Under
https://www.diyaudio.com/community/threads/dartzeel-amp-schematic-build-this.134362/
are describe various darTZeel clone versions but the diagram of the original models NHB-108 in fig 7 for distortion and noise waveform with fundamental notched out in the review under
https://www.stereophile.com/content/dartzeel-nhb-108-model-two-power-amplifier-measurements
so as the model NHB-468 in Fig. 9 under
https://www.stereophile.com/content/dartzeel-nhb-468-monoblock-power-amplifier-measurements
show an odd character of the distortion wave form;
only the lower half-wave has a sinusoidal character, while the upper half-wave is more like a triangular character (both mentioned diagrams also to see in the attached files No 1+2).
Every second half wave has the tip flattened (NHB-108) or rounded (NHB-468) in the upper area. Same diagram of attachment No 3-5 for the power amps Halcro DM38, Graaf GM200 and Pass Labs Aleph 4 don't show such an effect - lower and upper half-wave show identical character (clean H2 resp. H3 on Halcro's DM38).

I haven't heard the models NHB-108 and NHB-468 from darTZeel, but - as long as it is not a measurement error on the equipment from Stereophile - there is anywhere a deficiency in the circuit design which is also audible - so I think (go to the simplified schematic from attached file No 6 resp. to https://6moons.com/audioreviews/dartzeel/108.html) so as to to the various other schematics from attachment, which have a certain similarity in terms of the input stages and due the fact, that only local (serial) feedback (and no global NFB) exists regarded the "End Millenium" from LC-Audio (go for the circuit description to
https://www.octave-electronics.com/lcaudio/temil.shtml)

Where is to find a circuit description in detail for this topology from darTZeel ?

Thank you very much for an information.

hello,

about, Klark Teknik DN27 Graphic EQ, can someone point differences between these KT models ?

I have drivers and XO from a pair of Snell K III. (woofers need to be refoamed) If I build a cab the size of a Snell E can I get a decent clone or am I wasting my time? I was going to leave out the rear tweeter. Is there a big difference in the woofer between type E and type K. A good friend had a pair of E's that I admired for years. Thanks for any help or suggestions.

Planning my first non-trivial speaker build and would love any critique of my plan. Looking for a general all-arounder that lets me play with active xovers and a big multicell horn. I have lots of amps and different speakers but this would be my first foray into a more complex build. I have Klipsch Cornwall IVs as far as horn experience goes, other than that all of my systems have been full range or multiway standard drivers. So far my plan is:

Onken bass box

• Great Plains Audio 416-8b (here)
• Cabinet based on plans from Joseph Crowe (here)
• Industrial/basic style finish with exposed stainless hardware in most places
• Dayton speaker binding posts (here) mounted on plates (here)
• Belden 9747 internal wiring, soldered with silver solder

Midrange horn

• Great Plains Audio 288-8k (though it seems like they might have stopped making them?)
• 1505b wood horn from Marcus Klug (here)
• some sort of custom sled made from allthread

Electronics

• 1000Hz done with active box, either my current Lyngdorf or a future Driverack or similar -- will experiment
• amps -- will experiment

UHF / supertweeter

• will not add at first, maybe in the future

Thanks for any tips on matching or other things!

Hello,
This is my first post here. This forum is amazing and I would like to thank you for the great content and hugely supportive community.

After watching numerous videos on subminiature tube amplifiers(mostly from Thomas), I have decided to build one.

Initially, I've watched videos from "Uncle Doug" who is an amazing youtuber and teacher. He was the one who sparked my interest on valve amplifiers.
Thank you Doug !

As first project, I would like to start with lower voltages and small form factor amps. After looking on the web, I discovered the subminiature valves. 🙂

This is what I have in mind.I am thinking of replicating either a Fender Champ or a Marshall JCM 800 amplifier (I came across schematics from Thomas on numerous amps including JCM 800s).

With zero experience in this subject, I thought of using the following components:

- 6N16B and 6N17B valves
- Monacor TR-1005 100V Line Transformer MONACOR: TR-1005
- 4'' woofer was taken from a Logitech pc sound system
- Laptop SMPS
- DC-DC boost converter for nixie tubes

I have several questions:
1 - Are the components above ok for these amps?
2 - The speaker that I have is rated 25W and 4 ohm. Will the tiny amp be able to deliver enough power to drive it? Usually I see schematics with 8 ohm speakers, not 4 ohm ones.
3 - To have enough power to drive the speaker, would it suffice a two stage pre-amp, or would I need more stages to increase the gain ?

Thanks in advance.

Best regards,
Pedro

Hello

i saw the protodac some time ago and was wondering if i could diy myself one.. but i have a few questions...

• can i somehow use 2 chips for balanced output?
• if not can i use a transformer after the passive I/V stage?
• when i use a transformer, can i somehow get both output types out? (single ended and differental at the same time)
• could i connect the plain outputs of the chip to this board? https://www.audiophonics.fr/en/dac-...dule-for-dac-es9038q2m-es9028q2m-p-13977.html

sorry for the noob questions... fairly new stuff for me

thanks in advance, cheers

I'm offering one perfect matched pair of NOS R120 triodes for sale (= 2 pieces). Fully tested with Etracer, including curves.

La Radiotechnique R120 is a French indirectly heated triode produced in the 50s. Bling-bling: Jean Hiraga rates it highly in his book on triodes and it apparently won a listening test at the European triode festival from the likes of WE 300B, AD1, PX4, PX25.

Tubes are identical production-wise, with same date codes and matching is exceptionally tight:

Test conditions: 250v anode | -35v grid
Datasheet specs: 60mA (= 100%) anode current | 840R anode resistance | 6.4mA/v gm | 5.4 mu
Test results:
Tube 1: 66mA (110%) | 797R | 6.66mA/v | 5.3
Tube 2: 64mA (107%) | 812R | 6.52mA/v | 5.3

I'm asking 575 euros for the pair, including shipping in Europe at my expense (I live in Belgium). Priced to sell... you won't even find two non-matching R120 tubes anywhere near this price point 🙂

Here's the amplifier I wanted to build with them. Let me know if you also need a pair of nos Mullard ef37a.
http://www.pmillett.com/r120_se_amp.html

Some other matched pairs for sale: 71A globe, 841 = vt-51, 27 mesh, 01a, c3g etc.

Cheers,
Simon

Hello!

I recently acquired some bits from a Laney GH50L. I've trying to find the schematic, but I could only find the GH100L. I'm interested in the output and power transformer details, it would be great of someone can help.
Thank you!
Jose

Fellow DIYers!


This is to announce a group buy related to the F5Pi (https://www.diyaudio.com/community/...-m2-output-stage-perfectly-integrated.406024/) amplifier and hard to find mosfets for the US version.

The amplifier itself is mostly through hole, but there are some SMD components so those of you who are thinking of opting for this build should be comfortable with soldering 0805 and SOT23 components. This is not a beginners amp, so note that a reasonable level of ability is required.

