New member interested in valve equipment

Nice NYT article on Acoustic Sounds. May need an account to read.
https://www.nytimes.com/2025/03/05/arts/music/vinyl-albums-chad-kassem-acoustic-sounds.html

I am thinking about using a black aluminum mesh on the inside of an aluminium enclosure under a large hole to provide good ventilation for an amplifier. Please see picture for the idea. Does anybody have any tips on how such a mesh might be fixed to the inside of the top cover? In particular, it shouldn't rattle or be easily pushed inwards or take up too much space inside the enclosure. Thanks!

I have Boston Acoustic BA735 computer speakers that are two satellites and a sub-woofer. It’s old but for my purpose worked great for about 20 years. They have been connected to the same workstation pretty much for the last 10 years. Suddenly they have no sound at all. There was a little hum the past year or more but when I was listening to music I didn’t hear it. My hearing isn’t that great due to too many sporting events. The power indicator lights are on, so I think the power supply is good, but they are silent. When I adjusted the volume they used to make a little crackling noise, like the contacts were dirty. Zero noise of any kind now. I thought my PC needed an update or a new driver, but that wasn’t it. I tried a different set of speakers and they work fine. I opened the sub and all caps look good. The power indicator on the sub is also lit. These would be about $100 to get something reasonable but I’m just perplexed. I have a capacitor tester but I’m pretty sure you have to pull them off the board to test properly. I know there are versions of these BA735 speakers that are digital audio only, but mine have an analog and a digital input. I’ve tried other sources of sound without any sound either. They are simple boards and hardly any power. I have re-capped a few amps and sub’s but beyond that I’m clueless how to diagnose this. Everything looks clean and the cables all ohm test good. I’m not too afraid to destroy these trying to fix the issue. This is more of an educational thing for me than anything.

Were can I find a software who can calculate Open baffle?

Servicing a Philips D6260 cassette recorder, an uA420B integrated circuit is involved.
Searching the net for the datasheet yields no results... Anyone?

Recently I've gotten my hands on a Meridian G68J for cheap from a thrift store. It powered up fine there, but was completely dead when i got home.

What i found was what many others online also found out(many years ago), that G68 was using a cheap industrial open frame power supply from UMEC. The power supply appears to have been designed by a intern, as the main power transistors(+12VDC) is squeezed up against the power output connector, with no room for any cooling or possibility of adding a heatsink. The nylon plastic of the DC plug, and socket have been baked black from the heat, while the solder and traces turned crispy as they oxidized and glue fail from the constant heat.

It looked like a simple fix, just solder and bodge it up will get it running. Then it would fail again.

Fortunately, i still have contact at Skynet power supply, and a business account there to order directly from them. They are one of the much better(best?) switching power supply manufacturer around, and i trust the durability and the quality of DC output from their products. So... Well... They don't have a good replacement... (Their product catalog is one thing, but sometimes it is just not feasible to get them to build one for me if they don't already have stock)

Then I looked at Meanwell's medical grade open frame power supply... Damn, they have gotten a lot better since i last checked Luke 10 years ago. The quality of their DC output is really good, easily blows away UMEC that Meridian uses, and better than the replacement part supply that they later used for warranty repair.

I bought mine from Mouser (not Newark as I previously mentioned), part number RPT-75B. They are NOT pin compatible, but the same 3.96mm spacing. And uses JST connectors instead of whatever that's on the old one.

To make the upgrade simple, I desoldered the JST connectors and installed the same style of connector as on UMEC, so that I wouldn't need to recrimp all the wires. I'll just need to pop it out of the old 6pin housing, and put them in the new 8 pin housing in the right order... I'll be testing it later today.

Wish me luck....

Hello friends!

I am building reclocker with COAX input and USB output via Rapberry Pi4 (no other possibilities with USB out?).
HQPlayer software to upsample signal.

So far my first build is very simple and for testing purposes.
IFI SPDIF iPurifier2 > COAX out > HiFiBerry Digi+ I/O
Raspberry PI4 (running HQPlayer) > USB output 768kHz PCM > DAC.
powered by PUREPI II
Works great, but already looking for an upgrade.

I am trying to figure out what parts do I need for alternative build by Ian Canada.
Could you, please be so kind and guide me?

UCCONDITIONER PRO Ultra (what is the difference 3.3V or 5V?)
COAX input > IAN CANADA ReceiverPi DDC (130) [USB Amanero board support input] VS ReceiverPi Pro II [no power needed] (which is better???)
MONITORPI OLED Screen and Signal Analyzer Board for Raspberry Pi
RECLOCKPI (do I need it?)
FIFOPI Q7 II [stock Femto clocks @384kHz] (new version supports both 3.3V or 5V?)
IAN CANADA ISOLATORPI III
Raspberry PI4 > USB output to DAC
PUREPI II

Thank you in advance!

I'm looking for a relatively small inexpensive decent quality amplifier that can put 15-20 watts into a 16 ohm load.

The amplifier can be mono or it can be stereo provided it can be bridged.

I cannot use anything with any digital amp circuitry (class D, class T ETC...) nor can it use a switch mode power supply or voltage regulator as the amp will be used at work around a sensitive unit where RFI can affect the test results.

The amp can either have a built in volume control or require a passive preamp.

I'd also be interested in amplifier kits such as something from this site or one of the low cost boards on Amazon.

Hi,
I've been through three of the Dayton Audio SPA250 plate amplifiers over the last three years. This is my third one, and PartsExpress is no longer interested in honoring their warranty.
The failure is always the same; It starts popping. One pop here. One pop there. It can be 10 minutes between pops, or four days, and at any time of the day or night with no regard to source being active or not. Eventually, it just barely works.

