Hello,

New to this forum!
I’ve been trying to fix my Poly 61- the transfomer gets hot when switched on (i heard a bang near the power supply side one time when i was fitting a Midi kit) i have descovered this only happens when under load when other boards are connected, and the bridge rectifier gets very hot, so i’m convinced its this that is at fault. After connecting another board to the supply and taking chips off to lower the current load, the transformer cools and the bridge rectifier still gets very hot. I could’nt find any shorts on the other boards.
In the schematic, you can see this part is connected on the secondry side, and is labelled D3. I will attach.

Please can someone advise me which replacement bridge rectifier part to get? I’m unsure what the numbers mean, and the schematic power supply page is unreadable, it just states the part as 4B4B41?
I’m not sure how to test these components also, and if it is at fault, then it might be tricky to buy another seen as this one is at fault? Will a generic bridge rect diode part work as a replacement? I’m cautious of buying another part and using as it could cause more faults (and obviously dangerous), i’ve spent so much time trying to get to the bottom of this and I can see light (maybe) any help here to advise would be appreciated, thank you


Kind regards
Connor

SOLD -thanks for looking

For those interested, here's an opportunity to save a lot of money. I'd like to get rid of some capacitors that I have left over from various projects.

Mundorf MLytic 10.000 uF / 35V 2 pcs.
Mundorf MLytic 15.000 uF / 50V 1 pc.
Nichicon Gold Tune 10.000 uF / 50V 5 pcs.
Nichcon Gold Tune 4.700 uF / 50V 2 pcs.
Panasonic EEUFS1C512L 5.600 uF / 16V 20 pcs.
Panasonic TSHA 4.700 uF / 35V 2 pcs.
Panasonic EEUFR1H221B 220 uF / 50V 20 pcs.
Kemet LH 4.700 uF / 63V 3 pcs.
Panasonic TSHA 5.600 uF / 50V 4 pcs.
Panasonic EEUFR1V222L 2.200 uF / 35 V 6 pcs.
Panasonic EEUFM1V182 1.800 uF /35 V 6 pcs.
Yageo A750KK477M1AAAE016 470 uF / 10V 6 pcs.
Panasonic 16SEPG270W 270 uF / 16V 6 pcs.
Panasonic 16SEPF150M+TSS 150 uF / 16V 6 pcs.
Panasonic PLG0G182MDO1 1.800 uF / 4V 20 pcs.

New completely 254,9 Euro -so now I ask for the half: 125 Euros plus shipping.

The expected shipping costs can be viewed here (select parcel up to 2 kg including tracking): dhl.de

Due to the current customs chaos, I would only sell them outside of Europe subject to checking the effort involved.

The capacitors are new, guaranteed to be genuine, not from Ali or eBay (or similar). They are stored under good conditions, in a well-tempered, smoke- and pet-free environment.

The buyer receives some additional capacitors for free.

I recently bought a Pioneer PL-5. I got it hooked up and found that it didn't play speeds properly. I found a couple YouTube videos that addressed this problem. I took the turntable apart. Cleaned it, oiled the motor bearing, cleaned all the switches and pots with contact cleaner so and so forth.

I put everything back together and tried it out. I was able to adjust the 33rpm with the adjustment pot, but I couldn't get the 45prm to adjust at all and runs too slow. The speeds will would skip fast for a second and the back to normal and there is an audible noise as well when it happens.

I have a feeling that I will need to recap the circuit board, But I wanted to see if anyone else had any other ideas before I start doing that. Is it even worth the trouble recapping it? This isn't my only turntable and fortunately I didn't pay much for it.

Any input would be great!

Thanks

In Pearl 3 post #1,396 I offered to send out pairs of opamps, to perform blind listening tests in the Pearl 3 phonostage:

Mark Johnson said:

If anyone wants to listen to their Pearl 3 with "rolling opamps" in a single blind test, shoot me a PM.

I'll send you some dual opamps whose part numbers have been sanded off and painted over with different colored paint. You won't know which is which and I won't tell you the ones that are, or are not, in your batch. Maybe I'll send you four sets of identical dual-741's (perhaps RC4558 etc) in different colored paints, because I am a sadistic baxter. Maybe I'll send you some bleeding edge Telleurium-Gallium-Phosphide military grade opamps on SOIC-to-DIP carriers, mixed in with TL072 and LM358. Who knows. Maybe the best of the best of TI and Analog Devices and Cirrus Logic, all mixed together. If you're willing to possibly make a fool of yourself by "hearing" superior performance from 60 year old dual opamps, ... let's party.

You and I will split the cost of the parts and the adapters and the postage, until you post a message here containing your listening evaluations. Then I'll send you the other half of the money --- and your net cost (in money, not reputation) will be zero.

Do I have a protocol which guarantees there is no lying or changing-your-mind about what color is what opamp? Yes. And it is so obvious you should be ashamed of yourself if you even think to ask.

Let's party.

Click to expand...

Then in Pearl 3 post #1,765 I showed three photos (attached below) of the anonymized opamps.

Next, in post #1,817 I presented the (encrypted) table of opamp_part_numbers and their corresponding serial_numbers on the sticky labels.

And now, today, in Pearl 3 post #2,732 , the first listening evaluations of the blind test opamp rolling experiment, have been posted. I am thrilled that duyAudio member @Lvandoorn created a panel of four different listeners: himself, spouse, audiophile friend #1, audiophile friend #2.

Lvandoorn said:

Rolling the opamps in the blind....

I received 7 pair of opamps to test in my Pearl3. They are coded
A318, A170, A785 A848 , A957, A093 and A539. I added to those anonomous opamps the JRC opamps I received with the kit and a pair of Muses02 I allready had.
Mainly tested at my place with a heavily damped Lenco L75 with an Ortofon MC30 cartridge. Preamp is the balanced Iron pre from Zenmod, the 6-24 crossover from this Nelson guy, two modded ACA’s for mid and midbass, and a Reckhorn amp for the Slotted OB bass. Speakers are mahogony horns with JBL drivers from 480hz, Volt 12 inch on the SLOB baffle (60 to 480 hz) and Augie 15 inch for the slot loaded part. These tests I did together with my wife, no electronicly interested molecule in her body but she loves listening to music.
Secondly I did the comparison with a vintage Stax electrostatic headphone, very nice sound but compromised in volume. Tests done on my own.
And to verify that I was not completely imagining things I brought my Pearl3 to a diy friend with a very nice diy system ( I think) with a Lenco using a Denon DL-103 and all good Pass stuff. Together with a third audio fanatic (a semi-professional musician) I asked them to judge the 4 best opamps from my evaluation. While I did my best not to show my order of preference they agreed with me. Relieve!
So far so good, agreement between the four people involved was almost 100%.
Now to the disappointing part, of course it is all very system and record dependent, still very subjective but worse is that I find it very hard to describe the differences.
Records used were Friday Night in San Francisco (Al DiMeola Paco de Lucia John McLaughlin) Famous Blue Rain Coat (Jennifer Warnes) Ben Webster meets Oscar Peterson, Sonny Rollins Colossus, Miles Davis Ascenseur pour lÉchafaud, Dire Straits Love over Gold and J.J. Cale Troubadour.
To my ears the positives and negatives of the opamps did not change a lot with the different music. After the first round of listening the top two opamps were found and it required quite a bit of discipline to go back and listen to all of them, again and again….
I tried to bring some system in my judgment by focusing on low (clear bass notes, bass drum impact) mid (voices, guitar, sax) and high frequency (cymbal, high notes on instruments), speed and life feel. And tried to give an overall score, from 1 to 10.

I will tell my verdict of them in my/our order of preference with special aspects they did well or not so well in my opinion

JRC overall score 7. Nice sound, could easily live with those if I had not heard the others. Lowest score of all on life feel and involvement. Bit bland sound
A957 overall 7.2. no special remarks to make
A848 7.4 Did pretty well in overall sound and different frequency areas but no ‘speed’ or life feel.
A318 7,5 Weaker on bass to our ears, did well on speed and attack
A170 7,7 Nice, did well on almost all aspects but lacked life feel and involvement
A785 7,8 Really nice, Of the top 4 it lacked however most in speed and life feel
A093 7,8 Very hard to tell apart for me from A785. Just a little bit better in dynamics I feel
Muses02 8 Good, could be a permanent choice in my chain. Did everything really well in comparison to the rest of the field
A539 8, 2 In this shootout the best, more involving and more life feel, really excellent in speed and attack.

I am really looking forward to see the overall results of this (mostly) blind test and to see to what extent I agree and disagree with my fellow testers. And of course to find out where I completely was fooled by my ears...

And of course many thanks for this fun project to Mark

Leo

Click to expand...

Watch this thread for further developments including a timeline of how and when the decryption key will be posted, allowing everyone to see which opamp part# corresponds to serial number A785, A093, etc. I'm having a medical procedure at the hospital tomorrow, so there may be a few days of delay...

Best regards to all, -- Mark Johnson

Hello All, I recently was gifted AR 8B bookshelf speakers. Of course the foam surrounds are dry rotted and I have the kit to refoam the woofers.
While I am doing that I got inspired to tweak the crossover thinking that i can improve the sound over the original. The woofer is running free-range with no LP filter. The tweeter uses a 5.0 uF capacitor only. Per what I posted below, it sounds like this was done as a cost-cutting effort and not necessarily to deliver the best sound. I'm thinking a 12 db per octave LP crossover at 2000 Hz is a good idea to prevent distortion. According to AR, the tweeter has an "effective" rolloff of 18 db at 2000 Hz using the single 5.0 uF cap. Should a more sophisticated HP filter be used incorporating an induction coil and a cap, and should the HP filter use a 12 db/octave slope as the tweeter was designed to have a natural rolloff giving an effective 18 db/octave slope? Or should the HP filter use a 3rd order filter? Please advise, the more I look into this the more I am getting confused! Thanks!

"The two-way AR8B is the smallest and least expensive speaker system in the current Acoustic Research line. Like all AR speakers, it is an acoustic-suspension model, and it has a newly designed 6-inch woofer that crosses over at 2,000 Hz to a 1-1/4-inch “liquid cooled” cone tweeter. (The tweeter presumably uses ferrofluid or a similar material to damp and cool its voice coil.) The crossover network has been simplified and its cost reduced by designing each driver to have a natural rolloff outside its operating frequency range. As a result, only a capacitor is needed to protect the tweeter against damage from powerful low-frequency signals. The effective crossover slopes are 12 dB per octave for the woofer and 18 dB per octave for the tweeter."

