diyAudio

presscot · 2023-06-19 4:09 am

I own ADS L620 speakers. They're 2-way, with a 10" woofer and a 1" tweeter per enclosure. Recently, the local shop has been selling a pair of ADS L730. The L730s are 3-way with a 10" woofer, a 1.5 mid-dome, and a 0.75" tweeter.

And yes, the woofers and cabinet sizes of the two are the same. However, the L620s' woofers have midrange duties. They're crossed over at 1.5 kHz, while the L730s' are cut earlier at around 650 Hz.

I wonder if the midranges from the mid-domes have better quality (wider dispersion, lower distortion) than those of the woofers. Is it worth it, and will I gain a big difference if I go from a 2-way to a 3-way system with the same woofer?

Umbra57 · 2023-06-19 12:50 pm

Hey all,
I've been into music for years and am going to study a a Bachelor of Science in Music Technology later in the year. But I have never really considered DIY equipment, hell I didn't even really think about if it was possible haha. I'd love to start learning and eventually start making my own speakers.
I've been playing keyboard for about 10 years now and I spend my time playing in a band, mixing and listening to all sorts of music, but my area of expertise is Funk/Jazz fusion.
There seems to be a whole load of stuff on this forum. Has anyone got any pointers on resources or forum posts about how to get started/understandings the basics?
Thanks
Umbra

xXBrunoXx · 2023-06-17 2:28 am

Hello, I want to build a simple ( hopefully reliable ) Variable power supply for testing various electronics.
0 to 30v at 2A would be enough.
The easiest would be using LM317 ( I don't mind that LM317 won't go from 0 and instead 1.2v or something ) increasing it's output current with an " output transistor ".
Here is a quick google search on how to do that, most of them use PNP ( i don't really know why )
Is this the correct way to "convert" it to use NPN ?.
The only difference is current sink or source?
Please enlighten me.

¶Apollo · 2023-06-16 1:39 pm

Gorgoeous sounding amplifier!
Maybe the best amplifier you'll ever heard. Maybe the best ...
Asking 250Euro per par ex VAT 19% and shipping. Shipping to UE is 22 Euro, worldwide 38euro no VAT.
I prefer UE.

Best regards !

chrisg4 · 2019-02-11 6:27 am

Hi Perry,

I got this amp with a very blown power supply and one side on outputs (IRF1310N) shorted.
I removed all the fets, checked the psu drives/gate resistors, then installed new irf3205's. I installed a new HIP4080, I'm only getting drive waves on Q5,6,7 and Q20,21,22. there are no output fets in the board

Pics:

An externally hosted image should be here but it was not working when we last tested it.

gupsta · 2023-05-19 10:55 pm

I have a pair of Fostex F220a Full ranger drivers; big brother to the F200a. Sadly the foam is completely rotted 🙁.

I spent a while looking for aftermarket foam surrounds, however, I didn't find anything off the shelf that was close in size. From what I could tell most placing that sell replacement surrounds, don't actually manufacture them and naturally only cater for more common models. Fostex International were no help either. Perhaps I could try cutting down some 10" foam surrounds, but I don't see that working well. I did create an MDF form to size and created a leather surround, but the 1st attempt didn't quite work. Fs measured about 30hz higher inspite of the added weight; I think I got the surround curve too steep and should have made it shallower, I also didn't consider the variation in leather's elasticity. Still the leather did look nice for a first attempt.

I've no idea how foam is made, but I'm guessing it's beyond the average diyer's abililty unless the the sheet material can be reformed using heat and pressure ?

I've started experimenting with paper soaked in latex, but don't hold much hope of that working.

Also, I'm not sure what I should be looking to attain, the surround will block/reduce the rear wave cancellation and ideally should be light for a FR driver, but beyond that I am unsure, perhaps it should be elastic, deflecting with little force and returning dead stop to the center position.

Thanks for reading
Dave

bird_9527 · 2023-06-19 8:36 am

We design a FPGA-based digital player,how about it?

anyone want it can contact me.

raelman · 2021-11-08 8:31 am

Hello.
This is going to be a crazy sale, but who knows if there will be somebody ovr there as crazy as I am.

I never though t I would put them for sale but, the fact is that I have more than 6 floorstanders and, although The Loudspeaker 2 are the very very best, they are the bigger ones as well and it’s impossioble to listen to any other speaker while they are in position… and I like changes and try different speakers.
In addition, funds will go to help the widow of one of my best friends who suddenly died last week.
That situation made me think about a lots of things and, although downsizing was something I always thought I have to do, now it’s time to do it deffinitively.

You can read the thread of my build here:

https://www.diyaudio.com/forums/multi-way/354240-troels-gravesen-loudspeaker-2-build-close.html

My build has installed the Fostex FT96H (brand new) and I have replaced the original BMS 18” woofers with a pair of 18FH510 FaitalPro 18” woofers becuase they perform almost equal in the designed freq (Box tuned to 33Hz). With this 18” woofer you get a 98dB sensitivity system.

I have not played tyhe speakers more that 70 hours. Just almost break in process.

This is the fully passive version and crossover fits Jantzen audio components:
Z-Superior Caps for Tweeter and super tweeter, cross cap at the begining of midrange and Z-Standard in every other cap in the crossover. For bass section Elko Superior were choosen.

All the coils are oversized air core coils unless iron cored with discs at woofer low pass.

After lots of iterations, my crossover differs just a few from Troels one, and I can help you with the original crossover in the case you want to install the 18” BMS woofers. You just need to add some resistors and change one small coil. I’m pretty sure I have them stocked.

The box is built with birch wood (27mm) in all sides except bamboo front baffle (27mm).
All the wood was treated with two layers of Tung oil.

Price for this project is not cheap: 1500€ + Vat for the cheapest jantzen crossover and I have paid 1100€ for wood, 1900€ for drivers and more than 400€ in screws, damping material and small things.

I would let them go fot 4000€
Shipping is going to be a nightmare for me but it could be done into two pallets. Speakers would travel into custom made wood boxes (better to say tombs). I have checked price and it would be very close to 500€ within EU, so tyou have to add shipping to the price after checking because of transport situation.

Some pictures (read the build thread for more info)

Zero Cool · 2006-03-08 12:11 pm

Sony SCD-1 Firmware Upgrade Chip Version 2.53

If you own a Sony SCD-1 or a 777ES SACD Player and it has Firmware Version 2.40 and you experiance a loud burst of noise at the end of some tracks, YOU NEED THIS CHIP! This is the chip Sony released to fix that problem. Will upgrade any Sony SCD-1 or 777ES Cd player. I ordered this chip just before they were back ordered. it arrived after i sold the player. Now is your chance to buy one of these rare unobtanium chips!

$75.00 plus shipping:

$7.00 Fedex Ground Shipping within the US
$20.00 Global Express Shipping to Most countries.

toroechado · 2023-06-19 2:44 am

Hi to everyone!