So there are two options for anyone interested in building the amplifier:

1. You have the gerbers, you have your own jfets and mosfets and so all you need is the paper build guide and BoM (the guide will cover both Toshiba and US mosfets versions). Note that these will be circulated on paper to prevent unauthorised copies. There is a nominal charge for the printing etc, and then non-tracked postage to anywhere in the world for €10

OR

2. You want matched sets of 4x US jfets (MMBF5457/5460) with adapter boards, and 4x mosfets (Fairchild FQP3N30, FQP3P20) along with the build guide. The cost for this is €70 inclusive of tracked and insured postage worldwide.

The Jfets are matched at IDSS, and the mosfets have been measured for Vgs at 70mA and 90mA, resulting in matching for Yfs.


What other devices do I need?
The full BoM will be provided as mentioned above (all other parts are available at Digikey and Mouser etc), but you will also need matched IRFP240/9240. Gerbers are available freely to print your own boards at post #90 of the thread linked above.

What power supply is needed?
Bipolar 24V supply – but there are lots of options here, from a single supply for both channels, to 4x separate supplies for each front end and output stage. The options are too many to list. The front end pulls about 70mA per rail, and output stage about 1.3A per rail at 24V.


At some point later on in the year, it is hoped to offer a full set of boards similar to the amp that is shown in the first posts of the F5Pi thread if there is interest. This incorporates rectifier boards, 4x power supply boards (2 for each front end, 2 for each output stage), auxiliary supplies, front end and output stage boards, and boards for a version of the excellent Relaixed source select and stepped attenuator. Basically, all boards needed to build a fully integrated, end game quality amplifier as per the first posts of the thread.


How do I sign up?
First read the thread linked above – there is lots of information there. It is also worth your while reading the M2OPS thread as well as the output stage is based on this.
If you are still interested, there are a limited number of sets of mosfets we can provide – 20 sets in total. Please add your name to the list below, copying the entire list from post to post as you go. Mosfets are limited to one stereo set per person. Once the GB closes, I will send paypal invoices to all subscribers.

Example:
woodturner-fran - BoM only (so cost to woodturner-fran is €10)
EUVL - mosfets and BoM (so cost to EUVL is €70)

(Copy the list and add your name and which option you want)

Fran

Hello! I am looking to build some bookshelf speakers, and I'm hoping for some recommendations. I have read through some threads on a similar topic, but most discussions here seem to be at least 5 years old. I will be high passing whatever I end up with to play along with a couple of 8" subs, so I don't really need anything with deep bass. For this reason, I'm thinking something sealed might be ideal for me. Right now, I am considering the late Jeff Bagby's Kairos design, but unfortunately the plans for this speaker don't seem to be available at the moment due to the closure of Meniscus. Even if not for this, I would still be interested in looking at other options. Specifically, I am looking for a fairly high end bookshelf speaker with a width not exceeding 10" (and preferably not exceeding 9") that I can integrate with a pair of 8" subs at ~50-80Hz. Does anyone have any recommendations? Maybe something with pro drivers would be suitable? (Although in that case I might have to go ported given my size requirements)


Thanks!

Hello All,

After having my B1 Korg for approx 3 years and loving the sound I decided to install a motorized volume remote control, it is not one of the complete kits from the store. I originally installed dual 50K DACT stepped potentiometers to allow for independent left/right volume and was very happy with the sound.

The new motorized pot is a dual 50K “Alps potentiometer” (log taper, and assuming it’s actually Alps brand ) which controls the volume just fine, but there is a noticeable attenuation of the upper treble that didn’t exist before.

Has anyone experienced this before when changing out potentiometers? I’ve read that builders have preferences for brands, and that certain components can have “a sound” but I honestly did not expect this drastic of a difference.

This is the item I purchased…
https://www.ebay.ca/itm/16493711073...var=464467343788&widget_ver=artemis&media=SMS

Any recommendations, suggestions, in-site would be great.

Thank You

I have finally gotten started on reviving the Big Old Coax OB speakers. My buddy John Busch left these Coax drivers to me when he passed away last year.
John had used them in a couple of different OB configurations, the version I knew - we had at RMAF 2008. It had just the 18s, on OB no helper woofer. They were amazing! John and I worked to fine tune the passive crossover while we were in Denver. We never got it perfect, but it was much, much better than 90% of what was on show that year. Extremely dynamic with amazing imaging.

Today I made a couple of crude test sleds to get these up and running again. I wanted 30mm OSB,for the baffle but that didn't work out. So I have 13mm MDF (yuck). Here's hoping that the 2x4 braces add some rigidity to the baffle. Might need to add a cross brace below the woofer. It will get wings once it's up and running.

These are the biggest coaxial drivers I know of, and no longer made. They have substantial frames and weigh 17 kg each! The 18" cone serves as a horn for the 1.4" compression driver. This allows an acoustical crossover point of around 750 Hz, which this compression driver can do on this cone/horn.

I'll be using two QSC pro audio amps with plenty of power, and DSP active crossover because I have it, and because it should be fast to implement. Crossover work will begin tomorrow.

I am going to begin a new thread and consolidate my rebuild process . I acquired a pair of Beveridge 2sw-2 ( maybe they are 1s) in January. I have been reluctant to begin work due to life circumstances , however, over the past couple of weeks things have changed and I felt like tackling them.

I own a Beveridge Model 3s that has been converted to a all tube input and Direct Drive tube output amp . We will see what is up in the comparison when the time comes.

This pair is physically in good condition however, the amps are slightly different. One is raw aluminum one is painted black. My understanding from another forum is that the aluminum amp is a later model. My guess is there may have been some kind of failure back in the day and the amp was either returned for a replacement or rebuilt. Each amp has the sub woofer amp and active crossover. The black amp has a switch that affects the input capacitance of the SS driver amp. I read that this was a eq that Modjeski called " air" and "more air" . The only other difference is that the aluminum amp has Modjeski's servo control on the fan and the black amp does not. Both SS driver boards and HV boards are identical in each amp.

Both amps have been muddled throughout the years although the boards themselves are in remarkably good shape.
I began with a thorough cleaning. The aluminum amp had a catastrophic failure of the HV cap string and had underrated HV diodes in place , a couple were cracked. The original diodes were listed as M40- I could not find any data on them. In the end I used Diotec HV6 diodes 6Kv 200mA as replacements.

All HV caps and load sharing resistors were changed along with all diodes - I had to end up changing the caps in the voltage multiplier as they were just not doing their job.
These were sourced from Surplus Sales of Nebraska .1mfd and 4kV - the form factor was almost exact to original.

Lots is said about the HV transformer and my impression is that some might believe it supplies 3.2 kV directly. It does not. the ac output of both my transformers on the HV is 1.21kV and it feeds the multiplier.