Click to expand...

I thought that I should share my recent amplifier build:





Single-ended 6S41S cathode follower amplifiers that deliver 7 W each. Here is the schematic:



Running the output tube as cathode follower gives a very low output impedance for a single-ended amplifier. These amplifiers can drive difficult loads, but the concept has its cons. The output tubes need over 500 V peak to peak to deliver full output. The driver tube 6E5P-I is a small power tube with high amplification when connected in triode mode. It has a gain around 50 and can deliver quite a bit of current. By using an interstage transformer, I can get the required voltage swing without a very high supply voltage. Also, I step up the signal 1:2 with the interstage transformer and I also step up the signal with 1:2 with the input transformer.

The sound quality is great. It is most certainly the best-sounding amplifier that I have tried with my current speakers.

A couple of years back I scored a decent pair of the old RadioShack Optimus 8B speakers for $50- with some other stuff tossed in for free
Somebody over at AudioKarma was desperate for a set of the mid range and tweeters so I took them out and flipped them [ at a reasonable profit] and the boxes with that great woofer have been sitting in the shed for a long time and I have no idea what to do with them now.
The boxes are in excellent condition although missing the original grill, which I suppose is why they were only $50-
I'm at a loss as to how to proceed so I'd appreciate some thoughts and inspiration from the collective minds of the forum members. I haven't actually finished anything since I made that huge 18" part sub and I am feeling frustrated
Edit
Nova 8B

TI high power amp chip from tpa3251 family

They are in a plastic tube and have been since I bought them about 10 years ago from Digikey. Shipping would be from Germany.

I would like 100 euro for the lot with shipping on top.

I will post photos later.

Thanks

I'm into Audio of all sorts, and have to do most of the repairs myself as it's almost impossible to get any repairs done specially to vintage stuff. This site has valuable information.. Thank you

I'm wondering if there is someone out there that has a working amp circuit board for a realistic sta 2700.

I'm looking to build an Aleph Mini, currently trying to gather parts to order, for now I have found:

https://www.ebay.co.uk/itm/266392011176?mkevt=1&mkcid=1&mkrid=710-53481-19255-0 - the pcb
https://www.ebay.com/itm/156560013829 - mosfets
alternatively, but I'm not sure if it'd be quite right - https://www.ebay.com/itm/115126018088?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=wGG0QMocRHa

https://a.aliexpress.com/_EIU0SPC - enclosure

I'm just not quite sure about the PSU, what board / transformer should I use, and how to wire the potentiometer, switch.

In my search for a monster open baffle woofer I stumbled the W21 21" open baffle woofer. It looks interesting but the more I research Lii Audio the more something seems off. I cannot find much objective information on them. Most of the people talking about them seem to have conflicts of interest. Then I found there are more than one version of this driver....some may even be copies or made by another company?

The driver on Alliexpress looks very different from the one for sale on lii-audio.com website.

The first one seems to have a single voice coil, the latter double. The first one has a lowish QTS of 0.39 and MMS 201g while the other one sports QTS 0.82 and MMS 644g.

Normally I would assume the Alliexpress is fake but then I read this by caisson rj:

I am happy to see some people talking about Lii Audio Xizi founded in 2006 and Lii Song founded in 2016 which is a copy of the original Lii Audio. I visited both headquarter in Hangzhou and it was clear to know which one fake it. If you hold both speakers in hands it's is really obvious. The short story is that Xizi Lii Audio hired one guy to expand the business outside china and that guys screwed him and founded Lii Song and took the foreign market. There is currently quite a lot of new drivers made by Lii Audio that are coaxial drivers that are simply harder to copy for Lii Song so in the future you will see more and more drivers that Lii Audio will only sell. I am talking 21 inches coaxial stuff, premium range etc.

CAN SOMEONE SET THE RECORD STREIGHT? SHOULD I BOTHER WITH ANY OF THESE DRIVERS?

ALSO...IS A 21" DRIVER WITH A 201g MMS even realistic?

https://www.aliexpress.com/i/1005003529835421.html

https://www.lii-audio.com/product/w21/

Does anyone have experience with any of the Lii audio/Lii Song 15/18/21" woofers?

Some sound clips of this speaker recorded with my phone and powered by my SuSyLu 100w Class A amp:

Test of SuSyLu 100W Class A Amp - YouTube

Example of speaker in dark “espresso brown” stain and satin lacquer with Duratex coated baffle.


Example of beautiful build by as8912:


Another Example of a floor standing FAST TL by Plott:

This is a great shot of the internals as provided by Plott:


Example of a floor standing TL version of this speaker by Moutik:


Example of a smaller sealed version with PS95-8 full range drivers by Jimk04, here.

I wanted a speaker design worthy of the exceptionally high performing ScanSpeak 10F/8424 Discovery 3.5in full range driver. I decided that a short sealed Dagger TL coupled with a sealed bass unit would give me the best overall transient response and clarity. I decided to mate the 10F/8424 with the superb Dayton RS225-8 aluminum cone woofer for bass duties. The design ended up as a 24 liter volume for the woofer and a 1.1 liter 3-sided pyramid Dagger for the 10F/8424. The important external dimensions are: 10.0in wide baffle, 7.5in CTC distance from woofer to fullrange, and 24 liter internal volume (sealed). You can make the height and depth to suit your individual case, but it will need to be deep enough to house the Dagger. The internal dimensions I settled on were 8in wide x 12in deep x 16in tall.

However, if you make it out of 18mm plywood like the ones I had my cabinet maker build - make the box using these dimensions.

Dimensions of sealed box version: most important is to make the width 10.0in (external) and CTC spacing between drivers 7.5in and adjust the depth and height so that you have about 24 liters volume. If you make it out of 18mm plywood it ends up about 18in H x 13.5in D. The 10F is located 4.5in top to center. You will need a rear chamber for tweeter (fullrange) so use a sports cone or wooded “Dagger” tall 4 to 5 sided pyramid. Stuff Dagger and main box with polyfill or fiberglass to taste.

New SketchUp Plans by @jrKC for sealed version here.



The short sealed TL is made of three 6in wide x 12.5in long triangles. Construction will use 1in thick pink XPS foam and regular foam core for the short TL. The front baffle will also use a thin sub-floor plywood in order to provide adequate support for the heavy 8in driver. The design will have the option of a bass reflex vent that can be sealed for use with a Linkwitz transform, or opened up for some additional bass when group delay is not an issue. The system will use miniDSP for XO and EQ duties and bi-amped. Here are predicted results in 4pi space with baffle step and diffraction effects accounted for. XO will be at 500Hz with 4th order LR. The RS225-8 is an exceptionally flat response driver and choosing a slightly higher XO frequency will keep the distortion on the 10F very low while giving more weight to the mid bass as it comes from an 8in woofer. Calculations show that with Linkwitz transform, bass extension should be about 42Hz (f3) with max SPL around 101dB.

SPL vs freq for sealed case at 24v (no Linkwitz transform) - the hump at 2.5kHz is the baffle diffraction:



Impulse response for sealed case:



Group delay for sealed case is 2.5ms at 100Hz and 5ms at 50Hz:



For bass reflex option, here is SPL vs freq at 24v:



Here is group delay for bass reflex (2.5in dia x 11in long vent - rear firing) case, not too bad actually (about 10ms at 50Hz)



Here is the Sureply thin baffle with driver holes and drivers to show basic look:



Here is construction on XPS enclosure beginning:



Here is the enclosure with Dagger TL internally mounted and bracing, wiring, and terminal cups installed:



Currently waiting for liquid nails glue to dry...

Edit April 27, 2015: New LR2 XO @350Hz and new sound clips of many different genres. Have a listen, this speaker sounds fantastic!

10F/8424 & RS225-8 FAST Ref Monitor - Page 2 - diyAudio

Here is the new LR2 XO @350Hz:


Update April 30, 2015: New Butterworth 1st order linear phase XO (BW1 XO):


Phase for BW1 XO:


Step Response for BW1 XO:


200Hz Square Wave with BW1 XO:



1.6kHz Square Wave with BW1 XO:



New sound clip with 1st order BW1 XO: http://www.diyaudio.com/forums/atta...or-10f-8424-rs225-8-fast-bw1-350hz-clip-b.asc

Edit May 14, 2015: Stereo Pair completed!



Edit Dec 16, 2015: forgot to post final lock-down configuration with Harsch XO:


IR:


Step response:

More info on final setup here: 10F/8424 & RS225-8 FAST Ref Monitor

Distortion:


Group delay about 5ms at 50Hz:


Edit Jan 5, 2018: using passive 1st order transient perfect XO for past 2 years.


Recent implementation with film caps and air core:


frequency response and phase using passive XO:


Impulse and step response:


Latest tweaks to the passive 1st order XO with simulation files:
10F/8424 & RS225-8 FAST Ref Monitor - Page 95 - diyAudio





Edit Dec 3, 2018: BOM for XO is here.

Edit: Dec 27, 2018 - Wxn just built a pair using SB23NRXS45-8 and TG9FD-4 with DSP from a DCX2496 here. The results look great and he did a great job on the cabinet:


Nice waterfall:


Edit: Dec. 27, 2018 - I should have mentioned that Aatto built a nice set using the SB23NRXS45-8 with 10F/8424 as well but using a bass reflex box and miniDSP and also with passive XO, but can't remember what he is currently using here:


Also, forgot to mention the nice set with RS225/10F that I built in espresso brown stain - these are working out real well as the WAF is excellent as evidenced by the fact that they are upstairs next to the TV 🙂 :


And of course, here is my current setup. These have been my main speakers for over 2 years now and, I keep coming back them because they sound so nice and balanced. The sharp percussion and wonderful stereo imaging also bring me back. Here they are in my speakerlab, now re-done post basement flooding (back in July 2018) with a new engineered wood flooring, so the echos are a mess and sound treatment is definitely needed now that carpet is missing. Looks nice and clean though - the clutter is building up again (mostly foam core speakers in storage around the corners).


Edit Dec 16, 2019: Thanks to JPS64 for making a super layout for the XO PCB. This will make building this speaker that much simpler.


Edit Dec 21, 2019: new TL floor stander for RS225:
10F/8424 & RS225-8 FAST / WAW Ref Monitor

Measurements of TL here.



Edit Dec 22, 2019: Just wanted to remind folks that there was a design made for this speaker XO with an RS100-8 and RS225-4 here:
10F/8424 & RS225-8 FAST / WAW Ref Monitor



Edit Mar. 20, 2020: Revised plans for the TL in all 3/4in BB plywood.