One of my power amplifiers, a Harman Kardon HK 775 developed a problem. It starts making a cracking / poping noise and the DC offset goes crazy. It's an intermittent problem. I'm almost sure the problem is one (or more) of the input stage transistors so I need a suitable replacement. The adjustment pot a new mutiturn bourns.

I already tried the KSC1845 and the KSA992 but I noticed two new problems. First, the noise floor went up and second, these transistors got super hot. Any other alternatives? I don't mind making some modifications in order to fit a replacement with different pin order or using SMD adaptors.

Any suggestion please?

Dneu2011 · 2023-06-17 9:31 pm

Looking to buy some pairs of 2.2uf Poly/Film Caps for a few Mofo builds and my Dac. Used or new is fine.

Shipping to 77040, Houston, TX.

Bryguy · 2023-06-17 2:49 am

Doesn't happen too often that I come across an audio company I've never heard of, but I came across this mysterious little amplifier on Facebook marketplace earlier today and I just had to bite. It comes from this company, "Dragon Audio" which has left almost no mark on the Internet. They seem to be an OEM company? I'm not sure. Here is their website: http://www.dragon-acoustic.com/

Anyways, here's a pic of the inside of the amp I bought. It's called the Alpha 1000. I'm not too familiar with amps and such, but it seems to be built from generally pretty good parts? Not sure. How'd i do? (Paid 100 bucks)

CinnamonRolls · 2023-06-19 1:21 am

A post by JohnPM (REW) on Audiosciencereview said USB mics can be used to measure individual drivers for crossover simulation if an acoustic timing reference and clock correction are used. I'm curious about the process. I tried it using two speakers: speaker to be measured on the Right channel and the acoustic reference speaker on the Left channel. I noticed that the clock update comment was different for each sweep even though I did not reposition either speaker. However, I am in a reflective environment. Should successful measurements show the same distance offset in each measurement when done properly?

pbilous · 2023-05-12 4:53 am

Hi all,

Not sure if I can combine few voltage source and run it. For some reason it gives me funky output.

Help is much appreciated!

Attached screenshot and sim file.

bfb1963 · 2023-06-18 3:31 pm

Anybody successfully removed the plastic covers of these things? I am thinking of using a heat gun to loosen them up.

Michiganmike711 · 2023-06-17 9:13 pm

My dipole speakers have 4 ohm AMT tweeters and I wish to get another amp to enable parallel hookup and >15 watts output per driver. However, I am confused in that somewhere I read a Y connector to each amp was required, as well as using all the output binding posts. In the construction manual, only a single input to the amp is used. Is this due to wiring of the binding posts? I much prefer what I see in the manual.

Thanks much, best.....mike

VOiD25 · 2023-06-18 10:39 pm

Selling 2 Eminence N314T-8 Compression drivers and 2 B&C 15TBX100-8 subwoofer drivers.

All of them are brand new, still in original box.

$170 each for the Eminence Compression Drivers or $320 for the pair OBO

$270 each for the B&C drivers or $500 for the pair OBO.

Free shipping to the continental US.

New

marka250 · 2023-06-18 10:02 pm

Hi all.
My name is Mark, but you’ve probably already figured that out.
My reason for joining this forum is to pick your brains as much as possible. Really I’ve found that this forum has a lot of discussions going on and I want to learn as much as I can about DIYAudio.

But first a little about myself.

I’ve been interested in HiFi audio since I was a kid. I remember picking up from local dealers and requesting from manufacturers their marketing brochures for particular models I was interested in. Also liked reading Stereo Review and Audiophile magazines.

I’ve been looking to build speakers for a long time and recently learned that there is a large community interested in building amps. I’ve really been thinking about starting.

Now my first question is in regards to AliExpress. I’ve found a lot of boards and such on AliExpress at what appears to me ridiculously low prices. So my question is, do any of you have any experience or opinions regarding AliExpress?

Thanks in advance,
Mark

Sorry the end of post is kinda rushed. I wanted to finish before my lunch break was over. (3min.) to go. 🤪

SuperAudioGuy · 2023-06-15 6:00 am

I have a pair of M-Audio M3-8 3-way powered speakers. Product Page Certainly not high end, but I really enjoy them. -One of those rare situations when a product outperforms it's price point. According to the mumbo-jumbo, it's class A/B amps in a tri-amp setup.

One of them has decided to start making a @1550Hz tone from it's mid driver at all times, regardless of what is or isn't connected to it. The tone is immediately present and steady when powered on, and sweeps down quickly when powered off. Volume pot on the speaker does not effect volume of the tone. Input signal does not effect tone. Transistor? Capacitor?

My first instinct was to find a used one with a good amp (or new old stock) and just swap out the amp plate, but no one seems to be selling, and a tech wants 2/3 the original cost of the speaker before they even look at it. (not to imply that they don't deserve it, but I'd prefer not to spend more than the purchase price to repair it.)

I'm an Audio Engineer (which doesn't mean much lol) I know how to solder, use a multimeter, and read a schematic. Is this something I can potentially figure out and fix on my own with some help, or should I just begin the grieving process? 😢

Thanks for reading.

Buckapound · 2023-05-27 2:48 pm

Hi all,

I'm looking for help with a project I inadvertently screwed up by shorting the outputs of this (short ugly story), causing damage that I am trying to repair. I had it working before the mishap, so I know its problem was directly caused by the short. I am trying to get this board working as I have already built a Wayne's BA line stage preamp around it. I would just buy another kit, but Glassware's site has shown it as out of stock for a while now and I haven't gotten any response to my query about availability.

Here's what I've done so far:

1) Replaced the two 10R power resistors, which overheated during the brief short.

2) Replaced the LD 1084 regulator chips

3) Replaced all the MUR410G fast-recovery (Schottky) diodes in bridge with ones marked SR5100-MIG that are of same type and the same voltage and current specs.

4) Replaced all the 1N4007 diodes with same.

I managed to get the unsoldering done with no noticeable damage, and re-flowed the solder on top to make sure traces on top are connected to the diodes. All diodes in place show similar voltage drops across (~1V for the Schootkys). Reisistors on board show nominal resistance. I have no way of knowing how I can check the regulator chips. Both legs of the transformer show the same resistance

When I hook it to my Variac and crank it to 50VAC, output shows something around 4VDC, but one of the power resistors heats up much more than the other. So, there's clearly still something wrong with the one channel, which seems to confirm that the replacement parts are OK--at least on that side. None of the caps appear swollen or out of the ordinary looking, but I don't have any way of checking them except to verify that none are shorted out.

Obviously looking for help with next steps. Any suggestions? I have been working on this project for a couple of years and would really like to wrap it up, but I'm stuck at this point. If I replace the PS with something else, it absolutely has to fit within the 4.5" x 4.375" (114 mm x 112 mm) footprint. I've inspected the board several times and can't find any visual defect that would cause a problem. I can send a picture of the board if anyone thinks it would be helpful.

