I've got these PSUs for sale:

2 sets of Salas BiB v1.1 with IRF+, IRF-, BJT+. 1 board set includes remaining PSU +/- parts not included in IRF/BJT kits. One board set 3rd + power rail has been split off.
Set with just IRF and BJT is $50 shipped. Set with full PSU parts is $80 shipped.

1 set of Salas L-Adapter 5V - full kit. Missing Q1. $60 shipped.

1 Reflektor-D - full kit. $60 shipped.

1 DIYinHK 5V 1.0uV 800mA kit. $50 shipped.

Prices are CONUS. I will ship internationally, however the price is $20 more.

Just a quick intro here, hopefully more about myself will emerge from future posts.

Found this site looking up info on tube amplifiers after diving in head first and acquiring a couple of very interesting old things in various stages of neglect. Still working on them and looking forward to actually hear them sing.

See you in the tube section.

The specifics of horn design in speakers utilizing compression drivers determines numerous aspects of sound quality. And of course, the ultimate test of any well designed and built speaker is in the listening. Therefore, I’m hoping that I might be invited to hear speakers using any of these horns. Having these actual listening experiences will best enable me to decide between these horns for building my speakers.

I have my short list of drivers for a two or three way design: Radian 745 or 951neoBe, Yamaha JA6681B, SB Audience 65CDNT, B&C DCM50.

These are my Altec midwoofers. https://josephcrowe.com/blogs/news/altec-416-8b-in-100l-sealed

My subs. https://www.rythmikaudio.com/F12.html The Altec and Rythmik sealed cabinets were built by Jim Salk.
https://www.salksound.com/model.php?model=Rythmik+12+Subwoofer

I would only need for your system to include a nice DAC with a USB input. That way I can play via my laptop uncompressed WAV files
of CD track rips and what I believe are high quality Youtube files of live concerts.

I’m in New York and can travel a respectable distance by rail within the US.

Thank you.

I scored myself a hantek dso2c10 for the equivalent of USD $115 from Ali express.

Including shipping and tax.

Finally a decent scope!

During my MEMs microphone project this year, I needed some specialized measurement features for calibration of reference microphones and of the MEMS microphones themselves. Since I could do get under the hood in Praxis code and (when I could remember!) knew how it worked inside, I went in and removed the necessity for the AudPod hardware and modified as needed. Since then, in some spare time, I've been cleaning up the user interface and making a calibration scheme that didn't depend on AudPod, and am posting it online as "PraxisFREE". Feel free to download it and play if you want, it's at


Liberty Praxis, from about 20 years ago, was kind of a swiss army knife for audio measurements with computer "soundcards" (nowadays known as audio interfaces). It was like a big matrix of very configurable measurement stimuli and signal acquisition types along with a bunch of math processes for time domain and frequency domain data. It can't do everything that modern systems like ARTA or REW can do, but maybe can do a few obscure things that others don't (?).



The Praxis scripting had to be dropped (the correct tools for that weren't found on any of my old backups) and a large number of measurement types had to be deleted or disabled due to their dependence on functions of the Audpod or their just being too much work to resurrect again. But PraxisFREE now supports sample rates up to 384k (or even 768k, if Windows ever supports that natively), and the FFT and IFFT processes, as well as curve smoothing are now much faster than they were.

And a disclaimer: Since this is no longer commercial and just free use hobby stuff now, please don't expect a lot of support or ongoing bugfixes. I couldn't check all the possible operating scenarios, so I expect some of them may not work right. Non-buyer beware!

Have fun,
Bill

Free to good home, nice looking Bob Brines design ML-TQWT using RS 40-1354. Pickup off my front porch. They sound great
but have too many speakers. Let me know if interested.

Is there a sound quality difference between running your current car subwoofer at 4 Ohms(300 Watts) or new subwoofer running 500 Watts at 2 Ohms?
Will be using same amp(capable of either)

hi I'm a fully qualified electronic repairs engineer and I would like help with hk nano 300

For Sale

Fidelity Research F6-54 tonearm - very clean - includes mounting hardware, DIN cable, extra weight and two (non- original) head shells
$325 including shipping to CONUS.

Mouser sells aluminum oxide ceramic insulators for $0.91 each. Some dude on eBay has 100 mica insulators for $9. Whenever something is that much cheaper, and on eBay instead of Mouser, I worry a bit about quality, so I wanted to check if it made much difference?

I want to make a multi-band analog domain parametric EQ to use for correcting headphone response. I have a few questions:

1. Should I try to find a kit, or start from scratch?
The kits I've found are all for guitar pedals, and I'm not sure how applicable they would be. The circuits don't seem that complicated, perhaps building from scratch is simpler?

2. PCB vs. point-to-point
I've never designed and printed a PCB before. I know there are services that make it easy. At the same time, if I can build this point to point, so much the better. Is this the sort of thing it would make much more sense to learn how to make a PCB for?

I guess that's only two questions. But it'll get on for now. I see several directions I could jump at, but I want to get some feedback from those more experienced before I go to Mouser....

Still sorting my stuff..

Here 1 set of F4 PCBs and 1 F4 transistor kit and some resistors and caps that I bought specifically for the F4 build.

Original prices without tax and shipping:
F-4 Circuit Boards 25 USD
F-4/BA-3 Transistor Kit F-4/BA-3 Transistor Kit x 1 $59.00

Offering for 60 Euros plus shipping from Germany.

Hi there!

Happy to be part of this diyAudio community.

I am based in the south of France and in my free time I work on some high performance audio projects.

I also enjoy collecting/restoring/repairing cars.

Thanks!

I have two Chromecast Audio devices in my house and they both still work well, but having problems with the optical input into a new DAC and am considering changing to something else. I don't really want to spend much, what would be a good replacement?

A friend brought me this from the states to be fixed, before lifting the board these are what’s obvious to my multimeter (except HIP4080 and TC4424) Sir Babin always insist the 4424 must be changed after PS failed also the audio driver IC must not be an overlook as they also fails easily. My problem now is can I just replace the one bank of P50NE10 only (aftermarket availability) or should I replace ALL?

Hi,

Two questions:

(1) I have a chassis with UMS heatsinks and a few boards that aren't designed around that specification. Is there any disadvantage to mounting MOSFETS on the heatsink and then connecting the pins to the board with some short wires instead of soldering the MOSFET directly to the board to enable me to use the predrilled and tapped holes on the UMS heatsinks with designs that don't adhere to those specifications?

(2) Could someone recommend a good thermal adhesive to bond some sheet aluminium to a pair of heatsinks for a DIY chassis project?


Thanks

I'm looking for ideas/suggestions to make a diy DHT Headphone amp for HifiMan Edition XS.

Specs
Frequency response : 8Hz-50kHz
Impedance : 18Ω
Sensitivity : 92dB

Salas advice: "Needs custom opt ratio and 1W audio power at least", I guess after the output transformer.

To make a budget proto I want to use not too expensive tubes so russian 6C4C/6S4S (2A3 equivalent) or 4P1L or similars

TIA
Felipe

Looking for Electrol R8077-1 relay for Tektronix AA501 distortion analyzer. Tektronix PN is 148-0134-00.