I'm driving a single Dayton Audio RSS265HF-4 10" Reference HF Subwoofer 4 Ohm, sealed in a sealed enclosure, using the dedicated sub-woofer output of my Onkyo amplifier to feed the plate.

Q: If anyone has this amplifier, would you be willing to help me identify the two resistors shown in this picture? Specifically, could you open your amp and take some photos/color bands from it?

You'll notice everything is nicely charred. However, I could not find any other evidence of blown components.

Thanks greatly, in advance.

Hello, I am 43 years old and I like audio-oriented DIY projects, that's why I signed up.

Hello,
My name is Fred from Washington State.

Hi folks


In a moment of bored inactivity awaiting arrival of components for other projects I got to thinking about using the AD768 DAC for audio. It's 16-bit and uses parallel input, which, it occurs to me, is what the early Burr-Brown audio DACs like the PCM54 & PCM55 used.




Here's some extracts from the datasheets comparing the AD768 to the PCM54. I'm not sure how to compare many of the specs but I do not that the AD768 has 10x the output current of the PCM54.

Hope this to be short thread. Probably also doesn't belongs to this forum as it is not DIY question.

I need recommendation for cheap D-class amplifier with Bluetooth from Amazon, should have at least one aux input and 20 watt is enough. Most important to be reliable, economical and sound decent. Budget up to 100€. Amazon is full of these things, but I don't know which ones are reliable.

Friend of mine recently divorced and husband took all hifi away, I have speakers for her, but all my amps are too complicated, many components and too many wires. She needs something simple in one small box .

Thanks heaps!

Hello from Switzerland,

This is my first post on the forum so I hope that I'm on the right forum (if not please redirect me to right place) and that I'll be able to provide all the information you need to help me fix the problem I'm facing.

The issue

The context is the following. I own a Linn Sneaky Music DS (first version, the one with no power switch) bought 7 years ago. The device was working perfectly until a few weeks ago (it was on 24/7 as there was no power switch...) Then one day it turned off and never woke up again.

I suspect that the problem comes from the power supply as when I plug the main cable, I can't hear anymore the switching noise I used to hear prior to the issue (a "click" that i could hear when the main cable was plugged into the device. After the click, the led of the device used to turn blue. Now it's just dead).

What I did so far

I went to various shops and to a Linn official retailer, but the all told me that the quote would be 150-300 CHF (~USD), that they don't know if they will be able to repair it, and that probably they will have to send the product back to the UK to have it fixed a the factory...

I also contacted Linn to ask them if hey could provide schematics for the power supply (the product was discontinued 3 years ago), but they refused... they told me to reset the device by pressing a button but it didn't solved the issue.

My request

As I cannot afford spending so much for a hypothetical repair (not to say to buy a new device) my last chance is to try to fix it myself. However I don't really know where to start... It would be great if you could help me.

Here is was I am able to do: discharge capacitors (it can help to stay alive), solder/desolder tht and smd components (i also have a hot air gun station), measure with a DMM.

I will provide pictures of the power supply in a future message (need to reopen the case and it's almost midnight here.) Meantime if you have any tips on where to start it would be great.

Thank you in advance and best regards,

Michel

SOLD


I purchased a full set of MOSFETs from DIY Audio Store for an F5T I'll never get around to building. All are sealed in their packaging as shipped to me and have never been opened. Interested? LMK!

As I am slimming out my DIY projects backlog due to the lack of time building all the stuff lying around I will post many undone projects and PCBs I collected over time.

Next in line are 4 Symasym Boards designed by Rudi_Ratlos.

Offering a set of green Symasyms

• Green Version comes without dedicated rectifiers on board (so you need an external rectifier) but the option (via jumper) to power the frontend with included PSU or separate external PSU

Both versions include a speaker protection section. I am offering every set with a matched quad (matched by Rudi Ratlos) of OnSemi NJW0


65€

+ shipping + PP fees

Hi I'm in New York. Forget why I originally made this account but I've fallen deep into Mackie HR824 Original world and now I'm sourcing all the help and parts I can to fix three that I have sitting around (the 4th is still in perfect condition).

High quality Antek 700VA toroidal transformer. New old stock, stored safely for some years. This model is no longer made. See pics for in/out voltages. Complete with mounting hardware.

2 available. Price Drop: CA$140 each

AFAIK, similar new toroidal transformer from electronics supply stores like Mouser, Digikey etc sells for ~CA$200 + taxes + shipping.





PS -- the closest current Antek model is AN-7440.

Tried buying it. This is what I found:

US$86 + USPS shipping $56 = US$142. Paypal says this is CA$215.

That does not include the minimum tax hit, which is 7% GST.

Total becomes CA$230.

This is a discussion thread for the Starving Student II, launched today. If you have any questions about the SSII, this is the place!

Links:

• Product page on the diyAudio Store
• SSII information directory
• 6L6's SSII build guide
• Pete's assembly guide / BOM / Schematics

Hello to everyone in here. I am 34 years old guy, who is interested into moving from car audio to home HiFi audio system.
Currently I am looking into build a speaker for my own usage for long time.

I have been at a bit of a standstill waiting for aluminum SMD adapter PCBs for my Lovoltech JFET projects and I was feeling bored, so I started looking for another power JFET to play with. After a bit of research, the UnitedSiC UJ3N065080K3S seemed like a good candidate to explore since I could not find a lot of info on its use in amplifiers. So, I found a LTspice model and fired up my favourite computer game and started to play.