Suggestions?

rongon · 2023-06-18 8:20 pm

I've been parting out a pair of Tannoy T185 Dorset speakers I listened to for over 20 years. The tweeters finally faded out and the woofer surrounds began to sag, so I had to move on from them. I sold the drivers a while ago, but I've recently removed the crossovers to see what they look like. They're pretty cool, actually. They have three inductors: one air-core 0.2mH, one iron-core 0.8mH, and a tapped iron-core inductor labeled 0.8 - 1.5 - 2.5 for the Presence control. That's a pretty neat part to have for experimenters. The capacitors are WIMA MKP and the resistors look like good quality wirewounds (at least I think that's what they are).

The crossover networks are on stout PCBs, with the external plate with controls attached to the back side of the PCB. (photos attached)

My speaker building adventures have been extremely ill-fated, so I'm giving up and getting rid of all the stuff I've accumulated over the decades, including these crossovers.

I have the crossovers up on the 'Bay' right now, but shoot me a PM and we can talk. I'm in the eastern USA, will ship. Buyer pays shipping. Bear in mind that shipping may be expensive to Europe, UK, Asia, Australia/NZ, South America, etc.

I still have the cabinets and the 10" passive radiators, which I'll give away for free but recipient pays shipping. I don't think it's worth it to ship the cabinets, however.
--

2023-06-18 9:33 am

Pavel Dudek (RIP) has a circuit using a different kind of decoupling for DC unity gain using low non polarized capacitor. Why no one uses it?

old repairman · 2023-06-18 12:07 pm

Hi All,

My trusty old Linn AV5103 processor/preamp PSU has stopped working. It was the start up cap and it works ok now I have replaced it. However as it's getting on a bit and the PSU PCB is in an enclosed case with no ventilation it runs very hot and all the caps are probably nearly dried out. I want to replace all of them but having trouble sourcing the reservoir caps. They are Jamicon 390uf/200v 85deg C. The only ones I can find that willl actually fit (in the UK) are all 105 deg C Types. The problem is the rated ripple current. The Jamicons are rated at 1.8A and the max I can find in 105deg C is 1.34 amps. The manufacturers data doesn't show the ripple at 85 deg. Anyone have any idea of how the caps are up-rated or solved this problem?

Paul Rayson · 2023-05-27 4:05 pm

Hi everyone, I had a schematic for the intergrated amp, but lost it as my old laptop failed, I did notice some differences about the circuit as to the 2 part version. Does anybody have a copy they could forward to me, I down loaded it from the net years ago, but unable to find it again, I would be most grateful if someone could help

vitopro · 2023-04-08 5:04 pm

Bought in december 2022

195 €

Tiago79 · 2023-06-18 3:53 pm

I'm the lucky guy (or not) who found and bought a brand new Audio Research DS-450 solid state amplifier in the sealed box! This amp has been in storage for at least 12 years, maybe longer! I have paid US$ 4.000 for it with no warranty from the vendor.

I haven't turned on the amp yet!

When I opened the box and took off the top cover I found some signs of mold as you can see in these pictures:

But what is making me worried are 4 capacitors. I don't know if it's moisture or if it's a possible leak.

See the pictures:

There are no signs of leaks at the bottom near the PCB, only at the top of them.

What do you think of these capacitors? Mold or Leaking?

I'm thinking of using a Variac transformer to slowly increase the voltage to try and slowly reform these capacitors and see what happens. This amplifier uses a linear power supply, but I don't know if its protection circuits will allow that.

What should I do? I would really appreciate if you guys could guide me.

Thanks a lot!

edbarx · 2021-03-25 1:37 pm

First of all, I will make it clear, I would like to investigate the open loop gain while a negative feedback loop is active. You may ask why. The simple reason is, because a differential amplifier is only interested in the difference between the signals at the inputs. No matter how much negative or positive feedback is applied, it will amplify the difference according to the 'infamous' open loop gain.

Remembering my long long journey to design my amplifier, which at this moment is accompanying me with beautiful instrumental music, I can recall some writing that a raw gain of 100 times is sufficient. Others still, yes, yes, on this very forum, claimed to reduce the open loop gain as far as possible. However, the few helping individuals, made it very clear, open loop gain must be big for an amplifier to perform well. Thanks to these individuals, this amplifier is a reality which works, and is stable enough to remain on for days without switching off.

The fact that the amplifier works and the music it pushes into the speakers sounds nice, is an indication the open loop gain is sufficient. However, let us see!

So, if a is the non-inverting instantaneous voltage and b the inverting voltage, and the open loop gain is G while the instantaneous output voltage with these parameters is v, these should be related by:

G = v/(a - b) .... {G, itself being a function of frequency}

Artmaster · 2023-06-18 3:42 pm

For all who interested. I made a few review about some exhibitors there. If you are interested in - I will try to answer.
As result of this event I got a lot of samples of audio devices and will be able to make detailed test, thanks I'm working for the best plase for it - Klippel GmbH in Dresden, Germany.

#HIGHEND2023, #HIGHEND, #HIGHENDSOCIETY, #HIGHENDMUNICH, #AUDIOSHOW, #HIFI, #WORLDOFHEADPHONES

https://www.youtube.com/playlist?list=PLqhKqIOMavyluwI9cZxXykeBLdBj7mm9f

Unrealcrafter2 · 2023-06-16 3:30 pm

Hello! I'm new here. I've been working on building a AB PP tube amplifier. So far I've come to this schematic. I was hoping to get some second opinions. Thanks in advance!

brunomiguel · 2023-03-23 8:02 pm

LME49830 Diy audio amplifier DC servo with matched genuine 2SK1530 and 2SJ201 mosfets "87€ more shipment"
Heatsink and connectors included,power supply pcb can be supplied the cost is 14€, the power supply can be used
for two modules or "stereo" the power supply have been designed for powers up to 800watt, power supply partial
assembled as example.
Tracked shipment, shipment to US on request.
Payment by paypal

brunomiguel · 2023-03-26 12:17 pm

I have for sale the following evaluation boards from Tripath.
All evaluation boards include the the cables and plugs, power
supplies are for the power section.
RB-TK2350-80€
EB-TA0103-110€
RB-TA0105-140€
Payment by Paypal tracked shipment,shipping to US on request.
For more information PM

Pano · 2023-06-16 9:25 pm

Hola, Bonjour, Aloha, Ahoj y Ciao.

The forum needs some help from those of you who have your computers set to a language other than English. Ever since we moved to this new software, Google translate - or whatever people are using - doesn't seem to play well. We will see the a post in Polish or Chinese or Russian but the person posting thinks it has been translated into English. It hasn't. Often we will see the quotes changed into some other language, even though they are in English here.

What's going on?

Can some of you who are mainly using something other than English have a look at this thread through Google translate or other similar software? Try posting through the translator and give us some screenshots of what you see. That would be a big help. Pretend that you don't speak English. 🙂

jreel · 2023-06-17 8:51 pm

Searching for an ACA front panel: drill hole and dimensions jpg

- I need your help... I am unable to locate this drawing for completing my ACA power supply for ACAs.

- Does anyone have a pdf (cad drawing) of the ACA chassis front panel with drill hole measurement and dimensions?

