• Locked
For Sale Ian Canada COVID and Post-COVID parts for sale. CONUS. Summer Sale.

The majority of energy spent on Ian Canada parts were during COVID. I did pick up some parts at the beginning of this year for some upgrades and have to let them go too.

I had an amazing time and learned a great deal, but I need to downsize for the flexibility of going abroad in 2025. The use of an external clock takes up additional space which makes it impossible for travel.

There's no rush on any transactions as I plan the whole Summer to spend on this sale. So, first time in a long time I'm spending the Summer on a sale and not a DIY project.

Standard PayPal only. 1/2 Buyer, 1/2 Seller Fees so split PP Fee. USPS preferred unless Batteries involved which require UPS. Buyer covers shipping fees. Let's try CONUS first. If you are outside CONUS and I have a rare product, I might consider. No trades.

I can test the part(s) before shipping so it may require additional time to ship. Everything listed was working flawlessly before disassembly.

COVID parts (50% off):

Q3. No clocks, just the placeholders. $67.50

Q3.png

LiFePO4 MKIII. I can throw in never used UcMate, UcHyrid (2). UcAdapter. I think I can throw in the Batteries too ($80 value). $100 for everything (UcBoards and 26650 Batteries).

MKIII.png
UcAdapter.png
UcHybrid.png
UcMate.png

ReclockPi. $37.50

RCP.png

I'll list the rest including external clock this month.

Post-COVID parts:

Help with burned PCB

Hi all , I am just getting into amplifier repair. I have read Perry’s guide and watched Barevids videos. I purchased a lot of amplifiers and have successfully repaired a few. I have what looks like a basic Zenon 5k Korean amp. The power supply fets, gate resistors and buffer transistors are all toast. The issue I have is the board has burned through. I have a few of these amps and I added photos of the burnt pcb along with an undamaged one for reference. Is there a proper way to repair this or is this unrepairable?

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TPA3221 Amp design Reset and Mute Pins

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Hi
this is my second time with class-d amp ,,the first one was with TPA3116d2 so i wanted to make a higher version power so i went to TPA3221 but to be honest i want to make a minimal components design to keep it simple and till be good and understand this kind of amps.
here is my schematic ..my question is i want to operate the Reset Pin and Mute pin as if this functions ignored or not exist in order not to use special circuit for either of them so am i doing it right in this design? Please advice

Loudness circuit on stepped attenuator

I add loudness circuit on stepped attenuator and my question is about quality of C1 capacitor. I think that C1 is in signal path and it's quality is important. My current C1 is ceramic type. Any suggestions which type of cap is best choice since value is only 470pF? I found Kemet paper, Silver Mica, caps, Wima MKP, Amtrans AMCH Polypropylene...

Thanks.

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2018 Ottawa and Environs DIY Audio Get Together

2018 Ottawa and Environs DIY Audio Get Together
April 28th
General Burns Lodge Ottawa, Ontario, Canada

Google Maps
Hint: Click on Blue Link (Google Maps) For The Map!
Time
10:00AM to 6:00PM


Shaping up to be as good as always.

List of Attendees

John Kucharski ( Multisync )
Andre ( Tell me your last name Andre I'm the worlds best name forgetter )
Grant Marshall ( Pilover2000 )
Felix A
John Weisberg
Pierre Lavoie
Daniel Lavoie
Ron Urquhart
Dave Dalfarra ( the one and only )
macboy (Aaron)
jjrh88 ( Name???)
TechnoDweeb ( Byron )
Me , not you, nope me....
soundchaser001 (Matt )
Richard Dolan

KEF Blade DIY effort now a more affordable venture

So anyone interested in tackling a DIY effort using the Q150 drivers, they’re on sale again at a little more than 40% off suggested retail……I already have the white pair with the raw aluminum colored Uni Q but I just ordered another pair of the Walnut version for another variation…..a hybrid active 3 way with powered bass module and 2 8” woofers

Sony TA-8650 integrated amplifier Disassembly

Does anyone know what is required to get the back panel on this amplifier to swivel down? Let me explain further. I have the top panel removed and there are two screws at the top and back that if removed I think will allow the swivel down to occur. But they have built-in washers that I cannot remove due to the side wood panels obstructing them. The side wood panels are each held on by two screws but these are very difficult to get to without removing other parts. This has been a weakness of me as part-time DIYer - getting this stuff apart. Any help is appreciated. Thanks, Don

Understanding Power Supplies

Hi everyone,

I'm embarking on learning more about microcontrollers, ICs, etc and I have a small project that I'm working on that will use a PGA2311. I've done stuff like this before, I'm a decent programmer, and I understand a lot about the EE side of things, but my degrees are in music, so I have some holes I probably need to plug.

One of these gaps in my knowledge is that on the spec sheets, it specifies +5V for the digital side, and +5V and -5V on the analog side. Does this mean the digital side is DC and the analog side is AC ? If not, how does one get both the positive and negative DC voltages ? I always thought of DC as being just... well... DC.

Any reading materials that anyone can recommend, or resources to go learn would be appreciated.

best,

matt

Help identifying static noise when powering up my Sennheiser Me66 with K6 power module

Hi, I have a Sennheiser ME66 on a K6 module and I get the attached noise when I power it up. Sometimes it takes quite a while before the static completely goes away, sometime it does not even go away.

I'm suspecting my capacitors but am no sound engineer!

Can you guys listen to the attached recording to help me figure it out?

Thanks

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Newby Push Pull Question

Hello,

I just registered and I am so happy to find this forum.
I am 22 and trying to build my first tube amp.
Hope that I can add some questions here.

I am building a push pull 6550 power amp with cathode bias. It looks that could be work.

My first question is.
I am measuring about the double AC current before rectification compared with the total cathode DC currents.
Why is that?

thank you so much

Hypex UCD180 OEM Build questions

HI, I have some Hypex UCD180OEM boards and a SMSPS400180 PSU and am looking to build an amp. I see these UCD180oem boards are different than the offerings from other Class D DIY based offerings like the ones UcD180 HG with HxR. I se theres a board used to connect the 2 modules to the PSU however I do not have such a board. I am assuming I can wire directly onto the header pins on the module. Anyone have any suggestions?