I modeled a source follower power amp first and it appears that 20 watts output would not be too difficult. I think the Lovoltech JFET may be better performance wise, but this SiC may not need cascoding. This would need to be tested in real life.

Next, I tried to produce a reasonable common source power amp. This required cascoding for decent power output and but I wasn't happy with any of the schemes. More study is needed.

I like preamps using power devices so I had to give that a try. I ended up with a high voltage cascode with feedback. According to LTspice, with a 140V power supply, distortion is vanishingly low and output voltage swing is out-of-the-world. Off course, this is a LTspice simulation, but it was exciting none-the-less. This could be gold, or fools gold, or maybe silver.

The LTspice simu;lations got me excited enough that I ordered a couple SiC transistors so I could do some real tests.

Good day everyone,

I'm a complete hack, but enjoy soldering and fixing electronics when I can. I hate the disposable world we have become. My taste is for McIntosh, unfortunately my budget is not. Hey, I can dream can't I? I've been fortunate to have been able to make a living as a photographer, but working for a little company I wear many hats. This summer will be my 34th year at this and I'm trying to retire in a few months. My "Honey-Do" list is long but I like to keep busy working on projects. I live in the land of ice and snow (Minnesota) and am a huge Zeppelin. Six months of the year here are very enjoyable. I have a cobbled together old school stereo cabinet filled with a reel-to-reel, CD player, receiver and turntable going to Polk Audio speakers with a sub. I don't get to listen to it enough.

Thank you in advance for your expert assistance.

~chris

Hello there,
I restored a TD-150: replaced the plinth, redid the wiring, replaced capacitors, new tonearm and board, and new drive belt; along with clean-up, lubrication, etc. I also removed the mechanical parts and belt guide for the 33/45 switch, so it only spins at 33rpm. That's all I need for the music I play.

It's working very reliably, except that on start, the platter won't spin without an initial push—by that I mean that I have to put my finger on the record label and spin the record for a turn or two until it gets to the right speed. After that, no problem.

I haven't done any measurable speed tests, but the pitch of the music I hear matches the digital files I own.

I observed the motor pulley by turning the platter upside down (to keep the same weight) and I noticed that on start-up the pulley is "wiggling" back and forth (about 1mm) very fast. There is a faint clicking noise. If I nudge it out of this, the clicking noise is gone and the assembly runs absolutely quiet and smooth.

The same problem persists with the platter off, with the motor connected only to the sub-platter. If I disconnect the belt, the pulley rotates freely, but in random directions, each time I turn it off and back on.

Before I start buying replacement parts or doing non-reversible modifications, I wanted to hear someone's opinion on the possible cause:

Belt too tight? I think I read somewhere that most replacement belts are. How do I check that, and how do I loosen it up?

Old or damaged motor?

Too viscous oil? In a forum I read I can use a 75W-90 motor oil, and that's what I'm using, but elsewhere I read I should use a low-viscosity oil to reduce friction.

Some electrical issue? The new caps are PP with the same values as the old (likely original) ones. I rewired the components according to the original instructions for 120V mains (I'm in the USA). I connected the hot wire to the motor blue wire (polarity is not indicated, so I guess it doesn't matter).



Anything else?

Thanks,
gm

Sou Michel K., empreendedor e apaixonado por design, acústica e inovação. O meu percurso profissional abrangeu várias áreas criativas, desde a gastronomia e gestão de empresas ao web design e carpintaria. Atualmente estou liderando a criação de uma empresa de luxo de alta qualidade dedicada ao design e fabricação de alto-falantes de alta fidelidade, explorando materiais como concreto, jesmonite e outros minerais para alcançar excelência sonora e estética diferenciada.

Minha abordagem combina engenharia acústica e design sofisticado, com foco especial no conceito Open Baffle, buscando oferecer uma experiência sonora imersiva e envolvente. Estou aqui para trocar ideias, aprender e compartilhar insights sobre tecnologia, materiais e inovação no mundo do áudio de alta qualidade.

Estou ansioso para falar com você e compartilhar conhecimento!

Greetings from German.

My Name is Lasse, i'm 22 years old and I'm very much interested in DIY Audio and professional event solutions.
My passion for everything audio related starten when renovating a small barn at my parents place with my grandpa and equiping it with a diy bar/counter. Obviously a cheap but suitable Sound System to throw some parties was needed and while diving into what speakers fit best the joy of good sound was born.
Since then i've built a front loaded horn subwoofer that i designed using hornresp (that didn't turn out too well but i learned alot) and recently started a portable, modular speaker project and started diving into the Akabak Simulation Software. Said project is also why I joined this forum to ask for help and advice on a few questions.

On top of that I recently started an apprenticeship as a professional sound technician for events, so feel free to ask for impressions regarding that field, but don't expect sophiaticated knowledge on anything since I just started learning.

Best wishes,
Lasse

Evening all - new member from UK here (an OAP!), with initial request for help finding a replacement sub-woofer driver for my old VideoLogic Sirocco system.

I have zero experience with DIY audio.

This is just the intro message. Will post more details in the Subwoofers page when I'm allowed to.

Best regards

Frank

Hello everyone, new member from the Netherlands

Hello to all DIYers! I am Brazilian and I am happy to be able to join you to talk about sound and how to do it yourself. My name is Aldemir I am 58 years old and have been working with electronics and acoustic audio and subwoofers for 40 years, which I have improved over the years, I am a technology lover and I hope to contribute to the group and the forum, so that we can grow. I use a translator to understand each other and I hope you accept me that way? Best regards, Aldemir.