Photo of the TLs in action next to the sealed version:


Edit March 30, 2020: Vistaton B80 Variant with modified XO



Edit May 19, 2020: this is the XO for the 4ohm RS225-4. You can use your favorite 8ohm 3.5in full range on top. Just make sure it’s 8ohms and adjust R1 to taste.



Edit July 24, 2023: Keantoken developed a crossover specific to the TC9FD-8 to be used in this speaker with the RS225-8. The response looks very smooth and has a wonderful step response. More info here:

https://www.diyaudio.com/community/threads/10f-8424-rs225-8-fast-waw-ref-monitor.273524/page-196

Schematic:


Measured frequency response appears to have 1st order XO near 1500Hz.



Nice stuffing/padding plan collected by GUJoe:

In a joined effort, Bill, Dagfinn and I went into much detail by developing replacement diagrams for MM cartridges, divided into two parts, first the output section with coil, that we called the Generator, and second for the complete Cantilever assembly.
An achievement never realized before to the best of our knowledge.
Having developed the transfer functions for both both parts, we were able to prove that these two parts don't "see" each other, in other words, the external load on the Generator does not influence the Cantilever's movement in any way.
Another benefit by having the replacement diagrams, was that it was now possible to find the optimal load in LTSpice for a specific cartridge as regards to it's FR.
Because being too long to put it in a posting, we have added the results in the attachment as a PDF.

Happy reading,

P.S. A few typos haven been corrected and further explanation has been given to indentation.

Excellent condition. Just a NC252MP in a nice box. Had been using it to power my main speakers, but upgraded to Nilai monoblocks. Thought about keeping it to power subs, but decided I didn't need something this fancy for that purpose. $375 shipped CONUS

https://www.audiophonics.fr/en/powe...tereo-ncore-nc252mp-2x250w-4-ohm-p-14185.html

https://www.audiosciencereview.com/forum/index.php?threads/audiophonics-mpa-s250nc-amp-review.45306/

recently my friend designed a small diy am reciever for fun and my question is will it even work since im not 100% it will actually work.
After simulating the amplifier in ltspice it works but im not sure about the radio part.

I have been playing with WinISD and have decided to attempt to design a speaker with a slot port. This is what I have made in SolidWorks pretty quickly. The slot is 1in x 8in with a total length of 32in measured from the centerline of the port. I included rounded corners to hopefully lower air speed.. I am asking here if this is realistic and if this works. I found a woofer that I could use to tune the enclosure to 25 Hz.
These are supposed to be decent-sized speakers. The total dimensions of the enclosure is 27x13x9.5, this is a section view to show the port path.

Hello Community,

i want to build my own audio setup for my desktop PC.
My idea is to have 1 tweeter and 1 midrange woofer on the left and right side,
completing the setup with 1 subwoofer in the center under my PC monitor.
What I am mainly listening to is obviously music, occasional podcasts and movies.
The audiosignal is coming only from the aux output (single ended?) of the PC.

The speakers:
2x Tweeter => https://www.parts-express.com/Dayton-Audio-DC25T-8-1-Titanium-Dome-Tweeter-275-045?quantity=1
2x Mid-range => https://www.parts-express.com/Dayton-Audio-DC160-4-6-1-2-Classic-Woofer-Speaker-295-309?quantity=1
1x Sub => https://www.parts-express.com/Dayton-Audio-SD215A-88-8-DVC-Subwoofer-295-484?quantity=1

The IC's I want to use are the TPA3116 for the tweeter and midrange speakers, the TPA3156 is for the subwoofer.
Configuration of the tweeters 2x15W, midrange 2x50W, subwoofer 1x70W.

Now, my first question is...is this even possible, meaning if this is a reasonable setup, does it make any sense what I am trying to create,
leaving out the fact that there are finished solutions for it?

If this all makes any sense, here is what I managed to do in Kicad 6 until now:
Tweeter schematic:


- I am planning to have a couple of external switches to control the state of the amplifiers,
meaning that I have one switch to mute them all and one switch for the shutdown functionality.

- From what I understand in the datasheet the three IC's need to be synchronized.
I decided to leave it to the 400Khz, for the simple reason because the recommended schematic in the datasheet, already does it this way.
How am I supposed to connect those three IC's together, the datasheet makes the example only with two same IC's. I didn't find any citings stating that there is the possibility of connecting more than two IC's togther, so I guess I won't be able to use a subwoofer in this configuration?
Regarding the master IC, which one should it be? I currently picked the tweeter IC as a master.

- My biggest confusion remains on the plimit voltage divider, which sets the output power limit for the speakers.

This is the formula I found in the datasheet.
For Pout, do I need to take 15W or 30W in the calculation?
Rs is the total series resistance, is this the resistance of the speakers on the output + Rds(on) (120mOhm) + the output filter resistance. What do I do if don't have a filter yet, do I need one?
In theory I have all the values required, except for Vp, so I altered the formula to solve for Vp. I got some results and tried to calculate the voltage divider values with the appropriate formula and came to 13,5KOhm and 10KOhm...obviously I do not feel very confident of the result because of the explained reasons above.

- For the supplyvoltage, can I power it all with 24V?

- When the power output of the amplifier changes, do I need to change any output components too? Like the inductors? Do they remain the same if I want to drive a 15W speaker or 50W speaker?

- The endgoal is to have all the components in THT format, except for the amplifier IC, because I would like to solder it myself. Is this a good idea or should I switch to SMD? Does it change anything on the functionality/quality of the endproduct?

These are the questions for now, I also made the schematic for the midrange and subwoofer, but the questions are the same, just for another usecase. So I am going to leave it out for now.

I am also waiting with the pcb design, since I am not so sure what I started here in the schematic...

With the hope that I have chosen the right section of the forum, I would like to thank in advance those who are willing to go through this project with me.

JohnAudioTech JAT501 Class AB Amplifier PCBs from JLCPCB

4 of 5 pairs sold. Last final set remaining.

$10 Canadian plus shipping.

Made from JohnAudioTech's publicly available JAT501 gerber files.
No modifications to John's design were made.
Inline layout, board revision 1.1

High quality PCBs. Standard 1.6 mm thickness, and completely flat.
Two layer, double sided, blue solder mask.

This sale is not for profit. It is being offered as a service to the community. And to help promote John's channel.

These are just the bare PCB boards. You have to source your own components, assemble, and test.
Bill of Materials (BOM) including part numbers is also provided.

Includes two hand made and tested Thiele network coils (labeled L1)

Shipping within Canada is $3.00 using Canada Post oversized letter mail (sorry no tracking).

Shipping to USA is $10.00 using Canada Post Tracked Packet - USA. Includes a tracking number.

Known issue, the board stencil has some typos.
Transistors labeled 2N5551C should read 2N5551.
Transistors labeled 2N5401C should read 2N5401.

The "C" variant has a different pinout.
2N5551 / 2N5401 (1. Emitter 2. Base 3. Collector)
2N5551C / 2N5401C (1. Emitter 2. Collector 3. Base)

One board has scratched solder mask that happened at the factory. The exposed copper was tinned. The traces are ok. See attached photos.

I was following Ian Hegglun's thread "Towards a wideband non switching Auto Bias power amp",
and I was inspired by one of his ideas - Alexander-type input stage and VAS based on op-amp LT1223.

I wasn't familiar with this op-amp, as it seems too fast for typical power amplifier.
There is no point to use expensive ($10.00), high slew-rate op-amp, just to throttle it
later on in order to make the amp stable.

But, if it's driving VAS not from the output, but via rails (like Alexander amp),
the whole amp is more stable and less temperamental.
This amp here shows slew rate of well over 200 V/us, and it's a very simple schematic.

My past attempts show that it's very difficult to actually build stable amp that
can achieve slew rates over 150 V/us. This is first amp I see, that shows phase margin over 75, and
also decent gain margin. In the sim, it seems to be solid, well behaved amp.
So I think I'll give it a try.
First, I came up with LatFet version (dual-die Exicons ECW20N20 & ECW20P20) - that's the one I'm
going to build, and later on with HexFet version.
Both versions show similar results in LtSPice.
Noise floor (1kHz FFT) is at -280dB, and all harmonics are below -120db (inaudible).

Update 29 March 2025: Based on the actual build, C4 should be removed. With it, amp had tendencies to oscillate (when using LT1223).
I keep it in the schematic, purely for the simulation purposes. Apparently LTSpice sim is slightly disconnected from reality.
Also, gate resistors have been changed to R2: 220 Ohm and R3: 100 Ohm.

Update 30 March 2025: If using different op-amp, C4 should be present (2pF).
The following op-amps have been confirmed to work correctly (besides LT1223):
LT1357, TLE2071, TLE2081, AD711, OPA134, LF356. These op-amps were not simulated in LTSpice, just confirmed that they seem to work OK
in the real amp. The schematic and sim may not be optimal for these op-amps, so there might be some space for improvement
if using non-LT1223 op-amp.

Update April 2025: Actual amp has been built and finished. See Post #47.

Update April 2025: HexFet version has been built and tested. See Post #55.

Hi,

I'm trying to offload several DIY audio parts and even a pair of full speakers. I will charge actual shipping/insurance costs to your destination based on your preferred shipping arrangement (coming from Aurora CO 80016). Here are the items I have for sale:
$1000 - DIY Aleph J in 5U Chassis
$1000 - DIY Bookshelf Speakers with 15W/8530k-00 ($220/ea retail) + Seas Millennium ($482/ea retail) + Jantzen Crossover
Free - Pair of planar magnetic tweeters of unknown manufacturer - will ship with first person to buy > $100 worth of gear from me
$110 - Pair SB Acoustics SB17NAC35-4 (1 impedance measurements never mounted + 1 BNIB)
$180 for 4 or $100 for 2 New Peerless HDS 830875 Midwoofers (1 taken out of cardboard to look at but never mounted or measured)
$180 for 4 or $100 for 2 used Seas ER19RN-TRD mid woofers (These were in surround sound speakers for about 2 years)
$80 for pair of GRS PT6825-8 8" planar mid/tweeter (new)
$70 for pair of GRS PT6816-8 8" narrow planar mid/tweeter
$80 for pair of Dayton RS52AN-8 2" Dome Midrange (new)

$2300 for all OR
$1500 for all except either the Aleph J or DIY bookshelf speakers

While there is a bit of ambiguity purchasing a DIY loudspeaker designed by me. All I can say is that these sound excellent. Except for overall output level, everyone who has listened to the bookshelf speakers prefers their sound over the pair of Kairos (Jeff Bagby design) I built previously. They image very well and don't require any EQ to my ears unless I use them in my office as desktop speakers. I've built lots of speakers from LX521, Troels "The Loudspeaker" and really find their sound signature second only to the LX521. "The Loudspeaker" was fun because it had no practical output limit in a domestic setting. Of course they are 5.5" drivers so best crossed over to subs if you want to play loud but without or for near field they sound fantastic. There is just something special about this pairing of great drivers. I've attached the final simulated response captured as a screenshot. I can provide design files in SoundEasy but can't launch the app anymore due to lack of support on modern computers. If I remember correctly I did end up padding the tweeter down a little more by ear but you can always manipulate L-pad to your liking.