EL34 PP Layout Proposal

Hi,

I found Guiseppe Amato’s DIY Tube page and this project inspired me to look into a layout editor for myself. Here are my results…

A) Guiseppe’s page: https://www.vtadiy.com/
B) The amp I am specifically interested in (Il Primo Bis): https://www.vtadiy.com/home/tube-amplifiers/il-primo-bis/
C) Guiseppe used an open source layout designer app which amazed me, DiyLC by bancika (who also builds his own guitars): http://diy-fever.com/blog/, http://diy-fever.com/software/diylc/

Guiseppe provided a picture of his build’s layout which I took and re-engineered for learning purpose. I herewith share my result with the community. Any feedback welcome…
EL34.png


You can find the schematics on Guiseppe’s home page…

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Aluminum trimmed subwoofer cabinet

I am finally adding a pair of 12” sealed subs to expand the dynamic range of the bottom couple of octaves of my previously described diy open baffle planar magnetic tower system. I need to assemble the ICE amp to drive them, and add a miniDSP-based crossover, but here they are still fresh on the workbench. I’ll add more details once I actually install them. The plan (if I haven’t really botched the measurements) is to put the subwoofers under the woofer towers so the foot print doesn’t get out of hand. I’ll add details as they emerge over on the original thread so I don’t hog electrons by running parallel threads.

Few

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Reverse engineering old 2 way speaker from church

My friend gave me this pair of speakers and i was thinking they may need some tweaking for hifi listening.
Woofer is Celestion, i have sent message to them to see if they have some info. Waiting for response.
Tweeter seem to be MB Quart MCD25M but there seem to be some variants.
Box is 25liter and there is a vent thats 45mm diameter and 18mm deep ,just a round cutout in front of box.
Filter is a bit weird but its probably tweaked for the application.

Maybe need to borrow mic and driver measurement equipment from friend or just alter the crossover abit.
It does not play very low but i guess its a combination of woofer/box and the weird capacitor in series with woofer.

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Vacuum tube replacement E424 (solid state)

Hello everyone on this forum,

I recently received a Philips 2531 radio.
But unfortunately all the tubes where missing.
So, I was searching for the E424, E442 and C443.
But some of these tubes are hard to find here.

But I really wanted to use the radio.
Via a Dutch forum I was instructed on how to make a C443 with a PL95 tube.
I tested this substitute in another radio of mine, and it works.

That brings me to the problem I have right now.
I am trying to make a replacement for a E424 tube.
And I found a page were someone tried this with 2 BF422.
When I was testing this circuit, I found out that it doesn’t match the curve of an E424.
So, I made some changes to the design, and the linear part of the curve matches quite good now.
I am curious, if there is anyone who has a suggestion about how to get het curve more like an original E424.
I would like to have a rounder curve at the bottom, so that not only the linear part matches the E424 transfer characteristics.

*note
I also tested this E424 substitute in another radio. And it works.
Because in that radio the grid is biased with 0 Volt.
So, it than operates in the linear part of the characteristics.

This E424 tube is mostly used as preamplifier and detector in Philips radios.

Here are my test results and my schematics.

If you have any tips or tricks for this replacement, I am happy to hear about them!

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2N3055 the early years

According to wikipedia "The 2N3055 is a silicon NPN power transistor intended for general purpose applications. It was introduced in the early 1960s by RCA using a hometaxial power transistor process, transitioned to an epitaxial base in the mid-1970s"

The epitaxial process gave it a higher transition frequency which is arguably better for most applications.

What I am particularly interested in is the European sources of the 2N3055 in the transition period i.e the 1970s. Any information gratefully received.

Cheers

Ian

Bob Heil, Audio Engineer to the Who, Jerry Garcia, Peter Frampton,RIP

From the NYTimes, April 23, 2024:

By Alex Williams

Bob Heil, Whose Innovations Enhanced the Sound of Rock, Dies at 83
A groundbreaking audio engineer, he provided the large-scale systems that brought tours by the Who and the Grateful Dead to life.

Bob Heil’s career as a groundbreaking sound engineer who brought thunder and rich sonic coloring to tours by rock titans like the Grateful Dead and the Who began behind a pipe organ in a 1920s movie palace.

Mr. Heil, who helped usher rock into its arena-shaking era by designing elaborate sound systems that allowed rock juggernauts of the late 1960s and ’70s to play at volcanic volumes, first learned to appreciate the full spectrum of musical tones as a teenager, when he took a job playing the massive Wurlitzer pipe organ at the opulent Fox Theater in St. Louis.

“We had to voice and tune 3,500 pipes, from one inch to 32 feet,” he said in a 2022 video interview with the audio entrepreneur Ken Berger. “Voicing taught me to listen. Very few people know how to listen. Listening, you’ve got to mentally go in and dissect.”

<SNIP>

Although he worked behind the scenes, Mr. Heil was enough of a force that the Rock & Roll Hall of Fame in Cleveland credited him with “creating the template for modern rock sound systems” In 2006, the Hall installed a public display containing his mixing boards, speakers and other items.

Mr. Heil developed some of the first effective sound systems for large rock concerts in the 1970s. The two men here were unidentified.Credit...via Heil Sound
“The concert business became what it is today because he made the experience so much better for the customers,” Howard Kramer, who at the time was the Hall of Fame’s curatorial director, said in an interview that year with The Houston Chronicle. “No one made the leaps in live sound that he did.”

Mr. Heil got started in the business in 1966. Up to that point, top rock ’n’ roll bands often had to rely on feeble sound systems that were drowned out by screaming fans. That roar, Keith Richards of the Rolling Stones wrote in his 2010 autobiography, “Life,” was often so deafening in the band’s early days that audiences could hear nothing more than the drums: “We used to play ‘Popeye the Sailor Man’ some nights, and the audience didn’t know any different.”

Mr. Heil gave rock shows the sound arsenal they needed. “We were the first company back then to build a package P.A.,” he said in a 2008 interview with the audio magazine TapeOp. “You could come to Heil Sound in 1972 and leave the facility with a complete system: snakes, road cases, everything — even a modular mixer.”


