capability, passed through a bridge rectifier, a capacitor, then a 5 volt fixed regulator for three amps then another storage capacitor. When all was done I found the average current drawn was under one amp, for 5 watts of power on the board. The first revision of five circuit boards used the larger, heavier, more expensive transformer, the next revision used a more appropriately sized transformer and bridge rectifier.

Remote Control:
The remote uses a four-input encoder chip to encode the four user buttons: volume up and down, Input selection and mute. The encoder chip stays in low power mode until one of the user buttons are pushed taking that line high, the encoder outputs a code for as long as the button is held. The output of the encoder is tied to the reset pin of a CMOS version of the 555 timer. A high bit from the encoder turns on the timer which outputs a square wave of approximately 50 percent duty cycle at modulated 38 kHz, set by C2, R5 and R6. The output of the timer drives the base of a transistor which turns on and off the infrared LED which operates at 950nm wavelength. Resistors R1-R4 keep the inputs to the decoder low until a button is pressed. Resistors R7 and R8 are used to limit current and R9 develops a voltage across it to bias on the transistor a little quicker. Capacitor C1 is current storage buffer for the timer though it may not be needed on the CMOS version of the 555.

Capturing the Schematic and laying out the PCB:
The next step in the design effort, after testing and debugging bread boarded circuits, was to draw the schematic in a software package to layout a printed circuit board. I found a free trial version of a nice package from DipTrace but the schematic grew beyond the free version of the software so I purchased a version that could handle 400 nodes. There was a learning curve on using the software but patience had a full schematic for a main board, a display board and a remote controller schematic done with time. After determining the space available in the preamp chassis, 7” x 12”, and the rear panel layout of the connectors and the front panel, 6” x 1.75”, for the display and control buttons I started the main board layout. The software places all the parts on the board but you have to drag them around to their optimal positions. You then run the automated router which turns the schematic lines to traces. Keeping the digital traces away from the analog and changing audio signal traces to extra wide kept me busy drag traces around and rerouting traces for quite a while. It seems that laying out a printed circuit board is as much art as it is engineering skill, there are many things to check on and make sure nothing is missed. After everything is double checked with a full sized printout of the circuit board, I then had a board house turn out five high quality sets of circuit boards.

Building up one set of boards went quickly and amazingly it came up and worked but with a few issues. I found the first problem of the input selection relays on the board were mirrored in the layout so they had to be placed on the bottom of the board so they worked correctly (corrected in version 2). The display flicker was solved by the afore mentioned capacitor on the display latch chip. Another problem took a little longer to find, when the input selection button was pressed the mute circuit would activate. The problem was finally found in the ribbon cable from the display board to the main board where the routing software had the two lines side by side in the ribbon cable. I knew that digital signals are supposed to be separated with alternate lines being ground lines but forgot to check for that (Also fixed on version 2). Then I removed the fuse and measured the current draw of the board this is when I found it needed less than one amp of current so a much smaller, less expensive, transformer could be used (another change in version 2 PCBs). A second version of the circuit board had all the bugs worked out but I forgot the display flicker Capacitor but that was easy to solder to the backside of the circuit board.

One thing to be careful of when assembling the display board is the seven segment displays are different for the volume and input display one is common anode and the other is common cathode, don’t get them mixed up. As with any build, carefully observe the polarity of diodes, LEDs, capacitors, transistors, and logic chips when inserting them in to the circuit board.

So how does it sound? I thought it to be very transparent, neutral, but not trusting my own ears since I, as the designer, might be biased I had my audiophile business owner listen to it and he thought it to be very transparent also, which is really the best you can wish for in the control system.

The Bill of Material, BOM, spreadsheet gives component reference designations, manufacturer part numbers, Mouse and Digikey part numbers, and my preferred vendor for each part since pricing can be different or a part not available for one vendor. The pricing used for the total price is for buying some of the parts in volume. If you buy PCBs in Lots of 100 you can get the price in the BOM but you also must pay a $150 per board design NRE charge, about $1.50 per board on the original order of version 2 boards. I don’t even want to remember the price on the original version 1 boards at five pieces each plus the NRE charges. I can supply gerbers and the drill file if anyone wants to turn their own boards but to make things easier and less expensive over all, my audio business friend said he could supply sets of PCBs from his stock for $120, it covers material costs and shipping. I also have five of the version 1 boards with the bigger power supply, built and tested, for $400 per set, includes the remote control.