Likewise the Aleph-J amp is in the DIY Audio Store deluxe 5U chassis and is a beast. I really like the sound of the amp but have been using Hypex plate amps for my recent builds so it's been sitting around. I've used it a bit in my home studio but it's really just too big (and runs too hot) for that space. I had a 300b amp running "The Loudspeaker" but changed to the Aleph-j in that application (I sold those speakers a while ago).

For references check out my eBay/Reverb rating (user jf4828 on both). I'm happy to do transactions through those platforms if you prefer but would have to charge a bit more to cover selling fees....

I'm happy to snap some more photos if needed; just let me know what you'd like to see 🙂

Joel

$145 shipped. These drivers have been mounted briefly, but not seen any use beyond testing.

$100 shipped CONUS. Brand new. I bought these on soundimports and never used them. "Gold" though it's clearly more of a coppery color

Hello everyone. My name is Andrés and I'm from Argentina.
I use Google Translate to write and be understood.
Vine a este sitio buscando información, ayuda, consejos y curiosidad.

Hola a todos. Me llamo Andrés y soy de Argentina.
Hago uso del traductor de google para redactar y que me entiendan.
Llegué a este sitio en busca de información, ayuda, consejos y curiosidad.

I'm looking for a schematic of a transistor amplifier. This isn't a push-pull amplifier. It's a different setup.
I've attached a simplified diagram to clarify the order.

Unused. $75 shipped CONUS

I had hoped someone else would post this but prompted by comments in recent threads I am posting to see if there is interest in a group project on the topic of high fidelity on-wall speakers.

Outline speaker design:
- against wall required with mounting options to be fleshed out in discussion
- clean 105+ dB peaks at listening position
- 60 - 20kHz passband with subwoofer support below 80 Hz
- smooth directivity with details to be fleshed out in discussion
- standard range rather than premium range drivers
- budget in $1000 range but subject to movement in discussion
- active crossover for R&D with passive version later if interest

Outline project approach:
- focus on simulation to develop design and options in a quantitative manner
- no specific drivers to be considered until the speaker configuration is designed

A few points to kick off discussion:

No passive crossover constraints in the initial design but if there is still interest in a passive crossover version after the active crossover version has settled this would be performed later. So not rejecting passive crossovers just suggesting pushing their additional constraints to later in the project.

Handling the front wall well in the simulations may require a modified approach with BEM being one way to handle the 3D details. I have some experience with the open source acousto software though not all good. Others appear to have experience with AKABAK/ABEC. Is the latter suitable? Other options?

Commercial products like COMSOL are likely the fastest and easiest option for detailed simulations but few if any are going to have access. Should the project use only software that everyone can use to check the design and/or develop further for their own designs or is expensive commercial software OK?

Will need a repository to store simulations, design documents, possibly lengthy detailed posts and the like. Options? How well did the Open Source Speaker group project get on with their choice?

Options for woofer loading in the presence of the wall? Given sub support and wall mounting the smaller size of a sealed cabinet is perhaps the way to go?

If we opt to place the woofers on the side, the midrange on the front with the crossover frequency between the frequencies of the wall reflection nulls for the drivers then a pair of opposed woofers is looking attractive. It will also reduce cabinet vibration substantial and possibly help reduce the complexity of wall mounts. On the downside it would require space on both sides which may limit things like TV screens.

Cardioid is an alternative approach to handlng the front wall which we should consider. It will need more cone area and more complexity but would seem to be a candidate for high-fidelity speakers.

Another option to consider is a shallow speaker with a wide baffle. This is the simplest approach but also the one likely to handle the wall least well. The pros and cons to be quantified by simulation even if we don't adopt?

Brand new. $60 shipped CONUS or $45 local pickup in Dayton Ohio

Found

Looking for 1 complete crossover & mounting plate for the Realistic / Radio Shack Nova 8B or Optimus 5B speaker system. Prefer a complete one with uncut wires. Will take a pair if necessary.
Thanks!

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Crimping is king these days.

I am considering two DACs one (ZEN Air DAC) uses the Burr-Brown Native DSD1793 DAC chip; the other one (Topping DX3 Pro+) uses the ESS ES9038Q2M chip. Which one is better?

Hello all and thank you in advance for any advice you can give!

I'm a long-time music lover but relatively new to tube audio equipment. I built both the TU-8200 stereo amp (currently running KT88's and with upgraded caps) and the TU-8500 preamp. This stereo is used 99% for phono input (Project Carbon Debut EVO with upgraded sub, platter, and cartridge). Currently running through Fostex BK-16 Folded Horn spearkers I also built.

I've been generally very happy with the sound. The volume is ample for my moderately sized open living room/kitchen. I rarely use this stereo with headphones.

However, lately I've been reading a lot about 300B tubes and other options and the TU-8900 looks really intriguing. I am wondering, how much of a difference am I going to notice trying out the 8900 with my setup. Open to trying different speaker and/or preamp options in the future, but the first step would be the new amp.

For reference, my musical taste is varied but a large amount of what I listen to is both old and new soul and funk with a healthy amount of fusion and jazz thrown in. Lettuce, Tower of Power, Stevie Wonder, Bill Withers, Weather Report, Earth, Wind & Fire, Amy Winehouse, Khruangbin, Donny Hathaway, The Meters, Otis, JB, Aretha, Herbie, well, you get the picture. However, I listen to a fair amount of other stuff, occasional hip hop and electronic music, jazz, psychedelic, etc. I grew up on classic and 90's rock. I don't listen to rock as much anymore but occasionally throw on things like Led Zeppelin, Pink Floyd, Soundgarden, Alice in Chains, Radiohead, Flaming Lips, etc. Rarely play classical and occasionally some folksy stuff (Dylan, Joanna Newsom, Joni Mitchell, Cat Stevens, etc.).

So I guess I'm asking if, for my musical tastes, will the 8900 offer something above and beyond what I already have? If so, for the music I frequent, would 300B or 2A3 be a better choice? At the price of these tubes, it would get a bit costly to do much tube flipping.

Thanks again!

Best,

Josh

I hope this is the correct forum for asking for help with an Op Amp ? I recently bought a genuine Lehmann Audio Black Cube Linear Headphone Amplifier with some modifications. Mods include a larger transformer, Mundorf capacitors and some circuit changes, but most intriguing is the op amp has been replaced with what appears to be two Burr Brown op amps on a carrier. The text reads BB (Burr Brown logo) and SL232 but I can't find any info on this on-line. It's possibly an older amp ? It comes as stock with an OPA2134 which isn't bad at all, so I'm surprised it's been replaced.

Any info much appreciated.

Hello everyone,
I decided to build my first RIAA phono stage, using OPA1656 and the schematic shown in the datasheet.
Where possible, I tried to use 0805 smd components for resistors and capacitors (exclusively Thin Film and C0G/NPO), except for the two 100nF that decouple the power lines. These are X7R. About the four 100uF capacitors, I chose Nichicon UES Bipolar.

The only change to the circuit concerns the removal of the 150 pF capacitor (for the capacitive load), replaced by three capacitors (22pF, 47pF, and 100pF) selectable or not, through a 3x SPST Dip Switch, for 8 possible combinations of capacity (0, 22, 47, 69, 100, 122, 147, 169 pF).
Considering that an average interconnect cable has a capacity of around 100pF, being able to add values between 0 and 169 pF, allows you to optimize the right input capacity in the most critical range of many cartridges (100 - 250 pF), especially those that prefer low input capacities.

I attach the schematic and some images of the PCB layout, in its current state. I have already made all the connections, but I have not yet added the ground plane on the bottom, so as not to confuse the traced tracks. I used 20 mills traces for all the signal lines, and 30 and 35 mills, only for the power lines.

But before completing the PCB I would like to hear some opinions on the layout and ask some questions:

1 - Is this preliminary rooting good enough, or are there obvious errors? Can it be improved with small changes?

2 - For simplicity I used classic 2.54 mm connectors for inputs and outputs. The input RCA connectors will be the standard through-hole type, fixed to the rear panel.
If placed at a distance of about 35 mm from each other, they will be located almost exactly above the two fixing holes of the PCB, on the input side, with the advantage of being able to use really short input cables (15 - 20 mm or even less). Slightly longer cables for the outputs I think are less of an issue.
From a sonic point of view, would it be better to use different connectors?

3 - About the Output capacitor, the last two lines of page 21 of the datasheet, state:
"... C5 is chosen to be the same value as C4; for simplicity however, the value of C5 must be large enough to avoid attenuating low-frequency information."
In my schematic, C5 corresponds to C13, C14 (100uF).
How do I check or calculate if the value is large enough, to avoid attenuation at low frequencies?

4 - Any other suggestions or criticisms, will be useful. 🙂

Regards,
Marco


I attach the schematic and images of the pcb in its current state.

Schematic From OPA1656 datasheet:


Actual layout without ground plane:


Board preview:

If anyone’s got some spare BF862s (not the sketchy ones from eBay - tried those, definitely not legit), I’d be happy to buy at least 10 pieces.

Hi people 😀

I have necessity to build a kit similar to this
http://www.siliconchip.com.au/cms/A_101145/article.html
For the dog of my neighbor. (I cannot sleep anymore 😡 )

what type of piezo tweeter can I use?
which is it the maximum power that I can use? 😕

I have to look for datasheet of the manufacturer..

Folks:

Does anyone know of a source for Aikido Noval pcbs aside from Glassware? Glassware has been out of those boards for months, and my many emails to Mr. Broskie (all with some variation of “Tube” in the subject line) have all gone unanswered. I have the Gerbers for the Octal variant but would prefer to build a Noval Aikido. If the Gerbers are available, I would happily have boards made.

Thanks in advance!

