TDA8932 amp

[printer2]

Bottom one. I was rearranging the parts and.  somehow the cap ended up where it is and I didn't notice it. Wonder if some NFB from the opamp would be interesting. Something to while away the hours on.

[PRR]

Well, actually both.



The bogus connection of the "grid" cap ruins your push-pull action through mids and trebs.

Bogus Presence cap connection just makes the knob work backward.

[Ben N]

Seems like it might be useful for the small powered monitors I've been meaning to make myself forever. Some kind of limiter on the input might be a good idea.

[printer2]

Thanks, should have looked up a schematic to compare to, did not really think it through. Been busy making guitar sawdust and have letting the electronic side of my brain laps. Trying to get a few well on before the window between too humid and too dry ends.

[tca]

Here is an idea for a 3D printed small box for a mono amp



Cheers.

[Renegadrian]

Funny, hated this board since it came...only to discover just today that I swapped input and ground!!!  anyway...it seems too dull for a decent amplification...maybe it's for the cab (16 ohm) I think they perform better at 4 ohms...

I bought some other amps in the meantime...as they are so cheap...
best one is tpa3116 board, sheeeeer power!!!

[anotherjim]

Dull? Should be flat. Are you using a high-z buffer in front?

[Renegadrian]

Dull? Should be flat. Are you using a high-z buffer in front?

no buffer I tried with this preamp here
It seems...lifeless...output is...mmm ok but...it seems like 1 or 2 W.

[anotherjim]

It will be low power with 16ohm. 16ohm is too high for most solid state. Class D could be made for high power into 16ohm, but there are far more 4ohm speakers in the world.

That pre-amp may be OK with single coil pickups, but do you see that 100k bias resistor? Total input impedance is 83.3k. I'd build a JFET buffer in front for 1M input impedance.

That 1M resistor to ground at input is for pedal use with a bypass switch to cure switch popping. For fixed use in an amp chassis AND  you have the grounding switch contact in the input jack as is drawn, that 1M can be removed to raise the input resistance a little to 90.9K.

[Marcos - Munky]

Digging up an old topic, I got a few of those boards. Used an Alembic F2B with J201s as the preamp, everything powered by an 19V 2A notebook power supply. Tested it in a 4x12 8 ohm cab.

This thing is loud! It's a little bit noisy, but it's everything outside of an enclosure yet. Also, I found out the noisy gets lower as the preamp board is closer to the TDA8932 board.

But the TDA8932 is getting a little bit hot. I ran it for about 5 minutes and I was able to put the finger on the TDA. After about 10 minutes, I still can touch the TDA, but can't keep the finger on it for a long time. I still need to do some tests for longer times, the datasheet claims this chip can work under 140 °C and in my tests it is surely way under this temperature. But probably is a good idea to use a small heat sink.