Mr. Heil put a distinctive stamp on 1970s rock with the Heil Talk Box, an effects pedal that was a signature of Peter Frampton’s monster-selling 1976 double album, “Frampton Comes Alive!”Credit...Carl Lender
He also put a distinctive stamp on 1970s rock with the Heil Talk Box, an effects pedal that transformed guitar parts and vocals into an interstellar drone. Joe Walsh used it in memorable fashion on his hit “Rocky Mountain Way” in 1973, and the Talk Box was a signature of Peter Frampton’s monster-selling 1976 double album, “Frampton Comes Alive!”

Mr. Heil’s career took a major turn in 1971, he told Mr. Berger, when a manager for the Who frantically called him in St. Louis, asking if he could get his crew to Boston the next day. The opening show there, part of the band’s tour in support of its hallowed album “Who’s Next,” had been a disaster, with one newspaper noting that the band’s “soaring brand of rock could not be heard” under the venue’s “miserable conditions.”

Roger Daltrey, the band’s lead singer, threatened to fly back to England until Mr. Heil arrived with his rig. When Mr. Daltrey “did the sound check,” Mr. Heil recalled, “it was OK, because it was a monster P.A.” He would work with the Who for the next decade.


Mr. Heil with a microphone used by Roger Daltrey of the Who and the mixer he built for the band’s 1974 tour. The equipment was part of a 2006 exhibition at the Rock & Roll Hall of Fame in Cleveland.Credit...Wayne Crosslin/St. Louis Post-Dispatch
Robert Gene Heil was born Oct. 5, 1940, in St. Louis, the elder of two children of Robert and LaVerna (Bills) Heil. His parents owned a clothing shop in the small town of Marissa, Ill., about 40 miles east of St. Louis.

As a youth, Bob not only played the accordion and the organ but also became a ham radio enthusiast, which gave him an early opportunity to fiddle with electronics. After graduating from Marissa Township High School in 1958, he spent time studying at the University of Illinois in Urbana-Champaign and the St. Louis Institute of Music.

Mr. Heil in 1959, when he worked as a demonstrator of Hammond organs.Credit...via Heil Sound
In 1966 he opened Ye Olde Music Shop in Marissa, where he rented Hammond organs and repaired instruments for professional musicians. He also began to design his own audio systems.

Before long, he was supplying them to country acts like Dolly Parton and Little Jimmy Dickens as they came through St. Louis. His big break came in 1970, when management of his old employer, the Fox Theater, called him and told them of a crisis: The Grateful Dead was set to play there, but the band’s P.A. system had been confiscated by authorities in a drug raid.

On a subsequent call with Mr. Heil, Jerry Garcia, the band’s lead guitarist and vocalist, “almost dropped the phone” when he learned that Mr. Heil had a sophisticated system featuring an amplifier by McIntosh, the high-end audiophile brand, Mr. Heil told Mr. Berger. Performing Musician magazine later called the resulting concert “the night that modern live sound was born.”

In addition to his daughter Ms. Staley, Mr. Heil is survived by his wife, Sarah (Benton) Heil; another daughter, Barbara Hartley; a stepson, Ash Levitt, the president and chief executive of Heil Sound; a sister, Barbara Schneidewind; and seven grandchildren. Both daughters are from his first marriage, to Judy Mortensen, which ended in divorce.

By 1980, Mr. Heil had grown weary of life on the road, so he created a new line of headsets and microphones for the ham radio industry. At one point, Joe Walsh, another ham enthusiast, told him he wanted to use one of his microphones onstage.

Mr. Heil protested that the microphones were not concert quality. Mr. Walsh disagreed. “I was at his house and went downstairs to his little studio and he proved it to me,” Mr. Heil told TapeOp. “So I had to start listening all over again.”

Audiomatica Medusa turntable with Clio Pocket

I own a Clio pocket system and I found the instructions on how to build the Medusa automatic turn table: https://www.audiomatica.com/wp/?page_id=3024

I will not build exactly this one, but it will be also based on GRBL, Arduino and CNC shield. I will use two smaller motors and a pulley between them, just because I had them from a 3D printer. Powered from an old laptop supply.

From a serial terminal, it works perfectly. I got it moving also from Clio Pocket - if your Windows use a decimal comma instead of a decimal dot, you need to change that in Windows to get it to work. At least in the current 2.2.0.0 release.

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CD Lens adjustments (Philips)

Hi there!!
Recently I repaired a Philips CD620 that was in a very poor condition, with serious damage in the main board.
After 2 weeks of work, I repaired it and now it’s full working.
Everything was allright until today, by listening the album Dangerous (Michael Jackson). When playing the last tracks I noticed some distortion and artifacts.
When I repaired it I forgot to adjust the lens, so I opened it again to do it.
When I checked the values for Focus and Laser current, it was very very low. So I adjusted the pots to get a better value and now it’s “working fine”.

BUT, here is the problem:
The service manual says that the correct values (using a test cd) has to be:
- 50mV for laser current across a specific resistor.
-400mV (+-40mV) for Focus across certain point and ground.

I have not a test cd, so I took 3 of the best quality cd’s I own and adjusted the pots to get an average value near to the values shown in the service manual.
Example: with cd1 I get 35mV(laser) and 360mV(focus).
With cd2 I get 32mV(laser) and 470mV(focus)
With cd 3 I get 37mV (laser) and 420mV (focus).

The first problem is that I cannot set the laser current to 50mv across the resistor. The max value I can set is 37mV. Is this value too low???
Once adjusted, I tried some other CD’s with different quality pressings and I get very very different values, examples:
  • 22mV (laser) and 560mV(focus)
  • 21mV (laser) and 980mV !!!!!!!!(focus)
  • 34mV (laser) and 160mV (focus)

I think this values are so far to the ideal.
But, remember that I adjusted the lens with 3 of my best pressings (reflective quality, etc etc) and the average values I can set are: 37(laser) and 400(focus).
So the only thing I can suppose is that the lens is well calibrated but the different quality of my other CD’s makes the lens to work different with very different values for laser current and focus.

The thing here is that now ALL cd’s sounds fine. No distortions. Just pure sound.

