Two of our five amazing presenters!

Online Event via Zoom!

Saturday October 16th, Noon-3:00 PM PDT (GMT-7):
Steven Dear, Audio Perception,
Demian Martin, New Tools and Techniques for Audio Measurement
Andrew Jones, Issues in Loudspeaker Design

Sunday October 17th, Noon-3:00 PM PDT (GMT-7):
Michael Rothacher, Weird Amps
Updates on Amplifier and Speaker Build Camps
Nelson Pass Current Topics

And a live Q&A with presenters each day. More to come!

Tickets are available:
Burning Amp Festival '21 Tickets, Sat, Oct 16, 2021 at 11:30 AM | Eventbrite

I have seen on Aliexpress PCBs for the Audio Note Meishu. Any expeinece with that PCBs ? I am very currious about the quality.
With the original Meishu I am very happy.
Dieter

There are guitar amps (Ashdown LB30 is one, see attached file) with a line-out provided by a tap on the output transformer . This would seem to be a way of using the tone created by a small SE amp and boosting it to gig levels with a power amp. Does this work as described or are there other factors involved? And how would you best implement it when winding a transformer?

Hi Guys,

Has anybody recently had any success trying to contact Conrad Heatsinks?
I am getting the impression they have gone out of business.

I've been attempting to get a shipping quote to New Zealand.

I've tried doing an enquiry through their website but the form has an error at the submit order stage.
I've also tried emailing them directly but have received no reply.

Just got this amp, noticed one of the power resistors on the output stage was toast. In the schematic it suggests 2W, so to make sure it didn't happen again, I ordered some 5W replacements, installed them, recalibrated as per service manual, but after about an hour of use, I noticed the amp could fry an egg on itself, I have nothing above the amp, so it has free airflow all around it, yet it is ridiculously hot.

Service manual suggests I should wait 5 minutes, then calibrate for 2.5mV between TP3&1 / TP4&2 and 0V between 1&E1 / 2&E2. I followed this, but the voltage continued to increase between test points, so I left it warming for about 30 minutes until it stabilised, then calibrated. Now after an hour of use it is working more like a heat generator than an amplifier. Sound doesn't appear to be affected in any way.

Possibly not related, but the mono switch only seems to work on initial power up when the amplifier is cool

Hello everyone! I'm here because I thought I'd be able to achieve something awesome by buying a couple of things from China and plugging them together, and that didn't turn out quite as planned. 🙄

I have a Pioneer DVD player that outputs DSD over its HDMI output, so I wanted to get an HDMI-to-I2S audio extraction board, connect that to a nice DAC, and get amazing audio quality on the cheap. Unfortunately, when the DVD player outputs DSD audio, the DAC introduces a bunch of white noise that gets at least as loud as the music it's supposed to be playing. Sometimes playback will start with no noise at all, but it will gradually increase.

I've tried two variations of ES9038Q2M DAC board: this one and this other one. I've also tried two different HDMI audio extraction boards: this one and this one. All combinations exhibit the same behaviour.

I tried introducing an I2S isolation board but that didn't help, maybe because there are design considerations I need to take into account but didn't. I also tried series resistors and pull-down resistors on each of the channels, but that didn't help either. I attached a cheap logic analyzer to the HDMI board output, and I can see (as well as the 24MHz sampling frequency of the logic analyzer will allow) that the ones and zeroes are where they should be when they should be. My lame multimeter shows that the voltage on the signal pins is around 3.3V, which is within the 5V that the datasheet says the ES9038Q2M can tolerate. My cheap digital scope shows what looks to my eye like random noise on the analogue output when the problem occurs. I've tried powering it from a couple of 12V wall-warts that came from external hard drives, and also from the ATX power supply from a PC - that made no difference to the outcome.

I think I've reached the limit of what I can achieve without further guidance - I've scoured the internet trying to find similar issues but I didn't get anywhere. Does anyone have any ideas for what I can investigate next or what I should revisit and how? Is there something I'm missing or something I can try?

http://www.diyaudio.com/wiki/index.php?page=LM4780+Pavel+Dudek+GB

Finally Pavel has said OK to run a group buy deal. Please sign the list above if you are interested. The first step is only an interest check.

Forgive me if this is the wrong forum for this question, but I'm about to build my second set of speakers and could use a bit of advice. I built a set of pensils a few years ago, but for this new build I want to build a custom entertainment center and build the speakers into the actual cabinetry. I know I could simply buy a set of in-wall speakers for this use case, and mount them into the cabinets, but since my entertainment center is going to be 16" deep, it seems like I could get better results by custom building something to take advantage of that depth instead of using in-wall speakers that were designed to be installed in 4" thick walls.

Anyway, here's a sketch of what I have in mind. I plan on doing a 3.1 set up. This is our main TV in our family room area, so I feel like I need a center channel for the TV, but the stereo performance is just as important to me. My question is, can anyone recommend a kit that would function well if built into an entertainment center? I can make the speaker "compartments" any size I want, but in this sketch I have them at 16x18x16", so I was thinking something similar to the Seas A26 kit from Madisound might do the trick?

I own this 1997 VW Quantum, which is a version of the VW Passat SW and it has a pair of speaker on the left, driver's side, and another pair on the passenger side. The configuration is mid-range + treble on the door and bass just over the dashboard cover. Considering it has a 4 cylinder 1.8L gasoline engine, it seems to me, the idea was to place all the bass over the cover to mask the engine roar, am I right? If so, it must have a low-pass before the dashboard cover and a high-pass just before the door speaker. In this case, what should be the cutt-off frequency of the filters, because I think the cross-over filter is not deafult as I bought it second-hand, maybe third or fourth-hand. Picture 1 and 2 are random while the others are the actual car.

I have been searching for the silver Tinsel lead wires. Would like to know which brand of Tinsel lead wires that are used for the speakers like Scanspeak, Seas etc. If anyone knows specific brand name that they use please let me know.

Yello!