You can use this controller in your personal preamp, and I don’t even mind if you want to use it in a commercial design, I just ask that if you make any improvements you feed that back to the group so we all can benefit. Hint: the first thing I would change is the transistor in the remote, instead using a FET for lower standby losses. (Note: This was fixed in Remote version R2c) So the only other thing that could change is I ever turn the Main board is updating the one-shot U18 kluge design to a real one-shot chip, although it works fine as is.

Updates: ************************
Since the first posting it was discovered that the Linx Tech LS series Encoder and Decoder chips have been discontinued. In the later posts there is new schematics, gerbers and BOM for the later Revisions of the Remote and display board with the new Linx Tech Encoder/Decoder chip. All Board Gerbers and Schematics are in post 150, The last version for the V5 main board are in post 179, schematics are in post 165 are not recommended as the one shot timing is too finicky and the volume display can flicker.

Since the first design of the volume board used paralleling resistors in a digitally weighted design, it was found that the input resistance would drop to 162 ohms, loading most sources too much, so the resistors were changed so the load only dropped to 300 ohms. The best values were 20K, 10K, 5K, 2.5k, 1.25k, 625R, 312R 156R.

***********************************
So the design started to morph, instead of a set of push buttons for volume up and down someone wanted a rotary encoder so that started at new project. Then a ladder resistor scheme which has either a constant input or output impedance was looked at and I chose a 10k input impedance. So starting at post 225 the design started to take shape. It has a power supply board, a Digital board, a Display board, an Analog board, and a remote controller board. The first design was done with only logic chips, to clean this design up a bit I used an EEPROM to hold data for the display on this design. Sonically the first listening tests were excellent so I proceeded to work the bugs out and improve the design with forum input.

The latest of the second design are:
Schematics - Post 280
Faceplate CAD - Post 282
EEPROM Data File - Post 282
Digital Board 3.0 - Post 278
Display board 3.1 - Post 352
Power Supply board 1.1 - Post 326
Analog board 1.3 - Post 326
Remote Board 2.0c - Post 150
BOM 3.1 - Post 330
Build Instructions - Post 287

For a dipole experiment, I am looking for a pair of inductors between 15 and 20mH. Someone has something nice, including the willingness to ship to Switzerland?

Many thanks!
Erik

Hello guys,
I’m Roseline from TN, and I just joined the forum.

I’m an electrical engineer with 13 years of experience designing biomedical devices, primarily patient monitors. While I manage an engineering department, I still handle most of the analog designs and some processing algorithms. It’s been 10 years since I last designed power amplifiers for fun, and I’m considering creating a hybrid op amp/lateral MOSFET amp just to challenge myself.

I’m also finishing up my first kit project, a Hagerman Clarinet line preamp, to complete my two-channel system.

Hello
I'm trying to open this CR for a Phillips VCR.
There are only two screws (red), and after removing them, I tried to separate the parts by applying pressure with a plastic card. It's not possible. I'm asking the older technicians who have worked with these devices: Is it possible that the plastic rivet (green) needs to be removed?
Thanks in advance!

I'm the owner of a Marantz TTS15-1/Clearaudio Emotion turntable that I bought in the US and I moved to Italy. Basically after trying to save money by buying a step-down transformer and a pulley which ended being the same as the one I had from the US (by the way only the MarantzTTS15-1 for the Japan market have a 60 and 50hz pulley, EU and North America both share the same pulley) I realized that I needed to change the motor (synchronous AC motor) and that Clearaudio wants to rip me of of 400-500 euros...

Is it as simple as opening my current motor and finding an equivalent Premotec 50hz motor, ordering it and installing it? Do I need to do some soldering. Have no experience but willing to learn as it could be a fun projet. Not sure where to start and any help would be greatly appreciated! Thanks

Offered here, for your consideration, an original prototype FirstWatt F6. Built and sold at auction in support of Burning Amp by Papa in 2023.