Thank you, John

Moondog55 · 2019-10-11 4:46 am

On the off chance that somebody still has a usable woofer and wants to pass it on. I have a singleton and I prefer stereo subwoofers
I have a pair of Vega 124's here but I always thought the 15" was a better driver as it moves so much more air.
Price negotiable and as always I would prefer to swap if possible.

wgh52 · 2023-04-25 6:38 pm

Please PM me if you have any of rhe devices available:

2x miniSHARC as board or as kit
1x openDRC (with or without Remote)
2x digiFP board
1x nanoDIGI (with or without Remote)

I'd prefer to buy from the European Union, possibly in Euros. Please PM me with offer price, photographs and location of device.

Thanks and regards,
Winfried

wgh52 · 2023-03-31 10:19 pm

Hi folks,

The nanoDIGI is long gone from miniDSP portofolio and seems hard to find these days...
Suiting my 4-way dig. input active Speakerproject well, I'm looking for a nanoDIGI 2x dig in 8x dig. out.
The remote control would be nice to have.
Colour does not matter
Power supply is not needed.
Cables (USB or SPDIF) are not needed.
I'm not looking for miniDSP 2x8, 2x10 or other multi analog out systems.

Offers from Germany or other European Union countries are preferred.

Thanks and Regards,
Winfried

davirix · 2023-04-06 11:52 pm

Hi All,

After few weeks of very moderate and gentle use, my hypex nc122mp, connected to a SMSL DAC and manzanita speakers (see https://www.diyaudio.com/community/threads/fast-fun-inexpensive-ob-project.110583/post-7289387) decided to let me down.

Few minutes after a short listening session, while being switched off although still connected to power, the amp started to make some noise and emitting a dense smoke. See this video: Login to view embedded media .

I opened it to find out two filter caps were visibly damaged, and there was liquid condensed all around, not sure whether water.

Hypex said they cannot do anything and I have to go through the manufacturer, which happens to be a chinese no brand assembler selling on taobao who just put the Hypex card in a box with cables and a switch, is unlikely to provide any post sale assistance or warranty.

Shall I throw it to the garbage or what?

Any reason why this may have happened, shall I stay away from Hypex, how to prevent this in the future? Any tip is welcome.

D

audiothings · 2023-06-18 5:50 am

Writing in for a friend...

Four loudspeakers of identical make and model were tested under identical circumstances... The disparities in their response was only to be expected (+/- 4 dB or so < 8 KHz?), given that they are not high end drivers meant for any audiophile purpose... Please see REW graph below...

However the SPL readings when running program material and pink or white noise, show a 12 dB discrepancy between the drivers.

How can the over all output show a 12 dB discrepancy when the frequency response seems to show a +/- 4 dB discrepancy?

WhatsApp Image 2023-06-18 at 10.01.51 AM.jpeg

audiorado · 2023-06-18 7:42 am

I dont need this anymore,if someone can use this just email me!
Tentlabs shunt reg -15V
Output trans look on the picture for typ
One piece of some chip look on the picture
Two LM3886TF on gainclone boards,some parts alredy soldered

p_haslam · 2023-06-18 10:10 am

Hello Wonderful people.

I would be very grateful for thoughts on this. I've built one of the level adjust circuits from Doug self's book. I'm getting, I've got a +/-17vDC supply but am getting - or + 17vDC on pin 1 the buffer output. Here's my schematic

I really thought I'd finally nailed this, after endless oscillation problems. Having read a bit I think it is going to be a input offset voltage problem? Leading to saturation at one of the rails? Which I believe is a problem of the feedback network and bias current? Apolgies if I'm making a mess of this.

Self uses the NE 5532, wonder if I'm using the wrong op amp (had several LM4562's lying around)

I don't get that same output vDC at pin 7

Peace and Love

Pat

Patrick Bateman · 2023-02-02 4:58 am

Sean Olive from Harman posted an interesting paper on room diffusers:

https://zelfbouwaudio.nl/forum/download/file.php?id=156692

The paper is a bit dry, but the conclusion is basically that you can diffuse sound very effectively using a cylinder that's split in half and mounted to the walls of the listening room.

I thought this was particularly interesting, because cylindrical subs perform really well and they're very inexpensive to build.

I'm not sure what construction places are near you, but where I am, "White Cap" offers Sonotubes in diameters up to about 36-48" in diameter.

I've also found in my speaker experiments that it's possible to take smaller sonotubes and bend them into larger shapes.

For instance: the circumference of a 12" sonotube is 37.69". The circumference of a 24" sonotube is 75.4". So you can take a 12" diameter Sonotube, cut it in half, bend it, and get a hemispherical sonotube that's 24" in diameter.

Which is handy if the only places you have access to are Home Depot or Lowes, which only carry Sonotubes up to a diameter of twelve inches.

Pokerstar · 2023-06-18 10:13 am

Parting out my 316r's
Here's pics of one of the woofers

SemperFi · 2023-06-14 10:08 am

In linear amps the output transistors are the components really taking the heat when the current and voltage are out of phase. How is this in class-D amps? The switching transistors are either fully on - or off and have pretty much no voltage over it when conducting the load current. So all though the load current increases with say a cap in parallel with the load resistance, the power dissipation in the transistors are not much increased...? How about the output filter? Does it too only see an increase in current and not much more power dissipation? Assuming the ESR of the inductor is relatively benign.
Ignoring the loading issues (frequency response, peaking, etc) on the filter due to complex loading, where if anywhere, is the extra power dissipation taking place in a class-D amp with complex load? Is it just the extra current that we take into account or will there be anywhere with a larger voltage drop as the current is high giving the same dissipation issues as with linear amps?

garagepunkfan · 2020-11-09 5:40 pm

Hi guys, first thread here. About a month ago I scored a pair of cheap and rough Cerwin Vega 316R cabinets. Missing the woofers and one of 6.5 midranges has had the cone poorly and irreparably repaired of two punctures. I kinda toyed with the idea an Econowave conversion for a bit, but the construction actually lends itself a certain amount of difficulty in clearing real estate for the waveguide and the compression tweeter. My thoughts now shifted toward a nuts and bolts restore with original drivers, but those parts are simply not out there to be had, not even a recone kit for the mid from Simply Speakers.

After Sean from SS informed me of the lack of availability for the midrange recone kit, I queried about substituting a Skar Audio FSX65-8 6.5" replacement, as the original driver lived in it's own sealed enclosure (and therefore substitution less critical), while the rest of the cabinet is ported. His answer was an enthusiastic thumbs up, so choice for the midranges is settled....

The original HS-5 tweeters are accounted for

The 8 ohm 15" woofer is another matter, since it lives in a ported cabinet. The original model is 154W, part number unknown. I am told it has the cast aluminum frame, but know little else.

I am soliciting recommendations from the group, and have been looking at the Goldwood Sound GW-15PC-8 as a replacement.

Inside cabinet measurements are (not including port chamber)
18.25W x 26.75H x 16.25D for 4.59 cu ft.