I'm building a home theater subwoofer. I have managed to get hold of 8x cheap Logitech Z-2300 sound systems. I'm going to take their subwoofers and put in a new enclosure. I am 99% sure that the Z-2300 subwoofers are the same as a Tang Band W8-670C (see pdf below). Could someone help me design an enclosure with as low a tuning frequency as possible.

These subwoofers have the FS at 40Hz, is it then possible to tune a enclosure below this or what will happen then?

The place I have is 2,478mm wide, 450mm high and max 500mm depth. (It will be under the projector screen)

Thanks
//Rian

I found lots of feedback directed at other people who want to run 12AU7s at extremely low plate voltages, (e.g. 12V) but what about something more realistic and easily obtainable, which for me is probably somewhere between 150-180 volts of raw B+? I have two nice little identical toroidal power supply transformers which, with their 30V secondaries coupled, put out exactly what goes in, 120V, so I'm guessing post-bridge-rectifier-and-double-pi-filter, probably another 40 volts on top of that. All I'm attempting to do is get decent "warm" coloration at unity or maybe slightly more than unity gain from a homebrew preamp using a 12AU7 which I have lots of, or a 12AX7, of which I only have a few to play with. Would a little over half of the 300V rated maximum give enough S/N headroom for that application?

Thanks in advance for everyone's sage input on this. 🙂

-e

Hi!

I have a pair of Lii Silver 8's that I'd love to use in a bookshelf enclosure, something compact ... I've been experimenting all week, and out of my 6 or so prototypes, they all have one thing in common - A MASSIVE nose dive at 110hz .. is there anyway to get to at least 70 without a massive transmission line box? Thanks!

I am looking for your thoughts and opinions on how, cosmetically, to restore an EICO HF-87 I recently acquired. I picked up the HF-87 that had been in Sheffield Lab Recordings (sheffieldlab.com). Some of you may have seen this advertised, but I got it for much less than advertised, partly because of my previous restoration of one. The studio had converted the amp to rack mount and fixed bias. While quite competently done from an electrical standpoint, it leaves a lot to be desired on the cosmetic side. No matter what happens, I am doing a 100% full strip down restoration. While functional, the caps are shot and so are the tubes. It needs a complete overhaul.

My big question is, do you think I should revert it back to the original condition chassis (no rack mount) and self-bias or restore it as the studio had it with the custom rack mounting, but in a way that looks very nice? Definitely a new front panel.

I have attached a pic of one I did years ago that had a bad power transformer. Either way, I will likely lose the green paint... but I am really split on restoring to original(ish) vs. leaving it with its unique history from the company. I really could go either way and be happy.

What does everyone think?

Hello people.

I've reached that stage in my project where I doubt my work, my self and my ability to follow though.
Picked this up for $50.00. In trying to find the proper schematic I realised the builder wasn't focused.
Now I've built a pair of Eico hf30 clones from some Baldwin amps I acquired; survived their spark tests
and I even kept all the smoke in them! So I can read a schematic. Back when I had a Metcal and Pace I
could solder but now I'm using a stained glass soldering iron (don't ask).

So....if you don't mind, please examine the pictures and let me know f you see something I missed or that doesn't make sense.
(I stopped working on it about a three years ago!)

Thank you in advance,
Respectfully yours,
Todd

I've been gradually pulling together the makings of a stereo guitar rig - got a nice rack preamp, stereo effects, stereo 4x12, etc. Still need a power amp though, and as I thought about it I realized that I've got all the parts that I need already on hand - a couple of SE 5K:8 OTs, a PT with enough oomph for something relatively low-power, tubes, a sufficient choke, and even a chassis that will work. I put together this design, and would love to hear any feedback anyone might have.

It uses an E1148 (effectively half of a 6SN7) to drive a 6P7S (basically an 807). It sims out to yield 10WPC with 9% THD from a 1VRMS input. Each side idles at about 65mA (21W) on the plate and 4.1mA (1.2W) on the screen. I can't get more headroom out of it because I'm limited on B+, but 20W of "guitar clean" is way more than I can see myself being able to use at home anyway. PT doesn't have a bias tap, so I'm having to do a cap-coupled supply. (Cathode and back biasing, both cost too much Vak.)

The 100K input grid leaks will be individual volume pots. I thought about putting in a presence control, but there's barely any NFB to speak of, so I don't think it would be all that effective.

Anything boneheaded that I'm overlooking here, before I prototype it?

Hi All,

I am just about to assemble my first tube amplifier and have designed what I think is a workable SE UL circuit, of course subject to minor tweaking once built.

I already have most of the parts listed, but wanted to run it by everyone before I start drilling holes and cutting transformer leads.

I have used a mosfet follower as it allows me to use one hammond power transformer with no requirement for elevated heater supplies.

Please critique at will, I am particualy interested to know about the power suppy design - working with tube rectifiers is new to me, I believe I am right on the edge of the 5AR4's capability.

The amp will initially be run with EL34's but I may change the cathode resistor and run KT88's at some point. I realise the power supply input cap and resistor may need some tweaking to provide the correct anode voltage.

Proposed key components as follows:

Power transformer: Hammond 374BX, 750V CT:
https://www.hammfg.com/files/parts/pdf/374BX.pdf

Power supply capacitors,would love advice on these as I don't have much safety margin: 500V Rubycon LXW series:
https://au.mouser.com/datasheet/2/977/e_LXW-1600626.pdf

Choke: Hammond 193J (10H, 200mA):
https://www.hammfg.com/files/parts/pdf/193J.pdf

Output Transformer: 5K Toroidy TTG-EL84SE:
TTG-EL84SE - Tube output UL transformer [5kOhm] EL84 / 6V6 SE - Shop Toroidy.pl

Any advice is appreciated!

Greg

Hello everyone,


I am looking for an all-in-one 8-channel DAC solution for a low-power application. Four pairs of channels will be fed from the DAC to stereo amplifier boards with <15 W of RMS power @ 8 ohms.