Thanks

I'm planning to make a discrete headphone amp with SSM2212 as input pair transistors, who has an extraordinary performance with hFE higher than 600 and 1nv/sqrt(hz) input noise.
However, if I use NPN SSM2212 as input pair, i may need another PNP pair as current-mirror at SSM2212's collector side, and another single NPN transistor as current-source at SSM2212's emitter side.
SO, if I cannot find the PNP pair and the single transistor with such a great performance as SSM2212, will them eventually make the whole input noise level higher, making it worthless to choose SSM2212 as input pair transistors?

Dear all,

my father has an ancient, fully functioning Technics SL-PG100 CD Player.
Technics SL-PG100 CD Players

We would like to upgrade the thing a bit, trying some other DACs, because the sound of the player is horrible (despite good reviews on the internet we simply don't like the sound). We listened to the same CDs on the same chain with my Mitsubishi M-C5100 (2x Burr Brown PCM56P) and the difference was like 😱😱😱

But my father insists on keeping his Technics due to functions, emotions, don't know the real reasons, except that he'd like to upgrade the DAC part now.

I told him about I2S and I think we could use tons of great DACs if we could feed them with the player's I2S signals coming from the transport.

I found a basic DAC-related schematics of the Technics, here it is: MN66271 Datasheet(PDF) - Panasonic Semiconductor

From that it's not sure for me where I can locate the I2S input signals going into the DAC. Or maybe I should look elsewhere within the player and try to steal the I2S signals from there ?

The first we would try is this one for example: AKM AK4495EQ DAC Module Board I2S 32bit 384khz 2x L7805CV Regulators

Would you be so kind helping me figuring out what to connect with which corresponding side, if possible electrically at all ? (Without conversion).

Based on the linked datasheet above for the Technics, I see following:


AKM DAC left, TECHNICS (PANA MN66271) right
-------------------------------------------
MCLK <- ?
FSCLK <- ?
BCLK <- Pin1 BCLK (SRDATA bit clock output)
DATA <- Pin3 SRDATA (Serial data output)


The missing parts I need to figure out still + the 2 other findings to be validated ..
What do you think, can it work somehow to get "standard" I2S out of the player and feed this DAC board with that ? 😕

I have been discussing the development of this special speaker in the What’s On the Bench Tonight thread lately. It’s matured enough to deserve its own thread now. This is a 2 way stand mounted speaker, originally inspired by the 10F/RS225 FAST speaker but now with a Dayton PS95-8 paper cone midtweeter and SB Acoustics SB23NRXS45-8 paper cone woofer. The tweeter is now on top and there is a reflex port for extended bass. The crossover is kind of complicated, but the result is worth it because this PS95 has incredible reach into the upper registers for a lot of air. The SBA woofer has great bass and a superb mid range. Custom crossover uses all bespoke components including all air core inductors. No iron cores here for this special speaker. Xo point is at about 900Hz (FAST) and about 2nd order but positive absolute phase. Cabinets will be hand built and assembled one by one in Texas.

Here is the design thus far on CAD:


Prototype tested looks like this:



Measured response:

Impedance sweep (blue trace) nominal 8ohm speaker with minimum dip to 5ohms from 2-3kHz:

This is a commercial speaker so I can’t give away the crossover. Crossover PCB layout looks like this:


Subjectively, it is similarly voiced to 10F/RS225 FAST but with higher top end reach, lower bass extension (vs sealed box) and slightly higher 85dB sensitivity.
You can listen to a recording of sound clips here:
Login to view embedded media

Hello! I am a new member to the community, however I have been reading different posts on the forum for some time now.

I am building Troels Gravesens SBA 941:s and wish to get some feedback on my modified cabinet construction.

//Max

A friend asked me to look at a Hafler DH-500. I have yet to see it.

He's complaint is the amp shuts down after four songs. He thinks the thermal protection may be causing it, but the amp is not getting hot.

I know this info is minimum, but was hoping the issue has been addressed before and whether someone knows what the fix might be or
where to start.

I'm an Electronic Tech by trade and have worked on audio gear for 30 plus years.

Thanks in advance. Bill KR3LL

Greetings from Charlotte, NC. Music and stereo equiment has been a life long hobby of mine. Now I am looking more and more into building my own stuff, mainly speakers.

Horn response nails it again (Fb)

Sounds pretty good, but it’s a mouse fart compared to the tapered pipe I put the other one(7” version) in.

Hi!

I'm NJSwede. I'm originally from Sweden and live in New Jersey, USA. Not too surprising, I know.

Although I don't work with electronics for a living (I'm a software guy), I like to say that I pretty much grew up in an electronics lab. My dad worked for Ericsson and designed some of the cell phone and cell tower chips you've all used thousands of times. So electronics was a very common dinner conversation topic. Now in my 50s, I decided to take up electronics as a hobby a bit more seriously and one thing led to another, and I started getting into amplifier design. Now I'm totally addicted to it and literally dream at night about amplifier topologies. I like to design and build things from scratch and so far I've designed and built an experimental from scratch Class D amplifier and a couple of blameless-style Class AB and I think I'll get the hang of it once I have a few dozen under my belt. 🙂 No, but seriously, the latest one sounds pretty good.

I live in a small town in New Jersey with my wife, two teenage kids, four dogs and a bunch of other animals. When I'm not busy with family, animals and amplifiers, I love to go for long (and by long I mean 200km and above) bike rides. Yeah, lack of activities isn't my biggest problem. Finding time is.

I'm a bit of an audiophile skeptic which tends to annoy some people. So my preemptive apologies for believing things like human hearing maxing out somewhere at 20kHz. 🙂

I joined this site because the quality of the content and the knowledge of the users seems a few notches above other communities. While I tend to have problems keeping my blabbering mouth shut, I'm mostly here to listen and learn.

Hello all.

I am looking for a DIY speaker kit. Maybe someone of you has an idea with DIY kit could fit to the following requirements.

1. Music: mainly Jazz, chamber Music, Old Music (Bach, Handel etc), Vocals, sometimes big orchestral music. some Rock and Pop
2. Smallish room (12. sqm, 3x4 meteres),
3. Near and mid-field listening, 2 meters (sometimes 1,5 meters, sometimes 2,5 meters)
3. listening mainly medium or lower volume level
4. Ideally 89db or a bit more. not difficult to drive
5. I prefer 3-ways systems

Thank you.
Christian

The LM317 datasheet recommends a 100nF disc capacitor or a 1uF tantalum.

Let's ignore the tantalum. I have found the following comments:

Use any of the film ones and not the ceramics, as those you show there have a breakdown voltage of 25V, and at that are likely not going to be 100n any more but likely under 30n

Vs

C3 & C9 should be close to the reg leadouts. But do not use low ESR film capacitors.


So... what should I do? 🙂 Ceramic or film?

The plate amp's power LED is still on, but the sub will not produce any sound from either RCA input or speaker input.
I can't find anything obviously fried inside, and this plate amp is discontinued and difficult to find replacement. Box opening is about 9.25" x9.25".
Any known quick fix for this amp or what might replace it?

I'd love to be able to afford a DDAC but it's impossible so I bought a dual dac board from Aliex.
Its an LHY Audio product as is my SPDIF to I2S board that uses a Dir9001.

I didn't buy it with the opamps as I planned on using my Sowter I/V transformers.

Pleasingly it worked first time and sounds very good both via optical (LG Oled tv) and coax (Teac VRDS10) inputs.

I used 150R 0.1% I/V resistor which give the correct output level. The dacs are correctly configured for Mono, I2S, Left and Mono, I2S, Right.