Hi to everyone from Canada.

Much thanks to everyone contributing and running the site. My approach to most things is a DIY one such as working on cars, motorcycles, snowboards, household things, etc. One thing I find worth paying someone else to do is making fresh pasta. 😀

My set up: Totem Arro speakers, SVS Micro 3000 Subwoofer, Loxji D30 DAC, Korg Nutube B1 Pre-Amp (not built by me) and a Threshold model CAS 2 Amp.

Cheers and I hope to contribute but also gain some more knowledge.

I've got a Kenwood KA-5002 amp that is all original except I replaced the trimpots on the driver board with multi-turn trimpots as that permits the adjustments to be made more accurately.

Ever since I've had the amp the null balance switch and one coil wire on the relay has been disconnected.

When I touch the wire to the relay coil terminal the relay actuates.

What could be the problem there, what is the purpose of the null balance switch and should it be momentary push or latching?

Also do I need to recap the amp or is it ok as is?

Checked the DC offset voltages and they are -45mV and -27mV so there's no legitimate amp stage fault causing the protection circuit to kick on.

Here's something interesting.

My unit's serial number is 411160 and should be the 240001 schematic, but mine has the four diode one transistor circuit that the serial numbers from 430001 have and mine looks to have the 240001 speaker protection circuit, but it all looks factory wired except where someone disconnected wires and soldered them back to maybe troubleshoot it before I bought the amp.

So I'm not sure how to even begin troubleshooting given no schematic I have exactly matches the official schematic or maybe that was an undocumented mod perhaps?

Sure the amp works fine without the speaker protection and has ran like that several years off and on, however I know why the speaker protection is there and that it is necessary to have it.

So looking at the protection circuit I wonder if QY5 or QY6 is bad as all terminals of the two adjustment pots have +52V on them as they should so that means QY1-4 is not turned on and the relay should not be on.

in my 2.1 Kinter 3118 boombox the left and right 3fe25-4 get more juice than the point one GRS 10PT.
I dread to spend money on filter parts but figure they might make life easier on the dinky 3FE25.

220uF and a 2mH coil with 5 ohm DCR is what I'm figuring on. Just a cap might do - at lower peak levels

A light-bulb limiter on each 3fe5 might also help.

Hi there,

I’m looking to try buy an item from hifisentralen.

Is anyone a member there who could help me?

Thanks in advance. Seb

Hello,

I have a Rotel RC-1580 pre-amp with a dead transformer. Of course, it’s swathed in Rotel branded plastic, with no visible specifications, so the secondary voltage is unknown; I’ve emailed Rotel and scoured the internet, but have been unable to find a specification, nor a source for an original Rotel part.

Can anybody help in either respect? I need either the spec of the transformer so as to source a replacement, or a supplier of an original Rotel part.

Thanks very much!

L

Hello, you might have seen a numerous amount of dayton audio KAB series amplifier modules and extension boards, these look virtually identical to the wondom/sure electronics boards, just with a different name and color of PCB. Does anyone know if you can use these boards interchangeably? Even their dsp software wondom's pc ui and dayton audio's KABX looks the same.

I offer here for sale 3 sets of PCB boards, and some smd components (most of them) and 3 transformers.


All info here in this large thread: all info

• Housekeeping Circuits V4.3 - schematic and bom - part 1
• Housekeeping Circuits V4.3 - schematic and bom - part 2

I prefer to sell all at once, the price for all 80EUR + shipping.

How are ya'll heating up the boards on larger amps for soldering? I'm currently hanging my rework gun (896°f) over the area I'm attempting to work on. Simultaneously I'm using my solder iron (896°f) and have tried multiple tips but it just isn't working. I feel like I'm going to burn the board.

Hello,
i recently bought a MiniRig 4 (minirigs.co.uk)
probably the most analog sounding commercial bluetooth speaker i tried so far, but im wondering, could i 3d print something to get deeper bass or enhance the enclosure? im not really looking for a overall volume increase, but an actual low end extension (even just 5-10Hz) or reduction of some resonances....

i could also design a holder/second enclosure with some micro perforated panels (helnholtzresonators) if it would be beneficial

1. placing the speaker in a cardbox board (orsomething 3d printed which is tunneling air from the back of the speaker to to front) seems to also increase bass in relation to the other frequencys, tho im unsure if i can get really deeper bass here without an very large box, it seemed to boost specially the region that is already quite present

2. if lower bass extension is not possible, i would atleast look at reducing some resonances as the cabinet is quite heavly vibrating, might be able to load up REW again to do some measurements what could be improved (imo the biggest bump is around 80-120Hz, while extension goes down to about 60hz)

Any Ideas here?

Hi all, My son has blown my subwoofer, it is passive with a dual 4 ohm coil 6" speaker and no capacitors, the current protectors and the two 5W resistors are damaged and the values unreadable, I have bought two new protectors but need help with the resistors, ideally if someone out there has one I would rally appreciate if they could remove the inspection cover and tell me the values or take a photo, or if not would some have the knowledge to work out what they should be, they definitely end in 3RJ, and possibly start with a 3 so 3R3J, 3K3R???...the inductors measure 3ohms.... thank in advance

Consider me silly.

If I reduce the VCC of Aleph 1.2 to +-34V, (changing to a transformer with lower secondary output) and turn up biasing current such that it would produce output of:

60W@8 ohm
120W@4 ohm
240W@2 ohm
480W@1 ohm

Would it reduce the dynamic performance of the amplifier badly?