The only product I have found so far is the following:


8 Channels 384kHz 32bit ES9016 PCM DXD DSD Audio DAC - DIYINHK


However, I don't need such a high resolution DAC—96 to 192 kHz and 16 to 24 bit is sufficient.


Sound quality is still important, but I am hoping that someone knows of a cheaper DAC + board setup. I need USB-C (Windows compatible) to 8 channels of analog line-out.


Thank you!

Hello Everyone!

After being out of my system a little while I decided to hook up my Aleph J again. Before putting it into my audio rack I powered it back up and let it warm up for an hour to check if the bias or offset had drifted at all and to my delight they were exactly as they were a year ago with a bias of 420mv and almost spot on offset at -0.1mv

The one thing I did notice right away is that all the big 3watt Panasonic source resistors that were once a very light blue were now a light brown colour. There aren’t any burn marks or discolourations that I can see on the pcb, and as per the build recommendations the 3w resistors are elevated from the board for heat dissipation (about 1/4”) and the amp seems to be functioning as expected.

I have read that the J runs “very hot” compared to other FW amps so I’m not sure if this is a problem or not. The amp is well ventilated with nothing on top or around it and the heat syncs are at approx 51deg C. It’s also my first Diy build from a few years ago.

Should I be concerned?

I've got a turntable that sometimes will turn and sometimes will not. Pulling off the platter, turning it upside down, etc., you can easily find the little motor. Belt-drive type.

This motor has a spindle that sometimes will spin and sometimes will not. When it doesn't go on of its own accord, a gentle twist and the spindle will take off and run smoothly.

How do I convince it that it would be happiest spinning away all the time?

I have been fighting "something" ill defined but I can hear and my wife very clearly, that is unpleasant is some recordings, played on some electronics on some speakers, for a good 10 years. I think I have finally cracked the code, so to speak.

Yesterday, I was able to make the symptom come and go based on which tweeter was in play, and which DAC I was using. Yes DAC.

The symptom is an upsetting "glare" for want of a better word. I tracked it down to a narrow frequency range, around 3100 Hz. Any recording engineer knows that band well. The good ones at least, which may be part of the problem. My theory is this being in the most sensitive part of our hearing, we may be genetically biased as it is the shrillness of a baby scream in distress. It is most evident on cymbals, trumpets, and soprano voices. Things strong in that band but have copious strong overtones. No, the problem is not simple EQ, though you can reduce it, doing so changes the balance even with a Q of 6 on the filter. Just cutting above 18K does not change the problem at all, so it is not solely the source. This problem is so clear as to be above small differences in level and EQ. Those we can hear too, but they are different.

The action I believe is upper harmonics exciting the tweeter breakup and the resulting IMD is down in the critical range. Likely all over but we seem to be sensitive to a narrow band. As they are not present in a CD due to being above the Nyquist limit, it is our playback chain.

I can make it more or less depending on the amplifier or DAC. I can make it decrease with a low pass filter on the tweeter. I can make it go away by switching to a tweeter better behaved above 18K. It may follow, the reason amps sound different is how they handle harmonics, dominant pole vs Miller compensation measurably changes this. DAC output filtering has many options as does the output buffer. Again measurable. Unfortunately, I can't afford the equipment to measure it. I can use my wife's hearing and to a lessor extent mine.

The key was getting some new Sennheiser headphones. I could hear NO difference in the DACS. My old Grado's I could. Well, they were not well behaved above 20K either. I could hear it in the speakers, 27TDFC or DXT vs XT-25. I have some old cheap VIfa domes that were far worse. XT-25's, DACs sounded the same. So it is interaction between source, through the playback electronics, and the transducer. That is my working theory. I swapped out the Parasound amp (biggest offender) for my old MOSFET, and swapped the Schiit Asgard internal DAC for the JDS AtomDAC+, another clear step. Now the speakers. So, ordering a pair of XT-25's and a set of CSS woofers today for a new build. ( If I had the budget, it would be Purifi and Scan Speak)

Cymbals a dead give away. Trumpets, and soprano voices. Maybe, after 45 years, I can crank up my Big Band and my better half does not leave the room.

Could this be why some prefer ribbon tweeters in spite of their higher HD? No breakup? I have always dismissed them as the are usually implemented way too bright and we don't have tone controls anymore. At least not in showrooms.

Another Plitron toroid from my "future projects" stash. Quite heavy (40lbs, 18kg), so local pickup in Carlsbad CA would save on shipping this beastie. Asking $250 + shipping.



Cheers, -Casey

So i am working on a build .. a Bluetooth Speaker Circuit .. using a CSR8000 series Chip ...

The circuit i would like to build ideally would have switching for mono or stereo mode - directly off the BT Chip Output and before any other circuitry .. The Switching ideally electronic not mechanical

For instance -- a mode step through button .. 1 press BT stereo .. 2 Press BT mono - 3. Press Aux Stereo - 4. Press Aux Mono

Stereo Mode - the drivers will sound Right + Left .. Mono Delivers Left + Left to the Drivers .. sorry for the sketchy description ..

the speaker will be a traditional simple build .. using quality marketplace parts

Preparing to downsize. I have a large number of 25,000uF, 250VDC capacitors for use in big power supplies. They were all re-formed many years ago when I had my shop. These were destined for use in a mega-amplifier I had planned to build. Some of you DIY old-timers might recognize the rather ambitious project from the pictures.

These are a mix from Phillips, Sprague, United Chemi-Con, and possibly others. They are 3" in diameter and about 9" tall. They will ship from Encinitas, California. Asking $15 each, plus shipping. Local pick-up is also fine. I can investigate shipping costs for anyone with real interest. I can negotiate price if you are interesten in quantities.

Thumbnails might be distorted. Click on images for proper resolution.








Cheers,
-Casey

Hello, been 10 years since last time on this site. CD Changer powers, ejects, displays fine. Won't select a CD or play or read. There is an internal motor that runs constantly (CD Transport?) Any thoughts? I believe it's a main board failure on a control (CD Select) issue? Any thoughts?
Thanks All! Dan C - AudioPlus

Has anybody got an original Fatman iTube (aka Dared MP5)? I have just acquired one and it sounds good, however I thought I would measure the DC Offset as the power stage is an STA7265 and it’s reading -130mv and -140mv at the terminals. Has anyone else had an issue with these units please?

