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

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

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.

Long story short:
7x ROAR18 with different drivers tested, measured, used at a DJ gig in a 500-person venue with impressive results.

Pros: Lots of headroom, especially in the kick range, usable up to 120 Hz and possibly higher.
Cons: Needs EQ in the low end for a balanced sound, big and maybe a bit too heavy for one man to throw around.

The long story:
A friend of mine wanted "decent" sound everywhere in his big barn where he works on his hobby (cars) and asked me for help. It didn't have to be very loud, but it's a big place, about 20 m x 10 m x 11 m (LxBxH), so a single sub wasn't going to cut it. Knowing his taste in music a little, I knew he wasn't necessarily looking for the lowest possible notes, but a tight kick was definitely needed. Instead of designing something from scratch, I thought Martinsson's ROAR18 might do the trick. This was helped by the fact that I had already built and listened to the ROAR15 just to see how it would sound. Although it didn't get very loud in the low end, it responded pretty well to EQ at the expense of max SPL (40Hz was certainly doable).

The ROAR18 seemed to dig a little deeper on paper, especially with a small "mod" that I did: use ALL the internal volume available (so the long channel is about 10 cm longer; this seemed to simulate fine: a bit less sensitivity in return for a little lower response). So I figured it would also do well with some rap music (also a prerequisite). And another big factor was that I had a couple of different 18's lying around, plus a bunch of broken and discarded 18's at work, where I was happy to pull them out of the trash (with permission)! They were Celestion CF1840JD's that needed their magnets realigned as the glue had failed, so it was quite an operation with a few recones involved.

They were not the best for the ROAR18 (not the biggest BL), but they simulated ok. So I decided to build a ROAR18 to evaluate. After listening to it, my friend approved and I set out to build 6 more, since that number matched the cut list of 15 sheets of plywood (244x122 cm) and the number of 18's I had on hand; hence the odd "7".

First one built:





In-room measurements with and without EQ:




The large build:

With wood prices through the roof, I opted for cheap underlays (32 Euro/sheet) because they were for a permanent installation and didn't need to be "road proof". The three that were for me (the white ones in the photos) I laminated with epoxy/fiberglass. These latter ones had wheels and weighed a whopping 84 kg.







I finished them a few weeks ago and asked another friend of mine at a place called "Landbouwbelang" in Maastricht, the Netherlands, if I could measure them there since they have an outdoor space with little interference from nearby walls and such. He went one better and asked me if I would like to try them out at a party that was going to take place there in two weeks. Yes, of course!

Measurements were taken at 2.83 V, no filters or EQ, with the mic at 1 m on the ground and the speaker facing the river, see photos. Everything seemed fine, although the 109 dB/W at 106 Hz seemed a bit high to me, but I double-checked my measurements and levels...



The drivers are:
-5x Celestion CF1840JD (8 Ohm 1200 W RMS/2400 W program)
-1x Celestion CF18VJD (8 Ohm 1600 W RMS/3200 W program)
-1x Beyma 18P80Nd (8 Ohm 800 W RMS/1600 W program)

The measurements were done with Umik-1 and REW V5.20.13.


I think the measurements and photos speak for themselves 😊.




The gig:


(left and right of my setup are the in-house system speakers, Xtro + 186 Horn)

The setup for the gig was as follows:

1x Nova DC8000 processor
2x Powersoft D4002 bridged to 2x CF1840JD subs on left and right stereo channels, delayed to 45 cm -> 4000 W into 4 ohms (these are the black subs on both ends in the show setup)
1x Powersoft M50Q channels 1 and 2 bridged to the CF18VJD sub and channels 3 and 4 bridged to the 5th CF1840JD -> 2x 2500 W at 8 ohms (both mono summed)
1x Powersoft D2002 bridged to the Beyma 18P80Nd sub -> 1x 1200 W at 8 ohms (mono summed)
1x RAM Audio S6004 for my Synergy tops (build link here: https://www.diyaudio.com/community/threads/synergy-horn-for-135-db.305852/) -> 2x 1480 W into 4 ohms.