Port opens to the floor of the inside chamber, is rearward facing at the bottom and measures 18.25W x 3.00H x 17.00D. The crossover points are 500 and 3500Hz respectively.

Any help is appreciated

chiunana · 2014-11-18 1:03 pm

Hi there,
It's been a year now i got this Sansui AU 4900, i made a video of the problem i have..

https://www.youtube.com/watch?feature=youtu.be&v=0wEJfoN5FwQ

Crackling all the time. Actually it's strange 'cause for periods (days) the amp works good. But then, suddenly, it appears again and never ceases.
I got the service manual.
I searched for dry joints, couldn't find anything.

Do you have some hints of where to look at, which stage i should consider first?

Thanks to all of you.

Chiu

herbal_verbal · 2022-11-16 12:59 pm

Hi everyone, after some weeks struggling by myself I found it's time to ask for some help. Luckily I found this very alive forum full of audiophiles like myself! I'm a newbie in DIY repair. I'm giving it a shot on a Mitsibishi DA-U200 amp. It's not rational to put so much time in an old amp, it's purely because of the sentimental value. And I love the warm sound of the late 70's / early 80's amps. My backup amp is a 90's Yamaha Natural Sound (AX-470). And that sounds so flat to me after all those years of warm sound!

Now to business:

After some repairs on the Power Supply (see below), I still get strange DC readings on the speaker outputs.
Idle Current is a nice 27-28 mV on both channels
Output on Right speakers is about 12 mV DC on both A and B speaker outputs
BUT output on Left speakers (A and B) is only 4 mV DC!
So I'm "missing" about 8 mV DC on the left channel!

I guess this is caused by some part of the (pre)amp short circuiting? From what I read on other forums, this could be caused by virtually any resistor, transistor, capacitator or diode...

So my question is: what could be the cause? And where and how to start measuring? I have a simple multimeter, without "capacitance" function, but it does have a hF function for transistors (don't know how to interpret those readings)

What I did before all this:

Bought this amp third hand, because I used to have a similar one in my teens (and blew it up by attaching different impedance speakers and cranking the volume open...)
After a few weeks of happy youth revival:

Left channel "explodes": lots of crackle, very loud, that keeps going on even after I pulled out the mains plug. Luckily my speaker survived...
I suspected the big 6800 uF 35V cans on the Power Supply.
Left capacitor indeed drained very quickly compared to right one. After 10 seconds, left one is down to 1,5V, while right one still at 20V
I replaced the big caps with new ones with same specs: 6800 uF and 35V. Problem remains same...
I checked the voltages on the Power Supply with my multimeter and got strange results: AC voltage on some parts of the Power Supply while it should only deliver DC. Then I asked my brother in law for help as he is a technician. He tipped me to measure the diode bridge
Diodes on D21S5VB are ok, resisitance is 0,8 - 1,5 MOhm in the counter-current direction and 0 Ohm in the right direction of the current.
Then the small ceramic capacitors C11-C14 0,01 uF. C12 & C14 gave suspicious readings so I replaced those and when problem remained replaced C11 & C13 as well.
Now the Power Supply gives a nice 34V on both channels (so 68V total)
I measured most resistors, they all gave good values
I checked the Idle Current, those were way out of margin on both channels
Set idle current back to the factory settings (28 mV +- 2 mV) by following the instructions in the service manual
But I still get the same strange readings in the speaker output...!!
And that's where I'm stuck now.

planet10 · 2023-06-15 5:29 pm

https://audioxpress.com/news/neutri...-operational-protections-and-ease-of-assembly

dave

mrorionrob · 2023-06-17 4:28 pm

what is the single triode version of a 5670 twin triode tube? looking to build a dual mono tube pre amp

lazio2000 · 2023-06-13 11:55 pm

Hello to all Sansui & solid state enthusiasts.

this receiver needed many transistors replaced, they have been carefully replaced with modern parts, list available upon request. Upon slow power-on via Variac (approximately 70 Volts) I am noticing immediately the power transformer making a buzzing noise (excessive noise based on previous repairs) it is also becoming warm to touch and you can begin smelling the resins or paint softening, not a good sign. The voltage rails on the power transistors are ok on one collector side and not good on another. If I disconnect the tree secondary wires from the transformer to the amplifier board, the buzzing is gone. My gut instinct tells me that there is something wrong with the amplifier board or the power supply itself for the high voltage rails. I also cannot get the -23 VDC rail to show (the positive is fine). DC Offset & BIAS seem to be very responsive. Any pointers may be much appreciated, thanks
All semiconductors have been checked, resistors & fusistors as well, caps are within specs.

Bergarth · 2023-06-06 9:20 pm

Any boards out there you'd recommend for newbie easily make multi channel amp? Hypex Options way to costly- I just want 30-50W for my tweeters and 100W for my woofers for all 7 my bed layer DIY speakers. I see Hypex you can sting enough modules to a 1200W PSU but that's big bucks I dont have- so looking for something similar for us normal people that don't have thousands sitting around and something we can di our toes into the murky waters.

mobyd · 2023-06-18 1:16 am

Icepower ICE500ASP, as found in RCF TT22 powered speakers. She go blinkety blink on the LED onboard and doesn't get up to full voltage. Anyone got a schem or any idea what fails in them?.

clog · 2015-10-12 3:57 pm

For more than a year now I'm lurking in the Diyaudo forums and am highly impressed by the amps some people design and/or build. The more I read the more I wanted to build an amp with my own hands. I have no electronics background but am aware of some basic principles.

Question was what amp to start with. At first I thought well let's take on one of the - let me call them - "evergreen amps". such as the Symasym or Rod Elliots P3A. Then came along a group buy of the PA03 organised by peranders (sjostromaudio.com).

The PA03 is a LM4780 stereo amp designed by a well known Czech developer Pavel Dudek (nickname: Upopa Epops). Peranders offered (and offers) a very high quality pcb for this amp. The board is a kind of all in one solution as the power supply is included on the board and all you have to do is populate the board. Connect a transformer, hook up your audio gear and off you go.

Well that's the theory. But I soon discovered that there is more to it than that. But my mind was set, my first amp had to be the PA03. For technical details about the amp I refer to the website mentioned before.

In several posts I like to show the progress in this build, I think it will take a few weeks to complete the amp. As a newb I like to learn from comments on the build and perhaps get an answer from more experienced readers when I'm stuck. At the same time I hope to be able to show other starters that is is possible to build your own amp.(At least that's the idea !!!!!). Another reason to show my build here is a post in the Group Buys section by Upopa Epops, the designer of the PA03 in which he complained about the lack of response from builders of his design.

Okay So I joined the group buy and a few weeks later a beautifully designed board dropped on the doormat. Ok what now, First I needed a case for my build. Then I saw the case build by philbool (See the post "My first gainclone"). Wow what a beauty is that. As I have no access to CNC tools and a custom build would be too expensive I decided to look for a second hand amp case. I checked the local thrift shops and websites for second hand electronics. And then I bought this old Pioneer M10X power amp. It seemed suitable for my purpose. But now what ??? As a genuine newb I have no tools at all, no DMM no soldering iron, no nothing !!!!! Mmmmmmm, time to think about it.