Thanks Steve

Hello, my Bose Mini Soundlink’s amplifier board packed in. wAY beyond warranty.
I scrounged the Passive Radiators and the drivers and wanted to re-use them. I can not for the life of me find TS params for these guys. Any tips for volume of a sealed, ported, or passive radiated box?

Selling my spare Pioneer DEH-80PRS headunit, in good used condition.
These have 3 way electronic crossovers built in and time alignment, making them an absolute powerhouse for running an active front stage in a car.
They don't come up for sale often anymore.

$210 paypal goods & services
$20 shipping within lower 48 via UPS Ground

Thank you for looking

I've been trying to upload the pics, it's not working. Will try again later

I'm adding VU meters to my First Watt F5v2. The meter drive board needs 12-18V AC or DC.

The power supply in the amplifier outputs 27.5V to the amplifier boards.

Looks like there are three ways I could power this board:

#1) Drop the 27.5V in half with a simple resistor circuit (attached)
#2) Use a small 120V to 12V transformer within the amplifier chassis
#3) Use an outboard 12V "Wall Wart" and keep all this stuff outside the chassis

What would be the best approach with the least introduction of possible noise?

Thank You

Quite simply, I'm looking for a pair of opc's The Wire LPUHP pcbs. Possibly parts too, but not a must.

Thanks for looking!

SOLD SOLD SOLD SOLD SOLD SOLD

Boozehound Labs JFET Buffer Full kit: Pc Board and components. MSRP $99. Asking $50 with shipping included to lower 48 only, please.

Hi All,

I'm a little bit confused about the use of a DC Choke in series on unregulated power Supply to increase the ripple performance on a solid state power amplifier.
Usually the series DC Choke are common for Tube Amp but not in SS, i'm just finishing my power amp power supply that use 8*51000uF Cap Bank, trafo is 0.8kVA and dc out is +/- 45V, the power amplifire is able to deliver 200W on output.
What kind of choke can be used in my case to improve the PSU performance?
When switch off the Main Voltage, can be in some way the circuit affected from flyback effect from DC Choke?
Someone have experience with this kind of circuit?

Thank you in advance

Hi all!

I made a 4x channel 40W (per channel) audio amplifier based on the E-TDA7386. It works amazingly! But I am wondering if I can bridge the outputs together on all 4 channels to create 1x 160W output? Is this even possible? Or maybe I could bridge the right and left channels to create 2x 80W?

Attached is the circuit and PCB top and bottom.

Thanks in advance!


EDIT: I am trying to run a 100W subwoofer temporarily on it.
EDIT2: Apologies for the rough schematic. FYI, the audio input caps are 100nF.

Hi,

I am replacing my audio GD NFB29 DAC by an SMSL D1se.
The SMSL use a Xmos Xu-216 interface for usb that need to be +5V supplied (the Audio GD did not).
My player is an Etalon Olimex (Arm small linux card optimized for audio).

For your experience, if i supply the Xmos DAC usb input by a +5V/gnd source that is not my player but a linear low noise supply and just get the usb data V+/V- from my player to the dac to the same usb input, will it works ?

My audio GD needed a ground handshake with the player to work, is there a risk that this Xmos would not work if it has no ground contact with the player (only data +/-) ?

Thank you for you advices.

Bernard

Hello.
I'm searching for nice pair of 10inch coaxials, that has built in horn mouth. Don't want cheap beta10cx, but I will do DSP so I'll accept even ripped FreqResp.
My budget is about 400USD(shipped). send me proposals if You have any.
It would be best to have one common magnet for both HF & LF.
My most hunted one is pair of 12" radian 5312neo.

I had an email request for a simple follower to drive TAD 4001's. Since it
is inefficient to design without sharing, I also present it here.

You are welcome to tart it up as you like...

😎

Just a stupid question regarding this amplifiers (SAP15P/15N) and yes I had a good look in the forum and couldn't find an answer...
All this amps share the same amplifier board with the "infamous" and now obsolete Darlington and my question is:
Is there any advantage in replacing the 8 crap 2200uf capacitor in the filter bank for say 2 10000uf Nichicon ones ?
Any drawbacks in doing it ?
Thanks in advance for any advice

Hello,

I am looking for a pair of v-fet - any model.

Many thanks,

Guillaume

20220129 NEW ITEM

18) SUMR 50VA Primary: 2X115V Secondary: 2x40V Price: 25e

20220121 Post updated with what is still available.

As you know, projects not always go in the direction you planned. So I have some parts that are looking for a new home. Feel free to make me offers, as I am not 100% sure if the asked price is fair.

3) O2 Headphone amp (PCB) Price 4e
4) Cviller CRC PSU with 8x27ku Price 30e
6) Salas LV Shunt Regulator + and - 15V assembled Price 50e
8) Quancho Heater PSU PCB Price 5e
9) Hans Pollak volume control (4 relays version) for Bruno Putzey Balanced preamp (5 PCBs) Price 3e
11) SainSmart Signal Relay board 8 channels (Good for 4 inputs balanced stereo input switch). Price 10e
12) SainSmart Signal Relay board 4 channels (Good for 4 inputs SE stereo input switch) Price 5e
13) F5H headphone amp PCB from Prasi Price 3e (one channel, there are two designs)



I'll post pictures in the next messages.

Kore-eda Amplifiers -- preamp and power amp, both are chip-based design. How about?

http://www.sakurasystems.com/products/koreeda.html

For sale 2 sets (of two) Alpair 7 Gen 3 speakers. I am the original purchaser. Never used.
$80.00 for a set of 2. $150 for both sets (4 speakers total) if sold to same purchaser. Free shipping. Double boxed. Paypal.
Thanks.

Well, the best way it is, to avoid the use of the mains earth and thus this additional components.