Regards,
Scott

You may have seen this neat dc/dc available recently, especially given the wide variable B+ setting capability, and quite high power rating, and ability to run off 12VDC.



For low power valve amps (eg. up to 6V6 push-pull) they should make it very convenient to power just from a 12VDC 4-5A plug-pack.

The initial intrigue is what control IC's are used, as the 8-pin packages are defaced.

To help the guessing game, the attached doc has my first pass at a schematic drawing. No doubt I've misinterpreted a few parts, and the IC pin numbers are based on what I think are the pin 1 dimples that haven't been defaced completely.

Some strong power saving pulse skipping is going on, which appears as low frequency ripple at times, and at other times it is just pulse skipping at 70kHz ripple. The FET drain waveform is pretty clean and fast, given the simple pcb and parts. The current sense filter cap ground and IC ground seem a compromise of layout. The turn-on appears to be trying to occur close to a zero-voltage dip. No load loss is pretty good.

http://dalmura.com.au/projects/YH11068A.pdf

Ciao, Tim

I built an amplifier using several TDA7293 chips connected in parallel to make good use of my extra stock. The result honestly surprised even me!

I added a buffer stage at the input using opamps like the OPA1641, OPA1655, or OPA627, because I'm using an ALPS RK27 potentiometer for volume control directly at the output of a NOS DAC.

If you prefer, you can easily disable the buffer. Simply remove the opamp and short pins 2 and 3 of the socket.
In this case, R2 should be 47K, and you should remove both C23 and R1.
If you would like to keep an RC-filtered input instead, use R1 = 100Ω and C23 = 100pF.

Now, I’m excited to share some measurements with you!


EPIC W



1W Measurement (2x42VDC)



Output Noise (input shorted)



Schematic



Positive Regulator



Negative Regulator

Dear friends,
there are many enthusiasts of loudspeakers building here so I thought this link would be very useful for someone.

http://hificompass.com/en/speakers/measurements

It is needed to register at the website to have an access to the speaker drivers compare feature.
With no registration one can click on driver model name in the table and get to the speaker driver measurements page.
There is the mesurements description above the table. Just click on it.

To moderator - sorry if I place this thread in a wrong place, you can transfer it in the correct place.

Best regards,
HiFiCompass

An illustrated guide to building the Aleph J

This is a guide to building the Nelson Pass / Firstwatt 'Aleph J' amplifier.

A few links to start off -

Aleph J Manual (From firstwatt.com) http://firstwatt.com/pdf/prod_aj_man.pdf

Amplifier PCB (From DIYaudio) Aleph J (2 PCBs included, which makes 2 channels) - Circuit Boards

Discussion thread - Aleph J for Universal Mounting Spec - diyAudio

Bill of Materials (BOM) - diyAudio

Schematic -



Ok!

The bulk of this guide is going to show the green PCB, which were proof-of-concept prototypes. The boards worked great and we needed to make very minor changes to the production boards, which are blue. There is effectively no difference between the prototype and production boards. Also worth note, the photos of the PCB will be from two different builds, mine (6L6), and Grimberg's. There are no significant differences in how the PCB was stuffed or utilized. I think Grimberg did a prettier job stuffing the PCB than I did. 🙂

Also, this build will show a 5U 'Big Amp Chassis' from the DIYaudio store. (Because that's what I have on hand.) The Aleph J can be made into the 4U 'Jack of all Chassis', everything will fit and the heatsinks are (just) big enough. All the specifics surrounding the 'premium' chassis (back panel, perforated base, pre-drilled heatsink, etc…) are functionally identical, the differences between the 4U and 5U are mainly just size. Regardless of the chassis you use, this amp does get quite hot, and good ventilation will be required around the entire chassis.


On to the guide.

Here is the PCB. It's a great layout, please thank member Didiet78 for his work making this. 😀


Front


Back


Stuffing the PCB

The normal order of operations is to do the little things first and place the bigger things as you proceed.


This PCB has 4 connections that are normally going to be jumpers. (R6, R30, J1, J2) You can see them here. These connections can be jumpered with little bits of wire or cut-off resistor leads, your choice.
These 4 pads are there in case you need to add some resistors in case of oscillation, which may happen to some builds. It's rare, but if you need it, there is place on the PCB to add some compensating devices.


R27. SEE TEXT

Let's talk about this - as it is somewhat confusing.

There are 3 places for R27 on this PCB. The first is the pad next to the cap C2. (in the above photo it is empty) I suggest making that one a jumper.
Where the jumper is placed in the photo should be open, and under the green insulation you will find the place for a pot.
SO - place a 100K pot where the pot will fit and jumper the vertical 'R27'. Set the pot to 68K before you turn the amp on the first time.


Here you can see how the pads for the pot are arranged - (underneath where it says "LTP Bias" and similarly under "offset")
The small oval pads are where the pot connects. The larger round pads outboard of the silkscreen are for a resistor if you choose to put it there in lieu of the pot, or can be used to measure across the pot in circuit. Cool, huh?

Also, it does not matter which of the center pads you use - some pots have all three pins in a row, some have the center pin offset. Either type will be fine.



Add the resistors. Shown here are big-bodied Dale RN60. If these fit, and they do, most other resistors will as well. Use whatever parts suit your fancy.





Now add the bigger (3Watt) resistors. It's a good idea to leave some room between the PCB and the body to let air circulate. As shown here -






The best advice I can give you is this - measure every resistor before inserting into the board.


Continue on with caps and the small transistors





Eventually the board will look something like this -


For reference, know that the Power Mosfets (obviously not mounted yet…) on the Left side of the PCB, near the electrolytic capacitors are for the Constant Current Source, and the Mosfets on the Right side, closer to the red input film capacitor, are the Outputs.



Note that in this photo, the vertical R27 is jumpered, and there is a 68K resistor in the horizontal spot. I later replaced the resistor with a pot.


Here is the pot in that position. I used a single-turn because I had one on hand... I strongly suggest multi-turn pots on all of these projects.

Yes, have my LED colors reversed. The V+ should be red. I've even had it marked backwards in the schematic. Lol. 🙂 You could make them all blue, this is a Pass amp, after all… 🙂

The LED on the PCB are there to show that you have the rails connected and the amp PCB is getting voltage. If you want to extend the leads on one of these and make it a panel light, feel free.






Power Supply

The power supply for the Aleph J is going to follow the basic pattern of the Pass/Firstwatt DIY amplifiers. Please look at the following schematic --


The basic topology is this. 18+18V transformer, of at least 300VA, CRC filter with 8 15,000uF 25V capacitors and 8 (4 per rail) 0.47ohm 3W resistors.

May you use a transformer with more VA? Yes, of course.
May you use larger Capacitors? (more uF) Yes.
May you use capacitors with a different voltage rating? Yes, as long as you have 25V or more. (25V, 50V, etc…)

Remember that the factory Firstwatt amps use 300VA transformers and (8) 15,000uF 25V caps. If that's good enough for Papa… It should be good enough for you. But almost everybody makes it bigger. No problem at all. It's easy, so you might as well... 🙂

In this build I am using the old (smaller) DIYaudio PSU board. This particular one has no blue soldermask on the top of the PCB. It is otherwise identical. The section for the discrete diode bridges has been snapped off.


IMG_0822 - My Photo Gallery
Here shown with the Filter resistors (0.47Ohm, 3W, light blue), the Bleeder (2.2Kohm, 3W, dark blue) and LEDs.

For some reason I can get the LED color correct on this PCB… Red for V+, Green for V-


The PCB can accept (8) caps with 10mm lead spacing and 30mm diameter, or (4) of 35mm diameter. These are 33,000uF 35V Panasonic T-UP series caps.


I prefer to use diode bridges in these monolithic blocks.




Bridge connections.






IEC inlet.






120V AC wiring shown - this is the primaries of the transformer. AC will attach to the center terminals.





You are free to comment or question. 😀

Hi All,

I'm Brendon from Perth Australia.
Thank you for welcoming me into this community...

I'm a newbie in the audio world and look forward to learning more a d enjoying the journey.

Last of my DIY parts

Bundle of Soekris two R2R DAC boards with many kits and accessories
this bundle includes:
1 - Soekris DAM 1021-02
This is new and tested confirmed working 100%. comes in original box from soekris with molex connectors, the USB cable to pragram the firmware and Neutrik XLR connectors are new and perfect. these are the pictures: Login to view embedded media
2 - Soekris DAM 1021-01
this is the one that is installed in the box. i have used this for coax and usb input a lot and sounded glorious. pictures below

3 - AMANERO USB ITS INSTALLED IN THE BOX,. pictures below

4 - AZ OLED lite Green color
this is perfect and tested. it is installed in the box. picrues below.

5 - Normundss kit for soekris 1021
here are the pictures:
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6- the aluminum box with vu meters. this is an awesome box and i prefer to keeep it. it is complete and i have all parts and will be included

7 - the linear power supply has really good and expensive and like new capacitors. the transformer is antek As 0509. this is free if you buy everything.



price with box: $400
price witohut box $250

paypal friends and family



Dayton audio 6.5 inch designer series woofer. quantity = 3. two are tested and like new and have solder residue. one is new https://www.parts-express.com/Dayton-Audio-DS175-8-6-1-2-Designer-Series-Woofer-295-428?quantity=1
Dayton measirement mic with calibration gragh. new
all together $111 friends and family

everything together $444

The most important thing in an EMI filter are the coils, these must have a particularly high permeability and a very low internal resistance, smaller coil values and very large X2 capacitors are best in order to achieve a lower cutoff frequency of the filter, be careful with Y capacitors, too high values can trigger the FI!

The last picture shows a Chinese DC filter and EMI filter board, which sits directly in front of the transformer in a ChipAmp amplifier.

I had a few of these laying around.

6 sets are allocated to Poland.

The rest are up for grabs.

$10/each .+ shipping at cost.

R

Rod's instructions say "a 0.5°C/W heatsink for normal hi-fi use if the quiescent current is maintained at the minimum recommended of 20mA."
I don't know what to do with that.
This is the heatsink I was considering and I found this calculator, but I'm not sure what value to use for Ts (max).

I have a few hundreds of these original Toshiba beauties. Hfe Y, 120-240.

They are sold in small quantities or unopened plastic bags of 50 and 100.

Price: $6/pair in small quantity.
$5/pair in bags.

Shipping at cost.

R

Hi there !

After an attempt to design a bluetooth DAC, with questionable technical choices, I decided to be reasonable and make an S/PDIF version.
The DAC is still based on the PCM5102A chip, without additional preamplification stage, and the 100x50mm 4-layer PCB receives one ground plane per layer, connected together by vias.