Can I be sattisfied with the results? Or is the laser current too low? Service manual says 50mv and I get 37 as much.

Or maybe the diode is in the end of its life?

Postdata. Sorry for my horrible english.

Supercap Charger PCB

Hello, i wanna utilize these here: https://de.aliexpress.com/item/1005002737105856.html but you need to limit charge current, balance (which is included on the chinese board), and manage/control when to charge again to make it a "standalone" power supply

since you dont wanna include measuring circuitry of the voltage, one could just use a power switch IC (which limits current well) and a isolated microcontroller to recharge in a timebased manner depending on the max. current consumption

4,8V - 5,2V, 250F, 100mA = 15 minutes discharge time
4,8V - 5,2V, 250F, 300mA = 5 minutes discharge time
4,8V - 5,2V, 500F (2 banks), 100mA = 30 minutes discharge time
4,8V - 5,2V, 500F (2 banks), 300mA = 10 minutes discharge time

Any better ideas here or am i on the right track?

Balanced line driver (SE to Bal) board suggestions?

Hi

I need to convert a few SE sources to balanced. I have seen quite a few boards on AE featuring the DRV134 and similar. Some require DC and others differential AC with various levels of filtering etc. I could not find any discussion or reviews on diyaudio.

Can anyone suggest one of these affordable boards or link to a discussion I may have missed?

Thank you

For Sale DDDAC Clearance sales - Workshop - Demos and Prototypes

I really need to get my workshop cleared up. I have several boards, products, components etc. which are just lying around. A waste of my money and a pity as they are not getting a home to be part of a music system 🙂
So, I will start cleaning up my workshop and edit this post with anything which could get out for sale...
This is all private sales and there will be no invoices.

Pricing will be my idea, but I am always open for (serious) offers. The longer something is on sale here, the better your chances are for a lower price. 😉
Shipping depends on region and kind of shipment. I will agree with the buyer on this individually.

Please come around so now and then to see what is in the shopping window.

Doede

ok, let's start:

1) My very first hand-made MK3 prototype. This is still without the electronic rectifying. In fact, very close to the "old" PSU - The choke recommendation is out of date - see my blog... )
The DAC board itself is also very close, but no separate gate driver for the MCK and the UFL are not soldered on it. Also, daisy chaining is only possible by flat cable. The board is stereo and work 100% of course.... The analog section capacitors are Elna Silmics - those are obsolete now. When sold, I will clean up the loose wires of course and free up the solder holes. Could add UF/L if required

My price expectation for the set (PSU and DAC Board) excl. shipping cost is 555 Euro.
2024-04-23_17-31-17_IMG_4024.JPG 2024-04-23_17-31-54_IMG_4027.JPG


2) let's see what I dig out next.

Pioneer 8500 II rebuild

I purchased a ~1970s vintage 8500 II Pioneer Amplifier from Japan. I am wondering if anyone here does restoration on older equipment and has recommendations on replacing the transformers vs using it on a step-down transformer. The Japanese unit is designed for 100 vac at 150 watts. I assume I can run the unit on my Variac and see what I think.

It looks like (from the service manual) I could replace the existing transformers with 120 to 35-volt transformers (I'll verify the voltage when I have a unit). Using Anetk toroids would be pretty cost-effective if they fit. I don't know if there is an advantage of one option over the other. In any case, I would keep the existing transformers in case I want to put it back to stock.

Any advice would be appreciated. I do plan to re-cap the electrolytic and fix whatever else I find. I'll probably preemptively replace a few transistors that are known to fail as well.

Need some help sizing an SUT

I need more gain out of the phono amp I built and am exploring the SUT route. I have a Dynavector DV20X2H cartridge.
Output 2.8mv
Impedance 150Ω
Recommended load >1000Ω

From the reading I have done and I'll admit I don't have a comfortable amount of understanding but it seems like I would want to increase the output to roughly 5mv to put it on par with most MM carts. What ratio SUT do I want? 1:2?
Then to get my 1000 loading parallel the 47000 with a 5.1k resistor which is divided by 4 the square of my ratio.

These numbers seem a bit extreme. Is the output of my cart too high to use a SUT?
I also posted about raising the gain of my amp. Maybe if thats possible would be a better solution?

Design Study of 3D Printed Loudspeaker Port

Hello Everyone!

I would like to share with you the concussions of a study I have been working on over the past months to design an optimised 3D printed port for a desktop loudspeaker. I tested various methods to reduce unwanted resonances, while keeping an eye on port turbulence.

EDIT 22/04/24: The design study has been significantly revised to include more information and correct some erroneous conclusions.

3D Printed Loudspeaker Port Design Study V2

Baseline Original vs Practical CLD Final.png


Original post:

3D Printed Loudspeaker Port Design Study < Clicky Click

Here are a few snap-shots:


1706639529392.png

1706639584407.png

1706639612066.png

1706639634566.png


There is a whole lot of info in the paper beyond this including the effect of holes in ports, reduced wall thickness, constrained layer damping and what bending ports does to the response. I encourage you to check it out, since it took me a lot of work 🙂

While I unveil the fruits of the efforts, I must confess I have the intention of eventually offering a DIY kit and a finished product for sale based on the methods revealed in this study. I hope this doesn't detract from my wish as a fellow enthusiast to share what I discovered.

Thanks also to @stv for encouraging me to make the effort writing up what I was doing. His thread on port resonance is a gold mine. Also thanks to @andy19191 for early feedback on the document.

Simon

Any HVAC technician here?

My GF mother inherited little house in Florida and 3.5 tonne AC unit just went belly up. Last year they replaced $$$ blower motor since it was still under 10 year warranty. Now they are told that compressor failed and local HVAC company suggest a whole new unit for 8 grands. They quoted $2.5k for compressor replacement. It's not easy (for me ) to find relevant info but from quick internet search Copeland compressor costs around $1K . Anybody with account in HVac distributor can check the exact compressor which will be drop in replacement for compressor in Bryant 707CNXA4200AATP?