In case of dual monaural constructions the RCA input connector is now mounted without isolation to the chassis envelope.

Unfortunately most transformers require mandatory the use of the mains earth for safety reasons.

This means at the same time, I have to introduce components between the metal chassis envelope and the GND from main board/star GND from power supply (to avoid double grounding).

I observe a wide range of different ways in commercial amp products - each manufacturer chooses other components resp. values resp. topologies.

Sometimes only a resistor (10 ohms until 1000 ohms) is present, somtimes only a MKT cap (10 nF until 1 uF), and sometimes both of them (the attached gainclone example with LM3875 e. g. uses a 100 ohms resistor and a cap with 0,22uF).
Also the wattage and the kind of the cap are highly variable (very small until very large).

The choosen position at the chassis and at the PCB are also different. Sometimes near the input GND, sometimes near the output (loudspeaker-terminals) and sometimes at the power caps (star ground).

Also, the thickness and the length of the connecting cables between the main-PCB GND and the chassis (over the mentioned components) are very different. In any cases I did observe an extremely thin wire.

Follow question rises up:
How did I calculate this devices between chassis/mains earth and secundary GND for lowest possible hum (highest possible signal to noise ratio) so as highest possible reliability and where are to find papers and test reports in this matter?

Hi everyone!
Sometimes, and specially when we do not have a lot of money to spend on Hifi, we believe we might get lucky and do a good deal.
I saw a Cyrus two on a street market, for not a high price, and unable to test it I decided to take the risk and brought it home for a somewhat small amount of money.

I was no lucky. 🙁

What I check out so far:

No sound from speakers; Sound ok on one headphone channel, distorted (kind of like electronic trash noise on the other channel) on the other.

I know some electronic basics, I am ok removing and replacing components, but I am awfull identifying what is wrong, so maybe I can get some help from fellow DIYaudio users...
Nothing looks burned inside, and both the fuses look ok.

Where should I begin? 😱

All the help would be helpfull so I dont stay with an expensive boat anchor 😛

Best,

Sergio

it's $55 MSRP, it has extended HF response and high power handling, what's the catch?

https://ds18.com/collections/pro-au...er-with-2-phenolic-voice-coil-500-watts-8-ohm
https://ds18.com/collections/pro-au...er-with-2-titanium-voice-coil-500-watts-8-ohm
looks like it could be run very wide-band for domestic settings

Hi,

I’ve just purchased a pair of Quad II 80. While unpacking, one of the protection covers for the transformers got stuck and started to break. Now to remove it completely and safely I have to remove the cage grill protecting the valves.

The manual doesn’t say anything about how to remove the cage. I guess that the long tool provided (see attached photo) is to be used, but if the screws shown in the attached photo are those to remove I do not see how it can be done, as the screws are covered by a small metal plate.

Does anybody know how to do it?

Thanks

Duelund Capacitor 50.0uF 100Vac-200Vdc VSF-Al

$800 or best offer for pair shipped USA

Decided this is an amp that may not be for me, so I offer the complete set of boards here.
All came direct from Chas, the 2 amplifier boards are from his early batch and so are not ENIG, but the rest are from his production run and so are ENIG.

Looking to get back what I paid so they are £40

Thanks

hi,
i've found some byw29s at nearly no cost.. may i use it in gainclone power supply instead of mur860s? is there any drawback or advantages over murs?
thanks in advance..

Have gotten some boards made for a 4 channel amp based on IR4302.
JLCPCB do not stock IR4302 so could unfortunately not get these mounted.

So have purchased some chips and I'm ready to try mu luck.

But how to best go about it 😕

I do not have a stensil for the IC so can't just use that and some reflow solder paste.

The PCB is HASL - Hot Air Solder Leveling, treated from manufactory.

Of course step 1 is to thoroughly clean both pcb and chip with Isopropyl alcohol.

I could give the inner pads, the large ones a very thin layer of solder paste, with a toothpick or something.

I could then apply all other pads with liquid solder flux.

Should I also flux the chip?

Placing the chip as precise as possible and apply heat with a hot air solder gun.

Will the chip move into place by it self??

I'm thinking that soldering the small outer pads with a pointed solder iron after is the way to go ??

Any good suggestions, by some with real experience in soldering items like this??

I'm used to solder components down to 0603, MS8, TSSOP, SOP etc.

Thanks in advance and kind regards Baldin

Hi!

I know the Line Magnetic LM-mini84ia is not a diy amplifier, but I hope to qualify to the forum by wanting to modify said item. Admin is free to remove and tell me to F off if I'm stepping out of bounds! I'm also not a native english speaker.

I recently bought a used Line Magnetic LM-mini84ia integrated/headphone amp. The thing is the headphone output is really bad, as soon as the volume goes up to a little louder listening levels I get massive amounts of distortion. IEMs works better than my headphones (dan clark aeon 2C). I know the headphones require a little more power so I think the juice is running out.

I open the back of the amplifier and found a 470 Ohm resistor inline with headphone socket.

The speakerjacks sounds really good and provides a lot of power, I would like the same in my headphones 🙂

Somebody have any insight to what kind of modifications I can make (possibly outsource) to not restrict power to headphone jack?

I have not been able to find schematics to the amp in question.

Regards Jakob

Hi,

I've recently started looking into build analog synth modules. The biggest challenge for me is to control resistance with a CV. For example, if I wanna build a simple RC low pass filter and want to control it with a varying voltage, I would need something like a Vactrol. I understand I can build my own, or I could buy them (very expensive). But something tells me I'm looking the wrong way.
Is a Vactrol really the only way to control an analog low pass filter? The fact that this part is hard to find, does it mean that everything is just digital now?

and if I do go to digital, I see that 12bit is quite common for an ADC and DAC. 24bit is hard to find and usually only available in high end chips. So does this mean that most DIY are done with 12bit? Is that acceptable in most cases? I know this is a subjective question, but I just wanna know if "most" people just go ahead with 12bit or if it is very unpopular.

Thanks.