It is powered from my 8ah Lithium power box which provides +18 and +7v and are regulated down to +5 for the digital part and +12 for the analogue sections. Onboard regulators then reduce the 5v to 3,3 and the 12v down to 5v..

I e xperimented with the secondary load resistor and found 3k3 to give the best results at the expense of a about a 3db drop in output (when loaded with the 22k input impedance of a Behringer UCA222.

I did a few checks using REW's spdif output and nothing untoward was seen.
Frequency response is flat as is phase zero degreee.

There has to be a way to get that 90 degrees on a stylus without the damn air pump!!


I don't want to go off track in other tonearm threads so I decided to start a new thread focusing on the discussion and design ideas for pivot style tonearms that can attain tangential tracking, a pivot linear tracker if you will. Sounds like an oxymoron but it can be done.

To be brief, most tangential tracking tonearms are typically air-bearing tonearms that allows the stylus glide across the radius in almost frictionless manner to simulate how a record is cut on a lathe. Other means of this gliding action can be also achieve via linear bearings like rollers on a rod or bushing on a rod, etc... Some concept arms even suggest using floating opposing magnets. The flaw of such tonearm is that the horizontal mass is enormous regardless of bearing quality, low friction or no friction. It limits the choices of stylus, depending on its compliance. And the use of an air pump is not for everyone to say the least - a personal pet peeve of mine. The genre of electronic servo detection pseudo-tangential trackers like the Rabco tracking across the record in tiny little arcs constantly self correcting its way to the end of the record is not part of this discussion here. Anyway, this thread is NOT about the above tonearms. We want to talk about pivot tonearms that can track tangentially by changing stylus angle simultaneously.

The best examples are actually currently available in production. By now, many people have heard of the Thales tonearm from Switzerland. It is a pivot style tonearm with an extra pivot at the headshell area right above the stylus. The changing angle is always 90 degree to the radius because it is part of a triangle that is inside a semi-circle that adheres to the Thales theorem, that is, "Thales discovered that the circumferential angle subtended by a triangle in a semicircle is always a right angle. As a result, the half circle above the hypotenuse of a right-angled triangle is called the Thales Circle."

http://www.tonarm.ch/kommentare/thaleskreis_e.html

6moons industryfeatures: Thales

.



.

With the basis of the Thales Circle, the designer Micha Huber devised a tonearm that can track any point inside the semi-circle always 90 degrees to the center of the record, voila a linear tracking tonearm that pivots without any linear motion. Genius! The tonearm appears to be executed with quality construction and precise worthy of a Swiss watch. So far it is the ONLY tonearm on the market that is capable of 100% geometric accuracy in maintaining tangency, at a price,of course, as it sells for, I believe, 6000 €.

.



.

Visually, it has the look of a Rube Goldberg device but looking closely, everything seems to have its specific function for good reason. I don't want to write a white paper on the Thales design but for those who are interested in examining it more closely, feel free to explore its website. But this tonearm does give a good example of the objective here.

.

Thales will introduce a new tonearm named "Simplicity" that looks simpler and elegant and even though it is not 100% accurate in geometry but it reduces the tracking error to a maximum of 0.008°! Pretty damn good in my book.

.



.

There are historical predecessors of such design and one can find that in the classic Garrard Zero 100.

.



.



.

And the Burne-Jones arms.

.



.



.

One can also find examples in contemporary designs like the RS Labs RS-A1 arm with a pivoting headshell.

.



.



.

"Prototype of the 'Bajulaz' tonearm on a TD-124. It was designed by Ing. Bajulaz to overcome the geometry problems of the conventional tonearms, but allegedly it wasn't so good for the new stereo cartridges and therefore never went in production."

.



.

I will continue to upload more pictures and present ideas to stimulate discussions and, hopefully, inspire the DIY spirit.


.

Hi,

Just bought some brand new Nippon Chemi-Con electrolytic capacitors from Mouser. Is a KMZ series, 470uF 420V.
I am surprised that all the 4 pcs have value 412....414uF. So is below with 13% from nominal value. I agree there is on +/-20% limit, but being brand new, I expected to be closer to the nominal. I tried to apply voltage for 24 hours and still the same, no change. I measured it with a RLC meter.
The date code is 1NT058. After some research, I found that the first digit represents the year of manufacturing, so is 2001, 2011, 2021....??
Any comment on this?

Hi. I just bought this amplifier board. Can anybody please tell me what this pot is for and how to correctly set it? Is it just a gain pot, DC offset, bias? It is a 50k pot and it is next to the signal input.

I have closely examined diagrams of power supplies that use rectifier tubes and have noted that they feed the filament with alternating current (AC). I have considered whether it might be an improvement to drive the filament with direct current (DC) instead.

The purpose of the filament is to generate an ionized field by releasing electrons, which are then attracted to the anode (I am disregarding the grid here). When current passes through the filament, a magnetic field is generated. With alternating current (AC), this magnetic field constantly changes direction, which can lead to changes in the geometry of the ionized field. This phenomenon could negatively impact the efficiency of ionization, as the free electrons will be influenced by the fluctuating magnetic field and may not move stably toward the anode. The constant change of the magnetic field could thus disturb the desired ionization process.

However, if the filament were driven by direct current (DC), the magnetic field would be constant, potentially creating a more stable ionized field. DC could therefore possibly improve efficiency by avoiding the disturbances caused by the fluctuating magnetic field from AC. The constant direction of the current would ensure more stable movement of the free electrons and more consistent ionization of the gas in the tube.

We are familiar with a similar phenomenon from old cathode ray tube (CRT) televisions, where a magnetic field could distort the image by altering the electron's path. This interference is an example of how a changing magnetic field can affect a process where the path of the electrons is crucial. In the same way, a fluctuating magnetic field in a filament tube can alter the movement of the ionized electrons and disturb the ionization.

Hi, first time Post, here goes. I purchased a Luxman pd-441 from usual place ,ebay waiting for delivery, but it does not include a tone arm or cartridge or arm board. I have a Hana SH cartridge I bought after seeing lots of good press on it, probably should have got the sl mc but I have 3 phono pre amps, a Rega mm, a Music Hall mc/mm and a Vincent 701 tube 2 box mm/mc. Along with Marantz 7702 pre amp processor, and Crown CS 8200 , Carver/Subfure 2 ch amp, & B&K signature 200.7 and 4250 amps with Martin Logan ReQuest, CLS II and Summit 'stats. Need advice on choosing a Tonarm for the DD pd-441? My budget is $500, but could spend more if there was a unicorn that was such a good to match. Seen SME and FR-54/64 advertised, and found a link for Italian Arm Bosrd maker for a variety of collars . Graham looks interesting, but seem in the $5000 what about linear tracking arms? I thought they made sense, but have been mostly a digital music collector. Found a neighbor with a collection of lps he needed to frt rid of, so I became a vinyl collector.

Borrowed a Pro-Ject debt carbon from friends, have owned Tecnics and have a Gerard 301 in storage, but the Gerard looks like a changer, in a deep plinth eith a rats next of wires, no plug, like it came out of a console. Also have a old Dual needs work, what project should I concentrate on? I appreciate the community, and have knowledge building engines for Drag Raving along with computer building and ripping bluray and said & cds to my computer. I use driver and Make MKV daily. Love Atmos and projection movies, let me know if I can share my knowledge.