I changed all the female banana jacks as they pitted and blackened with age , I did not want HV tracking on these. They are expoxied in so a bit of pain, I was looking for nylon nuts to secure the banana jacks but none to be found... I ended up threading 5/16" size to metric thread of the banana jacks.- I did not want any metal nuts and I wanted to be able to replace in the future if necessary.

I have one amp reliably running right now and will begin the second one. The panels measure equivalent from stator to stator and from each stator to diaphragm - there was some concern initially with corroded eyelet connectors but that was resolved. It runs pretty hot drawing about 2.2 amps @120V . Voltages are good at about 3100v +/-

Some pics from this journey. One more to go and then some testing with the panels.

When buying vintage CD player models in used condition from the upper price range, one should generally make sure that, electronic spare parts were used that were not made exclusively for the manufacturer and were also used in common brands and products.
This applies in particular to mask-programmed processors e. g. the MAB series from Philips with individual programming code (Txxx).

The "MD-1" transport seems to be therefore an example (but I am not absolutely sure).
According the youtube video under
Login to view embedded media (go to 0:11) the MAB 8441P T164 operates as servo processor, this type was also used in CD jukebox models from NSM and B&O Beocenter-Series - in the models 8000, 9000, 9300, 8500 and 9500.
This means, as replacement part still good available despite the age of 35 years, due the fact, that this program version "T164" was not exclusively made for Krell.
(according post #14 under
http://bbs.hifidiy.net/thread-540709-1-1.html
is the "T164" the professional version of the "T082" version used e. g. in Philips CD640/CD650)

But what about the display processor ?

The display itself, type "NSM4202A" which is probably in use - go to
https://www.diyaudio.com/community/...ement-for-philips-sony-cdm-transports.259790/
no issues should occur by ordering of replacements (is in the meantime no longer an issue due present remakes).

But the question is, which display processor is in use. Maybe the "MAB8441P T018" ?
If yes, this program version was also not exclusively made for Krell - go to Micromega's "SOLO" (first series) under
https://www.diyaudio.com/community/threads/micromega-solo-cd-player-help.191732/page-3
(images in post #52+53) and according
http://www.hifidiy.net/index.php?s=/home/marticle/detail/id/9630.html
and
http://bbs.hifidiy.net/thread-1048391-1-1.html
this user processor can be replace by the "MAB8441 T042"

If no, who know the type of the used display processor (in any cases also used for the operation instructions via RC) ?

Maybe the Krell model "CD-DSP" also haven't in the transport and display section processors exclusively made for Krell.
But all this I don't know exactly (unfortunately no images to find in tear-down condition of display PCBs for checking this).

Thank you very much for further advice.

Some URLs:
https://www.hifinews.com/content/space-age-cd
http://bbs.hifidiy.net/thread-1289393-1-1.html (very interesting details concerning first generations of Philips CDM mechanism and driver boards - unfortunately not in english)
https://www.octave-electronics.com/services/cdupgrade/cdupgrade2.shtml
https://audiodripper.jp/krell-md-cd-transport-restore
https://blog.naver.com/cellop2/100113477066

P.S.: Vasiltech published several years ago a CD-Player-DAC-Transport List with the used laser units (please note: URL corrupted or not adapted to current requirements).
If one had the same concerning the user processors, this would be very helpful in making a good choice when buying a used vintage CD player from the top class line.

hello,

I picked up some amplifiers that I'd like to install on speakers.
https://stewartaudio.com/products/av8-2-lz-d/

how to make the most of the low power of this model? I think of use it in artists' cabins or talent monitoring with a video display...

I need inspiration and guidance 😉

thanks

I'm looking at options for a a portable Bluetooth stereo speaker system. 60-100 wpc @ 8 ohms would be preferable, with very long battery life.

If I could find an amp and battery to power it, I'd aim for a pair of 8-10" woofers with a pair of 1“ soft domes crossed at 1.6 KHz 3rd order, fully DSP and EQ'd flat. From this system, I'd like an F3 at or under 40 Hz anechoic and into the 20's when corner loaded in a small room. Maximum output well over 100 dB @ 1w @ 1m, 3 to 4 ft wide with a sturdy handle on top. Is 40 lbs or less too much to ask?

Please let me know what options are available. Thank you.

Hi!
I have a CDP reVox B225.
It was working not fine.
But I enjoyed.
Recently, it shows as attached.
No working.

When plug in, says attached.
How can I fix ?

I am repairing a DD Z2B, which has the output shorted. It originally carries FDA24N50F, but they are sold out everywhere.

Is it possible to use FDA24N40F instead of FDA24N50F?

Thanks

Last week in my workshop : the "legendary" Iverson Power Amplifier.

Pictures of front and backside. The original time counter has been replaced
by one made in Germany and has already counted more than 8000 hours.

Speaker posts and RCA sockets are not original.

Hey

So I grabbed some vintage Bowers and Wilkins speakers built in 1982 and have found some specs, I'll attach here.
What I find weird is that it says the wattage is 15W protection circuit yet in the manual is says there is no wattage limit due to protection.

I have also owned the DM23 which have the same tweeter and it's said that they can have an amp from 10-100 watts. So really can it be true speakers this large are only 15W?

I am also thinking about building another amplifier as my Jean Hiraga 20W Class-A does not seem to give them the power they need so am thinking about an F5 Turbo which I've heard and built before for a friend and loved it!








87db

Hi all. I scored all these transcendar transformers new in the boxes today at a storage clean out, and now I'm curious.

4- OPT HC-51-OT, appears to be 50w UL 5k

4- OPT HC-100-OT appears to be a 100w PPP variant, somewhere around 2.3k with UL.

2- smallish maybe 15-20w 5.6k UL, no identifying numbers on these

2- HC-480-PT, looks like 120>HV, and 2 heaters.

I'd really like to hear from anyone who's tried out either of the larger PP OPTs. Or who knows of any info, amps they were used in? Or maybe I won't, maybe these were customs? I can't find any info specific to them on the net.

Thanks all,
Loren

At work I have a pile of boards that each have two Apex PA88 high voltage op-amps on them with heatsinks. these are rated for something like 450V and 100ma each. the boards were used to drive Piezo sensors so the are set up with a single ended input, One opamp inverting and one non inverting with a bridged output. power requirments would be +/- 200v up to 225v max. so they could output 400-450V P-P at 200ma! gain is set around 18-20db something like that but can easily be changed.
The Apex PA88 are crazy expensive new. so they have been hanging on to these old boards and have finally decided to let go of them. so I am curious if they would have any use for audio stuff? maybe for driving electrostatic panels directly? or as Tube drivers or. driving output transformers directly for testing or something. would there be any interest in them?


Zc

Hi. I have a EMT 981 cd player where none of the buttons are working except open/close drawer.
I have not found a sevice manual for this cd player, so hard to start searching for the cause.
What could be the couse of this symptom?