For those that knew him, these items were my friend Matt's. His mother is starting to unload some more of his audio things. The Speakers are the main items going right now. Locale is NE Indiana.

2x JBL 2246 (2" exit) with (pretty sure) Radian diaphragms. They have been restored by Matt. He purchased new rubber magnet rings and sticker decals. They have aluminum non-faceted horns (8" x 17"?) and are mounted with magnet support brackets. I cannot find the horns he used in an online search. If there is anyone interested, I will try and find out what domes are actually in these. I will need to take the caps off to find out for sure. I see these listed for $839 when PE sold them. Asking $600/ea, please make offer if interested, no low-balls will be entertained. Pictures and more info on request. Shipping is plausible, but realize these are 33# for drivers alone.

2x Cerwin Vega 18" carpeted pro-sub cabs 2' x 2' x 2' est, fitted with B&C 18TBX100 18" subwoofers. Obviously these cannot be shipped. I am willing to drive a little or make arrangements if possible. InDIYana 2022 delivery to event also possible. Pole sockets installed. Asking $600 each.

2x Cerwin Vega 15" 'tops' cabs retrofitted with 15" Selenium woofers with smooth response. Original tweeters are gone. Hole is present for 1" exit and horn. Original xovers are still installed. $300/each. These are also too large to ship. Poles included. Cabs have reinforced handles, added bracing, vinyl sheet damping and stuffing, as well as Speakon plates installed. InDIYana 2022 deliery et al from previous listing also applies here.

Please let me know if interested,
Wolf

Hi,

I have one power supply (smps3ka400) which can be used to power 8 amplifier boards. There are as standard only 3 connectors 'out' on the board. I thus have to split anyway.

I thought the cleanest way would be to take one out and split this into the 8 amplifier boards. I saw somewhere in a build a board where he put 1 wire in and 8 came out. I need a huge "wago" splitter in fact.

I would like it to be safe off course, clean and safe...

Tanks in advance!

Somewhat basic question. I have some tube pin cooler connectors that keep seizing the internal threads. I believe they are aluminum and the screws seem to chrome(ish) plated brass. After a month or so of running for a few hours per day, the screws are impossible to remove without snapping the heads off rendering them useless. Interestingly, the steel set screws that clamp the parts on to the tube pins seem to not be effected. Usually, I can back the screws in question out about 1/2 a turn before the problem sets in. I could try some aluminum screws and I have some anti-seize compound I could try but any other ideas?
The connectors in question are expensive and hard to source.

Hi there,


I'm very new to SPICE simulation.


I'm getting this when trying to simulate my circuit in KiCad:


I'm not sure if I can safely ignore the warnings for the connectors.
The Zener diode model might be relevant, as it's connected to pin 8 of the LM3886 (U1).


Really not sure what the -v model warnings are about. I've got a VEE component added, and global label of "-V" to make connections easier.


Anyone able to shed some pointers for me please?

Hi everyone,

about 2 months ago I decided to take on the project of designing my own amplifier which is supposed to be driving my subwoofer in the future.

The circuit I chose to use is a dual TDA7293 parallel design.

I have attached my circuit diagram to this post. Please be aware, that I have already figured out and fixed the follow mistakes made:

- Capacitors C10 and C10P1 (1000u smoothing caps in negative supply rail) are polarized in the wrong direction, have turned them around on PCB
- Capacitor C3 polarized in wrong direction as well

I have also attached an image of my PCB layout.

The power supply is a 24-0-24V toroidal transformer with a rectifier board attached to it (which did not have any problems and has worked perfectly fine from the beginning). It has 2 63V 10.000uF caps per rail.

Now the problems started when I first turned on my amplifier board.

On the first try I had both TDA7293 chips soldered to the board. I have shorted the audio input signal to ground.

In the instant I turned on power, both chipamps literally exploded, meaning they blew off part of the black cover of the IC.

Ofter the past weeks I quadruple checked again for mistakes in my layout and then soldered on a new TDA chip (this time only the one in the master position, because I had heard of the possibility of instability in parallel mode).
But the same thing happened again, instantly after powering on, a flame shoots out the bottom of the IC and that's it...

My last hope are now the great people in this forum who might be able to help me figuring out, what the problem with my amplifier design is.

I'm looking forward to your responses and suggestions and please don't hesitate to ask for any more info required to assess the situation.

Hi Guy's

To try and keep the shipping costs for the pcb's as low as possible we are going to offer two shipping locations.
Please indicate below which is going to be the closest shipping location for you.

Guessing on which forum to post this test.

Anyway, looking to see WHY a couple different DACs sound different. This is not a debate if or what, just a measured test.

One thought was how well they rejected USB power or signal noise. So I bought a $12 e-bay special galvanic isolator and the $80 Linear Technology demo board for the LTM2884 module.

Just looking at the 5V line going into the isolator and the 5V coming out:
Cheap board: 5 to 5.5 mV input. 5.5 to 6mV output. Isolated maybe, but not very clean!

LT board, same 5 to 5.5mV input, but .9 mv steady out. Measured with my Fluke as my scope died so can't show fancy pictures of what the noise looks like. Same cable.

Not making claims on audibility, but just objective measures of one aspect.

Curious, my Focusrite I wanted to use for a loopback test does not get recognized with either board, but my other DACs do. Need to figure that out so I can do distortion analysis of the DAC, and not just of the Focusrite. I thought not enough current, but the LT board 5V does not droop, so don't think that is it.

My conclusion: I make no claims about magic sonic improvements, but the LT module works and the Chinese one does not as far as the power line goes. It has what it claims in an AMD chip on it, ADUM3160. IF it is real, it does not do very well on the power side.

More tests to follow if I can get any that are not masked by the Focus rite as the DACS are both cleaner than it is. Just tested with a poured USB hub, and still the PC does not recognize the box. Odd. Going to contact Focus rite.

Note, the AMD chip lists @ $3, the LT module lists @ 40. Maybe a reason 🙂

I'm looking for a pair of the following for use in a 2-way design

ATC PA75-314 (STD/Bass)
Volt BM2500.4
Volt BM251.3

Seperately after a pair of Volt CX220.1 too.