I'm a wee bit of a hoarder when it comes to my hobbies (but nothing like some people - Cal Weldon, I'm looking at you ;-)) and for most of the past decade I've been rather busy with work and life. However as I've been winding down the work a bit I finally found time to build the big 2-ways I've had in mind for a while. In the spirit of using things I already have stashed away I tried to buy as little as possible - and I mostly succeeded! I recycled a pair of >30 year old cabinets I rescued a decade ago. The baffles were made of half a sheet of MDF I had lying around. Stuffing was from a half roll of fiberglass that I had leftover from a construction project. Vinyl wrap was from a 15 years ago project. I used whatever fasteners I had (to be fair, I have a lot of fasteners as I tend to buy in bulk whenever I need something). I even used leftover spray-paint (from painting my shutters) for the front baffle. You get the idea.

To be honest, It would have been a lot easier and taken a lot less time to complete had I just built new cabinets from scratch. But speed was not my aim here.

The business end of these are JBL2217s for mid-woofs, Radian 650B CDs mounted to the well know QSC 14"x10" waveguide Parts Express sold long ago. For those unfamiliar with the 2217, it's almost identical to the 2226, but with a 14" basket. The same motor is used for both, so TS parameters are almost the same. But the 2217 has a lighter cone due to its smaller size. If you like 2226s for domestic use, you'd probably like the 2217 even more. The only real rub is that JBL doesn't appear to have made very many and 2217s are very hard to find. The Radian 650B appears to be very similar to their current 1" products. It's pretty beefy and unlikely to fail in any domestic application. You can probably get a Be diaphragm for it, but my hearing no longer extends high enough for me to try. Crossover is active - I use a MiniDSP 4x10HD along with an 8 channel 125W/channel amp (a Savant 8125 - similar products are marketed by Lexicon and Crown).

The old cabinets are mahogany and built with dovetail joints. The cabinets are quite stout, but cosmetically terrible. They were built to house a 12" coaxial and 15" sub, so I had to turn them around, uusing the former back as the front and former baffle as the back. Some surgery was needed to make that work. As you can see, the corners were in bad shape and needed extensive surgery. The finish was quite bad as well. I quickly gave up on the idea of refinishing the mahogany and went with vinyl wrap (which actually looks pretty good from a couple a feet away). Cabinets are about 38" x 20" x 13", so a little under 4 cubic feet (about 100 liters). Given that these are sealed, exact volume isn't so important.

The baffles are made of 1" MDF, but those drivers weigh a ton! So added some blocking to the MDF at the attachment points for better screw holding.

I don't have much of a workshop and most of my tools are really for home construction/repair. So I had to DIY a bunch of jigs and such (remember, I'm trying not to acquire more things) and I mosly worked outside. So that slowed me down as well. Yes, that's a DIY trammel you see on my pawn-shop router to cut nice circles.

After holes were cut, I did a test fit (looked good) and then painted and clear-coat the baffles in "almost JBL blue". The exact color name is "Inked" by Behr. For reference, that ruler is 12" x 8" (it's a big cabinet).

I also added 57uF of blocking capacitor ahead of the CDs to protect them from user error. These were some film caps mounted to tags I had in the parts bin.

Finally, here they are in their natural habitat. I had to build a couple of dollys for them as they are just too heavy (about 90lbs or 40kg) to reasonably move around. A quick 850Hz/24db crossover and a little eq later they sound quite nice. Lots of slam. Plently of extension. Distorion is quite low. Needless to say they can get "call the cops" loud before distortion kicks in (I was wearing big gun muffs when measuring distortion at about 120db @ 1m and I still could have gone louder). Given that they are sealed I use a fair amount of low end boost on the 2217s, but I also have 3 subs distributed around the room (one visible inside the fireplace), so I have them rolling off at 50Hz.

My room is not great acoustically, so my frequency response measurements are a bit suspect. Over the winter I plan to build and deploy some room treatment and at least one bass trap. I'll post some response graphs once the room is improved for better measurement accuracy. I'm happy to share any information anyone would like about this project, but I doubt anyone else would replicate this given the scarcity of the drivers used.

Some of you might find it interesting:
https://eu.mouser.com/ProductDetail/Texas-Instruments/TL081HIDR?qs=pBJMDPsKWf2IEA%2Bv86wIaw==

yet another noob here.. can somebody tell me if there's a way (test) I can do to find out if I didn't fry the mosfets I just soldered onto the F5M board? (They got pretty hot) Forgot to use the ol' tweezers as a heat sink trick.

Long Live W. C. Fields (one of a few great comedians to ever live) you are not forgotten m'friend - don't ask me where that came from.. lol

G’day,

I’ve recently bought a Marantz 140 amplifier - Japanese Version (Using a Step down transformer in Australia). I would like to know if anyone has a Japanese service manual for this amplifier? Otherwise, is there any difference apart from the transformer to the American Version in regards to replacement capacitor values/resistor values/other parts inside as I have an American Service manual here.


Thank you

Hello dear diyaudio friends

I'm giving away these Kaneda DC1 PCBs for free. You only need to pay the shipping costs

It is a Kaneda DC1 line preamp PCB, a phone preamp PCB and a regulated power supply PCB

These are used PCBs and I'm not sure that they are still OK

I can desolder the big "golden bullets" Roederstein electrolytic capacitors so I can ship everything in a bubble wrap envelope

I’m searching for the following items. If you have one a more items, please make me an offer.

Manufacturer sealed bags of:
2SJ74-BL
2SK170-GR
2SJ74-GR
2SK370-BL
And maybe other rare signal JFETS or dual JFETS

BurrBrown PCM1704-K DAC chips

Analog Devices MAT02 and MAT03 dual monolithic transistors

2 x Starkrimson® Ultra Amp Module

XRK Audio RTR TPA3255 Reference Class D amplifier

Please also take a look at my other offers in the Swap Meet


Here are some different shipping rates:
They may differ a little from country to country, for a exact quote for your country please ask.
Of course, I will charge only the prices I will have to pay)

(Prices for bubble wrap envelopes are valid for most countries worldwide, DHL package prices are a bit cheaper within Europe)

Bubble wrap envelope up to 500 grams (Deutsche Post):
Without insurance and tracking: 3.70 Euro
With insurance up to 30 Euro and tracking: 7.20 Euro

Small DHL package worldwide (up to 2KG):
Without insurance and tracking: 10.99 Euro
With insurance up to 50 Euro and tracking: 14.99 Euro

Small DHL package within Europe (up to 2KG):
Without insurance and tracking: 5.99 Euro
With insurance up to 50 Euro and tracking: 8.49 Euro

Shipping within Germany will be cheaper, please ask.

I will ship anywhere in the world. Shipping costs strongly depend on the number of capacitors you are going to buy and which shipping method you prefer. Of course, I will only charge the real costs, I won't charge anything for packing materials and effort. I prefer to use Deutsche Post/DHL, but you can decide which shipper and which shipping method (letter, registered letter, small package, normal package, insurance, tracking) I should use.

As payment method I prefer PayPal for friends and family, so no extra fees will be added. Of course personal collection of capacitors in Cologne and payment in cash is also possible.

Kind Regards

Phil

I've got a push pull 6BQ5 amp that is cathode biased.




The measurements are as follows with a 130.1 ohm cathode resistor.

Plate voltage 340.3Vdc

Screen voltage 341.7Vdc

Cathode voltage 10.27Vdc

Cathode current 78.94mA

I'm thinking of converting it to fixed bias as that eliminates the need for the cathode bypass cap and gives slightly more power output.