Tascam M2600 Meter Bridge (MU-2632)

Hey all. I recently picked up a TASCAM MU-2632 meter bridge unit. It’s an old unit and I can’t find much info on the meter bridge specifically online, but it looks like it was used with the M-2600 MK2: https://reverb.com/item/29128921-tas...24-meterbridge

It looks like it uses 8-pin mini DIN connections (I’m not really that experienced with DIN connections) that provide signal to each of the visual meters.

Is there any way that I can add this to my VERY basic home studio setup? It would probably really just be more decorative than anything, but I wondered if there was a way to take an L-R 1/4” Jack signal and somehow get those into the unit to watch the lights dance?

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Amplifier question

I've got a pair of speakers I modified several years ago to add a dome tweeter crossed over at about 13kHz. Ran them on a Lafayette LA-375 amp for a few years and most recently on an Adcom GFA-545II amp.

As best as I can remember the Lafayette has a flat frequency response to 20kHz based on testing I've done and the spec for the GFA-545 is down by .25dB at 20kHzs according to the specs.

Why did the speakers sound better in the treble on the Lafayette, but not as good in the treble when run on the Adcom?

I would have expected the Adcom to sound better given it's newer and uses a better circuit design, but that isn't the case.

I've never heard this much difference in sound between two solid state amps with the same speakers.

EDIT:

In a way the adcom almost sounds too flat like some of the silver face Yamaha receivers do.

For Sale QUAD 77-11L Speakers

Selling pair of Quad 77-11L Bookshelf speakers. Price is shipped USA. Overall in great shape, one small ding in rear right corner Ive touched up. Recently polished to mirror finish.
275 shipped Cont USA

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uTracer...

Some time ago I started to design a uP-based tube tracer, but, as normal, ran out of time - then in the middle of last year I found that Ronald Dekker, a Professor at TU/e & Philips Research was designing one. Ronald's site is at Ronald's electronic project site.

His device is called the uTracer - the project page is at The uTracer, a miniature Tube Curve Tracer / Tester.. This is a full-featured tester with a Windows-based front-end - the specifications can be found at uTracer specifications.

To cut a long story short, I bought myself the kit as a "me" Christmas present - took a day to build and test. The kit is of excellent quality - the design is very sound - e.g. short circuit & overload protected etc. - you would hope this was the case given the author's profession! The component quality was also very good and the supporting documentation very clear. Layout is good and the build process modular with continual testing. Its very professional.

Now been playing with the results for a few hours - very pleased indeed. All the PSUs (heater, anode & screen) are well-designed SMPS supplies and run cool - I've had the board running non-stop for several hours and it just gets slightly warm.

Whilst the electronics design is "open", the s/w is not - However, Ronald publishes the communications protocol between the PC app and the board should you want to write your own GUI. His rationale for not releasing the s/w source is that he doesn't want it to be ripped off by others - a fair comment in my book, especially when you consider the extraordinary amount of work he's put into designing this, and, for the benefit of all, fully documenting the process and design rationales in his blog - a really interesting read...

All running happily. Examples below of two plots - just playing to learn how to run different classes of tubes... to start with I chose a typical audio triode and pentode.

The attached photos show:
  • Setup screen for the 6CA7 tetrode test
  • On the test bench being intimidated:
  • Electro-Harmonix 6CA7 - Supressor connected to Cathode, 200V on screen, Grid stepped, Va varied and Ia plotted. 25W SOA is also shown. You can clearly see the "tetrode kink" on the graph
  • Svetlana 6C4C (aka 6B4G) - Here, I've overdriven a Russian 6C4C to check that the Iamax limit works (when I hit it the uTester give a "compliance error"). This graph has a 15W SOA curve and a 2.5K Ra load-line as well...
  • Completed controller board

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For Sale Vintage meters Marion Weston Triplett

Up for sale different meters:

1) Marion HM2, 500mA + 100mA - 40,-eur pair
2) Marion HS2, 50 micro +30 Mili ampers - 40,-eur pair SOLD!

With red and/or black overlays
Hermetized, glass soldered to body (but can be desoldred with skill).

3) Marion MM2, 200 miliampers + 10V, (silver/metalic) 2 1/2inch meters - 40,-eur pair

4) Weston model 301 black 3 1/2inch meters,1A + 8V - 50,-eur pair

5) Triplett model 426 VU meter 1 pc - 100,-eur

Meters can be purchased in any combinations (by pairs) from total 80,-eur, or equal in USD.
Crypto payments also welcomed.

Items will be packed carefully with international tracking across all distance.
FREE shipping across EU/UK.

Call for other locations.

See my other items.

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Adding a mains Thermal Switch - Advise & Opinion wanted

Hi there folks,
I am repairing a friends Yamaha active subwoofer. It uses a Sanyo STK power module. This 60W module has a Tc max of 125 deg. Celsius.
The original power module is a direct short across V+ and V- . The Sub. design has no 'finned heat sinking' and only uses the sheet metal
control panel as cooling. I am assuming that the power module 'blew' due to being pushed very hard at a high temperature.
There is room very close to the module to mount a 240V thermal switch. My local electronic parts shop has a 100 deg. (trip) thermal switch.
My question is >
Is 100 deg. too low, too high or just right in such an application ???

4P1L-4:1 lineoutput transformer driving SFR E130 SE

Parts and tubes have overfilled basement shelves and I was "ordered" by my better half to clean up....

The driver and output stages are built with parts I found while I slaved.....

Psu was made for a 50 se amplifier some years ago. 394a-lclc, Dave Slagle's lc modules feeding Rod Colemans filament regulators. The high voltage is way to high for the driver and output tubes, so I chose to drop the excess adding two simple shunt regulators.

The SFR E130 is a really nice tube. Pretty much similar to the rs 242, but lower internal resistance. Driving it into a2 yields just below 4W.
I had some concerns that these amplifiers would lack power to drive my speakers properly, but for daily listening they are more than powerful enough. The attached measurement is taken at normal listening level. In the middle a Linestage with VT-25 (separate psu not visible). It can be configured as only AVC (Dave Slagle/Bent audio modules) or 4:1 or 2:1 stepdown.