I will use this module for S/PDIF to I2S conversion: https://www.audiophonics.fr/en/inte...spdif-to-i2s-dir9001-24bit-96khz-p-17274.html
For volume control, I'll use this: https://www.audiophonics.fr/en/preamplifier-modules/motorized-volume-control-board-50k-p-15006.html

From what I understand, the DIR9001 module will synchronize to the S/PDIF clock, and the PCM5102A will also synchronize via the I2S bus. I still connected the MCK pin of the DIR9001 module to an oscillator, so the DAC should keep running correctly without an S/PDIF signal, because my Tripath amp does not like to operate without a source.

I placed an LC filter at the 12V input because the DAC will be powered by an external SMPS power supply. Please tell me if the values of this filter are correct.
As advised for my previous design, the low noise 3.3V LDO is cascaded to a much larger 5V LDO to lighten its workload.

As this design was quite conventional, I couldn't resist adding a quirk, a high pass RC filter, for optional use.
Indeed, I chose the PCM5102A because it is the only decent DAC chip that I felt capable of implementing, being a beginner. But I know that it tends to be a little too generous in low frequencies.
So I added this high pass RC filter which cuts at 48Hz in the hope of being able to obtain more controlled and clean bass, if the need arises. I can use capacitors with significantly different values to fine-tune the filter. Let me know if this is a bad idea 🙂

EDIT : I just saw a big error on my high pass filter which in reality is a low pass 🤣. I am going to correct this and I am thinking of using a relay in order to be able to bypass this filter easily.

And here are the pictures :

Looking in another thread whith an unusual current limiter an idea struck me.
Here is a simple current limiter working on the base current of the output transistors.
Of course there is some potential problems. We must have output transistors with a known current gain jus as well as the drivers and the limiters.
And when the base current is limited the fast switching will also be limited. But it is simple and nearly fits a SOA with max current at low voltage for the output tranistor and 0 current with max voltage. If the current gain is 100 for all transistors max current is about 15 ohm from full voltage. Max current 5,3 A in this case and the half with the output short to ground.
The IS 1 and 2 is just for DC simulation.

I'm planning to build the above crossover and have a 25ohm rheostat I'm hoping that there is some way to use for P1.
Is it possible to sand a portion of the metal rheostat body and solder the 15ohm resistor to it as a 3rd lug, or do I just
need to purchase a wire wound 25ohm potentiometer with 3 lugs? Rheostat in question is pictured below.
Thank for your help.

Hi, my name is George, living in Germany.

I am looking for interesting discussions about audio/hifi equipment and sound improvements that I can use in my home.

Hello,

I'm searching for the latest firmware for my Marantz NR1504.

The reason?

Certain internet radio stations don't play anymore on my Marantz NR1604 and NR1504.

For the NR1604, I found, asked and received the firmware on this forum. Thanks again. And this solved the problem.

So I'm looking for the firmware now for the NR1504.

Many thanks in advance!

Stijn

I'm finally restoring my inherited Quad 303!

I'm following this guide:

https://www.rs-online.com/designspark/refurbishing-a-classic-quad-303-amplifier

I've replaced all the capacitors and everything went good 😉

Now to the problem:

Adjust RV100 for 33.5 volts between tags 5 and 9

One of the channels gives me an irregular reading of 38-41v with the pot all the way up. With the old pot setup it was reading 60v.
I only had to make minute adjustments to the power supply pot and the other channel.

What do you guys think is the culprit?

I'm a noob with a soldering iron.

After months of research on Multiple Entry Horns, I’ve decided to build my own. While there are some excellent designs available, I’ve decided to design my own due to size constraints and budget limitations. My goal is to build a complete system for under €2000, including drivers, amplifiers, DSP, materials etc.

I’ll be documenting the journey and sharing the lessons I learn along the way. Since I’m new to this, I’d greatly appreciate any feedback or suggestions for improvement.

For those unfamiliar with Multiple Entry Horns (also known as Synergy or Unity Horns), I’ll include some resources below. In this post, I’ll refer to them as MEHs.

Why Synergy horns?
Synergy Calc V5
Synergy Patent
SynTripP: 2-way 2-part Virtual Single Point Source Horn | diyAudio
Scott Hinson’s MEH

The Design
Designing this project involved plenty of trial and error with drivers, designs, and Hornresp parameters. First I was going to build a 3-way MEH using four 4” drivers and two 10” drivers per horn + big subs using 15” drivers. However, when I discussed this with my better half, she wasn’t happy with the big size. So I changed it to a more compact design: 30x30cm 2-way MEHs paired with subwoofers.

For the 3-way MEH I got ideas and insights from Syn 9/Syn 10 and Cosynes, Scott Hinson’s MEH and SynTripPs. After deciding to go with a smaller horn, I began exploring more compact designs, such as: Two way synergy Horn, Portable Battery Powered MEH Build and others.

Size
Using Synergy Calc , I calculated the size and parameters for Hornresp. According to Bill Waslo: “with horns, bigger is better!”. While I would have preferred larger dimensions, I had to consider WAF, so I settled on a 30x30cm horn with an 80° coverage angle and horizontal pattern control to 850 Hz. After reading this discussion I changed the S1 value to 5.06 to match the CDs opening area to get a more precise Hornresp Simulation..



Drivers
Hornresp is a fantastic tool for modeling speakers, big thanks to David McBean for his contributions! After countless evenings testing various drivers and parameters, I settled on the following components:

Compression Driver - FaitalPRO HF108 (8Ω) I chose it because it works well in short horns and wide dispersion waveguides and people seem to like it a lot. The recommended crossover is 1300 Hz, which is what I’ll go with in my design.
Midrange - 2x FaitalPRO 4FE35 (8Ω) in parallel - they simulated well in Hornresp and have been used in some MEH builds before.

Hornresp parameters



3d printed horn
The inner section of the horn (shown in light grey in the 3D rendering) will be 3D-printed, while the outer flare will be constructed from 2 sheets of 19mm MDF with a dispersion angle of 130 degrees

The HF108 compression driver has a 31-degree exit angle, so the horn starts with a matching 31-degree angle and gradually transitions to an 80-degree angle at the midrange entry point.

To minimize unexpected cancellation notches, the inner corners of the horn are smoothed with 2mm rounded edges.





Mid driver Port location:
From Why Synergy horns?:

In a synergy horn we put the tweeter at the horn apex, easy enough, but how do we know where to tap in the midrange and bass drivers. We use the rule of 1/4 wavelength. So if we want to cross over from the midrange to the tweeter at 1200 Hz, we would have to tap in at 340/1200/4= 7 cm (2,8"). At the same time the cross sectional area (CSA) at the tap in point with in the horn. should be no bigger than in circumference, than the highest frequency being used in the bandpass. So at 1200 Hz the wavelength is 28,3 cm, so CSA can be no bigger than 28,3 cm, otherwise the hornwalls will no support the frequency. Same thing applies for the bass drivers. If we want to x-over from bass to midrange at 400 Hz, then the axial distance from the apex to tap in is 340/400/4= 21,2 cm (8,3"). This 1/4 wave rule makes sure that the drivers bandpass, is cut off and basically acoustically self terminate. What happens is that the frequency at play, for instance at 1200 Hz, travel toward the apex of the horn and then back again, but this time, 180 degrees out of phase, so a cancellation notch occur. In this way we can acoustically short circuit the bandpass, smart. What this cancellation notch will also do, is to acoustically lower the harmonic distortion above the cancellation notch. This effect can NOT be done electrically ONLY acoustically. This cancellation notch can be as big as -30 dB, so harmonic distortion is also lowered -30 dB. The result is a much cleaner sound, compared to other speaker designs.

Click to expand...

I’m crossing between the mid and the compression driver (CD) at 1300 Hz, which means the port holes for the mid drivers should be within 6.596 cm (calculated as 343/1300/4) of the CD’s exit.

I’ve been wondering if the critical distance is measured from the mid ports to the CD’s acoustic diaphragm or its exit. The CD’s exit seems to work well in previous designs posted here, so I decided to go with that. This approach also simplifies placement by allowing the ports to be positioned farther out.

To ensure I stayed within the critical distance, I decided to shorten L12 slightly (the distance between the CD’s exit and the plane of the mid-entry ports). L12 is 4.28 cm, meaning the centre of the mid-entry port is 5.84 cm from the centre of the CD’s exit, so it’s well within the required 6.596 cm for the crossover.

The circumference of the cross-sectional area at the tap-in point is calculated as 6.531*4=26.124, which is close to the wavelength of 1300 Hz.

However, when I model it in Hornresp, the cancellation notch appears well above 1300 Hz, and the mids start to roll off around 2000 Hz. I can increase the distances well above 6.6 cm before I get the cancelation notch near 1300 Hz. I’m not sure if I’ve missed something in my calculations and the measurements may differ when I measure the build speakers.

Mid driver Vrc:
I made the Vrc (closed rear chamber volume) fairly small 2 L in total (1L per driver). I still haven’t figured out how I will limit the chamber volume. Using tubes like those in the Cosynes would be challenging due to the distance between the mids and the compression driver.

Mid driver Vtc:
I didn’t feel like I needed to minimize the Vtc (throat chamber volume) as the mids can play high enough frequency already. Making it smaller using cone plugs seems more beneficial with bigger woofers (like on the SynTripPs) and also the B&C 4NDF34 which have been used in some designs. For now I’ve estimated 50cc per driver, but will measure the volume when I receive them. I might adjust the sizing after doing the final calculations with the correct volume.

Mid driver port size:
There are 2 entry ports per driver, 4 in total. The entry points are frustrumised, 2.76 cm in diameter closest to the driver and 1.95 on the inside of the horn, which translate to Ap1 of 24 cm² and Ap2 of 12 cm².

The ports are relatively small, with port velocity exceeding 17 m/s when played above 105 dB below 200 Hz. These are meant for home hi-fi use, so I don’t plan to play them too loud. I also don’t want to make them too big, so they affect the CD’s output. The ports are placed next to the corners to minimise the effect they have on the CD.

Vertical drivers:
This is something I haven’t seen mentioned often, and it seems to be overlooked in many MEH designs. I will place all the drivers vertically, on the side walls of the horn, to avoid driver sag.

2. All drivers needed to be nearly vertical. The suspensions of a lot of home drivers will take a set over time if stored horizontal...I've seen it way too often. Since I'm using relatively inexpensive drivers I wanted to avoid this since I don't plan on building myself new speakers every 5 years or so. Source

Click to expand...