Hello DIY Audio Community,​

We are a team of engineering students and audio enthusiasts working on a new approach to speaker design that leverages AI-driven parametric modeling and large-scale 3D printing to create customizable, highly optimized sound systems. Our goal is to explore whether these technologies can enhance acoustic performance, reduce material waste, and provide new levels of customization in speaker design.

We would love to hear your thoughts, experiences, and concerns on this topic, and we have a few questions to guide the discussion:

---

1. Current Challenges in Speaker Design & Performance​

• What are the biggest challenges you face when designing or modifying speaker enclosures?
• Have you ever encountered limitations in traditional speaker materials (wood, aluminum, composites)?
• How do you currently approach tuning and optimizing speakers for different acoustic environments?

---

2. AI-Driven Acoustic Optimization​

• Do you think AI and parametric design could offer improvements in acoustic tuning and speaker design efficiency?
• Would you consider using a software tool that automatically generates optimized speaker designs based on acoustic parameters?
• What level of customization and control would you expect from such a system?

---

3. 3D Printing & Manufacturing Feasibility​

• Have you experimented with 3D printing for speaker enclosures or acoustic components?
• What are the biggest challenges you see in using 3D printing for high-performance speaker construction?
• Do you think non-rectangular or organic speaker shapes (enabled by 3D printing) could improve sound dispersion and resonance control?

---

4. Adoption & Market Interest​

• If a modular, AI-optimized, 3D-printed speaker system was available, what would convince you to try it?
• Would lighter, more transportable designs make a significant impact for professional applications (event sound systems, rentals, etc.)?
• Are there specific features you would want in an AI-generated speaker system (e.g., real-time acoustic adaptation, modular assembly, material choices)?

---

5. Open Discussion & Feedback​

We highly appreciate any thoughts, feedback, or additional perspectives that could help us refine our approach. If you have experience with AI in acoustics, 3D printing in speaker design, or have faced real-world sound engineering challenges, we’d love to hear from you!

Looking forward to an insightful discussion.

Thanks in advance

As some of you already know I designed a PCB for a 50 watt monoblock version of the "Engineer's Amp". It uses 6HJ5 tubes, B+ of about 410V, and does an easy 50 watts out into 8 ohms.

You can see the details on my web site: Engineer's amp 50W monoblock

I have one assembled into a chassis now. I will be doing more measurements soon. It works very well 🙂

Pete

When designing small enclosures, I often tune them to emphasize the 100Hz to 300Hz range, but in this case I aimed for gentle low frequencies, assuming the enclosure would be used close to a wall.

The measurements and recordings were taken 1.2 meters away from the wall, but the low frequency range improves when placed close to the wall.





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Hi,

I am planning to re-cap my Adcom GPF-565 preamp, all the electrolytic capacitor was taken out, testing them with a component tester and a MESR-100 ESR tester, all seems to be good but I notice something that I think might not be a good sign as shown on the attached pictures.

A few of them seems to have liquid coming out from the bottom of the cap and some of the contacts have signs of corrosion.

Please advise and sorry for my poor English.

Hi everyone.
I recently purchased a good old Radiometer Copenhagen RV 36 millivoltmeter (no way i could afford an hp one - the cheapest costs 2 times the cost of mine), to use along with my other analog test tools ( farnel signal generator and gould oscilloscope). So far i was using my trustworthy uni-t digital multimeter with very ok results.
The thing is that the millivoltmeter (which used costs about 2 times more than the millivoltmeter new) doesnt’t go below 15mv- and it’s not a wrong 0 reference.
The multimeter shows 18-20mv at the same value but it can go down to 7mv. The millivoltmeter even when the showings are below 15mv, stays there.
I don’t know if i have to adjust something to change the sensitivity (like any of the trimmers inside) since nothing like that is explicitly mentioned in the manual. Banana jacks are cleaned and the probes are in perfect shape.
Any advice would be much appreciated. I attach the manual which contains the device schematics just in case.
Thanks in advance

Has anyone seen the inside of a sowter transformer can and knows the orientation of the transformer inside?

This is a group buy for pairs of matched Harris IRFP240 and IRFP9240 MOSFETs. These are NOS with 1996 date codes, and they are originally from Tandberg's stock. Remember, these are HARRIS, considered by connoisseurs like Nelson Pass to be the cream of the crop!

IRFP240 & 9240 MOSFETs Vgs is measured at 170mA in a steady temperature room and with a timer circuit for consistent and precise matching.

These will be sold as NP sets only. Matching will be matched N's and Matched P's.
Maximum order = 12+12 MOSFETs. If after 2-3 days there are remaining MOSFETs, I will remove this limit. I want to make sure everyone has a chance to buy some.
Qty for sale is 500N and 500P. Maybe a few extras, I have a few sets reserved for a some friends.

MOSFETs are $6 each or $12/pair + shipping
Payment via PayPal friends & family

Example Configurations:
First Watt F5, F2, M2x - 1 N+P pair per channel, so 2+2 overall = $24+shipping
F5 Turbo V2 - 2 N+P pair per channel, so 4+4 overall = $48+shipping
First Watt F4, BA2, BA3, Ampeg B2, B2R, Markbass, etc. - 3 N+P pair per channel, so 6+6 overall = $72+shipping
Llano A200 - 6 N+P pair per channel, so 12+12 overall = $144+shipping

Please enter your order below.

12 packs
others in the pics are extra
make offer in thread if interested

Many new members come to the forum with the same request; "What speaker should I build for my first project?"

Often they have some preconceived notions of what they want, but almost always the response is to look around for a well tweaked two-way kit. Sure, good advice. But there are as many out there, as design considerations for their own specific use and needs...and budget.