All I should need to do is set the grid bias voltage to where the cathode current is around 78.94mA, right?

I have a 500 ohm pot listed on the schematic as that's what I had on hand. I suspect that I will need a second filter stage for the bias voltage.

I'm also thinking of adding a 100mA meter to measure the cathode current so that I do not need an external meter to measure it. I may also install a SPST switch across the meter so that I can bypass the meter if needed.

I am, however going to have to get creative on installing the meter as it will not fit on the chassis due to the chassis being rather compact.

I currently have a 15Vac supply for the - bias power supply. Is it possible to use the 5 volt ands 6.3 volt windings in series for 11.3Vac and get enough bias voltage to bias the tubes at 70mA? If so that would eliminate one transformer.

What I will do is use a variable voltage power supply to set the bias voltage and see what voltage is needed for 70mA cathode current.

Also will the B+ voltages be too high for the 6BQ5 and 6SQ7 or are they ok?

Here's the measurements for the 6SQ7

Plate voltage 299.7V
Cathode voltage 43.2V
Cathode resistor 22.28k
Cathode current 1.94mA

Are the voltages and currents ok?

I could use a 6SR7 for lower gain if so desired.

In the communications receiver that is driving this amp I used a voltage divider at the 1 meg volume control consisting of a series 1 meg resistor and a 1 meg resistor in parallel with the volume control so lower gain from the amp would be beneficial.

It isn't shown on the schematic, but there's a 1 ohm resistor between the CT of the HV winding and ground which I used to measure the total B+ current. I might reduce the wattage of that resistor so that it acts as a fuse should B+ current jump up too high due to a fault or red plating tube.

I do have the Russian equivalent of the 6BQ5 installed.

Also the output transformer was what I had on hand (came from a GEC 912 PLUS amp I built maybe 15 years ago) and I know I could get more output power with a higher primary impedance.

One further question. Keep in mind this is not a HI-FI amp.

There any faults with the design or improvements that can be done to the amp?

I came across this exhibition too late to go and see it

https://www.lissongallery.com/exhibitions/devon-turnbull-ojas-hifi-listening-room-dream-no-1

I wondered what people thought about the speakers OJAS builds? I'm temepted to DIY a pair of these...cut my own wood and source the speakers (JBL 8" coaxial ceiling speakers.


https://ojas.nyc/collections/frontpage/products/artbook-shelf-speaker-2

Hi guys,

300B Push-Pull is normally being designed in class A or class AB1, which means there is only negative grid voltage applied and there is no grid current input. While if we go w/ positive grid voltage and provide the related grid current accordly, means let 300B work in AB2 mode, how it would be?

Let‘s take a look at the integrated 300B curves, together w/ negative grid curves and positive grid curve ( up to +40V), it's the real curves and scanned by the tube curve tracer，



As you can see, the linearity of positive grid curves looks not so good, not like the curves w/ negative grid values, that's why I'm thinking to use them in AB2 Push-Pull, instead of A2 SE output stage...

Now, how would it be happened if we put the load-line on this curves and calculate the related output parameters? Pls see the picture below:



Primary Zout of OPT is selected as normal value, 5Kohms, and the Q point is selected as: -90V grid, 420V (P-K)， w/ 5Kohms load, making sure the load-line does not go across the maximum static Pa, then as you can see the output power is up to about 52W, it is almost double of normal AB1 PP... in this case, positive grid value is up to +40V, and needs about 50mA grid current input...

While, the BAD thing is, Peak Ia now is coming to about 290mA when output power comes to the maximum of this design！ This is almost the saturation value of this 300B, although the manufacturer does NOT provide this value, but I tested it and got this saturation point.

Normally, like WE, peak Ia of AB1 application in the 300B datasheet is recommended to no more than about 200mA, and definitely there is no reference value can be found for the application of AB2 push-pull, as this tube is originally designed to work w/ negative grid only, no one would expect to use it by positive grid value......

So, the concerns now on my side is, can this design be working, or 290mA peak Ia is safe for the tube？If I really wanna this PP amplifier to work w/ about 50W power output?🙂

Any comments are really welcome, and appreciated...🙂

Thanks

I am registered here since 2012, I am an electronic engineer, and at the age of 81 years still doing repairs as a hobby. I am fortunate to have TMDE like VOM, Scope, Counter, LCR meter etc

Hello all, I'm from Scotland and have been tinkering with audio since I was a kid. Current interests are single ended solid state amplifiers.

Rockport (Avior2) styled 3way speaker DIY - finally completed.!

I love rockport technology speakers, both sound and style.
So I decided to make it by myself.















tweeter : scanspeak 6640
mid : audiotechnology 15H
Woofer : audiotechnology 23I * 2











Frequency response as follows. Crossover design is not finished yet.

New units, bought quite recently, not soldered, not measured.
Selling due to changes of the projects.

TW022 140Eur/pair
Wom-165 150Eur/pair

EU only, bank wire or Paypal.

Hello

I planned to build a budget 5 inch bookshelf speaker (either classic 2 way, MTM or TMM) for learning purpose (I don't dare to start with expensive stuff because I don't have the equipment or the knowledge atm)

planned to use this local brand driver as the midwoofer which is dirt cheap (about 3-5 dollars each) :

https://acrspeaker.com/product/5-538-curve/

Based from the woofer parameter in the pdf, I should go with sealed enclosure (probably smallish one per speaker with qtc 1.1-1.2 & then add either 220-330uf capacitor, make it third order sealed)

as for the tweeter probably gonna keep it on the same brand. just some mylar tweeter should be fine (don't worry that it can't reach 20khz its not intended for hifi, but I do wish it to be balanced enough) the tweeter no longer in the site specs but I still have the word document even tho its bare (screenshot attached)

question is what component should I need to cross it? & what order? also how is the schematic if I wanna combine it with the 220uf-330uf capacitor as well?

oh yeah also it got different impendance, (woofer 6 ohm, tweeter 8 ohm)

is 2 way vs 2 way with double woofer have different value for the capacitor & other stuffs? how to decide the value as well? how should I connect both woofer if I wanna go that route?

thanks in advance, best regards.

I sent this message to Barry, but his site says he stopped dealing... so here I'm with the same message:

a friend of mine bought a WF-55 a good while ago, and tried to build it, he's a naval architect and is not used to soldering and building kits so he failed. I do have some experience with electronics (learned 30 years ago) and did built a few audio amps. This WF-55 landed in my hands to "make it work".

I fixed the wiring errors, re-did the heather cabling better, re-soldered all dry points, and the amp is now working... almost. All tests measurements are within specs. However, I do have a solid hum in the output, without anything at the input. The hum rises with the volume. I verified the grounding, looks ok to me. Below find attached two scope dumps. One at half-volume, the other at full volume.

With a guitar it sounds decent (I'm not a player), but the hum is very disturbing, and in some forum the builders say it's dead-silent. So I think I must have something wrong.

First, output at half-volume, no signal at input:



First, output at full-volume, no signal at input:



the peak-peak hum is about 150mV, which is clearly audible. What annoys me more are the spikes. I verified the rectifier diodes (powered off, in-circuit), they look fine.

Would you have any idea what could cause these spikes ?

The distortion on the full-volume shot is as well strange. I could do more measurements, let me know what you think, and thanks for the advices !
Charles

Edit 8.12.2024 : the schematics is public on this URL. Sorry I should have added it.