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Adding a thermal switch to subwoofer Chip Amp

Hello there folks,
I am repairing a friends Yamaha active subwoofer. The amplifier module (CHIP) is a 60 watt Sanyo STK device.
The maximum operational thermal rating = 125 degrees Celsius.
With no cooling fins, the sub. design uses only the sheet metal of the control panel for cooling.
I am fairly sure the reason the Chip Amp/module blew-up was heavy drive at high temperature.
There is room close to the Chip Amp/module for me to add a 240V thermal switch.
My local electronics shop has a 100 deg. C thermal switch.
My question is >
Is 100 deg. too low, too high or just right for such an aplication ???

For Sale KEN-RAD 2A3 dated 1947

Selling low hours High values matched pair of Ken-rad 2a3 black glass. Values on the box picture. Sound extra sweet although they have some hiss compared to actual tubes production. This pair has soul for sure. Sell for 350 Eur + shipping

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Yamaha DVD-S2700 looking for firmware

Hi all,

I am seeking firmware for the Yamaha DVD-S2700.

I purchased the Yamaha DVD-S2700 completely dead. I've invested a significant amount of time into it, and although I've resolved some issues—such as
1. fixing the dead power supply
2. replacing the non-functioning tact switches—there
3. dead laser that I've replaced

Now the DVD reads all of the CD/DVD/SACD/VCD discs that I have, but I still have two unresolved issues:

1. It does not respond to the remote control. I have tried both original DVD15 remotes and a universal remote. The IR sensor seems to be functioning correctly because I measured voltage at the output of the sensor, and there's a noticeable change after pressing a button on the remote.

2. The HDMI output is not functioning (I have tried to reset HDMI according to service manual - but for a half of second it blinks "HDMI RESET" without changes)

I assume that perhaps a firmware update will help, but I cannot find firmware for this device anywhere. I have contacted Yamaha without satisfactory results. Does anyone have firmware for this device?

Best regards,
Sebastian

Paid work to fold turn several horn designs then put into a CAD file

Hello hello,

I have several files tapped horn profiles that i would like folded and turned into a CAD file to make it easy to cnc.
The horns are quite simple. Straight taper between throat and outlet.
The larger versions to be separated into parts to maximise cnc cutting.
happy to negotiate price so both parties win.
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Same voltage everywhere

I am trying to fix the US amp Merlin md3d amplifier that I believe it to be a Class A B. If I put one Probe on either the B+ and then the other probe anywhere else in the board it measures 12 volts. if I take that probe off and put it on the remote terminal the same thing occurs...... 12 volts everywhere. if I switch the probes in the opposite direction it shows negative 12 volts. I do not remember getting any other voltage reading other than 12 volts. anywhere I measure whether it be the power transistors, either side of the Transformers, all three legs of the transistors, i mean everywhere 12 volts. ...everywhere.

Universal rectifier and filter/smoothing board

Hello

i wanna build a rectifier board for my DIY dac, since i think this is the better route with better parts than buying chinese ones..

did people around here test different stuff and know what sounds or is best?

i have a "audiophile" thel power supply here which seems to have 12x 3300uF for smoothing and dedicated diodes, is this the way to go?
is just LOW ESR important?

2P29L Preamp

So I've been breadboarding some preamp circuits and wanted to try some "battery tubes" so, of course, the 2P29L caught my eye. Rather than posting to the 4P1L megathread I thought I'd start a new one.

I'm pretty much a copy and paste builder, not a designer, and my technical knowledge is limited, unlike many of the posters here.

I build low cost, "bang for the buck" stuff. So no expensive plate chokes, vibrator loads, output transformers or trick Rod Coleman filament supplies. Just keepin' it simple using a very basic circuit with parts I had on hand. It's a budget build not a state-of-the-art design.

I used a lower voltage PT at first, which worked OK but I remembered the rule of thumb that says a plate load resistor should be 3 or more times the plate resistance. So that meant using a 15k resistor. To accomplish this I needed more supply voltage so I changed the PT.

The current PS is built around a NOS Halldorson PT I picked up years ago at an estate sale. Because the voltages were getting a bit closer to the 450v rating of the caps than I like, I added a 500 ohm resistor between the rectifier and the first cap. It's definitely not optimal but it's good enough for a breadboard.

The 6BY5 is a dual damper diode which I chose mainly for its soft start characteristic and because I have a bunch. Plus I already had one set up on the breadboard. A different rectifier with more voltage drop might be a better choice and would, perhaps, allow me to ditch the 500 ohm resistor.

Four AAs supply -6.4v of bias to the grid.

Before switching to the 2P29L, I was experimenting with the 1LE3 and using a single AA on the filament. That tube only draws 50mA so the battery lasted a good long while - roughly 24 hours.

Since the filament current is 150% higher for the 2P29L I decided to try a cheap ($3.55) AC-DC regulated switch mode supply. The output is 3.3 vdc and I'm using a 10 ohm resistor to drop it to 2.1v.

From what I've read, I wouldn't be surprised if this filament supply didn't look too good on a scope. I don't have a scope, all I have is my ears.

I started with batteries, then went to battery in one channel and the AC-DC in the other, then both to the AC-DC. I couldn't hear any difference at all. Not saying there isn't any but it wasn't audible to me.

I added a 6800 uF 6.3v cap after the 10 ohm resistor to see if some filtering would be noticeable. I haven't listened to it with the cap much yet. I'll A-B it next week and see if I hear any difference but I figure it can't hurt whether it's audible or not.

I'm not good at describing what I hear but I find it very detailed yet it doesn't exhibit any harshness. And microphonics are not a problem.

I've used the tube in stock form and also with the aluminum shield removed. The nude version looks more familiar - like a small version of a 7868 - but there's essentially no glow at all.

Here's the current schematic. Comments and suggestions welcome, of course.

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Need help designing a preamp

Hello folks,

I recently got my hands on an EL84 PP valve amp output stage chassis (from a Dynatron Cavalcade GR1, I believe) and would like to turn it into a guitar amplifier.

Can anyone recommend any resources that would help me design a preamp for it? Or would it be better to just copy an existing design?
I have attached my attempt at tracing the circuit, along with some pictures of the chassis (please ignore the duplicate heaters).

Also, just out of curiosity, what are the two EL84 plate capacitors for (C7 and C8 - the two silver caps in the lower right corner)?