Now, I'm not suggesting there is a perfect speaker project to recommend, but wouldn't it be nice if there was a project many of us could build that was exactly the same for group reference and tweaking? I can imagine this starting an unending argument over choice of drivers, as we already have our own present systems and wants (including price points) for next projects. But it might be worth discussing.

It certainly would seem worthwhile for the newbie, who could get suggestions from others with the same frame of reference, especially considering pricepoint.

To begin an initial project among forumites, might be akin to designing ART by committee, but it might make for lively discussion, and that is valuable in itself. After we've each got our "reference speakers," we might then want to take it to a new level. I'm sure the successive projects of our members with this as a common thread, would show quite the diversity of cabinet styles, tweaks and applications to accommodate differing needs, wants and talents.

But the ability to have a common reference for A/B comparisons, even in different listening rooms, measuring of the drivers and the finished speakers, and using and posting of modeling ideas, as changes of the initial designs are discussed, might be a valuable tool for learning, teaching, and exchanging information.

One of the resident Gurus (I believe it was Planet 10) once said that it's hard to beat the well respected Vifa P13WH-00-08 and the D27TG-45-06 with a single cap for a simple two-way. This might be a good starting project, with many possible applications to explore. Vifa products seem to be available everywhere and this combination wouldn't be too expensive to build a couple of times in differing configurations. (His TLb comes to mind.)

Would anyone be interested in a project like this? Or would those interested, prefer (perhaps) better, pricier drivers, and possibly, the discount a "group buy" might provide?

In my quad 405 resistor R31 seems to be getting hotter than R30 anyone point me in the right direction?

This new thread is intended to supplant the recently closed Blowtorch thread which the Moderation Team had felt had run its natural course.

This new thread will be moderated very differently and will be subject to the normal diyAudio rules:

RULES

with which we would ask all those who intend to post here familiarise themselves.

In addition to the above rules this thread will also be proactively moderated meaning that posts and consequent replies that we feel are going to veer off course or that may lead to personal insults will be deleted.

If the message doesn't get through then those continuing with such postings will find penalties are swiftly handed out. For some of you even a 1 point infraction will automatically place you in read only mode. All those effected by that have already been informed.

What we would like to see here is thought provoking and interesting discussion of anything technical that is related to audio (and other spheres) but we do not want rehashing of material that has been flogged to death in other areas of the forum including the now closed BT thread.

Enjoy, have fun and keep to the rules...

I have a few more things to part with, hopefully they could be useful to someone. I have prices listed per item, shipping included in price. I will give a shipping discount for multiple items purchased.

1) Hakko FR-300 desoldering tool with 2 extra tips, comes with case, basic stand, a few filters, instructions. Asking $150 shipped. SOLD

2) Peak DCA75 transistor tester and PCA23 SOT23 holder. Uses one AAA battery not included. Original packaging / instructions. Asking $125 shipped. SOLD

3) CO-Z858D hot air rework station. Basic Chinese hot air rework with a few tips, original packaging. Asking $30 shipped. no longer for sale

4) Koolertron Dual channel signal generator. Basic newer Chinese generator, original packaging, instructions. Asking $30 shipped. SOLD

payment by Zelle or Paypal.

USA shipping only.

Hello, after having done all possible kinds of audio related things for more than fifty years I am ready for a new challenge;
small amplifiers / speakers for multichannel applications

diyAudio reference speaker project​

I truly agree great threads never really die. Let me introduce myself. I'm from the Malaysian state of Sarawak located on Borneo Island. I've been following this thread since the year 2008 when I first ordered the Vifa P13WH-00-08 and D27TG-35-06 from Parts Express. I built the 9.5 litres enclosures and used only the 5uF on the tweeter initially. Wasn't too happy with the sound back then, but family obligations got the better of my time as my 2 kids were of school going age.

Fast forward 10 years later and my interest in building speakers was rekindled with more spare time on my hands. I built Paul Carmody's Amiga in 2018 and during the lock-down of 2021, I built the Overnight Sensations and OSTMM as well. Was blown away with the sound of these designs and my confidence in DIY speaker building was bolstered as well.

3 years ago, I built ML-TQWT cabinets based on the Fostex FX120 for the P13WH-00-08 and D27TG-35-06 as I felt they needed a new housing and I wanted to see whether I was able to squeeze more bass from the new cabinets. I experimented with parallel crossover designs but was not too happy with them. Recently, I built the AR series crossover, but with a 33uF capacitor in place of the 22uF capacitor. It's unbelievable how much better the ML-TQWT design with these Vifa drivers sound!

I must thank everyone for your input all these years to come up with a great project! God bless.

Moved to Digital Line Level section.
Thank you!

This info I just received from ebay as a seller

Today, March 4th, 2025, the United States government implemented a 25% additional tariff on all goods produced in Canada and Mexico, effective immediately. For now, the de minimis threshold on US imports remains in place. This means new tariffs will be applied to goods produced in Canada or Mexico that are sold to buyers in the United States, valued at US$800 or more, regardless of item condition.