AYA DAC PCB (Rev2c) f.s. 99% complete, never found the crystal for it, and maybe a couple of resistors...
Lots of good components, including a "handfull" BlackGate NP caps.

Shoot me an offer.... or trade for used/vintage preamp or ALEPH J Mosfet and JFET KIT from the store as part of the deal.

​

TLDR;
I would like to build some cabinets for my Community Audio CS70 drivers, which are 4 x 12 and horn/tweeter. I would consider breaking them up, as my previous attempt resulted in very large, heavy boxes. Perhaps into 4 2x12s and tweeter boxes (might look like a reggae system but thats ok in my books) or if there is such a thing as a 4x12 mid/kicker arrangement, that would work.

Any start point for designs much appreciated. Proffesional woodworker, total amateur electro-acoustic phsyician.

------

Long version -

I posted on here a few years ago about a project and got some great advice, so im hoping for more.

I rebuilt some community audio csx70's, which have 4 12" drivers each, a compression horn and tweeters.

I am a joiner so I have a workshop and building boxes is very easy, however i know next to nothing about speaker design, so last time Bob4 amongst others kindly took me under their wise wings, and i came up with a PPSL design to house the 12"s with the horn on top. See attached.

So, initially i was quite happy with them. Especially once I found a pair of brand new 15"s in a charity shop for £20, for which i immediately made a dual 15 PPSL cabinet. Using a DSP to Xover everything, sounding much better as a 2.1 system. Especially as the speakers and cabinets cost me very little.

However, the top boxes are very large, and heavy, and i think on reflection dont do such a great job. They have a very narrow field, seem to be missing fullness and struggle to give decent warmth/punch. I have a reference mic and software but have yet to set the system up for proper testing. Must do that sometime, but parties tend to be waiting for music.

So especially now that I have invested in the expensive parts of the amps, dsp, graphic eq and various other stuff, i feel like id like to rebuild the top boxes in a better fashion. I might also sell the original sub to finance 2 pairs of matching drivers, so I can have subs both sides.

------

Anyway i appreciate this might be an annoying newb question but any thoughts most welcome!

I couldn't post a thread on LTSPICE group about the subject, I'm too stupid to do so.
So I ask here, sorry.
I can't understand why "changing beta of a NPN BJT" does globally nothing about the collector current although it does in the real world.

Nearly all of this forum is devoted to the problem of sequestering the rear wave of Rice-Kellogg drivers and without adding distortion to the front wave. Although it is inept engineering, almost all subs have resonances within their passbands.

The challenge arises since we are trying to move air using an inconceivably ill-matched heavier - but necessarily stiff - cone assembly, with ESLs and true horns excepted. And given the geometry, it is barely feasible to use an enclosure to separate rear waves from front waves without modifying the driver behaviour - with IBs excepted.

Using a long pipe to sequester the rear wave, such as my 17-foot thread has the following advantages.

1. If typically stuffed, no sensible resonance within the passband and good transient behaviour.

2. Sounds from the port are comparable to a fuzzy distance of about 24 feet and therefor do not peremptorily interact with the front wave except in a fuzzy way in a room.

3. Lowest frequencies coming from the exit port add to the FR and enable efficiency esp at low frequencies and exceptional low and sub-sonic bass.

A disadvantage, at least for my sub, is that it's about 13 cu feet, although it has only a 17 x 17 inch footprint. Also, more complex carpentry.

While folded 17-foot pipes are not for everybody, my point is that there hasn't been nearly enough creativity in addressing the rear wave problem. There are a familiar handful of enclosure archetypes that are seen in slight variation and driven by T/S models. For some reason people believe the silly "Iron Law". But more imagination would be nice.

B.

Trying to convert old TH amp designs to SMT as an exercise, I am looking for surface mount equivalents of 2SA992/2SC1845 and 2SA1381/2SC3503.
The first pair could be replaced by FJV992/1845 kind of hard to find, any better ideas?
No clue for the second pair. Any suggestions? Thanks.

I plan to design 3 Way Tower Speaker with Side firing (Both Side) Subwoofers !
is it feaseble ?
Connecting Both side subwoofer (6" X 4)in Bipole Configuration is work best?

Building custom designed amplifiers requires testing the amplifier without damaging it. This is tricky at first, as a newly built amplifier may be out of proper bias by a large margin. For the latter, main power current limiting is essential if not an expensive bench power supply is available. Such a power supply would need to cater for a wide range of voltages and currents and must be capable of supporting shorted outputs. This may seem bad news for potential DIYs but it is not gloomy as it seems, there is a very cost effective way of achieving what a current controlled power supply offers. This humble test is, the famous series light bulb test which uses a filament lamp as opposed to modern bulbs.

Since I built such a protector I am posting it here for any DIY users to illustrate that there is no need of very expensive equipment to make your own testing equipment. Some users have even created an oscilloscope for audio purposes by using a computer's sound card which its own AD converters capable enough for the audio spectrum. In the case of using a computer, it is very important to isolate it to avoid damaging its sensitive circuitry.

I am posting my series light bulb tester which uses a mains transformer to reduce 230V AC to half its value and pass current through a couple of lights before reaching an amplifier under test. Different bulbs with different ratings can be used.

Looking for a few chips. Let me know if you have some and don't plan to use.

Hi all,

Would anyone have a spare set of mini-aleph boards knocking around in a drawer unused? If you have the BrianGT/chipamp.com ones from years back, even better! and to top off the wishlist, if you also have a PSU board for it, then even better again!

If you're in the EU then even better but I'll take what I can get.

Lastly, if these are not available and Gerbers are available (I did look but without finding any) I'm happy to get some printed and could share them, but obviously protecting IP rights.

Fran

When you’re fine tuning your crossover for that last bit of voicing, do you prefer more woofer or tweeter at the crossover point? Assuming you’re dispersion is good either way, and response isn’t negatively affected. Say add 1db to one side and take away 1db to the other. Which driver is typically the better option to use more of?

