Input side recap done. And now THERE IS BASS and nice quality sound. Can’t wait for the output upgrades.
However, after the sound got better I found a flaw. The left channel is a tad softer than the right, so I took my multimeter to check the resistors.
The 100ohm resistors were found to be 100.1, 100.6, 99.6, 99.7 (left, left, right right) between the output of the op amp to the TPA. The tolerance is quite bad and systematically lower on one side. Could this affect the loudness?
However, after the sound got better I found a flaw. The left channel is a tad softer than the right, so I took my multimeter to check the resistors.
The 100ohm resistors were found to be 100.1, 100.6, 99.6, 99.7 (left, left, right right) between the output of the op amp to the TPA. The tolerance is quite bad and systematically lower on one side. Could this affect the loudness?
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I would say the tolerance is actually quite good given they are better than 1% !! You will not hear any significant difference due to the resistors.
I would check the resistance of the VR - Pot as this is much more likely to be different on each track.
This makes sense. Channel balance of el cheapo pots often is mediocre or bad. You may have a look at a quality brand like ALPS
I would love to instal an Alps Pot in the little Aiyima A04 and A07 Amplifiers but the room is so limited I doubt they would fit !!
I am seriously considering putting a 3e-Audio board in a slightly larger chassis so I can fit a more serious Pot such as an Alps. Just need to find suitable box for the MeanWell LRS-200 SMPS Power supplies - Surely someone must make one specifically for these units. I have some plastic boxes specifically made for the Mean Well SP-200 series but they are not the same size.
Thank you for this!
That solved it
I'm not sure why, but I could have sworn I read something about an internal pull-up on the /RESET pin, but when I went back and re-read it's just an open drain. I added an external pull-up and voila... amp stays on.
Everything is up and running again as expected, so on with the testing!
Regards,
Owen
Hi James,
If you have the 3E Audio and some MeanWell PSU, you can use this enclosure. I am using it for many projects (dual Mono, TPA32XX, or some other DIY amps). They are quite solid, made in ABS and really easy to handle.
If you need it, I can provide you a European link; they cost about 15 euros with a ventilation grid (each side)
Tandem poti balance looks like a common issue so I took some measurements with 3 samples from my stash. The setup is as simple as can be: A 1kHz sinewave generator feeds both channel simultaneous and the tapers are connected to left and right inputs of the soundcard. ARTA/tools/levels of two input channels act as a stereo level meter - that's it.
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It was the quite similar EMU-Tracker Pre. I have both soundcards, bought used for little money at ebay. Excellent for that price.
With 1% resistors tracking should be in the ballpark of 0.1dB excelling any rotary potentiometers.
3D Audio ? 3E Audio ? tell us more please )
For your info guys.
TPA32xx All in One Amplifier | 3e Audio
3E Audio has just released their new Finished TPA32XX Amplifier with Sigma DSP
Price is not on site yet... But I spoke with 3E Audio: should be very interesting.(they told me about $99 about 2 months ago)
As per info : For the first batch only they will offer OPA1602
BUT ! still no PFFB.... what a pitty !!!
Very Compact size in one Aluminium box
SY-DAP1002-165mm*140mm*50mm – L*W*H
SY-DAP2002 – 193mm*140mm*50mm – L*W*H
SY-DAP1002(TPA3250) – 2channel x 100W(peak)
SY-DAP2002(TPA3255) – 2channel x 200W(peak)
Pop noise free design no matter Power ON/OFF or AC lose
Bluetooth 5.0 with Aptx and BLE support
SigmaDSP(ADAU1701) for audio processing(analog and digital)
LED Ring visual display for user interface (volume,BT,status,etc)
Offortable user EQ tuning directly access into SigmaDSP
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