That's $1151.61CDN today. Could have been worse and applied to any value

TU-8150
Little brother of TU-8200
●Stock tube : 6005W x 2pcs, 12AX7 x 1pc (option: 6V6 with PCB adaptor)
* 6005W is a highly reliable variation of 6AQ5
●Rated output：　 UL connection 2.9W + 2.9W　
Pentode connection 2.9W + 2.9W *8 ohm load for all cases
Triode connection 1.6W + 1.6W
●Rated input : 　 140mV (INPUT-1) 410mV（INPUT-2) * UL connection
●Residual noise : 75μV rms（IHF-A)
●Frequency response : 20Hz-50kHz（-3dB）　
●Input terminal : INPUT-1（Front）3-pole mini jack (Priority)
INPUT-2（Rear）RCA jack
●Output terminal : SP output terminal (4-8Ω) Binding terminal (banana plug usable)
　　　 HP terminal (8-600Ω 6.3mm standard jack (Not balanced)
●Power voltage : AC120V 50/60Hz (2-slot inlet) 　
●Power consumption : 28W *No signal
●Dimensions : W210 x H122.5 x D252mm (incl.projections)
●Weight : Approx.3.5kg (assembled, excl. power cord)

https://flic.kr/p/2mybhNU
tu-8150 https://www.flickr.com/photos/64593884@N08/

Just want to commiserate a little. I really like working with Solen.CA to build cabinets for me. They stock most of the drivers and amps I use so I don't need to put a lot of detail into my DXF (i.e. CAD) drawings. Just the outer shape, driver locations and they take it from there. If I order electronics they also throw in a bit of a discount on the drivers and amps, and take advantage of a little difference in CAD vs. USD.

As of right now however that discount has vanished with a 25% tariff on anything shipped from there. << sigh >>

I hope this isn't breaking any forum rules everyone, if so I apologize in advance, I just didn't expect to have such an immediate impact on my hobby.

SOLD!


Have some used parts desoldered from a 3 way crossover. All parts are high quality with only minor signs of usage. All values are measured and within the part tolerance. The coils have custom made ABS pcb holders!

If you are a EU member and interested buying all parts together, please send me an offer per pm - private only non commercial!
(new price would be around 1400 - 1800 EUR depending on your source)

Have fun, Toni

Hi,

I'm looking for the service manual / schematics of Cyrus One (the newest, 2016-2019) amp.

Any hints?

Thx a lot to everyone

Continuing from https://www.diyaudio.com/forums/pc-based/341590-using-raspberry-pi-4-usb-dsp-dac-7.html#post5898526

Last posts:
phofman:
Keeping the async mode for the audio gadget would be technically best, but quite difficult to implement [alsa-devel] Options for ASYNC feedback source in USB-audio gadget (USB OTG)?




Tfive:
I read your posts on the alsa-devel mailing list. IMO all the stuff you describe is pretty complicated. My opinion:
a) adaptive in this case is perfectly fine if you have proper adaptive resampling, i.e. a pll implemented digitally with smooth, long term averaged adjustement of the resampling factor.
b) if you want to go async and at the same time avoid all the userspace feedback hassle and the daemon keeping an eye on this, why not use an existing alsa device as clocking master and slave the gadget to it. And then base the clock/timing feedback channel off of the master alsa device's clock/timing? The "master" device could be specified as module parameter.

hi! Can anyone help me find the theile parameters for m118-4 from jbl? I sourced the web but found nothing ! TIA!

I have seen these in a music academy today and find them interesting.
They are only about 6inches wide.
I would really like to listen to them but it's vacation time in Bavaria.
The sticker says Seeburg GL 16 vox
Cylindric Wave Radiator

Hi,

I’ve been away from here for a long time, so long in fact, that the powers that be insist I introduce myself again… I’ve been interested in hifi for 30 years, and tinkering with it more recently. Generally it fairly simple repairs, in terms of electronics, at least, but I’m hoping to improve my soldering, for a start, along with my technical understanding, so as to embark on a few more involved projects that have been in mind for a while.

I look forward to learning from others wisdom, here, and hope to be able to contribute something too.

L

Building a new system with old parts from my stash. I will use my 414-8A´s, reconed with original cones ca 15 years ago, as midbass in 60-70 liters closed boxes. They should cover 60-340Hz. How would you apply damping inside the box and would glass wool be good enough?

I spent a few hours last night chatting with GPT and I think at the end of the year I want to do this build.

--------UPDATED LIST--------
ScanSpeak Revelator 22W/4851T 8" Woofer
ScanSpeak Revelator 12M/4631-G00 4.5" Midrange
ScanSpeak Revelator D2904/7100-03 1.1"
OSD Nero HTA7200
DSP -- To Be Determined
--------------------------------

I also have 18" subs in their own boxes.

The crossover points would probably be close to 60Hz, 400Hz, and 3,000Hz.

Thoughts and input, please? Should this be a solid build?







--------OLD LIST--------

1. ScanSpeak Revelator 26W/8861T 10" Woofer
2. Scanspeak Illuminator 12MU/8731T-00, 4" Midrange
3. ScanSpeak Illuminator D3004/6620-00 Tweeter
4. OSD Nero HTA7200 (Hybrid amplifier)
5. Dayton Audio DSP-408 4x8

I have a few standalone DACs that I'm no longer using. To simplify things, all prices listed include shipping within the CONUS and transfer fees.

Musical Fidelity V-DAC(the first version). Includes power supply. $80


Fiio K11 R2R. Includes power supply. $120


SMSL M100. No power supply included. $50


Angstrom Model 200. This is an older high end surround sound processor but can be used as a 2 channel DAC. I believe it is based on Multibit converters but not entirely sure. Beware: This unit does not have a fixed output. Volume is adjusted from the front panel using up/down buttons and there are only indicators for minimum and maximum output. There is no display indicating actual volume level. $120

As the title says: can a thread be ignored so that I don’t see it again, even I have posted there?

