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Messages - Oooscar


I am starting to experiment with opamps as preamps, and/or headphone amps.
I am trying to add a tone control, and the big muff pi seems a simple one. I put it between the two op amps of a TL072CP but the sound I get is very bad. When there is not tone control, I get at least a clean sound when I listen with my headphones, but when I introduce the big muff pi tone control, the sound is noisy/distorted (in a unpleasant way). What I am looking for is a clean and filtered sound. If I want musical distortion I will add it later. But just to go step by step.

I have tried also to add the big muff pi passive tone control to the output of a JRC386D simple circuit, with just a capacitor at the output, and I get no sound at all. I am thinking if the output current of the opamp is not enough for the tone control circuit. When I remove it, I get sound in my headphones. I know that there is a circuit called Smash Drive that has a tone stack in the output of a LM386, but it is used as a pedal, and I have no tried and don't know if it has enough power the signal to drive headphones.

I am trying things with ingenuity, just step by step. Maybe some of you here have tried the same circuits or similar ones, or have more knowledge, and can give me some clues to help me get those circuits work.


The Newcomer's Forum / Re: TDA2030A based amp
April 13, 2020, 08:16:15 AM
Interesting. I bought one TDA2030A recently. Which is a good and not very expensive way to power it? That's the first thing, and I am afraid that 12 v and 1 A max. is not enough.



I voted for other, because it would be nice to have a combination of both as well. The schematic could cover preamp with tone stack on one side and tone control on the other side, and then, even if the PCB has to be for one of the options. I am going towards a practice amp, making it each time more complete. Now, I am starting with op amps. I saw a project on the forum with a PAM8403. And it sounds good.

Anyway, nice idea.

This project looks interesting. The schematic shows more components than a typical op amp preamp. I am not taking into account the tone stack. Could it be simplified? For instance, could the 220 resistor be removed? Which function does it have?

Thank you very much.

P.S. That's my first post, btw.