To be continued ......

In the pictures the new home for the PA03 and the PA03 board.

milezone · 2023-06-17 10:52 pm

Selling a single NOS Yamaha JA6881B:

https://www.ebay.com/itm/275908622734?hash=item403d6f798e:g:J1AAAOSwy5hkjfMi&amdata=enc:AQAIAAAA4CKGq4P9tzH8KoI94MjEWDKDmGYL4ygUOhYNPP7a+p/w58WaI9Rrh7IQazFGV8RKYDcc0pgoz/Gq+/Ret+qiis36uML767bh5qbW+/JzKLvbSffa+xhPVrB3oI/RM6ty77hoMTXZN/7IrXDfxO8ij+lP1w32xfbvj1esNNMm2ATfXkOjj/PiGZsO9Bw4qqJJpYjzdSvGRSBvMZsTmMLIek8j/W+UFSmxoAPOxSVgaBl9qFgpAmo0pFYcWJcfRYQPZrTQjOm8DyxwB4YZLtHvYt8cTIcyfz2dCC/eaaJm5YJq|tkp:Bk9SR_CqxLWZYg

jreel · 2023-06-17 8:26 pm

I need your help... I am unable to locate this drawing for completing ACA power supply for ACAs.

Does anyone have a pdf (cad drawing) of the ACA chassis front panel with drill hole measurement and dimensions?

Thank you.

ronnieponsones · 2023-06-14 2:00 am

What is a good JFET replacement (higher Vp?) for J113 to operate as a constant current source? the ACP+ circuit requires 10mA current source through a 125ohms resistor.

Tazzo1 · 2023-06-10 4:31 pm

Having a small clearout

3.3uf @ 400V Jupiter Copper Foil

Used for 5 months, not soldered to any device, eBay link is below for safe purchase

https://www.ebay.co.uk/itm/266293192389

2.2uf @ 100V Jupiter Copper Foil

Practically new, not soldered to any device, eBay link is below

https://www.ebay.co.uk/itm/266302180862

Will ship worldwide

planet10 · 2023-06-16 11:30 pm

If you have Alpair 11.2 MAOP, could you please post the data that came along with it?

Thanx in advance.

dave

Diabolical Artificer · 2023-06-17 5:39 pm

As per title, a pair of tasty CV4038 triodes FS, both test good, would suit a headphone amp build. £20 the pair + £3.50 postage within the UK.

Drop me a PM if interested, Andy.

Genius_Crunchy · 2023-06-17 2:35 pm

Hello, i wish to build a 3way loudspeaker using a 12db crossover and two bass drivers wired in parallel, but im having trouble understanding how to wire the impedance compensation, wich of both images is the correct way to wire them?

The speakers are the same model btw

Also when wiring them in the crossover i just need to put the filter behind the notch filter right?

First method( i belive this is the right way)

Second method

Surtsey · 2023-06-17 1:57 pm

I'm happy with my desktop speakers but never resist the opportunity to tweak. The current cabinet volume is 7 litres. I can swap the drivers into 8.3 litre cabinets but the simulation is less than impressive.
My sub's filter is 60hz 12dB octave.
Would you bother?

jonbjake · 2023-02-28 8:05 pm

Longtime lurker first time poster here.

I have been using this excellent TPA3221 board for some time now to drive a pair of NHT 1.5 bookshelf speakers, and I recently got a 2nd board in hopes of trying dual mono operation to get more power to these not terribly efficient speakers:

Unfortunately these boards come without documentation of any kind. Does anyone know how to hook this board up for mono PBTL configuration, and do you also know how to select a different input gain? This board has been a nice sonic upgrade from the various TPA3116 boards I've used, and I would like to optimize its performance.

Thank you in advance!

Elvee · 2021-12-28 11:19 am

One of my generators has died. It is an old beast from the eighties, a HP3335A. I salvaged it from the scrap heap ~15 years ago, and with time, care, love and patience, I managed to restore it to its former glory.
It had suffered water damage.
Now, when I power it up, everything looks normal at first: the turn-on display indicates the correct 1MHz frequency, but as soon as I hit a key, any key, the display goes blank and the front-panel becomes unresponsive, completely dead.
Clearly something to do with the controller.
I made the basic checks: supply voltages, clock and reset signals, etc., but found no anomaly.

Looking deeper, I can see that the MPU remains alive, even after the display has gone blank: the bus signals are active, the decoding seems to happen normally, and no line remains stuck. The scanning of the keyboard and display stops completely.

The troubleshooting procedure is centred on signature analysis, but I don't have an analyser.
I can however enter the various test modes:
-Test 1 (PIA) is OK
-Test 2 (ROM C) fails
-Test 3 (ROM B) is OK
-Test 4 (ROM A) is OK
-Test 5 (RAM A) fails
-Test 6 (RAM B) is OK
-Test 7 (HP IB) is OK
-Test 8 (display, keyboard) fails

I do not take these tests at their face value: for example, I tried replacing and swapping the chips of RAM A, but the diagnostic didn't change. The keyboard/display test fails, but in fact the µP has no way of knowing: it can only send stimuli signals, but if no key is depressed, there is no response possible.

I don't have a ROM C unfortunately, as it looks like a plausible cause.
I have checked the truth tables of the address decoders and glue-logic gates, as they would also be plausible causes, but I found no anomaly.

Currently, the hypothesis I find the most probable are the failure of ROM C or an internal bad contact somewhere in the controller's PCB: the humidity might have infiltrated inside the internal layers and corroded a connection after many years.

The service manual is available on the keysight website, or here:
https://elektrotanya.com/hp_3335a_synthesizer-generator_sm.pdf/download.html
Any other ideas?

olsond3 · 2023-06-16 2:30 am

I have created my interpretation of a modern LS3/5a using the original cabinet with updated drivers and crossover. I have just three pairs available if anyone is interested. They have lower distortion and more dynamic range than the BBC version. The waveguide blends the tweeter with the woofer very nicely. They are sealed. To created a ported version would require a larger cabinet volume. www.olsonspeakers.com

sonicles · 2022-04-04 10:55 am

Hi All. The SL-1500c has a built in phono-preamp and a switch to change its use so there is a direct connection to the cartridge via a 2nd set of RCA sockets on the back. The built in phono amp is then not in use. When I use an external phono stage there is a crackling popping sound about the level of a scratched record. This occurs with all 3x of my amps and different interconnect leads thus proving the interference is produced in the turntable. Strangely...Very strangely this noise is produced even when the turntable isn't powered! I contacted the seller and this is what he says. I personally think it's nonsense...THIS IS THE SHOP REPLY: "I’ve had a chat with our Tunbridge Wells store as they have much better knowledge than me about turntables. I relayed about the ticking noises you had been experiencing when connected to an external phono stage. I’ve been informed that there can often be incompatibilities with direct drive turntables and some phono stages (especially older ones) and it’s to do with a timing problem inside the phono stage. It’s not indicative that the turntable is faulty, but unfortunately a by-product of how it interacts with phono stages designed a certain way (despite the fact the noise comes from the turntable). Apparently, phono boxes from Project, Lehman and the likes are most likely to cause this problem. One suggestion was to try the very versatile NAD PPE phono stage as it is widely compatible with all types of turntables." .Please let me know your views or ideas what the noise is. Thanks.

bohrok2610 · 2022-10-16 10:39 am

Most are aware of the ESS IMD hump of ES90x8 dacs. Unfortunately the same hump is also present in ES9822PRO adc. So something to do with ESS dac/adc architecture.