Ported or sealed box:
While I was designing the 3-way MEH with 2x 10” woofers I tried modeling the low drivers in both ported and sealed box. I ended up choosing sealed after reading Arts comment from the SynTripP thread.

In retrospect, the 3dB gain the ports provide around Fb are probably not worth the -3dB 350 to 475 Hz and-10dB cancellation at 700 Hz. That upper cancellation requires more output from the HF driver to “fill the hole” in response they cause. Most 3" diaphragm drivers are already excursion challenged in the acoustical crossover range.

To sum up, don’t bother with cutting the port holes, leave the cabinet sealed 😉

Click to expand...

Subwoofers:
I haven’t decided on the subwoofers yet.
I’m considering adding two subs within the same enclosure as side-firing woofers in a push-push alignment. For example, two GRS 8SW-4HE drivers in a sealed configuration with a ca 42L volume. Here is a promising recommendation for these woofers.

If I go with this approach, I might decrease the vertical coverage angle of the MEH horn to 60 degrees to make space for the woofers below the horn. I guess it would be good idea to have the woofers close to the horn, within ¼ wavelength of the crossover frequency, but have also read that it doesn’t matter very much for frequencies below 100 Hz.

Adding the subs in the same enclosure would significantly increase the height of the enclosure, which may not pass the WAF. Alternatively, I could build a separate subwoofer placed approximately 1.5 meters away

Is it better to integrate side-firing subwoofers within the same enclosure or should I make a separate enclosure, which would need to be ca 1.5m away? I’d appreciate any feedback or suggestions on driver selection!



Amplifier and DSP:
As I don’t own any of the parts needed I have the opportunity to build the whole system from scratch.

The TPA3255/51 amps seem to offer great value for the money.
I’m looking into: Fosi ZA3, AIYIMA A70, Topping PA5 II and the upcoming 3e audio amps. I haven’t decided yet and would appreciate any recommendations.

Finding a DSP solution that fits the budget has been tricky. High-quality DSPs can be expensive, while the cheaper options often come with limitations.

I’ve decided to go with a Raspberry Pi 5 running CamillaDSP. For the DAC, I’ll start with the cheapest option: the AliExpress cards mentioned in this guide. RPi 5 Quad Stereo Sound with PCM5102A – Simple DIY Electronic Music Projects. User dptucunduva has had good results with it.

The reasons I chose it are:

It’s cheap and has good potential for upgrades. I can switch out the DAC module for a proper sound card like the Motu Ultralite mk5.
It’s a very flexible system, the Raspberry Pi can act as a streamer and allows for lots of add-ons like a remote controller, Those who use CamillaDSP seem very happy with it.
HiFiBerry DAC, which uses the same DAC chip seems to be decent according to the measurements here. I’m not expecting any fantastic results but see it as a cheap solution that has all the active crossover functions needed.

Next steps:
The CD and mid-drivers are on their way, and I plan to begin 3D printing the horn in early January. In the meantime I’ll focus on refining the horn design, adding mounting holes, figure out how to do the right vrc size. I also need to decide which amplifiers to use and start building the Raspberry Pi DSP. Additionally, I’ll work on designing the subwoofers and determining whether side-firing woofers are the best option.

Any suggestions or input would be greatly appreciated!

Hi!

Back with a Sony TA-F770ES. The pour thing has blown its output mosfets.
These 2SJ200/2SK1529 seem pretty close to the 2SJ115/2SK405 in the Luxman LV series that I successfully replaced with IRFP340/9240 with only very minimal modifications. I know from experience that these Sony amps can be pretty unstable, is there anyone that has tried this replacement before and/or can simulate what results this would give and if there are any mods that have to be done to the bias circuit for example ?

Thanks !!

I have been using the excellent and free software package called REW and a sound interface card (or DAC/ADC) to measure my amps for years now. It’s fast, easy and really costs nothing if you have a sound interface already. REW is normally used for measurement of speakers with microphones, however, it’s interface, GUI, and math engine are top-notch and lend themselves to an excellent amp measurement tool. I have been asked numerous times via PM’s to assist DIYA members make their own measurement setup using REW. Recently, I was asked again in the M2X thread when I chimed in that one doesn’t need expensive dedicated distortion analyzers from HP/Agilent/etc. all you need is a decent sound interface and REW. Plus a dummy load resistor and some wiring.

First of all, I want to thank member John Mulcahy, the author of REW - what a wonderful gift he has given to the DIY community. He is also always there to answer as technical question on REW.

So what can a sound card and REW do for you in terms of audio distortion measurement? Here is a typical FFT spectrum that I took using a $99 Focusrite Solo USB sound interface and REW with the Alpha 20 amp. This is 2.83vrms into 8ohms:


The plot above tells us several things about this amp: it has a dominant second harmonic distortion signature (sweet sounding), it has a little third order (gives it some bite), it’s devoid of higher orders, or higher odd orders specifically, which can sound fatiguing; it has an overall low level of total harmonic distortion (as seen in onset window); the mains noise at 60Hz and 120Hz is essentially zero - that is, it is very quiet and hum free; finally, the noise floor is about -110dB below the signal so it has very black blacks.

How hard is it to take this data? Well that’s the purpose of this thread. To show you how easy it is to do.

Another example of how REW can tell you how to tune your amp to achieve a harmonic distortion profile of interest. Some amps have this variable knob that lets you tune the type and level of distortion to your liking:

DLH Amplifier: The trilogy with PLH and JLH amps

Here is an example of measuring a preamp driving a 7k ohm load, this is the Aksa Lender putting out 20Vpp into 7kohms:


So where to begin? Let’s start with getting a copy of REW on your computer. Works on PC or Mac but I am only familiar with the PC version. Go here to download REW, and while you are at it, please donate some funds to John Mulcahy to continue his excellent work.

REW - Room EQ Wizard Room Acoustics Software

Once you install it, install software or drivers for your sound interface. I have used even the built in sound card in a PC to do this and it can work. However, those are generally very noisy and you won’t get the nice -130dB noise floor that some standalone interfaces can achieve. I personally use a Focusrite Solo (2nd gen) and 2i4 (2nd gen). They both have the same ADC’s but the 2i4 has a front end that is more flexible. I also think it has slightly better low noise characteristics. But you can use any sound card as long as it is supported by REW - and that includes any Java supported card. I haven’t found one that is not supported yet.

Next step is to connnect your interface by plugging in the USB cable, for example. Some of you might have other interfaces. The go into the setup menu and configure the sound interface. I typically the non-ASIO interface as I find that more finicky to work. Then choose your input device as your sound card and your output device as your sound card. Choose input and output amplitude to be “Master” and set to amplitude of 1.0 - this lets the full signal be generated by the sine wave generator and the full signal be captured by the ADC.

On the input settings choose the channel where you will connect your amp’s load resistor. Channel 1 is typically the “Left” channel and channel 2 is “Right”.

At this point you can see what the inherent self noise of your sound interface is without anything connected. Click on the “RTA” button along the top. In this dialog, click on the gear to adjust the settings. I use something like this:


You can try other settings. Making the averages smaller like 0.88 exponential and choosing 32k points will give you almost real-time updates to the FFT. You need to click on the span button to set your range of measurement from say 20Hz to 20kHz. On the vertical scale button on upper left click on dBFS. Then click on the red button to acquire your FFT spectrum.

You will see a relatively flat spectrum (hopefully) but this will tell you what the noise floor of your setup is. A cheap built in sound card on my pc only gets -110dB. The Focusrite get -130dB. There are ways to achieve better noise floor and much is discussed in threads elsewhere. For many of our SS amps around here the typical noisefloor of the Focusrite is fine as distortion is typically no lower than -100dB abd typically -80dB or so.

This is all fine and good but how do we measure distortion in our amps? Well we first need to make a dummy load resistor to simulate your speaker load. You need a power resistor with the same impedance as your amp that you are testing. Typically 8ohms or 4ohms. It also needs to handle the amp’s power output. A good one is a metal shelled 25w resistor mounted to a heat sink.

Here is an example of one with the wires you will need to make to connect it to a sound interface:


Here is a sketch of how to connect your load resistor to the sound interface and the PC:


For measurements of amp power up to 1w (8Vpp) it’s ok to connect the dummy load to your sound card directly. However, if your amp ever had a burp and hits the interface input preamp with too much voltage it can fry the input stage. I would recommend adding a ~10:1 voltage divider using a 20k and 2k resistor and taking the middle node attenuated output as the signal to your sound interface.

Edit May 10, 2024: circuit for floating balanced input needed for bridged class D amps here https://www.diyaudio.com/community/...ion-measurements-with-rew.338511/post-5925805

Also, if you are using Class D amp, you need a steep filter to keep the high frequency noise out while not distorting the low frequency to prevent aliasing the data. I used the filter suggested by Voltwide/Bucksbunny here: https://www.diyaudio.com/community/...ion-measurements-with-rew.338511/post-6714709



Depending on your sound interface, they may be good for 20v max input so that would give you pretty good protection. Never put full 25wrms (40Vpp) into your sound interface unless you want to fry it.

Now you need a way to generate your 1kHz (or whatever frequency you like) excitation sinewave. You can use the audio output of your sound card and the built in generator in REW. Then connect the audio out of the sound interface to your amp’s input. Adjust the level using the amp’s volume knob if you have one or the knob built into the Focusrite or the level in the generator interface.

Another way is to use an independent reference frequency source. A dedicated low noise high precision generator from HP is expensive. You can use a digital audio player with a good DAC as your source. I use a Cayin N3 which has the excellent AKM4490 DAC. Create a 1kHz sound file in lossless flac format using a program like audacity. Then play that into your amp as the excitation source. Those has the benefit of decoupling your source from your measurement to avoid ground loops. Especially if the source is a battery powered DAP. It’s also typically quieter.

So now connect your audio source to your amp, connect your amp to your dummy load, connect your audio interface to the dummy load, and connect a DVM to the dummy load and set to AC volts. Increase or decrease the amplitude of the 1kHz sine wave until the DVM reads 2.83vac. That’s same as 1w into 8ohms. A typical standard at which distortion measurements are taken.

That’s all for now. I will update later as I did this post with my phone and will get back with more details. But this should get many of you started.