The HP for the Roars was set at 27 Hz and 48 dB/oct. I set the LP quite high at 120 Hz and 48 dB/oct because I wanted to hear how they would handle kick and sub duties.
I used a 6 dB low shelf at 50 Hz with 6 dB gain and a 3 dB bump at 40 Hz with a Q of 2.871 (or 0.5 octaves). To even out the room modes, I delayed the outer 4 subs by 1.31 ms (or 45 cm), which gave a nice even sound throughout the venue. The limiters were set conservatively on RMS, but allowed peaks to get through.

The headroom was kind of absurd (at least in my book), which is of course a good thing: all night long the -9dB lights on the amps were occasionally tickled, only during the VERY LAST song they turned it up to -6 dB peaks, which was still enjoyable, but not for much more than one or two songs.

There were many compliments on the quality and amount of bass, and apparently it was much more powerful than the in-house system consisting of two XTro tops and four 186 horn subs. I was also pleasantly surprised with my 2" Synergy horns, they easily kept up!

Here is a playlist with a few videos taken with my phone:
https://www.youtube.com/playlist?list=PLZ9IxQRaHpo8qlY31TOXkLRJ4tjH5XnTm

Now I have to figure out where to place the subs in this big barn I built them for in the first place...
But maybe there will be another gig before they are permanently installed😎.

Any questions, remarks, comments, suggestions, let me know 🙂

Dear DIY People,

“Just” as info :

I noticed some construction problems in some Eton 7-375/32 HEX (in 2013-2014, I thought it’s a "casual" thing!) and then again I have the same problem in 2018-2020 with some Symphony II 7-312/C8/32 HEX!
The wires connection that goes from the terminals to the coil hits the cone during excursion.
We can mainly notice it when the woofer reproduce continuos low frequencies with excursions of +-2mm or more, and it's not just a question of "noise", it brings also to higher distortion.
Incredible to believe that we can have such a basic mistake on this price point drivers (over 200,00€ per piece),
NOT necessarily all drivers have this problem! Some does (more or less pronounced) some don't. Question of luck.
ALL DEPENDS on how "carefully" they glued the wire to the cone! Above the glue point the cable is very close to the cone.
I guess they should have found a better solution that it's not so sensitive to human error.

I will try to attach 1 photo and a Video (at the end of the page). In the videos is clearly possible to see-hear what I mean.
The test was made at 30, 35, 40 and 45 Hz, and I did the same test with drivers of the cost of 20,00/40,00€ values and there was no any noise! 🙁
But it’s enough to play records like the Billie Eilish one and you will clearly ear it…

P.S.
I wrote many email to Eton, just to share my experience and to "help" them for the future... NEVER any kind of answer.
I also wrote few times to Klang&Ton and to Mr. Holger Barske (email and Facebook) thought that they should be interested on this kind of concern... NEVER any kind of answer. 🙁



View attachment Eton 7-312-C8-32HEX-Video-CutSm.mp4

Thank you for the attention!
Take care and great DIY building to all of you!
Andrea

Hello forum members

finally decided to have ago at the JLH phono pre amp project. Have managed to pull most of the parts together passives and transistors etc. I have the original PCB and a new power supply board.

will upload some pics later when back in the workshop

regards

Hello there amplifier lovers! 🙂

Here is the JLH Original:


Here is my suggested circuit with EXICON Laterals:


The power supply should use Transformer 2x15VAC
which gives around 40VDC after rectifier.

Hi looking to learn from you.

Big hello to everyone. I'm here to learn. Thanks for letting me in!

Hi guys,
My youngest son pressed his little finger on both fostex108ez used in my Cornu speakers, and they are all sunk.
How would you guys fix this? They are quite small and the vacuum cleaner sucking option, which I use regularly on my subwoofers does not seem to be an option here. Material looks fragile, and I don’t want to further mess things up.

