Exploding TA2022 Tripath Chips!!!

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Hi Everyone,

I've built a couple of 41hz.com AMP10b kits, based on the Tripath TA2022 chip. Both of these kits worked for a bit, producing excellent sound into 8 Ohm speakers. I haven't once managed to make the amplifier clip or distort in any way, when it plays it sounds lovely.

...However, I only seem to be able to get about a day's use out of them before they spontaneously explode!

A few notes:

  • It's running off +/-33v rails from the 300VA torroidal tranny.
  • I've had explosions using a standalone Creative Zen MP3 player source and from my DIY TDA1543 DAC (running from a seperate transformer), driven by a Squeezebox over TOSLINK.
  • Explosions occur when I've unplugged the input source, or I've just been playing music loudly.
  • The amplifier has been set to both "general use" and "high sensitivity" gain, as per the build instructions.
  • All my components are in correctly as per the silkscreen.
  • All my soldering is fine.
  • I have currently not grounded the board, any heatsinks etc. It's just connected to the transformer (I'm wondering if I should)
  • The chip failure is always the same, a small piece of the front blows off on the left hand side, and 7-11 pins look burnt (I've read this is the output FETs)
  • I've had a chip pop even though I've fused both the 5v digital rail and the +/- rails (before the caps unfortunately).
  • I'm using standard 3.3uF DC blocking caps.
  • I've trimmed the speaker output bias to <0.01V
  • I've substituted the mute pulldown resistor with a 1k, as per recommendations on the 41hz forum.
  • The amplifier does occasionally mute itself if it is turned up.

Please can an experienced anyone make some suggestions as to why things keep blowing up, it's starting the get expensive as I'm about to install my 6th chip!!!? Surely these amps should either clip or mute, rather than killing themselves when things get loud, I'm assuming I'm doing something wrong but I can't see what.

(I would post on the 41hz forum, but can't register, and 41hz don't seem to provide support anymore or answer their emails. :( )

Joined 2005
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I have also had a few blow up just as you say - It was not a 41Hz amp, but a 6 channel prototype board I got my hands on a number of years ago - its power only required 12VDC tho...

Never did find out what the deal was...got about 15 of the 6 channel boards and most chips worked fine...
I don't know, but I'd try lowering the voltage a bit. Just to see.

As you know, 33V are definitely SUPPOSED to be OK, according to the TA2022 datasheet, but maybe the chips aren't as tolerant of voltage as they're supposed to be, and then maybe your household voltage swings a bit, and boom?

I THINK you could try to drop the voltage a bit with diodes, just as a check. One diode drops around 1-1.5V. I don't know if diodes maximize audio quality, but it might be an interesting experiment. Put a couple of diodes on the wires carrying power to the board, wait a few weeks and see if it still explodes :)

btw, I'm going to post a link to this thread to the 41hz.com forum. Hope you don't mind. There are some quality folks there.
I can't see that the voltage is a problem, the TA2022 is rated to accept rail voltages up to +/-40v and we've never had problems in the house with voltage spikes in the past.

I'm starting to think that I am probably using too much gain, but shouldn't the chip's overcurrent protect either mute or clip it? As it stands I can't see that I am getting 60W RMS / channel. When compared to my Quad 405 (80W RMS / channel), it will only go about half as loud ....before exploding that is .:hot:

There are also overshoot diodes on the outputs, I might need to just triple check with the schematics that they are in the correctly.

I came across that post, but sort of dismissed it because what he did seemed excessive. The chip datasheet and the Tripath eval board doesn't have all of the protection that he adds.

I was more looking for a simple solution, but also not rely on having to change fuses every day.

I'm thinking that grounding everything and keeping the gain down might be the best solution. Just accepting that this thing isn't that beefy.
I agree that plopla's method was excessive, but I think/hope that your simple solution can be found in it. I take plopla's post as an indication that this chip / design is sensitive to grounding, to the point of chip casualties. What I mean is that it's probably worth going over the ground connections of the amp and looking for things that are connected but shouldn't be. Basically we agree, I think :) Btw, grounding might be through the enclosure, jacks or pot, too.

A thought: indeed, fuses don't seem like a solution, as it seems to be voltage offsets that are blowing up your chips, rather than current flow. At least I'd think so, given that it also blows up when you're NOT playing things. Only guessing, though.

edit: And another thought: I doubt that it's the gain, not that I'm certain. Too high gain should AFAIK only raise the signal up to the voltage/current capacity of the amp, after which it will clip or shut down.

Good luck!
If anything is running from a switch mode power supply, apparently the ground can be contaminated with quite high voltage spikes, so that things can blow up when you connect / disconnect them. I honestly don't know any more than this, I read it in a Rod Elliot article :clown:
Nothing that is connected is running from the switch mode supply. The amp is running from the dual secondary transformer with the onboard AMP10b regulation, and the DAC is running from a seperate home made PSU with a normal tranny.

