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wuemura

TDA2005 making static noise

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Hello guys!

I want to use a mid-range and tweeter to make a center channel in my car, so i choose to use the TDA2005 plus an active crossover. When i turn the circuit on it has a static noise like, sound like a pink noise to me.

So i remove R66/67/68/69 to isolate both circuits, analysing the filters all sound OK, conecting the speakers at the output, silence but looks like the circuit is too sensible if my hand is near, injecting RCA audio signal over C21/22/23/24 the speaker plays at full volume and no quality at all, there is this static noise with it, in small proportion but it was there.

Reconecting R66/67/68/69 and grounding the signal with a 100K resistor at GND or AGND make no effect at all, it just get worse. Changing R54/55/56/57 to 2.2K the circuit is less sensible to hand movement, sound much better, but do not solve the static noise :(

Board:


Schematic:


Thanks

PS: I could not upload the pictures using the forum.

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Hi Wellington,
Your circuit has too many resistors, too many capacitors, too many opamps and too much gain.
Unfortunately, the TDA2005 needs to have a minimum gain of 32dB so it amplifies the noise from the opamps.
Maybe the useless R68 can be made an attenuator.

I have modified only the midrange. The tweeter parts need similar changes.

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Something is wrong, i removed all the opamps and the TDA2005 output is quiet, but still if my hand is near the caps it generates alot of noise. If i touch the 2.200 caps i can hear radio.... I will do it all over again.


Any sugestions that i should follow to do pcb layout and avoid this noise power amps have this problems?

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Hi Audioguru,

I did some more tests with only one stage, all other stages are out, injecting signa at R36 with all the changes, the sound is like AM radio with noise and stuff, using a 470K in R68 and injecting sound there still the same, lot of noise with sound. Removing this opamp and injecting signal at the same place (R68) i got a cristal clear sound, changing the TL074 make no difference.

Do you think it could be ground?? Or oscilation of the TDA2005??

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Hi audioguru,

I've changed everything values, tracks etc. When all is ready and i turn it on i could not hear any music at all, but, i could hear a clear, loud, no noise or distortion 1Khz beep  ;D ;D ;D

I will do this from ground zero all over again in separated boards, one for the main input signals and filters and other just for the TDA2005.

Thanks, when is done i come back here to post the schematic.

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Hi audioguru,

I've checked and re-checked the new connections but some how made the opamp's to oscilate, pins 5, 6, 9, 10, 12, 13 has a clear beep on it and the output also. The power amp blocks had a small "buzz", removing the supply jumper away from the input pins solve this issue.

No problem, i will rebuild it.

Thanks

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