Please, I am not being snarky here.
I have noticed here and elsewhere some very enlightened ideas on modifying. Even jumping in the old WAYBACK machine to remember the original POOGE in AA and SB.
But, I also see a lot of completely naïve attempts that may be more informed by a golden ear magazine reviewer than by sound engineering. Pun intended.

So, before you take on a mod, which I do encourage:

What do you know, or think you know, the original designer did not? Write it down. Look at it.
What do you think is deficient?
New technology?
Cost?
Different use?
Different feature?
Faulty design?
Packaging to suit your taste?
Can you measure the before and after?
Can you simulate the change?
Where did the idea come from? Understanding of circuit design, or some blogger's hot tip?

Many suggestions are well meaning and at first blush sound reasonable until think about it. $500 for some magic high purity gold plated cryogenically treated bi-wire jumpers? From a real engineering standpoint, a steel nail works just as well. Seriously. Save the cryo-treatment for your bench chisels. It works there following the laws of physics. ( Narlex Rictor, yea they do hold their edge better)

Cap can have issues, but some brand name will magically be better? Why? What value in the cap ( many) are you changing and how does that effect the circuit?

We have real data on resister design. Real data on Johnson noise, inductance and measured distortion, yet I almost never see mods concerning that.

I just saw a post where someone noticed a cap that was apparently hot to the touch. OK, sounds bad to me. Why? Mistake? Cheap? Fault? But the answer was a heat sink.

Another comment on adding I assume some magic film on a cap to reduce vibration or something. But that could be insulating causing a perfectly good component selection to run hotter than designed and fail.

I almost NEVER see anything about improving speaker crossovers, a huge opportunity. Even in the multi-thousand dollar speakers range, I see iron core inductors, too mall gauge inductor wire, wire wound resisters and electrolytic caps. That does not even count the overly simplistic design ignoring critical phase and linearity features the left out due to cost.

All I am saying is to think about what you are doing. There is almost nothing out there some thinking and money can't improve. Just think about it first. Consider where your ideas came from. Who knows, you might discover something really cool! You also might destroy an otherwise decent bit of kit.

This does not even approach the really discussing snake oil. $5,467 for a power cord to plug into what? Yea, 200 feet of Romex to you entrance panel. Several hundred if not thousand feet of aluminum wire to the pole. There are actually reviews testing power cords with claims of sonic magic bringing out details in the music. Really. A year long "shootout" of 27 power cords. How does someone with the where-with-all to buy a $5000 power cord get that kind of money? Clearly not with any common sense.

I saw an "audio grade" outlet for over $1000. Do use the $8 comercial grade outlets. Replace all the 97 cent "spec" grade in you house. Your stereo won't sound better, but less likely to fatigue, cause bad contact, and a fire. And don't use the push in terminals. Of course, don't do his unless you are an electrician, and if so, you know that anyway.

Hey, if you want to paint your amp case hot pink, that is your thing if you think it looks better. That's a valid reason. Not that someone said it would "brighten up the sound"

Does anyone what connectors 47Lab uses for PSU connections?

Anybody got one?

Current source, TO-92, 3pin, V+in, Set, V-in
Iset = 227[uA/K] x (273 + 25)[K] / Rset = 67.7 / Rset [mA] ;@25°C

Previously, for 2018 I built a full range floor stander with help from this forum using the Dayton Audio PS220-8 8" and the contour network from Curt's Singularity. I am very happy with the final result.
For 2020, looking to build a full range bookshelf speaker. I am recycling two way cabinets with a 14 liter internal volume and a front baffle of 168mm.
Tentatively looking at the Tang Band W5-2143 5" Paper Cone Full Range Driver and adding the Dayton Audio DC28FT-8 1-1/8" Silkie tweeter. The only other component being a cap 1uF to 2uF to the tweeter.
Nothing has been ordered. Looking for advice from this forum before proceeding.
Thanks,
Joseph

I dont understand the switching on my TL - SSE. It uses Hammond 1628sea connected to speakers at 8 ohm taps. When I change the Switching positions for UL or CFB I don't hear any significant change in volume or sound quality. I have used DPDT on -off-on switches as suggested in the guides. Is there any risk of damaging the amplifier if it is powered up and used with switch in the wrong pisition. Eg the off / centre position. I only ever run mine with these switches in one of the on positions (up or down position) because I am worried about damaging the OT's or something. As I said though I hear no difference and am wondering if this ia becauae i should be switching between on and off.

I recently picked up a pair of these and I think the mid dome got jostled during shipping. It buzzes at certain frequencies like the voice Cooke is rubbing.

so, does anyone know if this is repairable? I’ve contacted line about replacements, but am prepared for them to say not available. Can a new dome be put on? Can it be manually repositioned? Does anyone know of an equivent deiver that would work?

help appreciated.
Jeff

I'm looking for some clubs(or anything of the sort) in North Carolina, preferbly east of Raleigh. I'm on the coast 🙁 Just looking for some experience dudes to learn from 😀

Hello, I am new here and I am acquainted with the world of audio.

I'm looking for a durable 811A for a Steve Bench A2 amp build: http://diyaudioprojects.com/mirror/members.aol.com/sbench/a2part3.html

Since the SV572-160 seems to have reliability problems and 811a is equivalent (+ top cap), I'm steered towards NOS G811 (Ryazan or Rzep plants?).

I'm surprised to find tubes with a getter flash and others without, sometimes even in the same auction:



What's the deal and which ones should I get for a solid vacuum when not using them cherry red?

Cheers
Simon

Does anyone have these boards for sale, the store has been out of stock for some time

Thanks

I am building these little 317/337 psus and it calls for D44 and D45 transistors.

Here is the schematic for the positive rail.



I have the D44 but D45 aren't on my horizon and out of stock in my usual suppliers.
Digikey says that TIP132 is an alternative and having some TO220 tip147 here I wondered if they may be suitable? Thabks in advance.