Any advice would be strongly appreciated!!
Cheers,
Fran

Hey everyone, my name is Joseph, and my current system is a pair of Klipsch Fortes, where I instantly fell in love with the horn sound. I am working towards making my own 4 way active crossover horn speakers to upgrade to. I am starting with learning all about the function and science behind horns and how they are designed. While I won't be able to design my own horns for a long time, I still like to learn about how and why things are designed and made the way that they are. I am also learning about ciruit design so that I can possibly design my own amplifiers in the future. It is a lot of fun for me to learn new things, and this forum has a great wealth of knowledge that I hope to be able to tap into in the future.

Hi everyone!
I'm here to improve my knowledge about hifi electronics.

I have a TNT120 that I have owned since 1984 along with a AGI 511a pre amp and Magnepan MG1b's and just updated to LRS+'s.
I have always had a very low hum out the speakers from the beginning that couldn't be duplicate at store. It still happens with only the amp plugged into 110v socket with the ground connected or not and the speakers connected with Kimber wires. The manual states "The only Way to prevent this hum is to float this ground".
Any help would be nice. Thanks Larry

New guy here - Calif

TT nut. Buy / sell / repair vintage gear. Anything from 8-tracks to Macs with big blue meters. Love it all!

Hello everyone, have a good day all

I think the time has come we have to show our fun loudspeakers or outdoor ones.

Here my contribution (outdoor fun speaker) :

Cheapo drivers with diy aluminium sandwich cones. (there is a thread on it here on diy audio forum).

DIY whizzer cone and extra bass with 1mh inductivity forming a one and a half way system (=fullrange with added bass).

Cheapo TDA7498 amp with 34 Volt smps power supply. And whuzi audio preamp Bluetooth
with certainly only fake parts. But works.


Simple EQ with smartphone app.

Drivers were only 10 dollars but decent quality if you know how to use it.

I have these two capacitors surplus.

€100 + shipping.

R

Armbianmonitor:
https://paste.next.armbian.com/egohivineg
Hardware:

• Board: Orange Pi Zero 2W (Allwinner H618)
• Audio Module: MAX98357A (I2S)

Connections:

• BCLK → PI13 (Pin 7)
• LRC/WS → PI14 (Pin 16)
• DIN → PI15 (Pin 31)
• 5V/GND → Properly connected

Software:

• Armbian Version: 25.5.0-trunk.147 (nightly)
• Kernel: 6.6.75-current-sunxi64

Configuration:
/boot/armbianEnv.txt:
overlay_prefix=sun50i-h618 overlays=i2s param_i2s=on

Problem:

• No sound output via MAX98357A.
• aplay -l returns "no soundcards found".
• dmesg | grep i2s shows no output, indicating the I2S driver is not loaded.
• Missing I2S overlay: Checked /boot/dtb/allwinner/overlay/ — no sun50i-h618-i2s.dtbo (only I2C overlays are present).
• Loaded sound modules: Only snd_soc_hdmi_codec (HDMI audio).

Steps Taken:

1. Verified physical wiring (BCLK/LRC/DIN, 5V/GND).
2. Updated to the latest nightly build (25.5.0-trunk.147).
3. Added overlays=i2s, param_i2s=on to /boot/armbianEnv.txt.
4. Tried manual driver load: modprobe sun8i-i2s (no effect).

Questions:

1. Is I2S support for Allwinner H618 available in kernel 6.6.75?
2. Are there plans to add sun50i-h618-i2s.dtbo in future releases?
3. Is there a workaround to enable I2S on H618 (e.g., custom DTB)?
4. Would upgrading to kernel 6.7+ resolve this?

Diagnostics:
uname -a:
Linux orangepizero2w 6.6.75-current-sunxi64 #1 SMP Sat Feb 1 17:37:57 UTC 2025 aarch64 GNU/Linux

cat /etc/armbian-release:
VERSION=25.5.0-trunk.147 BRANCH=current BOARD=orangepizero2w

dmesg | grep -i i2s: No output.

Request:
Any guidance or patches to enable I2S on H618 would be greatly appreciated. Thank you!

Kazuo Ozawa and Bunpei are collaborating in a new application of GaN transistor as a replacement of SiC rectifiers for power supplies used in digital audio devices. They think this is a novel approach and worth sharing on this forum.