Here are 2 IMD vs. Level measurements of the same dac (AK4493SEQ) using ES9822PRO and AK5394. Should not be too difficult to guess which is ES9822PRO 🙂

olyken · 2021-09-21 5:00 pm

Does anyone have a copy of the Loudspeaker Design Cookbook? I'm not sure of the edition.

I'm in need of page 25. It is the first page of Chapter V1.

"V1. High Level Passive Crossover Networks"

pdf file would be great

Thanks

Olyken

ngkkelgin at aol dot com

dibalavs · 2023-05-29 3:04 pm

Hello,
I have next chain:

ESP32 -> [SPI] -> VS1053 -> [I2S] -> MA12070P

Currently I am unable to tune I2S parameters on MS12070P to connect with VS1053.

VS1053 has next I2S parameters:
BCLK - 1.5Mhz
LRCLK - 48000 Hz
MCLK - 12.288 Mhz.

On Merus Audio board from Aliexpress MCLK is connected directly to BCLK with wired jumper.
So looks like frequency of BCLK connected to MCLK on MA12070p is not enough to play sound. And I hear silence.

But when I cut jumper and Connect MCLK from MA to MCLK from VS which has 12.288Mhz, I also hear silence.
Datasheet says that 12.288Mhz is correct clock for MA12070p
What can be issue?

I tried to grab I2S stream by logic analyzer and convert grabbed data to WAV file. File is ok. I can play it.
I also tried to send test I2S from ESP.
when BCLK == MCLK== 2.88Mhz MA is playing audio.

Is there any way to connect VS directly to MA?

peterpl · 2020-06-13 2:00 pm

I want to build an integrated amplifier using famous power amplifiers L12-2 from China.
Instead of buying transformer, chassis, preamp etc. I decided to upgrade an existing amp a Grundig V8100 known also as Grundig V303. The amplifier has a heatsink big enough and transformer giving 2x41V DC to obtain 2x55 W for 8 ohm.
In power amp stage it uses STK4036X integrated circuits which are generally ok but whole device is designed for 220V AC. Actually, when using 230V AC in my country these ICs break down in many cases. So I want to disconnect them and put two L12-2s .

But initially I want to enable an equalizer connection and increase value of smoothing capacitors. I have noticed that in the back there are 2 sets of RCA sockets used for remote control outputs for dedicated tape recorder and CD. Since I’m not going to use neither of these devices these sockets can be useful for an equalizer. I want to plug it in between a connectors stage and preamplifier stage i.e. between plug P4A and socket P4L as on schematic below.
There I have a question to you because I see that preamplifier uses a potentiometer on initial stage ( sockets P41L and P5L) and than another potentiometer at the end ( see another picture) between sockets P5L and P8L which goes then to power amplifier. Why there is a 4 channel potentiometer being used in preamplifier stage ???
My another question relates to power supply. As you see below, after rectification current goes to main smoothing capacitors C653 and C562 having 6800uF/50V each. To them there are 2 resistors R565 and R564 connected in parallel. In my opinion in order to discharge capacitors when amplifier is not in use. But why these resistors are not equal ? One has 3.3K while another 10K.

myleftear · 2023-06-13 6:56 am

Good morning!
I am (ahem) working on my TD-125 to make it fully functional again.
Shouldn't be too far off as it seems to be in good condition and only some little/cosmetic details need to adressed.

One of them is the tonearm-board, which I'd like to replace (it has an obsolete hole from the thorens/tp-25 front-operated cue-mechanism).
Following up, I want to make a second board to fit a FR-24...

Beside the ovious: precision, correct distance, enough space for headshell + counterweight, is there a rule (of thumb) for the placement of the tone-arm?
What material would you recomment? HDF? Alucobond? POM?
In the PDF you'll find what I've got so far, the tonearm's size was scaled on the drawing (but not yet verified)...

Kev06 · 2023-05-27 5:12 pm

As background, I'm planning a pair of 3-ways for typical home use; maybe 90db with 105db peaks or a little more. They'll either have a wide mid-range driver (something like 400-600hz to 4khz-6khz) and a tweeter, or else a single driver covering both mid-range and high frequencies (essentially a mid-tweeter). Pro drivers may potentially have some attraction for both options:

I'd be happier to cross my (scanspeak 10") bass drivers to fairly small mid-ranges 'if' they had the type of dynamics that sensitive and high power pro drivers posses, and they should also suffer fewer concerns over power compression. To my surprise there do seem to be pro mid-range drivers down to 5" or even 4" these days, and a few brands (such as faital pro) even seem to be easily available here.
.
Or, as an alternative use of pro drivers in home hifi, it has been suggested that a compression driver in a horn would serve as a mid-tweeter, again without suffering much power compression and potentially having better dynamics than small domestic (wide/full-range) drivers used as mid-tweeters. Though the approach slightly misuses most compression drivers, on the basis that lower (home) levels of excursion allow them to play lower frequencies than intended. Seems reasonable, though some suggest their distortion may not be as good in this application, and I wasn't intending to spend several hundred £/$ per driver for anything monstrous or exotic.

My problem is that I've very little experience of using pro drivers in DIY so struggle to evaluate both possibilities. The cone mid-ranges aren't much different in principle to cone hifi drivers but they are intended for a different application, whilst compression drivers would be very new ground for me all round. I realise that in both cases size (cabinet volume for the midrange, and horn dimensions for the CD) might be bigger than wished. But what are the other disadvantages and/or advantages of (mis) using pro mid-range and compression-drivers in these kinds of home hifi situation? Good idea or not?

Thanks,
Kev

kevkevkev · 2023-06-17 3:55 am

Hello,

Thank you in advance for any advice. Please forgive me if I missed an existing discussion and re-direct. I am hoping to learn more and continue making my shopping cart.

For SSE build, the full 500V B+ at bleeder resistor R2 exceeds the data sheet 350V working voltage with a similar situation at R4, etc. All metal oxides this size that I am finding are 350V.

Is metal oxide specified for cost and performance (noise) tradeoff? Or is the surge capacity of metal oxide necessary?

The parts list specifies:
Metal oxide in the power supply R2, R3, R4. Also R14/R24, R18/R28.
Wirewound R1, R17/R27.
Metal film everywhere else.

I had considered a few options, but am not sure how to proceed.

Option 1:
Two 75k 2W metal oxides in series to step down.
Fitting two 75k metal oxide 2W (MOS2CT52R753J) in a series zigzag in the R2 space would each see 250V and dissipate 0.8W each. They are rated to 350V and could step down the B+ without exceeding rating and benefitting metal oxide if this is needed.