Hi there I'm looking at some Onken speaker plans that call for 3/16" through holes in a number of places. I'm not totally clear what type of hardware these are assuming, as I'd been just planning to use deck/wood screws on the build. Would this likely be for a t nut and 3/16 machined bolt? If so, do I need to worry about how to make those air-tight? Thanks for any tips, first time cabinet builder here.

Hi folks, got a DAC with a pair of 6s45 and one 6z4 rectifier. The 6s45 tubes had a kind of unpleasant, cold and edgy sound in the beginning using Nordost Silver Shadow spdif cable. After a while when they got broken-in I replaced Nordost with a copper-based AES cable, the edge and unpleasantness were gone, but some sterility still remains.

Now I have an option to modify it for using the 6x4 rectifier and 5842 tubes. The mod will be done by the DAC designer. The question is if it’s worth it. I’ve never had any experience with WE 417 or 5842 stuff.

If you could point me in the right direction I’ll appreciate that.

Strong MQA vibes, ill let you decide the rest..

Login to view embedded media

Hi, fellow audio enthusiasts. Can someone please explain to me what Denon mean when they say that you need an anti oscillation resistor on the probe for the dc meter when adjusting the Bias. It's got me stumped. I have searched google with no luck.
I appreciate your knowledge and am grateful for a site like this.

The above is for sale on ePay (US) currently - it is a very nice piece of kit. I have nothing to do with it and am not bidding, just noticed it and wanted to pass it on.

ePay ID: 235491683020

Hal

I’m looking to buy one of these. Let me know if you have one or even a partially built one.

Hello all, Is it safe to crossover a 17cm driver at 3khz, 3000hz to a tweeter? I wanted to build the SB ACOUSTICS ARYA, but am uncomfortable with the 3khz crossover to the tweeter. All comments welcomed.

Hello!
My friend is seeking a dipole subwoofer for his stacked ESL-57 and crossover at 80Hz. Is Acoustic Elegance Dipole 18 a good choice?

https://aespeakers.com/shop/dipole/dipole18/

Considering using the GPA 515-8 in an Onken 360 cabinet. Today I have some problems with the bass response from 200 Hz using the celestion 3070C.

The GPA Vas parameter is significantly more adapted for the Onken 360.

I was given a link to a DIYer's B&W 802 D2 upgrade page. One of the very interesting pieces of data there was a measurement of the raw B&W D2's tweeter in the cabinet, and I wanted to share it with you all in the hopes of reading expert opinions on it. Petr focuses onthe change in directivity above 3.5 kHz, while I focus on the 5 dB disparity in output.

This is not at all a well behaved tweeter to my eyes and would make any passive crossover a real challenge. Is the change we see due to some sort of built-in wave guide effect, or uneven reflections coming from the nautilus chamber behind the tweeter, or both?

Hi,

I've built my first pair of speakers (other than subwoofers). I've used components from a well-known American speaker component retailer.

The drivers are all Dayton Audio 8 ohm drivers - each speaker has a DC300-8 12-inch woofer, a PC105-8 4-inch "full range" driver as the midrange (one of its suggested applications), and a DC25T-8 1-inch dome tweeter.

Each speaker has a ~1.5 cu ft sealed main/bass enclosure (built from 18mm / 0.7" thick MDF). Inside, the top, bottom, left and right walls, and part of the back wall (around the PRV Audio 3DF500/3500 8 ohm 3-way crossover - 500Hz and 3.5KHz at 12dB per octave) are lined with two thick sheets of polyester wadding.

Built into each speaker is a ~0.07 cu ft sealed midrange enclosure (made from a 10mm / 0.4" thick rigid cardboard tube, with an 18mm / 0.7" thick chipboard baffle and rear piece). Inside, polyester wadding is fitted to one side of the length of the tube.

The woofer impedance jumpers on the crossovers are correctly set to 8 ohm, and the attenuation jumpers on the midranges and tweeters are set to -6dB (it's not enough attenuation, so I'd like to add L-pads, but I'll worry about that another time).

Now, obviously, until I add the L-pads, I'm using equalisation (system-wide software on my source PC, in my case), cutting the frequencies in the passband of the midranges by one amount, and cutting the frequencies in the passband of the tweeters by another amount.

However, unlike the woofers and tweeters, the frequency response of the midranges within their passband is far from flat. There's an enormous peak around 400-600Hz, into the double digits of dB.

This is despite me having been advised that the very reason for making the midrange enclosures as "big" as 0.09 cu ft (granted, I had to make them ~0.07 cu ft to fit), is to not cause such a peak around the midrange HPF of 500Hz.

Other than the midrange enclosures being slightly smaller than I was advised to make them, what could be causing such a big peak around 400-600Hz? And what can I do to get rid of it?

I understand that in 3-way speakers with passive crossovers, the woofers and tweeters are wired normally, but the midranges are wired in reverse polarity.

To my knowledge, I've done this - I've wired the woofers and tweeters normally at the driver terminals. Then, I've wired the midranges "backwards" at the driver terminals, then normally (both internally and externally) at the midrange enclosure terminals.

That of course is assuming that the colour coding of the midrange wires from the crossover is not reversed (black wire for +, and coloured wire for -). Could it be the case that it is?

Tomorrow, I'll swap the + and - wires "externally" at the midrange enclosure terminals and see (or hear) whether or not there's an improvement.

Other than that though, what can I do? Fit more polyester wadding in the midrange enclosures? Apply bitumen deadening to the midrange enclosures? Wrap polyester wadding round the midrange driver frame openings? Use smaller (3") and/or different make/model of midrange drivers in the same enclosures? Modify the midrange circuits of the crossovers to raise the midrange HPFs to say 1KHz? Anything else?

Any help would be much appreciated 😊

Hey All,
I have been supplementing my Adcom SLC-505 controller with a Shiit Magni pre- headphone amp. I still miss a bass tone control! As part of this re-building of an active pre-amp, I would like to place a passive stereo bass control (James?) in front of this 25K "Schiit" load. A 6db insertion loss could be compensated by bumping-up the gain via the switch. What would be a good circuit that would mildly boost or cut bass?
Thanks!
Paul

Hey fellow DIYers……I’ve seen many of these builds here and elsewhere…..even read through a few of em only to get left in the dust of confusion as to the design principles and the ‘why’ of it all. Not to mimimalize the design or the efforts undertaken to build them in any way……just what makes it the advantage over the more classic and conventional solutions when considered for practical in home applications. Thanks!

So I have a two pin 220v power switch that I have between the power socket at the back of my amplifier and the PSU that cut's the live wire between them when flipped, but is there any maybe electrical or safety benefit to instead having a four pin one that also cuts the neutral wire as well? 🙂

Also if this 2 pin is good enough and I want to add a 220v power LED this, I guess I should add this in parallel with the wire between the switch and the PSU?