Just about done with a pair of Scott’s Jaguars with Mark Audio A10.2 drivers. They’re still in my garage/shop; thus, the background. The supra-baffle is walnut and wenge. I’m enjoying them as I’m typing this. No doubt, they’ll get a lot more use. Great for many types of music, but acoustic guitar sounds really great. Female voices are great too: Karen Carpenter sounds angelic. Wreck of the Edmund Fitzgerald by Gordon Lightfoot is playing right now and sounds darn good, too.
I was looking for something other than a typical box, so these fit the bill. I’ve done a pair of CHR-70 Mar-Ken’s and these were a simpler build. I’ve got the parts and plans for the A12PW/A7P, so those are next.
I really like the “challenge “ of something different. I did a pair of Frugalhorns with A7s, so I might try a Frugalhorn Lites down the road.
Any suggestions on what type of amp works best with the A10s? I’m using an old Onkyo now, but I’d like to see if I hear any difference with other amps. Also, are these best away from a wall?

The design

Hello,

Back when I was just thinking about getting into electronics, a magazine in Denmark, 'High Fidelity,' published some very nice looking DIY articles. In the fall of 1984, they published a Class AB power amp and I joined a group buy to build these in 1990. Slow forward to 2024, and I thought that I would progress from looking at the pile of bits to actually making a PCB and throwing it all together.

Far more detail than you might want, in our local lingo, at Hifi4All thread .

Schematic below, just showing the amplifier part. (There's also a regulated power supply for the input stage, generating Vcc52/Vee52, and a relay DC protection / slow start circuit.)



There are cascodes in two places, at the 2nd stage with a constant collector voltage for the amplifying device, Q109, and at the output, with a floating cascode bias keeping the Vce of the output device Q115 constant (-ish).

The design evolved a bit after the original article. Originally, the cascode bias at the output was a resistor to positive supply (instead of Q120/R145/D105) and the same Zener diode plus resistor to produce the actual base voltage for the cascode device. The update to current sources was described in a reply to the letters page, noting that for high loads, stability problems in the original design were alleviated by the constant current.

I regularly work with amplifier design, but only in CMOS and only in integrated circuits, so I have never had reason to design exactly this type of cascode stage. In the article on Pass Labs about cascode amplifier design, Fig 9 shows both types of cascodes deployed in this amp. So far, so good.

I also read some detailed advice by Nelson and others, to add a bit of resistance in the gate of the cascode device, to dampen the possible oscillation based on lead inductance in the cascode device package., This design has that, indirectly, so still good.

I did frown a little at the capacitors connected to the cascode voltages, C114 / C115. They are described in the original article, and it is noted that their value controls the slew rate of the cascode voltage. If I were designing a cascode amp with a floating cascode bias, I think the first place I would put the capacitor was across the cascode voltage, i.e. across the output device Collector-Emitter Zener diode/Resistor pair, to stabilise the cascode voltage. But, since simulations showed OK-ish transient response, with square waves into 8 Ohm || 1 uF, I thought that I would give it a go. No device type was given for the cascode bias current generator, so I picked a slow (fmax 4 MHz) TO-220 housed pair of devices, KSA940/KSC2073. The cascode devices themselves are high power but not very fast, Motorola MJ11015/MJ11016. The signal output devices are pretty high power and very fast, Toshiba 2SC2565/2SA1095.

I am not very optimistic about the accuracy of the simulations, since the transistor models look pretty sketchy (well, compared to the quality we get at work). On the other hand, there is degenaration in all the voltage amplfication stages, and explicit capacitors to set the bandwidths, so I figured I would plow ahead. I was convinced by a wise member of the board where I described the project to build a prototype, so I did.

I did not keep a lot of the old PCB design, since I am using double-sided PCBs and I thought that I could get some benefit from deviating, notably a ground net which didn't have to connect all over the PCB by wiggling between other nets...

Here's the output stage board design, showing the part which is powered by the high-power supply, Vcc48/Vee48



Best Regards

Jens

Hello, friends! I am used to listening more than talking, so I will look for answers to my questions on this lamp forum by reading your messages.

Hello

I have seen these banana chassis plugs which are flush mounted, but where can you buy these?

Just got an AliExpress offer notification on my phone for this 😂

￡4,154.37 | New P6 lossless music MP3 flagship R2R DSD professional hifi player
https://a.aliexpress.com/_EINyJBO

Pioneer 4400 I ran 12.4 volts constant to HU and 12.4 volts switched when I got to third wite to land , the ground it had 8 volts on it . No amps no rca"s landed yet remote site also reads 8 volts at head unit and back by amps . Power from battery to amps 12.4 leaving 10.4 arriving . Amps won't turn on at all

Hi Guys!

My 3-way speakers sound nice - but the tweeters are just too quiet.

We know what these tweeters are capable of, as we have the same tweeters in a smaller model by the same maker.

I have removed the aging crossover caps and measured then [ESR - METER] and they are all near perfect, with minimal loss.

Below is a pic of the crossover.

Is there an easy way of making the tweeter a bit louder, without having to completely replace the crossover tweeter resistor and try reduced resistor values?

I occasionally read forum posts on this site as a result of google searches, usually specific to audio speaker and speaker array applications and occasionally in regards to some specific tube amplifier I am researching. My audio focus for the last few decades is strictly related to the music business, not audiophile, car or home audio. My knowledge of those categories is mostly 1970's - 1980's generation equipment.
I created this account to provide information to someone looking for information on a rare 1940's - 1950's tone generator/amplifier that is most likely Canadian military. I have a bit of a background in older Canadian military equipment as an end user of it in the 1970's.
My initiation into DIY electronics was making 1940's - 1950's floor model multi-band (SW1/SW2, etc), radios work again in the mid - late 1960's and playing around with that time period tube driven portable record players, Mantlepiece radios, etc., as well as regularly testing tubes at the local auto parts supplier or with my father's portable tester. Currently I regularly restore mostly 1960's - 1970's instrument and PA cabinets, generally using period correct speakers, as well as repairing and restoring electric and acoustic guitars, which I have also done for a few decades. I also dabble in mostly 1960's - 1970's Traynor tube instrument amps and their solid state pa mixers.

Hi guys,
After more than half a year of revision and testing, the official version of the installation kits are finally ready to ship. There are 2 models，AZ1021 SK andAZ1021 SK lite.
User Manual please see #55 and #108,DWG file of back panel please see #344.
DAM 1021 SK lite specification
1. MCU control DAM1021/1121 via isolate serial port. Real-time volume control, digital filter switching, input selection, PCM / DSD sample rate display.
2. 3.1 inch OLED display(256 * 64 resolution).
3. One key mute (IRRemote only).
4. Rotary encoder or IRRemote will be control full function.
5. IR Remote control support learning function, support most kinds of IR Remote.
6. Power-down memory, automatically load the last shutdown settings.
7. With two different styles of display window, the screen display can be turned off
8. Using ISO7421 isolation chip between MCU and dam1021 / 1121, to ensure that MCU noise will not be introduced dam1021 / 1121.
9. There is a onboard transformer for power supply, AC 115V / 230V switchable. The output is completely isolated from the double winding, one power supply for the MCU and display part. The other power supply for the ISO7421 isolation chip, And provides 5V (400ma) and 3.3V (200ma) output, easy for the USB module and 1021 isolation chip for independent power supply.
11. Using high-quality solid capacitors, tantalum capacitors, ultra low noise ADP151, rotary encoder using ALPS EC11 type.
12. Display screen with FPC connector. While retaining the 2.54mm display interface(suppose SSD1322 256*64).
Attention: The transformer is included in the kits.