Many thanks,
Alex

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Calibrate CD Player with Eye pattern

EYE PATTERN

I managed to get the eye pattern on my oscilloscope( thanks to members on this forum ). I made a YouTube video above.

Now I get a lot of bouncing on the eye pattern and it gets worse with the last tracks on the cd.

I have tried moving the pots other than the laser output but don’t see much change.

What am I doing wrong or is there anything else I can do to fix it. Also I really need an angled pot adjusting flat screwdriver as when the last track is selected there is no room for a straight screwdriver to fit from the back.

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AVC - is this the right way to connect?

Good morning to all!

While I'm wading through my various other things, I found one that's bugging me:
the build of a AVC, with autoformers (23 positions) I got from a serious guy in germany.
He's not very responsive though, thus I'm asking for confirmation here:

The correct connection of the Autoformer to the switch seems scary easy. So, according to the schematic from a different place, is it
  • first wire to input hot,
  • 2nd - 23rd wires to the positions 2 - 23,
  • switch output to next stage/output
  • in/out GND tied to AVC #24
While writing this, it seems to make sense, like being pretty close to the schematic.
Right?

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DIY Curve Tracer (analog)

We have a small team that is building a DIY Curve Tracer. Not a Tek577, but a lot better than anything we found that comes close. We are close to the final stages and have a fully operating CT that I'm making measurements with.

If you're interested, have look on my blog. Eventually everything will be shared but we'll wait until we have finished the project.
This describes how we came to the design:
Paul's DIY electronics blog: Building a Curve Tracer - Version 3

Here is the final desciption of building the Curve Tracer:
https://www.paulvdiyblogs.net/2022/06/the-vba-curve-tracer.html

My blog is not great for handling questions and replies, so please leave them here.

Enjoy!
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What is the most flat compression driver of 2024! (520Hz - 20+KHz)

greetings !
I'm posting this topic on this forum hoping that the subject doesn't spill over 🙏🏻

I am doing purely intellectual research which has no specific goal other than knowing it, I would like to be able to have the name of the hf\coaxial compression driver
as flat as possible with innovative technologies whether on the phase whether on the dispersion or other

My stone in the building only has the 4590 of BMS
never seen such a smooth curve over such a large range, I am waiting for your documentation, link, on other compression driver

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Debug Inversion / Center Channel Circuit

I put together a circuit which is mainly the combination of two circuits I found on websites.
One is for inversion (inverting the left channel, combining it with the right and getting the result).
The other is a center channel.
The designs appeared in several places and seemed to be recognized as correct.
So all I really did was join them and add a bulb and a few switches.

When I connect a small 8 ohm speaker all I get is a hum. And this occurs even without input.
I am using two LM386 ICs which are mounted in sockets (to avoid soldering the IC leads directly).
They're tiny so I had to take care not too short any.
The connections have been tested for continuity (with the leads) and discontinuity (among the socket leads).

Does anyone have any ideas how to go about debugging this?

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Frankstein full-range drivers speakers - what have I created? Why does it seem to work?

I got two Alpair 10p full-range drivers and plugged them into the woofer holes of old speaker boxes I took apart. I took the old tweeters out and left a big hole in the box. I also took out the bass port tubes and plugged up the back hole. So now the tweeter hole in the front is like a bass port? I thought these couldn't possibly sound good like this and put them in storage for a while. I just pulled them out and plugged them into an old Denon receiver and was pleasantly surprised by the sound. How is it possible this sounds half-decent?

IMG_4494.jpg
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Dark striped Glass on some tubes

Some of my 6AG5 tubes have some tiny dark lines around the cylinder section of the glass. Mainly a particular batch of Sylvania tubes. My rca and GE 6ag5 just have clear glass, and so do my chinese 6j3 (modern equivalent) When i look under an LED scope, i can see that its a bunch if tiny black rings on the glass.

Picture of one of the sylvania next to a chinese 6j3 to show what im talking about. Were NoS tubes and they all look like this one, and im pretty sure i've seen dark glass on tubes before.

What is it? I'm having trouble asking google and search correctly apparently.

I also think the sylvania have a nicer sound to them then my GE or RCA. I imagine it wouldn't have anything to do with this. Would it?

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For Sale DSP Headphone Amplifier

For background, I'm a professional hardware design engineer with over a decade of electronics design experience.

I've been working for a couple months on this DSP headphone amplifier using the following major audio blocks:
  • DAC: AK4493S
  • Amp: OPA1622
  • ADC: AK5572
  • DSP: ADAU1467
Audio quality measurements are quite close to the DAC/ADC chip specifications, actually the chip specs are beyond the capability of the audio test equipment I currently have access to (Prism dScope III).

I have two extra units from my prototype build available, would be happy to provide at cost ($375 shipped to USA). The GUI design is still very much a work in progress (using LVGL & SquareLine Studio), so buyer definitely would be able provide some input to that. Firmware updates are very easy with computer + WiFi connection to the unit.

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Russco/QRK/ Broadcast Electronics Main Bearing lubrication

BE 12C small.jpg


Any Russco or later 12C owners out there with bearing oil recommendations?

I'm finding I need to run my turntable for a while for the speed to stabilize. When I completed the rebuild I used some fairly heavy weight oil in the bearing well. Once warmed up it sounds great.

It also has a tiny bit of audible rumble when the needle drops. Any tricks on reducing that?

eso

For Sale 47000uF 100V EPCOS Electrolytic Capacitors, 5mOhm ESR

These are the best Capacitors you can find for power supply.
With their very low ESR of 5 mOhms and long life of 12000 hours you can not go wrong.
I got them from Digikey some time ago for a project but couldn't make it. They are new unused.
Part number is B41456B9479M000
These cost around $100 but I can give them away for $70 each

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Philips CD880 recap bom

I have taken my Philips cd880 from the attic in a case of cd nostalgia (and because I’m frustrated with the prices of vinyl nowadays). The player is 36 years old by now and stock condition.

The unit fires up and plays without problems really, although I find it a bit dull sounding.

Given it’s age, it’s probably a good time for a recap operation. Is there anybody who could share a BOM for a full recap?

Thanks!