For these years, Kazuo has made his efforts mainly on improving Salas Reflektor type and Taylor Follower type regulators. Recently, he applied GaN transistor, GS66502B of GaN Systems as a replacement of SiC MOSFET, C3M0280090 of CREE and obtained a satisfactory result.
http://john.asablo.jp/blog/img/2016/12/19/458cae.png
http://john.asablo.jp/blog/img/2017/01/17/460d69.jpg

On the other hand, Bunpei has tried such SiC rectifiers as manufactured by CREE, Rohm, Infineon. His latest favor was Infineon G6. He read Kazuo's blog post and thought, "Is there any GaN rectifier? That must be interesting."
There was a hint on a technical presentation given by Sanghyeon Park and Juan Rivas-Davila.
https://superlab.stanford.edu/poster/APEC2017_slides_Sanghyeon.pdf
They said, "Tying the gate to the source makes GaN transistor behave like a diode.". Bunpei's first attempt was not successful because the GaN transistor got very hot in his environment. He asked Kazuo to apply GS66502B with his custom board especially designed for cooling.

At the beginning of this month, Kazuo reported his first result on his blog page in Japanese,
GaN Transistorをダイオードとして使う: Konちゃんの虫眼鏡
expressing his very good comments on the new rectifiers. He applied the GaN transistors in PSU of full-wave rectification for an OCXO master clock generator.

Bunpei immediately purchased GS61008T, which has a thermal pad on its top , and followed Kazuo's approach. Bunpei applied the rectifiers to PSU of full-wave rectification with both 4 diodes type and 2 diodes type. Those PSUs are used for Chiaki's SDTrans384 SD memory card transport, ES9038PRO Dual Mono DAC and NDK DuCULoN OCXO master clock generator.
Bunpei's impressions for the new GaN rectifiers were very similar to those given by Kazuo. Both of them felt something very new and remarkable in the improvement of resultant sound quality. "It's a kind of quantum leap!"

Kazuo and Bunpei hope that DIY audiophiles on this forum will confirm their claim is not any bluff and will have a happy music.

You can easily purchase those GaN transistors, products of GaN Systems via Mouser. For cooling, Kazuo designed a special circuit board and Bunpei soldered a small piece of copper plate on the thermal pad of the GaN chip.

I've built my Gabster TD1 DAC in combination with an iancanada streamer.
It's my favourite 😍 till today
I'd like to share my experience and also get feedback from other people concerning this wonderful DAC.

Fadel

Now that I am retired I am hoping to finish projects and move them on before my family has to. I dug these out, built them 25-ish years ago. Mostly the Andrea Ciuffoli OTL v8.2 with a few changes to fit the transformers I had. Operating at 150v/200ma -52-ish v bias. 44W at clipping, the driver stage clips first. An ambitious project at the time, 5 total transformers. I am going to modify to a SRPP first stage based on the tubedvr design.

Hi. Just registered. Have built one of the Whammy head amps and currently looking at the Pearl 3. Always enjoy a bit of DIY as long as it's not a bag full of microscopic components...

Hello, I'm currently on a speaker build journey for my final project of University, focusing on material and modularity to elevate home speaker design to be more inclusive and adaptable to its environment, allowing its users to change its aesthetic. This project was born from the ambition to limit product vulnerability from trends, aesthetic boredom, and home decor changes, encouraging users to have a longer-lasting connection, which lengthens the product lifespan and how much the user will engage with the product overtime.

I'm looking forward to conversing with you and developing my knowledge and understanding for the science of speaker design.

I am repairing a "James" subwoofer model 6 amplifier "see schematc". I got it running, but it has 13% distortion and the output filters are hot, 100 degree C.

It is a bridged design and the (pos side) pwm is 1.8 khz IC13 pin 6 while the (neg side) pwm IC 4 pin 6 is 360hz. Shouldn't these signals be the same?

Thanks, Gary

Hey All, excited to join the community here. I've built speakers from Bill FitzMaurice designs about 10 years ago. Planning to build a pair of Keystone Subwoofers and looking forward to learning more about speaker building and system tuning.