DAM 1021 SK specification
1. MCU control DAM1021 via isolate serial port. Real-time volume control, digital filter switching, input selection, PCM / DSD sample rate display.
2. 3.1 inch OLED display(256 * 64 resolution).
3. One key mute (IR Remote only).
4. Rotary encoder or IR Remote full function control.
5. IR Remote control support learning function, support most kinds of IR Remote 6. Power-down memory, automatically load the last shutdown settings.
7. With two different styles of display window, the screen display can be turned off
8. Using SI8642 isolation chip between MCU and dam1021, to ensure that MCU noise will not be introduced dam1021.
9. Input support: Optical fiber，Coaxial, AES, USB（not included）, external I2S (LVDS mode).
10. RCA output can be switched between Buff and RAW.
11. Transformer board are detachable, support AC115V / 230V.
12. Use a separate winding transformer to power the USB module (amanero) and use ultra-low noise TPS7A47 for regulation.
13. Onboard TPS7A47 / TPS7A33 PSU.
14. A variety of DAM1021 power supply options.
Attention: USB module (combo384), the transformers are not included in the kits. In order to be more compact, the official delivery of the PCB will be smaller than that of the photo, removing the extra edges

PCB size & OLED colour
-AZ1021 SK : 220mm x240mm PCB 2OZ copper and immersion gold
- AZ1021 SK lite: 50mm x 100mm
-OLED colour：Green, Orange or Blue.The default is blue, please note the other colors.，There's only the blue OLED stock. If you need another color（green or yellow）, you need an extra $5 for the freight of purchase.

What is in the offer?

• AZ1021 SK: 169 USD ， Not available
• AZ1021 SK lite: 99 USD ， Not available

What do you get for the price

• AZ1021 SK lite: Finished board, what you see is what you get.
• AZ1021 SK: Finished board, USB module (combo384), the transformers, dam1021 are not included in the kits.

Shipping & fees, payment,Tax
ePacket (from China) shipping worldwide for free.If the ePacket does not support the area, need to pay an additional fee（ePackte, USPS FIRST CLASS MAIL INTERNATIONAL，Because of the delay of data exchange between China Post and USPS. It will take a few days for USPS to track the status.You can also track on this site without delay. ALL-IN-ONE PACKAGE TRACKING | 17TRACK）. Shipment is going to start in May 17th, once a week. I accept only PAYPAL, fees are included in the price.Please PM your email to me and you'll receive an paypal invoice for what you are buying.
Exclusiveof tax;

Best Regards,
Audiozen

I’m looking for 2, through hole, 100k Carbon film resistors. Size 0207.

I prefer Takman rex, old holco H4, Amtrans amrt.

All EU stores are out of stock or don’t offer these.

Anybody 2 pieces available and willing to sell?

.

Hello,everyone!
Looks like a great forum.Looking forward to discussions and I hope to contribute at some level.

Hello all,

Here is a vintage HP 546A logic pulser that isn't working properly
While the LED's flash correctly the pulser doesn't pull to the correct voltage level under load
Cosmetically excellent but for parts only
I'm thinking USD 40 plus postage or open to offers

Cheers, Ralph







https://audiofile.net.au/

if you have a spare pair, preferably 🇪🇺, I'm interested : )
stefan

The claim is that this new chip can complete a task in just five minutes that would take
10,000,000,000,000,000,000,000,000 years for some of the world’s fastest conventional computers to complete.
That's far more years than the age of the known universe.

And it's only 4cm²...

https://blog.google/technology/research/google-willow-quantum-chip/

New NooB in electronics - I only know about soundrecording. But interested in repair fix reuse of older equipment as I am a scavenger.

Hello to all - please help - whats bias current for this amp.

Hello DiyAudio Community
I am a lover for music and a lover for building stuff. I am currently planning to build a portable party box on wheels and with powerful and loud speakers.
But i find it especially hard to pick and buy the right speaker because i currently dont have much knowledge about this which makes me very insecure about ordering.
Should i go for high efficient parts to reach high spl? Like for example: 1 Faital Pro 15FH500 (250€) with 2 Eighteensound 8m400 -140€ per (or FaitalPRO M5N8-80 - 95€ per) and something like lavoce DN10.17 (130€)?
or what would you suggest i'd use? Budget for speakers is around 620€. Im from Germany so parts from companys like dayton audio will be more expensive here.

The box will be used both indoors and outdoors, mostly at smaller parties.
I listen to pop, hip hop, rock, hardstyle and techno.
Because its a box for mostly parties or nights with the boys it needs to be louder and will be played often at around 70-85% volume.
I really like bass but dont want to forget the mids which are also important for me.
My personal room is about 3x7 meters and the other about 4x5 meters.
The speaker size for the sub should be between 12" to 18" and mids should not be bigger then 8".

So, I’ve cloned the Devore O96. Now I want try the Heretic Loudspeaker A612.

Here’s what we know. Outside cabinet dimensions are 30.25” x 25.5” x 17.75” and made from are 3/4” birch plywood. The co-axial driver is a Faital Pro 12HX230 based on a photo on HL’s Facebook page (attached). A photo of the crossover is also on their Facebook page (attached). According to the HL website, the driver is 8 ohms and the crossover is at 1700 Hz using a 2nd order Linkwitz-Riley series crossover. From the photo it looks like there is an L-pad on the tweeter.

Anyone care to take a crack at the crossover schematic?

Hi again,

Made a post yesterday with a crossover design i was messing with trying to understand it abit. It was obviously a horrific setup as people explained and have tried again.

I'm just wondering if this would be a sensible setup or not?

I've most likely made some stupid mistake again so all go crazy at me haha

I don't actually have any of the speakers or anything it's just a hypothetical senario for me to get the grasp of things, i've included the specification sheets for the speakers too in case that is any help.

Thanks

I decided it would be fun to try some single ended experiments with transmitter triodes. I already had an 811A and 812A from when I was trying some RF stuff. I decided to get an 810 to round out the trio of triodes. I want to use these experiments to learn more about driver stages. So far I've built a few capacitor coupled, no-grid-current amps, so this is new territory for me.

I decided to start with the 810, partly because it's a magnificent looking tube and also because it looks like I could get decent results with zero bias. I can always add some positive bias to increase the power later. I'm attaching the loadline for a 5K OPT (Hammond 1628SEA).

I have a Hammond 126B interstage transformer that I thought I'd try, since from what I'd read it seemed the simplest way to drive grid current. I had already worked with a 12HG7 - with 30mA of plate current it can easily swing 100Vp. I thought that if I coupled it to the 810 with the 126B (5K:5K - max 30mA) I might be successful.

It was not successful (as many of you probably could predict!) and I'm interested to understand what I need to do differently. I'm attaching the schematic.

If I connect a 5K resistor across the IST in place of the 810 I see a nice sine wave. With the 810 in place I get significant distortion. I will post the waveform later when I'm home. As I recall it looks like one half of the wave is distorted. I'm guessing it's the half when grid current is being drawn and my driver is not capable of delivering it. Could it be that the output impedance of the driver is too high?