Option 2:
Single 150k 3W metal oxide with a 500V rating, such as NTE 3W415 (it is bit larger).
Royal Ohm, SR Passives, and NTE have some metal oxides with list 500V working voltage. Problem is they either require minimum orders or become physically larger. For reference, the holes are 25.4 mm apart. The parts list R2 is metal oxide 283-150K-RC with 350V working voltage L=16 mm. The NTE L=24.5 mm. Leads would have to bend and double back a little.

Option 3:
Single 150k 3W metal film with a 750V rating.
If metal film resistor is okay for R2, R4, etc. Vishay PR03000201503JAC00 (L=19.5 mm) and TE RR03J150KTB (L=15 mm) look good.

korg · 2023-06-14 5:37 pm

Does anybody have a winISD .wdr files for a Wharfedale SUPER10 RS/DD please?

Arthur Jackson · 2023-05-12 8:57 pm

Does anyone have a recommendation for a multimeter app for an ipad? I’m getting confused shopping on the app store.

Also, where can I get some lightning bolt probes?

laxandredeyed · 2023-05-29 9:31 am

Hi Folks,

Giving up on the idea of a 4 driver TL for bass guitar use, I have set about designing a rear loaded horn. It is not a subwoofer, but I thought this would be the best subforum to post this.

Design goals are as loud and low as I can get without exceeding ~350l (constructed box volume) in a full range enclosure.

I have a problem modelling the rear chamber (red section in the above photo)

With VTC set at he right value and ATC set at zero, I get a response I like

My problem arises when using any value other than zero for ATC. It doesn't matter whether I set the figure at 0.01 or 99999, I get the same response, which looks quite a bit different. I would have thought tweaking ATC should change the response.

Perhaps the correct way to model this is as an OD, but can someone explain why the value of ATC changes nothing once it's over zero? The same happens with VRC and LRC.

Also, I'm very open to suggestions for design improvement. This application is not hifi, so a smooth response is not required. I'm trying to keep the constructed box volume below 350l, and the drivers are intended to be run full range. I don't need excellent performance in the 30hz range, but some loading down there is very desirable.

My hornresp file is attached

DesmoJEC · 2023-06-15 6:47 pm

Hi all,

I'm finishing up a build of a pair of Maple Tree SS+ clones with an extra set of output tubes and a few tweaks. The basic design is unchanged as I'm not an expert, just a semi-talented tech with enough knowledge to be dangerous. Unfortunately the damn thing doesn't work, and I'm stumped so I'm hoping the experts here can critique the design and give me some ideas how to proceed.

The problem (I have built 2, and both behave identically): oscillation starting at the voltage amp stage 6SJ7 (you can see it on the plate and it propagates from there). It's a saw-tooth wave that looks like a capacitor charging and discharging at rythmic (but not constant) intervals. Like this: ......|\|\|\......|\|\|\..... etc
The oscillation will increase in frequency when you power down until the caps discharge but the waveform shape remains constant.

If you remove the 6SJ7 the rest of the circuit is stable and quiet.

I've quadruple checked my wiring and layout, ground scheme, ABC+ supply, etc. It matches the schematic. Power supply is clean and smooth.

Here's the base design, taken from their freely available owners manual (NOTE the 221K resistor in the power supply is actually 2.21K)

Now here's my schematic:

My suspicion: NFB loop may be off because I'm using a 3.3K OPT vs 6.6K to suit the extra tubes?
All testing has been done in UL but switching to triode doesn't change the fault.
I've tried using only 2 output tubes (per original schematic), same problem.

Any and all suggestions for improvements are welcome!

Randy Bassinga · 2022-10-11 2:32 am

Hello all
What are the forum recommendations for PCB design software? I am interested in getting someone to make a 10pc each or so. I will have about 10 or so different PCB designs. Mostly simple tube pres or mixer channel strips

Thanks and regards
Randy

mattattnet · 2023-06-17 12:24 am

SOLD

~~Asking $250 including USA ground shipping~~.

Here is a grouping of equipment that can be used for THD testing of your newly built audio equipment.

This equipment can readily be used with REW software as nicely explained in this thread by XRK971:

https://www.diyaudio.com/community/threads/how-to-distortion-measurements-with-rew.338511/

The equipment is:

-Linear Audio Autoranger MkII V 3.19 10K output option. You will need a typical 5V USB charger for a power supply.

- Akitika 2ppm 1 khz sine wave generator / oscillator. You will need (2) nine volt batteries for power.

- Focusrite Scarlet Solo, 3rd Generation USB audio interface.

I will include a TRS to XLR cable for loopback measurements.

peranders · 2004-06-07 12:42 pm

Pavel Dudek's LM4780 amp

Pavel, your schematics has been downloaded 220 times. :up:

EDIT: 9191 times 2004-09-20!

From that I can see a lot of curiosity. Several of us have stated that this design is a case of good solid engineering. For instance the Zobel network and output filter are put into focus. Safety is also at top priority even though it may not be totally necessary due to all internal protection of the LM4780.

Schematics can be found here

sbobba · 2022-08-27 7:56 am

DAC Soekris DAM1021_12 ver.4 (0.01%/0.02% resistor version), 150 € + s.p.

teknofosssil · 2023-06-17 12:02 am

Hello all, so here is my latest project. I bought a set of fairly tired RS 2.5 speakers which needed some restoration work. I changed out the midrange caps since the originals had drifted almost 40% (worst one). In the course of researching these speakers I found the schematics of the attached crossover but also information on the optiional crossover/equalizer. As I was always led to believe the advantage of a fully active crossover is the elimination of passive components (that provided the appropriate crossover point) in the path from the amplifier to the driver. In the case of the Infinitys (1st order slopes) I see they have a 120uF cap in series with the mid drivers for normal operation of the on board crossover. One would assume that this cap (and inductor) would be removed from the circuit when biamping. As implemented, when the switch on the speaker is set for biamping it parallels an additional 50uf. I have attached schematics below. My intent is to use Mr Passes crossover kit to create a similarly functioning device. (less the HF EQ)I am wondering about shorting these input caps and disconnecting the inductor just using the Pass crossover. From a practical standpoit I wonder if the caps are in circuit when used in the biamp mode to prevent low frequencies damaging the EMIM drivers. Any thoughts? Thanks!
-T

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WTB Pairs of 2.2uf Polypropolene/Film Caps

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For Sale 2pcs SylphAudio D400M PFFB TPA3255 PBTL Mono

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For Sale LME49830 amplifier PCB supply PCB DC servo with matched genuine 2SK1530;2SJ201 Mosfets

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For Sale Genuine Tripath evaluation boards RB-TK2350;EB-TA0103;RB-TA0105

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WTB miniDSP devices: miniSHARC, openDRC, digiFP, nanoDIGI

WTB miniDSP nanoDIGI 2x8

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For Sale Jupiter Copper Foil Capacitors

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