I built this Pete Millett design with the intention of selling it to fund future builds. It is presently for sale at USAM for $550. Full description there. I will knock off $100 and pay shipping if I can sell it here quickly. For $450 PPD you are getting a great build along with a DHT triode sound. Plug and play.
The separate black/brass box contains the power transformer, reducing the chance of unwanted noise.
The SP1 Korg NuTube is isolated by a product developed by Pete Millett, and it works. There is no gain in this buffer design, and so the volume control is used to keep any 'hot' source at a level that doesn't overdrive the circuit. The selector switch is made by EIZZ and they are what I use when I want quality at an affordable price as compared to Elma and other more costly selector switches.
Yes, free shipping in the USA lower 48 only! All other locations to be negotiated.

Please note that some of the photos were taken before completion of the build. This unit is completely ready to use.

Dear all,

Recently a Sphinx amplifier entered my workshop. It is a model 14 with 2 tubes and Mosfet's in the amplifier stage. These are the 2SJ50 and the 2SK135, very famous in Holland in the 80's when Elektuur came out with the Cresendo amplifier for diy purposes and these mosfet's.
The tubes are ECC88

The reputation of the 14 is not so good. Later, Sphinx made a rebuild which was more reliable. The biggest problem is the design of the PCB and the power supply for the tubes. But the sound is fantastic!

Well, my question, does anybody have a diagram for this amp?

Thanks in advance for the help and i'll keep you folks posted.

Ah, the problem is loud hum and oscillation.

Here are a pair of fully built, tested, biased F6 boards with NOS Toshiba JFETS installed and the green LED biasing mod installed for quick temperature stabilization after initial turn on. Output Fets are IRFP150’s which have a small advantage over the usual IRFP240’s with regards to durability and intrinsic matching. Boards have been completely cleaned and DC offset is near zero.

$OLD/pair delivered in the USA. This offsets the costs of the Jensen transformers and NOS JFETS. Plug & Play if you have Modushop 4U/300 with UMS drilled holes.



Payment preferred is PayPal F&F.

Thanks!

Anand.

Different power tube types in a fender bassman amp?

I thought power tubes has to be matched and the same but I’ve just taken the back of a 59 Ltd and it has a GT6L6R and a GT6L6GE.
One is noticeable taller than the other.

Is this ok?

I've just rebuilt this amp with new output transistors. I've also replaced fuse resistors, touched up solder, replaced bias/offset trimpots etc. I've replaced the caps in the power supply, power amp, and preamp.
It plays music, but it is impossible to get the DC offset stable.

• The offset adjustments are extremely sensitive, and adjusting one channel affects both channels, so I have to go back and forth while watching both channels.
• Offset keeps wandering. It starts at over a volt when I turn on the unit and slowly descends over a few minutes.
• There is a ~50-100mV of offset difference depeneding on whether or not speakers are selected
• Offset jumps about 200+mV when I switch to tuner. Seems there is no highpass filter on the tuner output and I'll have to add one.

This looks like one of those weird designs where the preamp and power amp are combined? Any other design oddities?

Are there some mods I can do to get this thing to settle down? Tweaking filters?

Selling a SME 3012 Series II Tonearm, in great condition

Including counterweight, bias weight and anti-skate weight

Including SME headshell and spacer block
With RCA conversion kit installed

Without cartridge

Asking 950€, will ship worldwide

Could I ask you for the ability to send private messages please?

Looking for the best SQ Phono LCR schematic, attached all schematics that I got it surfing the net.

Afternoon all,

I am not very well at the moment but am trying to keep myself busy. I’ve got a lovely REL Stadium III with low output, buzzing etc. Decided to pull the (mint) plate amplifier but did not note the polarity of the main caps before I unbolted them. The caps are marked clearly. Having been caught out in the past, can someone clarify if both negative poles couple in the centre? This would be my guess.

Kind regards

Mat

I have been working on these cabinets, finished the veneering a week ago.

The design was subject to a modification by Modafferi to incorporate his XO design (infinite slope).

I have both XOs. Just to illustrate the electrical responses:

Hey all. I'm wondering what the required thickness of a given material would be going from a box to a sphere to achieve an equivalent damping ability. It's tough to break an egg putting equal pressure all around but obviously not applicable in the opposite direction. I'm thinking of building a pair of 2 way spherical speakers. TIA

Hello everyone,

I am on the process of swapping the OPTs of a push pull EL34 amplifier with higher quality (and hopefully better sounding) OPTs.

With the occasion, I was thinking about moving the OPTs outside the amplifier chassis, in separate enclosures, and wire them with a connectorized cable.

In that way it'd become very easy to swap the transformers for an A/B comparison, and also it would reduce the weight of the amplifier, which is not an irrelevant advantage considering that I suffer of back pain and that the new OPTs weigh 10 kg each.

Any thoughts?

Ian Canada fully built/fully functional dac/streamer.
Built this for a winter project. Sounds phenomenal.
Details:
Stationpi Pro
FIFO q7
Ess Dual mono dac
Opa861
Dual Linear pi x2
Ess controller
LifePO4 mini 3.3v
UcConditioner 3.3v
Accusilicion 338 clocks
5in touch screen loaded with Ropieee
A lot more
Build thread here. https://www.diyaudio.com/community/threads/help-with-ian-canada-shopping-list.408502/
Shipping CONUS
$1500

Wanted To Buy:

I would like to redo my music and home theater with quality horns.
Unfortunately, I did not have the money when these were available.
I have heard a number of them though and enjoy the sound.

DIYSG SEOS horns 12" 15" 18" (pairs only please on 18")
DIYSG compression drivers Denovo DNA-360
DIYSG SEOS kits for 12" & 15" horns
One Acoustic Elegance TD15M, 8 ohm, non-apollo (North America only due to shipping cost of woofer)

Please PM me with what you have, thanks.


Oscillate

This is a not-quite working scope that needs some TLC (that I can't provide).

The CRT on this scope is dead or nearly dead. There may be other problems. One channel was working about 10 years ago.

I'd hate for this classic to go to e-waste. Come by and pick it up if you're in LA and can make good use of this (to rebuild, or for parts).

Up for sale is a couple of Terrapin Audio Cobalt Amorphous core MC Transformers:





Can be wired as 1:10 \ 1:20 or 1:40

These have been compared favorably to many top MC step up transformers (including TX103)

1:40 is perfect for Ortofon SPU series and other cartridges with low output,

300$ for a pair

===========================

Rare 6N23P Matched Pair of Silver Shield - Holy Grail 75' SWGP Reflector ECC88 6922 E88CC 6DJ8​

NOS

400$ for the pair




=========================================


6N30P-DR Matched Pair - NOS






500$

Only 3 units left, The size is 12x7x5 in. The side panels have been repainted due to water damage. The front panel is in good condition. only $16. each.