I'd appreciate any guidance. At some point I will want to look at other drivers including FETs, but for now would like to learn how to use the IST.

Thanks

Richard

Hello,

I needed a remote controlled, very high audio quality attenuator for a preamplifier that I built. After considering the various options, I decided to design my own LDR volume controller.

It took a lot of effort, but it works well now, I'm pleased with the result. I would like to share the project with the DIY community, in case someone is interested.

So, here it is:
- customizable impedance, between 5kohm and 50kohm
- customizable number of attenuation steps, between 20 and 80
- you do not need matched LDRs
- LOG attenuation curve
- you can display your own welcome messages on the LCD screen
- the firmware is easy to update and modify
- remote controlled with any Apple remote
- big LCD screen, the volume level is displayed with 4-char high digits, easy to see from a distance
- the screen auto-dims to a customizable level after some inactivity time
- rotary encoder with push button
- controls up to 6 input and output stereo channels
- I/O switching is done with best quality latching relays with Silver-Palladium contacts, to avoid any degradation of the musical signal
- you can name each input and output channel
- the controller remembers the settings after power off
- can control a delay relay to soft-start a tube preamplifier
- achieves a large attenuation range by increasing series resistance at very high attenuation level and by increasing shunt resistance at very low attenuation level
- the calibration compensates for the load impedance effect
- the on-board calibration relays are best quality and they are powered only during calibration
- the LDR LEDs are working at low current (7 mA maximum), they will last a very long time
- the controller is isolated from the audio ground to avoid noise and loops
- separate linear analog and digital low noise power supplies
- power supplies on separate board, to keep the power transformer far from audio circuits
- easy to calibrate anytime from a menu – no need to plug jumpers or an external module
- better audio quality than R-2R relay attenuators (no multiple relay contacts and solder joints in the signal path, no noisy relay coils)

It is Arduino based - there are more powerful microcontrollers available, but the Arduino is much easier to work with, any amateur can easily update and customize the software.

The DACs are simply the PWM outputs switched to 31250 Hz (instead of the 500 Hz default value) and easily filtered to clean DC by two R-C cells.

The whole thing should cost around 100€ to build, much cheaper than the equivalent commercial solutions available.
I ordered the PCBs from ShenZhen2U ?PCB|Source|Assembly|Components-ShenZhen2U , where 10 pieces of 2 layer PCBs cost 10€.
You can even make the power supply and I/O boards yourself, to save some money, with the toner transfer method or even "by hand", because they are simple and single layer.

If you only need the volume control without channel switching, don't order the I/O board and parts and configure the software for either zero I/O (the volume will be displayed in the middle of the LCD in this case) or one input or output (if you still want to display a channel name).

Project status: built and confirmed.

The latest version (23 November 2015) of the project package is here: http://www.diyaudio.com/forums/anal...urce-selection-controller-11.html#post4526605

Improved firmware by Wineds is here: http://www.diyaudio.com/forums/anal...urce-selection-controller-15.html#post4590382

Firmware modified to support both 2004 and 1602 LCD by Howarthcd: http://www.diyaudio.com/forums/analog-line-level/278667-arduino-based-ldr-volume-source-selection-controller-27.html#post4725171

Zdr's custom code for OLED and LCD displays + bugfixes: http://www.diyaudio.com/forums/analog-line-level/278667-arduino-based-ldr-volume-source-selection-controller-55.html#post4889131

Hello everyone,

At the input of an amplifier, we put a capacitor of a few microFarads to block the possible continuous component coming from the preamp.

What type of capacitor gives the best results?

• a chemical type Silmic II, BlackGate, Nichicon Muse,
• a MKP (Polypropylene)
• a MKS (Polyester PET)
• a MKT (Polyester)

What is your experience in the field?

Thank you for your feedback.

Hi, I am attempting to build some rear speakers for the rear. I don't listen very loud anymore, I just want as clean as possible. I plan on using a Kicker 47KEY2004 in biamp mode, one amp driving a Morel Virtus nano MM2 midrange and a Memphis Audio PRX10 tweeter. The other amp with a Dayton Audio CF120-4 mid bass.
First question is what is the best way to protect the Morel mid? At such low power, would the 120hz hi pass filter on the amp be ok? Or just use a 200hz bass blocker?
2nd question. For the Dayton mid bass, should I just seal it in the enclosure, or try a passive radiator or tuned port?
Thanks in advance.

I'm working on a Pioneer PLX-500K TT for a friend. He said that the platter would not rotate. Based on threads in this forum and others, this seems to NOT be an isolated case. Replacement motor boards cost about as much as a new TT, so that's not an option. Besides, I'm enjoying the challenge of troubleshooting to find the root cause. I was an electromechanical engineering student, so I once had a solid grasp on the concepts involved, but that was 20 years ago and I haven't done much electronics work since then. It's nice to get familiar again. Luckily, I have a few experts from a university electronics lab helping me with advice on occasion. But they don't have much time to devote to my personal projects, so I'm mostly on my own.

I could document everything that we've done so far, but I don't want to clog up this thread (unless somebody specifically asks for that info). What I will note is that we tested nearly all components and they seem to be ok, except for the motor driver (BA6868FM). There was a short between pins 1 and 2. The driver was replaced but that didn't help. The motor coil pins (15-17) on the replacement chip had no output. We replaced the driver again, being very careful not to heat the chip too much. Still nothing. The driver was then replaced a 3rd time. Still no motor rotation.

We'd like to feed a proper drive signal to the motor board to determine if the problem is with the motor board or with the main board IC. It seems that main-board IC pins 25 (DRI1) and 18 (FRS1) output a signal to the motor board IC pins 10 (EC) and 11 (ED/S) respectively. If we can supply that signal and there is no output at the motor coil pins, then the problem is likely still the motor driver chip.

I know it's a long shot, but does anybody know what those signals feeding pins 10 and 11 on the motor driver look like?

Bonjour, je suis un débutant dans le domaine et je cherche des experts pour m'aider à faire mes choix dans l'installation d'un caisson de basse (pour commencer) dans ma voiture !

Been looking into LE Audio and saw that Bluetooth has been making a lot of progress for audio. However, if you look at LC3 codec, it can support 24 bit 48kHz stream, but it has a very low bit rate. It makes me wonder how a 24 bit 48kHz stream would be reduced by at least 6 times to wirelessly transfer the audio stream...

What info is lost in order to stream this "high-res" audio?

Has anyone done any work to improve audio over LE audio, and if so, please share your experience!

Hello

Just curious of what other thinks about this.
Before buying, how this SMSL RAW MDA-1 dac would compare to my Oppo 105D?
Oppo with 2014's tech 9018 /LM4562 amps or 2023's SMSL 9039Q2M /OPA1612...Mmmmm!
Should I have surprises?

My first post, I'm not entirely a newbie when it comes to this stuff, but definitely not a connoisseur like most here.

I have an Audio Reasearch SP11 I got for a good deal in pristine condition the catch is it is missing the SP-11PS the power supply. Is there away to build a power supply for it? Thank you would like to here your suggestions..

Hello,
I have an unfortunately defective Threshold Stasis 3.
I discovered that 4 transistors in the power stage are defective. Should I replace everyone here with new MJ1502*? Or can I only replace the defective ones?

A few transistors on the front end are also defective.
MPS6571 replacement by ??

MPSA42 replacement by?

Maybe someone here who has already replaced it can help me.

Isn't there an assembly plan for the front end somewhere?