FS: Zilchlab Econowave Crossover PCBs



Before Zilch passed away he asked me to keep these crossover boards available and in consistent production for speaker builders everywhere. Pairs are available direct from me for $32 shipped CONUS w/instructions. Send me a PM if you'd like to build a pair of Zilch's Econowave speakers.

For more specific build information check out the massive original thread here on Audiokarma: Zilch's AK Design Collaborative - Econowave Speaker | Audiokarma Home Audio Stereo Discussion Forums

Not to mention Flex Your PCD Mettle on the Parts Express site where he really picked up steam: Flex Your PCD Mettle: - Techtalk Speaker Building, Audio, Video Discussion Forum

forced Grok-3 Beta to digest my Edelweiss-3 amplifier using Tesla strategy, step by step refining calculations of details then back to the whole thing, pushed Grok-3 to use real anode V-I curves for a typical KT-88 and driver tubes, to account to non-linear internal resistances of tubes with complex nested feedback loops, and got final calculations that correspond to what I measured and heard. The graph is for the case of negative 3.8 Ohm output resistance, with positive output resistance they are almost the same, with insignificantly lover distortions. It confirmed that in my amp there is no sound difference between EL34, KT-77, 6CA7, 6L6GC, KT88 and even LS-50 tubes, the end result is still the same with minimal adjustments, thanks to the overall design with nested feedback loops.

Q: What is the operational role of power inductors in Class-D amplifier circuits?

A: In Class-D audio amplification systems, power inductors perform critical filtering functions through these primary mechanisms:

LC Filter Core Function
Collaborating with capacitors to form:

• 2nd-order low-pass filter topology (typically 50-500kHz cutoff)
• 40-60dB attenuation of PWM carrier residue (300kHz-1MHz range)
• 90%+ suppression of harmonic distortion components

System Performance Optimization
Key selection parameters for modern high-performance designs:

• Miniaturization: 1210 to 2520 case sizes with <1.2mm profile
• Efficiency Enhancement: <0.05Ω DCR at 3A load conditions
• Thermal Stability: Maintain stability from -40°C to +125°C
• Saturation Resilience: 20-30% headroom above peak current (I_sat ≥ 5A)
• EMI Mitigation: <5nH parasitic capacitance configuration

AEC-Q200 compliant automotive-grade options
These magnetics enable Class-D amplifiers to achieve:
✓ >90% power conversion efficiency
✓ THD+N <0.005% @20hz-20kHz
✓ 85°C ambient temperature operation
✓ MIL-STD-202G compliant vibration resistance

Typical applications: automotive infotainment, professional PA systems, and compact IoT audio solutions.

Someone gave me a pair of these speakers. These are shop speakers for me. One needs to be re-foamed, it was not done correctly.

Is it worth messing with the 3uf and 5uf bi-polor electrolytic caps in the crossover? I was thinking of trying some solan caps in there, if they will fit.

Neurochrome Preamp Power Supply. SOLD

Neurochrome Universal Buffer. SOLD



These are like Swiss Army Knives. Super versatile. Used for a while in a preamp and now they just sit on a shelf.

I am just learning how the internals work on audio amplification, I have an old adcom 545 with an Integra DTC 9.8 processor just looking to improve how bright the adcom gets a higher volumes, I love the set up for the money I have in to it

I'm ready to test this marriage between a pair of my dc1000 driver's & some empty Lowther horn cabinets. The initial listening test was quite positive. Great fun. The Tannoy units TS parameters were close to figures I've seen for Lowther PM6's.
The little horns cut off too early for deep bass but the impression of depth is certainly an improvement on the lowthers. I know that's not what the Lowthers are all about but I enjoy experimenting. I might tinker with the crossover after testing but it doesn't sound bad to my 'mature' ear.

Hello everyone I'm from Michigan USA. I have vintage Pioneer, Sony and JVC components. I try to repair my own equipment. Thanks for letting me join.

What is the difference between the D amp chips?

Is the CS8673 inferior to the TPA3116?

I cannot read Chinese Data sheet - who can say something on this chip?