SOLD

These are the leftover parts from my conversion project. If anyone needs them, they are yours for the cost of shipping/packing (UK).
(Speaker boxes not included)

Anyone has design PS instead of switching that sell together with class D amp?

Any 5-10A 48V design can share thank you

for repairing a pair of ASL AQ-1006m i was paid a quad of 8045's, what do you think?

Well I got this taramps 3k bass from a buddy said it was blown and I could have it. We'll checked none of the fets were shorted so I took out the board from the heat sink. Wow ...taramps need to move this brass bar they put on the trace closer to the terminal. I did because it burnt all the way through it. I wish I took a pic before I fixed it. But my question, do you think this fix will suffice or should I bridge the top of the board too?. And this 10ohm 20w resistor was cracked. After a closer look. It melted the caps ..although i think they wernt compromised. They look worse than they are. Do you think this is related to the power trace failure. The amp is working. Then I seen the resistor and seen all the heat that was generated.so i tore the caps and resistor out. I hope it was related. BTW this amp was probably hooked up with too small of wire and god knows what ohm load the speakers were wired at.. with the gain high. With no regard to what clipping is.. some people....thanks guys.

HI all.
I want to make a inverter powered by a 12V wall-wart adapter to power valve heaters with the low side then drive a center-tapped mains transformer in reverse to get the high plate voltage.
Online I see mainly square wave drive designs, but I think this is a bad idea for a high gain valve preamp, so I set up a simulation.

I plan to use a XR2206 or ICL8038 for a basic sine wave generator.
I like the idea of using a sine inverter and can run the transformer at a higher frequency for easier filtering and adjust voltage by a potentiometer after the function generator IC.
This design outputs 130Vac. does this look like I'm on the right track?

I took the photo of the crossover in the topic Kef 104/2 tweeter replace...
I was asking the crossover experts if changing the values of 13 /14 /15 /16 caps and the resistors regarding the Tweeter power could also affect the performance of the two B200 woofers which are in push-pull mode?
thankyou

Come on light to protect mode and no pwm on power supply no pwm on output I change all mosfet and all ics this is a

Edge Xtreme EDX800.4FD-E0 if anyone can help thank you​

I'm in the final stages of building my first pair of 2 way speakers and already thinking what next. Ive built plenty of subwoofers. When I started this 2 way project it was originally going to be a 3 way but I must have heard at least a half a dozen people tell me not to go 3 way since it is a way more complex build. I reluctantly decided to go 2 way and Very glad I did. I learned a lot on this 2 way build but what I didnt learn is why are 3 way builds so much harder? Isnt it just an extra driver and crossover. Is it that much more difficult to match up 3 drivers? Anybody care to educate me on the subject? I'd appreciate anybody willing to take a few minutes to explain it to me. This forum has been a huge help for me already so thank you for that

hey @lowmass the science says a slightly curved array would perform better but that would require mounting some ribbons in orientation less than vertical ...

considering the ribbon is "free swinging" once it stretched out a bit from normal use overtime would it then begin to sag for those ribbons that are angled slightly upwards ?

the array would start off from the ground plane as perfectly perpendicular to it ( vertical ) but gradually curve backwards so that the ribbons at the very top would be angled back maybe 20 degrees ...

i am guessing plastic ribbons would be fine, but the way arrays work is they lose HF at 3db/octave because of the weird array math which means i need the loudest ribbons possible and can't use plastic ones - they have to be pure aluminum like Aurum Cantus

HELP ! ! !

A simple scheme and pretty

Hi all,
I am trying to repair a NAD C352 amp. The symptoms are that it powers on to an orange standby LED, and when you try to power it up, the relay on the power board clicks but nothing else happened.

I originally thought it was due to dead caps on the power board (they're notorious for this) but I later also determined that there is a shorted diode on the power board in the rectifier circuit, and also that the transformer itself is completely dead. I have determined this by measuring continuity on the primary and there's nothing. Completely open. And when you power it up, no voltage whatsoever on the secondaries.

I am trying to see if I can find a suitable replacement transformer but I am struggling to work out what voltage I need.

Can anyone have a look through the service manual and help me out?

https://elektrotanya.com/nad_c352_sch.pdf/download.html

Many thanks!

Needed a small amp to replace the underperforming amp for a speaker and found this.

https://www.amazon.com/HiLetgo-TDA2050-Amplifier-Digital-5W-120W/dp/B0CDWTL57H

Aside for a couple altered resistor values, the amp is the circuit shown in the datasheet.

https://www.st.com/resource/en/datasheet/cd00000131.pdf




The amp works good for what it is.

The plan is to use the second one for testing purposes to see just what this amp is capable of.

I'll do two things.

1. Use a 4 and 8 ohm load powering the amp at 24Vac with an audio generator supplying the signal and oscope across the load to see what the frequency response is and how much power it puts out.

2. Find the lowest resistance for R4 that keeps gain above 25dB (1dB higher than datasheet recommendation for safety) and the highest resistance value including R4 that keeps the amp stable while keeping a flat frequency response. I'll then use a fixed resistor to set the lowest gain and a trimpot in series. That way I'll have a variable gain.

I may also pick up two more of these amps and run them bridged to see if it's possible to eliminate the speaker coupling capacitor. That would limit me to an 8 ohm load though which will be fine. The phase splitter for testing will be an Edcor transformer with a 15k center tapped primary and secondary, however if the amp is proven successful I may either use a dual OP-AMP as a phase splitter or use the amp with balanced sources. The phase splitter could be built in a separate box with various inputs or I could use a balanced preamp if I actually decide to do anything with these amps at which time I'd add speaker protection as well given no speaker coupling caps.