Dear Friends,
after having succesfully repaired and upgraded my ML335 and ML336 amps a couple of years ago (other post), with your valuable assistance, I am planning to upgrade also my ML380S, although it is in good working stage.

After 20 or more years, i believe it is time for this.... While i was planning to change only the electrolytic capacitors (with Rubycon ZLJ series), I noticed the significant number of old opamps used in this circuit, most of them already obsolete or not state-of-the-art.

So, a 'crazy' idea came up: to change all opamps with the best i can find nowadays.
More specific:

• ADEL2020 (instead of EL2020)
• LM4562 (instead of AD823)
• OP275 (instead OPA2604)
• OPA828 (instead of OPA627) - not that easy as the OPA828 comes only in SOIC, but can be done i guess...

These are the top replacements i have found up to now. If someone has something better in mind it would be very usefull.

So, theoritically, such upgrade will give a huge 'boost' on the already very good preamp, right??

However, on a second thought, few questions came up:

• what about the gains. Unfortunately i do not have any detailed schematic, only few parts i found here. If someone has the complete schematic, please contact me.
• with the device be stable after such extended upgrades or am i going to destroy it instead of improving it...?

So, if someone has done such upgrades before, i would appreciate a tipp.
By the way, Hans Polak i would appreciate your opinion. I remember from the past that you are 'kind of expert' on Mark Levinson designs 😀

Thank you all.

Best regards,
Theodore

HI,
I built myself an amp with irfp240/9240 which has soft clipping at any frequency. I noticed that BEFORE the Zobel L//R network (0.7uH//10ohm) on a 10ohm//470nF load oscillates little, but AFTER the network oscillates a lot, as shown in the photo...in any case the probes are connected to the terminals of the amp and not after the meters of cable, is this behavior normal?
Thank you

Hi All,

Which DAC board can you recommend to play with the ESS9038? I’d like something like the Buffalo, with no IV on board and decent regulators.

Thanks,

D.

Hi I have a rega 3 brio which has one dead channel.

I'm fairly practical and have some experience in home electrics, plumbing etc. I have a multimeter. I was wondering how I would go about repairing the amp myself. What I need - equipment, diagrams etc? What skills I need to learn? Where I would get quality/original parts? If anyone has any thoughts to these questions it would be much appreciated. Also willing to be told go to a professional..

Thanks in advance

In this post I test the Fezz Audio Titania Class A/B integrated amplifier. The amplifier is on kind loan from a friend.



Details

• Made in Poland
• Push/pull class AB1
• 3 RCA input
• 2 x 45w
• Frequency response:18Hz-103kHz (-3dB)
• Net weight: 17.5 kg
• KT88 x 4 (power output), ECC83 (12AX7) x 2 (pre-amplifier and power drivers)

In this blog post I will provide the follow test data.

• Harmonic distortion (H2,H3,& H4)
• Intermodulation distortion, 12 band/octave test tone (IMD)
• Gedlee Metric (Gm)

I test at the following output voltages using a reactive 8ohm load.

• 0.06V
• 0.25V
• 1.00V
• 4.00V

The above voltages correlate to the following output power using the following equation.

Power = Voltage squared divided by Resistance

• 0.00045m watt
• 0.0078 watt
• 0.12 watt
• 2.00 watt

For a speaker rated at 100dB/1w sensitivity, the above power correlates to the following speaker SPL.

• 70dB
• 82dB
• 94dB
• 106dB

Harmonic Distortion ​

0.06v



0.25v



1.00v



4.00v

Intermodulation Distortion ​

0.06v

0.25V

1.00V

4.00V

Gedlee Metric (Gm) ​

Below is an overlay of the various output voltages.

Conclusion

The Fezz Audio Titania seems to really hit it out of the park at the 0.25v test voltage (86dB speaker output) with very low distortion for all tests (Harmonic, IMD, Gm), however bass distortion seems elevated compared to my Meixing Mingda tube amp results found here. For example the Meixing keeps bass distortion below 0.10% while the Fezz has 0.24% for H2 and H3.



Comparing bass distortion against the Mingda we see lower distortion.





So far I've tested four amplifiers to date. If I compare the IMD of each amplifier for the 0.25v output (10kHz region), we get the following summary.

Mingda: -70dB

Rogers: -65dB

Nelson Pass ACA Mini: -74dB

Fezz Titania: -70dB

Subjective Listening​

I conducted my listening test with the shallow horn speaker system No.1928 and found that the amplifier sounded very similar to the Meixing Mingda. In fact, I could not tell the difference between the two amplifiers except for the bass. I found that the Meixing Minda has tighter and more defined bass. This correlates to the objective data where we see the Fezz Audio Titania with slightly higher distortion in the bass region only.

For interest's sake, here is one of my test tracks. This song is particularly great at bringing out an amplifier's ability to sound authentic on wood instruments. Particularly at 3:22 where you can really hear the body of the violins. Both the Minda and the Fezz sounded excellent on this test track.

https://tidal.com/browse/track/30779574



Conclusion

The Fezz Audio Titania matches the performance of my KT90 Meixing Mingda Single Ended Tube amplfiier but does not quite match the low distortion of the Nelsen Pass Amp Camp Mini, but betters the Rogers Sound Lab.

Post a video (audio related) that inspires you


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Here is a little something that I've been playing around with for a few months. Mostly for my own pleasure and learning (it is DIY after all!), but I thought I'd share.

Orpheus is an op-amp driven, DC Servo equipped class-AB headphone amp with a real-world THD of 0.0044% (THD+N = 0.0074%). Clipping starts around 4.2v into a 32 ohm load.

The circuit presented comprises:

• A basic input filter;
• A simple voltage follower buffer;
• A non-inverting op-amp stage with an adjustable gain from around 2x up to 3x;
• A simple diode-biased, Class-AB push pull output stage;
• An op-amp driven DC Servo.

The non-inverting amp stage has been set at about 2.1x gain, which I found to be plenty. A potentiometer (R13) allows for an additional 1x gain as well as channel level matching. Gain can also be increased by changing the 1k feedback resistor (R5). At 6x gain, THD increases to 0.0044% and THD+n to 0.0074%. The amp stage has a feedback capacitor which lowers the gain of higher frequencies for stability.

The output topology is simple and gets the job done with 4 resistors, 2 transistors and 4 diodes per channel, having slightly less than unity gain. One characteristic of this topology is the possibility of thermal runaway, so the diodes should be mounted on the heatsinks. The output stage in this amp is quite lightly loaded, so this shouldn’t be a problem. I used BD139/140 pairs for the output, but others such as the TTA004B/TTC004B should also be quite suitable.

The DC Servo (courtesy of Rod Elliot’s wonderful website) using the venerable TL072 cancels out the DC down to between -1.5mV and +4.5mV, which is perfectly acceptable. The servo eliminates the need for input and output capacitors, and gives the amp a polite power on/off behaviour.