@Karlsonate gave me a hint:

https://www.diyaudio.com/community/threads/unboxing-zk-mt21-tpa3116.403857/post-7467281

Some subjective comparison between mini amps:

https://www.diyaudio.com/community/threads/unboxing-zk-mt21-tpa3116.403857/post-7501910

SOLD
Used lightly and limitedly for various applications/experimentation.
Reboxed and ready to ship

Shipping:
€16 within Ireland
€30 to a few of the nearest european destinations (UK, Germany, France, Netherlands, Belgium), otherwise very expensive.

Bob Cordell's Linear Audio Vol 4 article 'VinylTrak - A full-featured MM/MC phono preamp' led to a discussion that resulted in much additional material.
Bob has been so kind to place this on his website.

I'll shortly put up a link from linearaudio, but if you are interested in this stuff the additional material itself is well worth a read.

And, of course, if you want to reach out and actually touch the equipment (or Bob 😉) find us in the lobby at the RMAF coming weekend!

jan didden

Hello - I'm restoring a Dual CV40 amp to use with a Shure M95 G-LM cartridge (requires 47k input load).

I have a question regarding the modification of the resistive input load in the phono preamp (schematic attached).

If I understand correctly, in the set up shown, the signal sees the resistive load formed by the series resistor R2 and the parallel network of R1, R3+R8 (1.5k + approx 77k) - is this correct?

If I wanted to bring the load down to approx 47kohm, changing R1 to approx 53k should do the job?

Thanks in advance for your help!

Martin

There are a couple of these receivers listed on that auction site, but at prices a little higher than I'd like to spend. Do any of my fellow DIY'ers have one of these collecting dust that they wouldn't mind parting with?

I saw a post asking about a datasheet for an obscure component - that I happen to have. So I created an account and am currently jumping through whatever hoops necessary to actually help the fellow out.

Cheers.

Hi,

I have an Wadia DAC with broken VFD NEC FC20X2JA-AA. Does anyone of you know where to get one?

Thank you very much.

PhanTran

THESE BOARDS ARE SOLD. THANKS FOR LOOKING. These amplifier boards are the universal mount style from the diyAudio store. The jFets are original Toshiba 2SJ74/2SK170 that I had left over from earlier projects. They are matched. The IRFP240 Mosfets are quad matched with all 4 on a channel matched. Putting the funds toward an SET tube amp project.

The price is $50 plus shipping and I am shipping from Michigan US.

Hi diyaudio!

it's been a while since I've posted but I was wondering if any of you might be able to chime in on my latest research project.

Last time I was writing here I was looking for help on a hi fi amp i was building for my undergrad senior thesis. A few moves and thirteen years later I'm now a researcher at the Canadian museum of science and technology working to reverse engineer Hugh Le Caine's electronic sackbut instrument, which is part of their collection.

https://en.wikipedia.org/wiki/Electronic_sackbut#

My circuit analysis friend and I are a little stumped by the suggestion of a colleague that the 6as6 tubes in the oscillator section of the device are frequency counters: no feedback, no RC circuit with a time constant to flip flop a square wave at a defined rate. Just resistors:


I'm including two of the four stages. the caps on the left of the 6as6 stages go to a transformer coupled blocking oscillator. The output exiting left of the plate goes to a mixer-so the stages don't cascade. I really think this is just a buffer / gain stage to couple the aforementioned blocking oscillator to the strange resistive mixer that follows these pentodes.

I realize this is more of an amp forum than a synth forum, but since these pentodes really do look like a coupling stage to me (rather than a counter stage) I think we are squarely in the amplifier section of the tube circuit topology realm.

In short though - is there any conceivable way a pentode, wired like this or something like this (the circuit tracer may have missed something!) could act as a clock divider (e.g. take a square wave and output other square waves at ratios of the original frequency)?

Thanks in advance for your perspective, and let me know if there's additional info you might like to answer this more accurately!

Hi all,

I am trying to modify the attached circuit to use two parallel section of a 6922 tube for the gain stage instead of the 6GK5 while keeping the second 6GK5 cathode follower. In a previous version of this mod I had the two parallel section of the 6922 followed by a mosfet buffer and all worked fine.

