Preamp -> Class-D = Noise

Cyberzim · 24th September 2009, 03:38 PM

Hi there,
I have succesfully made a tpa3122 class-d amp on a breadboard.
It plays pretty loud, but not loud enough, and I have measured it to only being 5watt with 25V, and according to the datasheets I can get more.
So I made a preamp with a TL072, that have a gain of 1.
But when I connect the output from the preamp to the amp, it just start making a lot of noise.
What's the problem?

Thank you,

Simon H.A.

marchel · 24th September 2009, 04:06 PM

Have you connected the pre to another amp and do you still get noise?

Cyberzim · 24th September 2009, 04:27 PM

The opamp didn't work, but I found a LM358 opamp, an it works, but as soon as I add gain to the opamp it goes nuts.

Cyberzim · 24th September 2009, 04:35 PM

NVM, it works now, I just think it's because the amp is sometimes unstables because it's on a breadboard.

Thanks for help anyway,

Simon H.A.

24th September 2009, 03:38 PM	#1
Cyberzim diyAudio Member Join Date: Apr 2009 Location: Gentofte	Preamp -> Class-D = Noise Hi there, I have succesfully made a tpa3122 class-d amp on a breadboard. It plays pretty loud, but not loud enough, and I have measured it to only being 5watt with 25V, and according to the datasheets I can get more. So I made a preamp with a TL072, that have a gain of 1. But when I connect the output from the preamp to the amp, it just start making a lot of noise. What's the problem? Thank you, Simon H.A.

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24th September 2009, 04:06 PM	#2
marchel diyAudio Member Join Date: Nov 2007	Have you connected the pre to another amp and do you still get noise?

24th September 2009, 04:27 PM	#3
Cyberzim diyAudio Member Join Date: Apr 2009 Location: Gentofte	The opamp didn't work, but I found a LM358 opamp, an it works, but as soon as I add gain to the opamp it goes nuts.

24th September 2009, 04:35 PM	#4
Cyberzim diyAudio Member Join Date: Apr 2009 Location: Gentofte	NVM, it works now, I just think it's because the amp is sometimes unstables because it's on a breadboard. Thanks for help anyway, Simon H.A.

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