Do you think that connecting the socket earth pin to the ground on the board will have any effect, I mean is it totally necessary since at the moment it's derived from the centre tap of the transformer secondary?

Also nothing gets warm when idle, and even played loud the heatsinked TA2022 only gets luke warm.
I've built three AMP1-B boards and haven't had any problems with the chips exploding. I had them running on a switching power supply with no problems. I did manage to kill two chips from a reverse voltage spike on the 5v supply; it was a stupid mistake.

I don't have any experience with the AMP10, but there must be either something peculiar about the board or a problem with your setup.
This might be an unlikely cause. But it sounds like everything else is unlikely, too. Those chips are said to be very prone to damage from static electricity. So maybe they are being damaged before installation (or because of the grounding?), in such a way that they become more likely to fail as you have decribed.

Another approach: As a first test, you might want to try running with +/-30V supplies, for a while, since it sounds like some limit is being exceeded. If they don't explode, that way, maybe it will provide a way to get a better clue about the cause.

Also, if someone who is familiar with this chip and the circuit would read the datasheet very carefully, and note all of the critical voltage and current limits, and the critical circuit-layout notes and suggestions, it might be possible to see where in the 41Hz circuit there could exist the possibilities for generating over-voltage or over-current spikes, etc. For example, too much loop inductance, or maybe even just inductance in components/leads (I noticed that they recommend surface-mount, for a reason), could cause voltage spikes for quickly-changing currents. Another example: Ground plane near a sensitive input could give too much stray capacitance, possibly causing current spikes for rapidly-changing voltages. I am not familiar with this design and those are just basic theoretical scenarios, off the top of my head. Someone would have to check the actual details of the device and the circuit, to know what might be worth worrying about, or worth checking further.
Just to clarify, I'm using a 24v toroidal transformer, giving 33.6v rail voltages.

R41,R52,R37,R31 (feedback resistors) are all 10K, as per the build instructions for 27-35v rails.

I'm using the standard inductors that came with the kit.

Someone made a heatsink comment, I am using a nice meaty heatsink, that gets luke warm at most, so that's not the fault. It's also not connected to anything

I am also pretty sure that I haven't caused any ESD component damage, I'd have to be pretty unlucky to damage 6 ICs and 2 boards.

...as promised I will post some pictures in the next day or so.

Hi folks,

I've read some rumors (somewhere) about the Tripath chips (once in a while) blowing up when you connect/disconnect the input terminal when the Tripath amp is already powered up. If this would be the case the reason might be the introduction of a more or less excessive spike entering the input stage caused by a different DC-level from the connected source. The chance would be that the input can not recover from such a "saturation" fast enough before the power stage blows up.
I own an AMP-2, four AMP-3s (for an octal channel test amplifier powered by SMPS) and finally an AMP-5 from Jans 41hz-page but have never experienced myself such a behaviour till now - maybe it's because I never (dis)connent the inputs of the Tripath chips while the amp is running. After all I don't know (and I won't try it out) if the Tripath chips are prone to this phenomena. As I said - just rumors. So figure out yourself if this might be true or not. I also went through the data sheets but found no hint or something similar dealing with this phenomena.
Nevertheless any further experience from other DIYer concerning this might be extremely interesting.

With greeting from Germany
I am starting to think that running the AMP 10B with the high gain feedback setting is the problem.

I've just installed a new chip and gone back to the "general use" feedback resistor settings (I think they are all 22k, but I may be wrong). Everything seems sweet, but it still makes me cringe every time a loud section of music comes on!

Certainly the TA2022 example circuit from the datasheet suggests feedback settings very similar to the "general use" settings in the AMP10B instructions. The high gain option in the AMP10B instructions seem to be pushing things a bit with regard to the onboard inductor etc and if anything out of the ordinary happens from the inputs the output FETs expire with a loud pop and a puff of noxious smoke .

When using the high gain resistor settings in the past, the chip would often go into mute state, something that I haven't yet managed with the general use resistor option. I'm just going to settle for a slightly quieter output, cross my finger and hope for the best!

Despite all my problems getting this board going, I have to say that I have never heard anything that comes close to a 4 X TDA1543 DAC and AMP 10B TA2022 in terms of clarity/expression. It just sounds immediately and obviously more punchy and "better" than any consumer grade setups that I have come across (I've heard a lot). A Micromega Stage 5 / Quad 444 / Quad 405 stack sounds lifeless and boring in comparision.

My next little project is to try a non-NOS DAC and see how that compares, probably a PCM1798.

Thanks for all the help.
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