Update June 3, 2019: Here is a loopback using Focusrite Solo gen2 and Akitika 2ppm 1kHz oscillator at 1.0Vpp into 10k:


Update Sept 24, 2020: member Wtnh made a very nice and useful schematic and connection diagram for us to use. Although he used an EMU sound interface, a lot of it applies to other sound interfaces as well (like Focusrite, or any other with combo XLR/TRS balanced inputs):

Hi all,

I am building a class D power amplifier and got a bit confused on how to read the specification on the power switch and whether it will actually work for the purpose.
This is a 200W mono construction, 400VA/40V toroid transformer with 200 uF filter caps and a 2 second softstart from the late Newclassd solution

The power switch I have bought is specified to 10A 250V, but got a bit confused on the fuse power specification on 2W for one-pole and 1.6W for 2-pole. Have I bought the wrong switch for this application? Any suggestions to what spec I need - both for the switch and what fuse to use 🙂

The switch: https://docs.rs-online.com/dd66/0900766b81148d4e.pdf

and the specification sheet:

I've no idea how to read a circuit diagram. Can somebody please tell me the transformer output voltages on page 10?
Thanks in advance.

Let me start to say that this is only simulation with SPICE.
But I have no doubt this amplifier should do very well for real.
I challenge you to do something like it or even better 🙂

Design goals:
1. Fully discrete
2. Max 3 transistors
3. Voltage gain 4-5
4. Load 1Vrms into 4.7kOhm
5. Regulated 12V supply

Result in SPICE:
1. Voltage gain 4.6
2. THD 0.00011%
3. Frequency response 5Hz-300kHz -3dB

Hi guys,

What happens to a voltage regulator when started up on a variac?

I am about to test a tube power supply with a regulated 12.6v heater supply (lt1086) and a 265v regulated b+ (treg)

My question is will this hurt the regulators in some way?

My guess would be that there is no ill effect. That the regulators simply won't regulate when their input voltage is below their minimum drop out.

My punny brain can conjure some horror scenarios when this would cause wild current flow but I am guessing this is my feeble mind displaying it's feebleness.

This will be my 2nd go around at building multi-way speakers and have decided to try a MTM configuration. When designing the crossovers, is there anything I need to do differently than I would do in a TW 2 way crossover? The mids will both be the same make/ model. I've ran some sims through xsim and removed one of the 2 mids after building one to see if it reacted. It did but not in the way I had expected. The SPL actually went up when disconnecting the 2nd driver. 1st pic is with 1 mid. Pic below it has both hooked up. Would that be normal?

Guten Morgen involved people,
I would like to show you nice solution for MM cartridges from Nick Sukhov. He is a legendary audio circuit designer based in Kyiv, Ukraine.
MM Phono stage-XXI (Su-XXI) by Nikolai Sukhov, thanks to the "aperiodic" HF correction invented by him back in 1980 [first described in the article "High-quality preamplifier-corrector" in the USSR Radio magazine No. 3/1981 pp. 37-40, which became “The best publication of the year” in 1981] allows you to get rid of the input circuit resonance "MM head inductance + cable and phono stage input capacitance", due to which, above the resonance frequency (usually in the region of 14 ... 16 kHz), a frequency response decay is formed with a significant slope of 12 dB / octave ( like a second-order low pass filter). With aperiodic correction, such a drop is eliminated and the sound of $50 MM cartridges becomes as transparent and detailed as that of top MC k$ cartridges. Similar circuit solutions appeared 20-30 years later among high-end Phono preamps under the names "Neumann pole", "Damped EQ", "Enhanced RIAA - eRIAA", "Phædrus Phlux active phono cartridge". Thanks to the original "passive cooling" solution with 150 kOhm input resistor instead of 47, the Su-XXI provides an unprecedentedly low noise level of -85 dBA in full compliance with the standard input level of 5 mV @ 1 kHz (and not the "maximum input" - a typical marketing trick) and with an equivalent input MM-source 500 mH / 1 kOhm connected (and not the "shorted input" - another trick of the steamers). Finally, thanks to the use of a high-output impedance voltage amplifier stage with a load Z(f) in the form of an RIAA-chain (overall gain 1+Z(f)/R, voltage amp open collector stage gain is also proportional to Z(f)+R, so loop gain is almost constant across the entire audio band), a "passive-active" frequency-correcting circuit is formed with an almost unchanged feedback depth from 10 Hz to 50 kHz (55 dB constant loop gain). This design of the deep RIAA freq response correction of 40 dB eliminates the “diseases” of both excessive gain at high frequencies and insufficient gain at low frequencies, which provides both a high stability gain margin (22 dB) and a uniquely low THD of 0.00006% at a nominal input voltage of 5 mV @ 1kHz and 0.0006% at +20dB overdrive.

Anybody has a reference for a simple ADC board with an spdif output? I prefer coax output but optical is also an option. 16/44.1 is plenty for the use I have in mind.

I'd like to build one into my preamp so that all analog sources get converted before switching and sending out of the preamp. So it is for my fm radio, an old tape deck, turntable etc. DAC board are 13 a dozen but ADC boards look scarce.

I have been printing another large MEH. Finally got it finished and vaguely measured. It is 630mm wide and 360mm tall. The horn is 350mm long without the comp



Here are the measurements:

The measurements were taken with the mic at the mouth in a small room as in the image above so they aren't ideal but I will try and get some better measurements soon.





With the sims I had managed to get it up to around 2khz however it drops off rapidly above 1.3khz. I have managed to get smaller drivers up to 2khz before so thinking it is cancellations across the cone?

I might try doing some modelling in Akabak of just the front chamber and taps to see what I end up with.

Hello
I am selling a complete PCB for this project:
https://tolisdiy.com/2021/01/30/audio-measurement-pre-amplifier-part-5-updated-ver1-1/
The price for the complete set is 65 EUR plus shipping.

Hello everyone,

I have an Audison SR1DK with a weird issue. The output at startup is not at full power and it gradually rises to full power. Changing the gain does not affect it much, and the signal is clipped when the gain passes a certain threshold.

Also, does anyone know the value of this capacitor (C128)?

Hi everyone,
I'm trying to build this amplifier based on the Sanyo STK465 amplifying module (I attached the originals down below).

And this is my version:


I simulated this circuit using LTspice and everything works as I expected. I attached the simulation down below.

The problem is that when I build it in real life the DC bias point of the output stage is not going to 0V DC. It sits close to the positive rail and I can't figure out the reason. I can't proceed further until I get the DC bias point right, so I'm stuck here.

I'm currently using a 10K resistor as the load so i don't fry the output transistors, but the problem persists even with a 10 ohm load. R6 and R7 are there to protect the output transistors as well.

What I tried:

• I checked the supply rails and they are fine. They come from a dual power supply I built which uses L7812CV and L7912CV linear regulator.
• I checked the connections a thousand times.
• Tried to remove all capacitors (excluding the decoupling ones and the compensation capacitor C4) in order to focus on the DC response only.
• The circuit was originally built on a breadboard. I've now soldered the amplifier on a perf board, while the rest of the circuit (the input section, the output filter, the feedback) is still on the breadboard.
• I put a 10K potentiometer on the emitter of Q5 and tried to trim it (therefore decreasing the gain of the VAS stage) until I got 0V DC at the output. I couldn't get it to work: as I got closer and closer to zero, the output flipped to the negative rail; I then trimmed the pot on the opposite direction, and the output flipped back to the positive rail. I think this happens because Q5 gets shut completely off, causing the output to swing to the negative rail.

I'm at a loss. Why doesn't the VAS stage bias the Sziklai pairs in the output stage correctly? Do you have any suggestions? Thank you very much for your time and for your help.

Hi to all. I love music and have my dedicated room to listen and HT. I had a great pleasure to treat it myself, although still not perfect it has been improving. I am here to learn mostly and to share some of my experiences.

Best regards,

A. Duarte

How many mA does 1 opa1656 opamp draw from the transformer?

I bought a pair of these as basis for some experimentation.

I have listened to them a bit 'out of the box', but did not really like the sound. A bit harsh and a bit weak in the LF bass was the impression.
After some simulation, I have drawn the conclusions that the feedback DC cap could be increased (120uF), and so can the input cap (3,3uF). That could improve the bass slightly.
I put a 1000u bipolar for the feedback (to the left of the grey input cap), and soldered another 3,3u in parallel to the input cap on the back of the PCB.

From measurements I found that bias needs to be increased to reduce distortion. I added a 5k trimmer in the position seen on the picture and tuned it to the minimum Iq for lowest distortion at abt 1W. A value of 4,3k seemed to do it on both boards, and that resulted in a emitter to emitter voltage of abt 7mV, which translates to abt 16mA per output pair.
Distortion now stays below -100dB at abt 1W 8ohm. Improvement was abt 10dB with bias adjustment.

I'm looking to build a compact and lightweight speaker for bass guitar and electronic drums. I'm looking for 110dB at 40Hz at 1m in 4pi space. It may be a 2 or 3 way design.

At the moment, I've modelled NE265W-04 in a 30L box tuned to 33Hz in winisd. This is giving me 108dB at 40Hz at 23.6V (150W) in winisd so 102dB in 4pi. It's a 10 inch speaker and weighs 5 lbs.

I'd like to keep the box volume about that size. And I want to keep the weight of the driver down. And the power manageable. And I need a 4 ohm speaker. And 8dB more output without throwing 8dB more power at it.

Wishful thinking or can I do any better?

Is there a way to search for drivers that will work in that size box and predict the output at 40Hz without modelling? Just something to get in the ball park so I don't have model each and every speaker? Ideally a quick glance at the ts parameters should tell me if it's suitable.

I did try sorting based on peak excursion times cone area. But that doesn't tell the whole story.

I'm just trying to figure out how to use my fancy LCR meter. All I want to do is measure the impedance of a 1:1 audio transformer and compare against the data sheet.

Data sheet says impedance should be 15K with a 600 ohm load but the LCR is spitting out 3.2k. I have bought the handheld DE-5000 to verify the first LCR but ability meters agree.

All I have to do is hook a 600ohm load up to the secondary, right? I'm totally confused

deq2496 linear power supply.. capacitor update 2025

Hi,

Posted in Swap Meet forum, but may get a better/faster response from the source.
Would like to buy or have PCBs made for the Sony VFET amp, preferably the N-Ch version. Push-pull version OK as well.
If gerber files are available, please share or let me know where I can find them. Thanks!

Vince

Sold

Sold

I am selling 2 pairs of TW29TXN-B satoti tweeters.
Selling as i am moving to be tweeters
Looking to get $300 per pair
Buyer Pays shipping and paypal