New Dayton Audio pre built speaker

https://www.parts-express.com/Dayto...cwp6mZ1g6WVuAgRoj4iS5pTbRGxpS4hiohA0CgDPZf458

Just saw this on their site. Looks to me like a pretty attractive price considering the parts used (assuming you find the cost of the parts individually to be reasonable). Surprisingly no measurements are provided? At least as far as I can tell. Anyways, thought it might interest some

Help Understanding Tekton Tweeter Array Schematic?

I have a pair of Tekton Double Impacts and I am trying to understand the details of the tweeter array. I created the attached schematic from my pair.

Can any of you crossover gurus break this down and explain the functions of circuit?

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OPA1622 based 4 x Outlet Headphone Amplifier

Just starting to layout my headphone amplifier using the 4 x OPA1622, this project started from needing a headphone amplifier that could drive 4 x 32 ohm headphones from a digital source and needed or I wanted it to be battery powered ; my family enjoy watching movies together and headphones are our choice for listening and so this project came about.
The design will have individual volume control for each outlet and have 3 x sources of audio available, USB Audio Bridge, Optical SPDIF and stereo balanced analog inputs as well as balanced outputs all using mostly TI.com ICs. DIR9001 for digital interface, PCM1794A DAC, OPA1622, OPA1656 and OPA1637 for balanced output drive. Volume control can be selected for the XLR outputs or jumper out on the main PCB.
battery management is using TI.com BQ25616RTWR IC.

OPA1622 based Headphone Amp.PNG

For Sale Twisted Pear Audio modules Cronus / Hermes + BeagleBone Black (+SanCloud BeagleBone enhanced)

1)

1x Twisted Pear Audio "Hermes" + "Cronus" used - SOLD
Asking 50€ + shipping costs and any fees.

2)

1x Twisted Pear Audio "Hermes" + "Cronus" NEW, unused - SOLD
Asking 70€ 60€ + shipping costs and any fees.

3)

1x BeagleBone Black, Rev. C, 1GHz, 512MB, used - SOLD
Asking 30€ + shipping costs and any fees.

4)

1x BeagleBone Black, Rev. C, 1GHz, 512MB, NEW, unused - SOLD
Asking 40€ + shipping costs and any fees.

5)

1x SanCloud BBE WiFi - V1G - "BeagleBone Enhanced" (1GB DDR3 RAM...), NEW, unused - SOLD
Asking 60€ 50€ + shipping costs and any fees.


If prices are off let me know or make an offer.

Please contact me through PM.

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For Sale Tango Hirata TC-10-130 Chocks, NIB, 1 Functional Pair

Keep down-sizing.

Here is a pair of NIB Tango Hirata TC-10-130 chocks in die cast cases. Still sealed in the original package with documents. This model can be connected in series or in parallel to offer two combinations of inductance and DC current rate.

Please note that these two chocks are functionally identical but different in colors. When I visited Akihabara the electric town in Tokyo, the shop had two available in different colors yet I did not have time to wait for special order.

Specs (according to product insert; see photo):
Primary Inductance: 10H/130mA (Series); 2.5H/260mA (Parallel) at 5V, 50Hz
Max DC current: 150mA (Series); 300mA (Parallel)
Dimensions W56mm D50mm H80mm; Weight 0.8 kg
Color: 1 Metallic Gray; 1 Beige-White

Asking $380 for a pair or $220 for one piece. Buyer to pay actual shipping+handling from Boston, MA, USA.

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Experiment - Chinese JLH 1969 MOSFET board

Hi all. Last time I posted here was probably 5 years ago. Most of the time I come here to read. I can't find much info about the JLH 1969 MOSFET variant except one instance mentioned on the huge "JLH 10W" thread. Someone said this variant should have its own discussion thread but I can never find it. I am posting just to share my experience and not intend to "stir up" any dust.

One day I was browsing Aliexpress for something completely unrelated but then I noticed this board from China. They call it 1969M. I think M stands for MOSFET as output device. I read the description and it says to adjust Iq to 30mA and it will produce good sound. I have built a JLH 1996 dual rails many years ago (I think I posted it in this forum). Using MJ15003 as output and tested at different Iq, definitely bad sound if I set it at 30mA. However, curiosity set in. Paying less than $11 US shipped, I have nothing to lose and ordered them.

The boards came and I put them to test at the bench. Used a bench supply of 16VDC, I tested one board at a time. First board no problem set to 30mA and got sound on a test speaker. The second board's current adjustment was a bit challenging. The idle current oscillate. I short the input to ground and was able to adjust to 30mA and also got sound on the test speaker.

I then mounted them on an aluminum L bracket with a spacer at the bottom from the wooden board. The L bracket acts as the heat sink and front panel where the volume control is also mounted. I power the boards with a 24VDC LM723 analog regulated power supply. I also connect a ground wire to the L bracket so the boards will not become an AM radio. With the 24V supply, I have no problems setting the current to 30mA. 16VDC was probably too low.

I then connected them to my pair of JBL2800 which I am currently using. I didn't expect much but the initial listening impression is very promising. Afterwards, I replaced the input coupling caps with ERO MKT1813 2.2uF. After a day of two burn in for the caps (some of you disagree on coupling caps burn-in and I'm not going to stir up arguments here), the amplifier sounds really really good. The original input caps were not good, especially with piano music. The MKT1813 is way better for the job.

This amp sounds "liquid". I had another MOSFET amp years ago and this one reminds me of how MOSFET amp sounds. When I mean "liquid", it sounds like a very very small "reverb" effect is in place. The sound stage is wide and it fills from end to end of the room. The L bracket barely feels warm with a comfort volume level for a living room of about 15x15 ft. I have a tube-03 preamp with the Russian 6J1P-EV tube as the preamp of this amplifier. It seems to be the right mix for me. I know 30mA Iq definitely is not class-A but I have also not heard a solid state class AB amp that can sound this good so I take it. I do have tube amp and class D amps and I can say this amp is different. You know it is definitely not tube nor class-D but it is very comfortable to listen to. I can fall asleep while listening to this amp.....

[My source are modified (coupling cap) Sony CD player and Amazon Fire 7 streaming Pandora.]

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