This amp is of the original design configuration that used SemiSouth JFETs, not the MOSFETs that the commercial F6 used. Note the dual LEDs on the front. I have no proof but I believe Papa assembled this himself. The amp was opened and pictures taken at BA that year, I have not opened it nor messed with it or put it on any test gear, but I have listened to it lots in my main system. There is nothing at all wrong with this amp. To my ears, and in my system, it is the most detailed amp I have heard, but for some mysterious reason I favor the air and liveliness of my F5m and Aleph Jzm more.

I paid $2600. I am asking $2600, plus shipping to your locale (it will come in the factory original shipping box). If you happen to reside in Northern California, I'm open to arranging a pickup but please be patient with me as I work for a living and have some travel coming up. This isn't about the money, it's not a forced sale, I'm not in a hurry, no low ballers, I know what I've got, etc., etc. I've just listened to this amp enough to learn from it and I'm willing to pass (haha! Pass) it on to another aficionado.

Thanks for looking.

Am preparing to rebuild two Adcom G565 s. Was pricing 10 MJ15003. and 10 MJ15004. for $164 at Digi Key. Is this the best price for these and what about matched pairs? Do I need them? Was planning to replace all 5 if I find one or two are bad.

Hey guys - I’m from North Alabama and buy and sell all sorts of vintage audio but joined as I have a few old stereo cabinets (console units) that I’m in the process of refurbishing.

I do have a website that I’m building out with the components that I have for sale. Www.pressrewindvintageaudio.com and I also sell LED bulbs for vintage receivers!!

I’m also about to try my luck making a few cigar box Bluetooth speakers.

Derrick

Hey,

i'm Andreas from Germany. I try to make first steps in programming Bluetooth Chips from Qualcomm and hope i can find some help and informations here.

At the other hand i try to repair old amplifiers, when i get one.

Hello,

i have a bluetooth receiver with the QCC3040 onboard. I already got to unlock it and a connection over bluetooth and did a backup with Nvs.

I tried to change the name with the ConfigApp, but it doesn't work - i can't transfer with error and after that, the QCC is dead. I have to burn the backup with Nvs.

The QCCTool doesn't get a connection.

Actually I have to power up the QCC3040 by long-press the SYS_CTRL.
My first goal is, that the QCC3040 power up automatically when voltage is applied. Can i do this simple by changing a parameter with a program?

Second goal would be to change the name - maybe it is only possible by SPI?

Thank you very much for your support.

Hi everyone,

I’m an electrical engineer that works on Bluetooth audio devices. I have an interest in making an open source project and I think this would be a great place to get some ideas. Looking forward to learning more about the DIY audio world.

I bought the flagship DAC project from Ian Canada. Gabster's YouTube videos were very helpful putting it together but I need help connecting power. I'm using two Hammond transformers and I've confirmed with a DVM that I'm getting 3.3 volts from one LinearPi Pro, +/- 5 volts from a dual LinearPi Pro and I have another LinearPi Pro that I'll use to power a Raspberry Pi with +5 volts once I get the DAC working.

For the default setup of this project, where do I need to connect the different power wires? Should I use the output from the separate LinearPi Pro for +5 volts somewhere or do the +/- 5 volts wires provide that voltage?

Thank you,

-Robert

I have a ANK DAC 4.1, which uses a CS814=>AD1865 implementation.
The cheap USB input board failed, so I was planning to replace it with the XMOS based I2SoverUSB board.

But I also thought.. since I am at it, why not replacing the whole DAC board with a XMOS => AD1862 implementation.
The new design would use dedicated separated supplies for the digital and analog sections, and the outputs of the DAC chips would be directly connected to the I/V transformers that drive the original tube output stage, as per original audio note design.

Long story short.. anyone who has experience playing with the AD1865 and AD1862 would suggest one over the other?

Thanks,
Marco

Hi everyone,

I need some help with wiring my 6x Rockford Fosgate T1S1-12 custom cabinets. I plan to wire them in series (2 banks of 3), but I'm a bit stuck. Each cabinet has 2 speakon jacks and seems to have a bridge inside, but I bought them used and have no idea how they were set up previously.