The PSU is a simple +/-15v CRC filtered supply that I designed around the 10W Recom RAC10-15DK/277 SMPS module. It provides plenty of regulated power with good smoothing and rejection. It has provisions for a ground loop breaker if required (independent of the Protective Earth of course).





A more expensive second PSU was also designed using the Triad Magnetics FS36-170 transformer and LM317/337 regulation. The transformer is dampened with snubbing (Cs, Rs, Cx) and again, GLB provisions and independent Protective Earth are there too. The voltage can be varied a fair bit, which makes this PSU suitable for other applications also.






The amp PCB is 99x100mm and fits into the Hammond 1455 series enclosures. I opted for individual ground traces with a separate ground plane.



Op-amp selection:

For the DC servo, the TL072 with it's JFet-input is the best choice. The NE5532 will work, but not ideal.
For the amp, the NJM4556 is an excellent choice, but the circuit works well with others such as the NE5532. The circuit should be stable for other substitutions.

But how does is measure?

The frequency response measured acceptably flat and the amp has descending harmonics, dominantly H2.




* There is a 4KHz and 8KHz artefact from the Focusrite, possibly USB related.


But how does it sound?

I’m no connoisseur, but I’ll try to describe it the best I can.

I found the sound to be very detailed and the amp responsive to complex pieces. I heard details in songs that I haven’t previously detected and the reproduction of voices felt accurate and realistic. I found the amp pleasant and not fatiguing to listen to over extended periods.

Orpheus is powerful enough to drive all of my headphones, from my 150 ohm Yamaha HP-50 Orthodynamics, the 38 ohm ATH-MX50, 32 ohm ESS 422H Hybrid AMTs and my HE-X4. All of them paired nicely, but the best detail and bass extension came from the ATH-MX50 and the easiest, most relaxed listening was from the HE-X4. The ESS were a lot softer in detail, but I find that is their nature and not entirely to my taste.

Noise wise, the amp is dead silent at full volume with no input connected.

The finished amp:

Thanks for reading.

Hello to all solder sniffers!!
Just joined.
Hope I can expand my Valve horizons here. They are a mystery to me,,,,,,, at the moment!!
So, question from someone new to valves but not electronics in general.
My grandfather was a valve nut,,, when he passed he left boxes of them to my father. I now have them and want to build a hifi amp with them while my father is still around (as I promised to a few years back ;-)). He's now 80's so time to pull my finger out.
I have so many valves its a nightmare just going through them. BUT in one box there are 3 matched pairs of KT66's new in boxes from maybe the 50's 60's,,, (maybe earlier) GEC, Marconi and another,, can't remember.
Hundreds of other valves,,, I've checked up on some and some good audio ones. My Grandfather used to fix radios, TV's all that kind of stuff as a side line.
So looking for some advice,,,
First stereo Valve amp project,,, not too huge or technical,,, but sounds great and good learning base for other builds later.
I'm sure many here have been in the same position,,,, be happy to hear from you.
Have a good day all.
Cheers.

Hey folks, I am looking for an existing DIY project that can make use of 8x Excel W12CY001 drivers I have in the basement. Any suggestions would be appreciated.

I am revisiting my old project - 4way DSP2DAC crossover with ADAU1452. For the moment I am having trouble starting up ADAU1452 core with MCLK. While working with analog devices engineers to figure out what I messed up, I thought I'd post it here.

Looking for Blame MKIII- HX boards .

I've been investigating different ways of building a better turntable plinth. There appears to be a lot of myth and misconception surrounding the techniques used in proper plinth design, and not just from the DIY crowd. I did a lot of on-line research, but the best resource I found was this site:

http://qualia.webs.com/plinthbuilding.htm

He also posts at these sites as well as others:

plinth building - audio qualia
Lenco Reference :: Damping factors
audio qualia - Information


The author does a great job of explaining the physics behind a seemingly simple concept of building a supporting structure for your turntable's components and applies the necessary amount of scientific rigor to the problem, rather than guessing at the results or just hap-hazzardly combining materials that may look good, but produce specious results. I highly recommend anyone interested in the subject to read through his website, but the short version of it (if I may paraphrase and with apologies to Bryan) goes something like this:

There are 3 areas of acoustic interest regarding the plinth, divided by 2 boundaries: One measured (resonant frequency) and one computed (critical frequency). All solid objects will have a resonant frequency (or multiple Fr) at which they will vibrate when excited properly. The critical frequency is computed and is affected by the density (P), thickness(h), Young's modulus (E) and Poisson's ratio (v) of the material: fc=[c^2*sqrt(12*P*(1-v^2)/E)]/(2*PI*h) (where c=speed of sound in air). The critical frequency is the frequency where the material becomes acoustically transparent. Vibrations that originate in the plinth (or a component such as a motor attached to the plinth) will propagate freely into other components and radiate sound into the air. Airborne vibrations at Fc or above, will freely enter the plinth and propagate into other components attached to the plinth.

Below the resonant frequency, vibrations are mainly controlled by the bending stiffness of the material. Between the Fr and Fc, mass loading mainly controls the vibrations and above Fc, only damping controls the vibrations, although damping has an effect across all 3 areas. Ideally, you want some spacing between Fr and Fc for mass loading to be effective; if Fc is at or below Fr, increasing mass will have no effect on vibration control. Increasing thickness lowers Fc and raises Fr, which are both undesirable, so you want a material which is thick enough to provide good stiffness, but not to thick that causes Fr and Fc to converge or cross. The ideal single material would be very dense, stiff (but not too stiff), thin and have good natural damping characteristics. Unfortunately, there doesn't seem to be a single material that hits every check box, so the next best thing is to combine materials into a layered construction.

The situation described above is valid for a plinth made of a single layer of homogenous material. It gets a little more complicated when you start to layer different materials. Finite Element Analysis may be the proper tool to analyze layered approaches, but simulators are only as good as the models you feed them and so far, I haven't found an adequate model for multilayer panels. I took a more empirical approach and measured/computed individual materials that seemed like good candidates, combined them in a number of ways and measured the composite results.

One of the most common approaches is to use a technique called Constrained Layer Damping or CLD. A number of mfrs claim to use CLD plinths, but technically, they aren't CLD. CLD uses two stiff outer layers that are attached to an inner damping layer via a visco-elastic layer between each section that dissipates the vibrations as heat when the layers flex. The VE layer needs to be elastic, but have high sheer strength and be thin enough not to create a "sprung" design. The author of the reference website explained it this way: If you hold a piece of glass between your fingers and strike it, it will ring. If you loosely place another piece of glass on top of it, the first layer will be damped and ring for a much shorter time. If you tightly bond both pieces of glass together, they act as a single layer of glass and will ring when struck again. I'm confused by some of the commercial designs that seem to ignore the basic premise of CLD design. Instead of a damping layer sandwiched between 2 stiff layers, with visco-elastic material between them, they have a stiff layer (aluminum) sandwiched between 2 damping layers (MDF or acrylic) with rigid glue holding them together, and fairly substantial hardware bolted through all three layers (feet, platter bearing, tone arm mount) that will reduce the isolation created by separate layers. ClearAudio does a good job of this using thin aluminum outer layers, with a thick layer of Panzerholz between them, which has excellent damping characteristics. VPI uses MDF-Aluminum-MDF which does not provide the optimum characteristics, and bolts the layers together as well as gluing them. When I eventually settled on the materials and construction that I wanted to use, I mounted the platter bearing and tone arm to the top stiff layer only, they are isolated from the damping layer and the bottom stiff layer. Likewise, the feet are attached to the bottom stiff layer only and isolated from the damping layer and top stiff layer. This provides maximum coupling between the platter and tonearm, but minimum coupling between the platter/tonearm and the outside world.