The heaters are 12.6 DC regulated DC heaters with the tube connected in parallel. The original circuit had the two heaters for the 6gk5 on each channels connected in series. With the first tube a 6922 I can no longer do this as the 6922 and 6gk5 heater have different impedances and thus the voltage on each heater will not be the same. I modified the heater supply to feed two 6922 in series and the two 6gk5 heaters in series. both of these are connected in parallel to the 12.6v regulated supply. In doing so I am getting a high buzz on the output of the preamp. Music is playing and it looks like the voltages measure OK but the buzzing is very high. Any idea what's going on?

Thanks,
Ron

I'm the new owner of a Magnavox CDB460 (one of the models with a TDA1541 inside) that I picked up for $80 shipped. The seller said it "works great" but of course now that I've got it here, it won't read any discs. It wasn't packed super well, so something could have rattled loose in transit.

It powers on, the tray opens and closes, the disc spins, but then reports "ERR" on the readout. Interestingly, it does the same thing without a disc inserted -- motor spins for a couple seconds, then reports "ERR".

I popped off the cover to observe, and I don't see any light from the laser at any point in the process. I don't have a service manual, so I haven't broken out the multimeter just yet.

The seller is offering to refund 20% and let me keep it, or refund the whole amount if I send it back.

I'm a tinkerer -- I've cleaned and recapped a Marantz 2215b, I've put together a shortwave radio from a kit, and I've built some simple guitar pedals. I don't have any experience servicing CD players, but I'm happy to learn. Does this sound like it's worth repairing?

Another possibility is to harvest the relevant bits from this unit and put together a TDA1541-based standalone DAC for use with other digital sources. But I don't have any experience with that, either.

Bought a pair of these yesterday. Looking forward to restoring them. Having said that, they seem in very good condition. Does anybody have any information of these. When were they made, driver set up...? The 'condenser' I can see has '1943' on it. Surely, this isn't the date the speakers were made?

I want to build this circuit. My question is, are the two protection diodes no longer needed?
Thank you in advance for your answers.

Here are a few groups of things hopefully someone can find use for. Each group / item is priced individually with USA shipping included. I will give a shipping discount for multiple items purchased.

1) Twelve 25 or 50 watt wire wound aluminum chassis mount power resistors. If you cannot read the values, let me know. Asking $20 shipped.

2) Twelve Tantalum resistors, older Audio Note and Shinko: 1/2 watt: two @ 390R, two @ 1K. 2 watt: two @ 47K, two @ 100K, four @ 300K, asking $20 shipped. SOLD

3) Large cement 8 ohm leaded dummy load, 6 1/2 x 1 1/2 inches. 100W free air, 200W sinked. Asking $10 shipped.

4) Sixty older Kiwame japanese carbon film resistors, good to at least 750 volts. 46 @ 2 watts, 14 @ 5 watts, if you need a list of values, let me know via PM. Asking $50 shipped. SOLD

5) 4 or 5 - nines silver wire remnants with 20 gauge insulation tubing included: 4 ft. of 24 ga mundorf gold/silver alloy, 7 ft. of 24 ga, 4 ft of 20 ga. Also a spool of over 50 feet of 30 ga teflon coated instrumentation wire that now goes for 8$ a foot....Asking $50 shipped. SOLD

payment via Zelle or Paypal.

USA Shipping only.

61yo male from Athens, Greece. Mostly into vintage stuff.

Hello,

I'm looking into possibly using a compressor/limiter between my souncraft signature12 mixer an my F5m amp. I want to primarily use it as a "Brickwall' limiter to ensure the amp never sees more than 3V.

I want to be able to set a threshold voltage, in my case 3V as opposed to setting a ratio like 10:1 or 20:1 since that is less accurate. I'm also looking a solution which has short attack and release times. I rather not design my own hardware for this, but would be willing to build a DIY.

I've looked at Rane, DBX, Empirical Labs Distressor, Waves C4 and a few others but they are packed full of features I don't need or want. I just want the Brickwall limiter and not color the signal.

Does anyone use such a device or have suggestions where I can find a simple device with not so many additional features? ( I plan on getting a 19" rack to mount my amps and other related gear )