Ideally, I want to run a single cable to the first sub and use jumpers to connect the other two. If anyone has any advice or can point me in the right direction, that would be most appreciated!
I’ve attached pictures of the current wiring inside the cabinets.
Thanks

Steve

Hi
I have a Denon DN-X900 mixer that has 2 or 3 channels that I cant get sound from. I think it's two. ch3 and ch4.
In these mixers all the inputs can go through all channels ,it's a case of selecting the input you want on that channel.
I was looking at the Schematic and it doesn't look obvious to me what could be the source of the problem.
I don't have a scope so it might be difficult to find the cause of the fault.
I've had the mixer for a while. I don't have it open at the minute as I want to see where the signal goes first.
Last time I had it open I had a good look but couldn't work it out. I checked ribbon cables and a few other things.
Maybe someone here has repaired one ,or had a similar problem with these.

Cheers

Schematic
Service Manual

Anyone use their leftover / extra Car Audio stuff for home HiFi? One would think - by now - the name brand car audio stuff would have specs that far exceed what is considered good for noise, distortion, frequency response et al. 12V power shouldnt be a mountain to overcome...

I picked up a Rockford Fosgate R-150 / 2 at a gamble price; the blue light came on when I powered it up. Sounds good to my ears in my garage system. I'm going to try a FRFR for guitar / vocal with it, with two FR speakers and amp / cab models upstream.

Hello
I just purchased my first tube amp, a Dynaco ST-70. I opened it up and with the help of the original assembly manual and compared what I have to it . What I found
were a number of things that have been changed.

1) The selenium rectifier has been removed and from what I have read is a good thing to do. There is a modification for this that replaces the selenium rectifier with a 1N4007 diode but this has not been done.

2) There are two 1N4004 diodes that have been added to the base of the rectifier tube. This was based on another recommended modification and the diodes are in the correct locations but 1N4004 diodes were used instead of the recommended 1N4007's.

3) The 2 capacitors soldered to the 7 lug terminal were changed from 50uf (not sure of their original volts) to 200uf 100volt capacitors. In my research I did not find this to be a recommended modification so I'm not sure if this was a good idea.

4) RCA style inputs and outputs replaced the original screw set ups. For the outputs two transformer wires from each side that were used in the screw type terminals were capped and not used. I could not find information online of how to do this change correctly so I can't verify if this was done properly.

5) The main PC board was replaced with the Vintage Electron Inc 6GH8A stuffed board which appears to be installed correctly.

Other than these changes it appears stock. My main concern is changes number 1 and 2. Did the addition of the two Diodes in modification #2 to the base of the rectifier tube make the selenium rectifier modification unnecessary? and should the 1N4004 diodes be replaced with the recommended 1N4007 diodes.

Thanks for any help you can offer

Bob

Unlike 4”-6.5” cone drivers, frequency response of dome midrange drivers (1.5”-3.5” diameters) are different, i.e., 500-700Hz for the lowest frequency responses.

Anyone who has had the dome midrange drivers in your system, how do you cope with them? I mean you may not be able to build a traditional 3-way system configuration whose crossover points are of around 60-200Hz and 1.5k-7kHz.

In 3-way system, did you assign the crossover point of 8”-12” drivers at minimum 500Hz to match with those dome midranges? Or you add a (about 5”-6.5”) midbass driver to make the system 4-way?

I plan to use the ADS 1.5”-2” home audio domes because I like them when they perform at home. But I don’t know they’re still good in car. Are they decent enough, in car environment?







Please share your experiences about the dome midrange drivers in car audio system, please.

Hello Audio Enthusiasts! Some of you may know my work on www.audiocircuit.com, where for many years I have been helping to advise Acoustat owners. I was an engineer and manager with Acoustat, starting when the David Hafler Co bought Acoustat out of bankruptcy, right up to the very end of US production under Rockford Corp ownership (sad day that was!). So I thought I'd lend a hand here, too, because I LOVE Acoustats and want to help as many owners as possible to keep their Acoustats running for many years to come. I don't sell parts or do repairs, but my advice is FREE! So let me know how I can help YOU with your ACOUSTAT's! (And this being a DYI crowd, I don't mind discussing modifications to the speakers.)

Andy Szabo