Hi,

I have Bartolucci plate chokes for sale. They were purchased maybe 10 years ago, if I remember correctly.

Model is FMPC 226.

Good thing I wrote that down because the web isn't online anymore.

They were rated at:
200H @20hz
DC current 20mA
Rdc 516R
Freq response 4Hz - 80kHz +-3dB

Price is 200€/pair!

If you have any question, don't hesitate to ask.

Hello. I have Mirage OM6 speakers and are pleased with the big bipolar/omnipolar soundstage. Now I have the chance to buy OM8 very cheap. I think they use same tweeters and midranges so I can use them a spares. But I got another idea; what about using the top,skipping bass module and using open baffle in bass instead? Would this be totaly wrong combining two different solutions? Bipole top with dipole bass?

I have a class-A small signal TIA challenge to be solved with BJTs.
From your experience, which transistor models are similar or better to the BC550 in noise figure, but much higher voltage VCE0?
Maximum input signal, for example, is 5mVp@1KHz delivered by a pickup coil. If I design for 80dB amplification, the output signal is already 50Vp which in class-A it requires VCE0>100V.
This is not a power amplifier, it is a preamp.
Which direction&part do you advise and recommend?

1x L-adaptor high current PCB $18
2x Salas SSLV 1.3 $25 each
2x Reflektor-D $18 each
Plus active devices 18 x measured PF5102 (measured at <7.5ma for $1 each) and 12x BC560C for Ubib, $18 (Setting UBIB for 5v needs the measured PF5102)

Free shipping in UK for the above, would prefer the equivalent in £. Can supply links to the build guides and original group buy.

Originally purchased from Teabag, brand new and unused.

I have a few PCBs to build an active 2-way crossover (4th order, Linkwitz transform in both LP and HP sections).
The schematic of the circuit and the PCBs are shown in the photos below.

The cost is 19 Euros for one PCB (shipping is included). For 2 pcbs, the cost is 33 Euros (shipping is included).

I will provide also the PCB assembly guide.

If you are interested send me a Private Message.

Im looking if someone maybe have for sale completed board and ready to use of this papa designed preamp?
Plese contact me if you have one for sale.😉

Hi all,

I can see there’s a lot of experience of the NS1000M here, so maybe someone can help me?

I’ve just joined the club with a really nice lateish pair, and want to start tweeking them. I want to initially go active on the bass, and use a simplified crossover on the mid/tweeter. I will use an active crossover for bass to mid at 500hz LR 4th order, so don’t need a low pass on the mid. And I want a simple mid HP filter / tweeter LP filter, 2nd order, with no L pads.

So what is the consensus for cap and inductor values for what I want to do:

1) Stick with the Yamaha values as they are now?
2) Or is there a better crossover point to aim for? If so what are the values I need.

I’ll be using low power class A on the mid/high, and class D for the bass.

Cheers,

Jonathan

Hello all.

I have extensively repaired this amplifier and all is well and working good.

I was wondering if somone knows what VR102 the 5k pot is for on the board? The service manual does not mention adjustments.

In the parts description it is called volume? Does this need to be adjusted and how is the proper way. I have not moved it from the factory setting.

I've been investigating MarkAudio drivers & I'm itching to try a design. It occurred to me that a 4" driver (like the inexpensive CHR-70) mated with a low cost high efficiency 6" or 8" bass driver could simultaneously achieve baffle step compensation & relieve the load on the 4" driver, when crossed over at the baffle step frequency. A double chamber bookshelf style box is required, no biggie. The crossover could be fairly simple too. Has anyone published a DIY design along these lines? Thanks in advance!

Hello,

I'm just curoius to know if anybody has had any experience with these knockoff hypex modules:

https://www.ebay.com/itm/186177367845?var=694210321088

Just ordered one with this PSU to power it:

https://www.ebay.com/itm/375000352708

I know that people aren't going to like the chinese stuff, but just looking to see if anybody has had any success with these yet.

thanks and cheers.

Hi All,

I'm inventing something for the effects pedal market. As in distortion pedal, delay pedal etc. I know only a bit about electronics and circuitry. Engineers will help me later. For now I'm just trying to understand this:

Is it possible to remove any given pot from a pcb, as in the "Time Knob" on a delay pedal, and replace it with a digital means of parameter control?

If so, how?

Can the now empty points extruding from the pcb be connected to a DAC of some sort, thereby opening the possibility digital control?

I'm knew to this forum thing.. please be gentle. 🙂

Thanks in advance.

Pete

I have the following brand-new rack cases in kit form for your audio/electronic projects at clear-out prices:
Item Case size Available Unit price
A. 2H x 12W x 7D inches 13 C$14.
B. 5 x 12 x 7 5 C$18
C. 3 x 17 x 12 10 C$20.
D. AL 3 x 17 x 12 19 C$30.
E. AL 4 x 17 x 12 11 C$35.

Note: All front panels are aluminum
AL=all aluminum ideal for your preamp project
All come with handles, hardware, and instruction
Shipping extra. Give me your address to work out the cost

Hello guys,
I am searching for a store that is selling KEF drivers.
The shop "setelec-shop.fr" unfortunately is down, as they stated in an e-mail I received from them, when asking about it.
Do you guys know of any other sources? I couldn't find an alternative besides ordering directly from KEF on here.

Appreciate any help!

Is anyone following these areas? I've watched POE lighting gain popularity lately with server racks full of POE switches dedicated to lighting. Rated inherently safe @ <60V- 802.3bt (100w poe) and subject to Class 2 wiring standards (US, NEC). It feels like this could change the way a lot of wiring/lighting is handled. Then I ran across an article on Digital Electricity, packetized electricity at 200 or so packets per second with fault protection, also deemed inherently safe. With IEC/NEC approval, widespread adoption is likely on the horizon. I'll need the 2023 code on hand soon so will go ahead and pick it up to get at first hand look at the details. I'll dig up a link to an article I read a month or so ago. Interesting stuff.
So, anyone else seeing this? Anyone here actually planning on implementing it? New commercial projects might look a little different soon.
Cheers