need help with my 1w amp (tda2822m) noise

[lml]

Hello this is my first post. Its actually my first project too.

I wanted a portable amp so I went for the 1w PUNCH amp on this forum, and I couldn't find the tda7052(mono) so I went for the tda2822 (2 channels) and I had to change the shcematic a little bit to make it work. I added 1 electrolytic cap to the positive part of channel im not using and a ceramic one to the negative, then grounded them.

The amp sounds very good, but the problem is that there is a mad background interference noise that is very loud, and its worse around middle volume from the guitar pot.

Im using 5v power source on a 4ohm speaker. Its a protoboard by the way, maybe the wires are causing the interference noise? please help

[B Tremblay]

Try this:


The NJM2073 and TD2822M are pin-compatible.  A 2N5457 or MPF102 will be better for the buffer than a J201.

[lml]

thanks ill buy the compenents tomorrow and try better luck with that.

[PRR]

> there is a mad background interference noise that is very loud, and its worse around middle volume from the guitar pot. .... Its a protoboard by the way, maybe the wires are causing the interference noise?

Yes.

Especially the savvy observation "worse around middle volume". With pot full-up you get guitar directly. With pot full-down you have a solid ground. But half-way up the signal is neither here nor there, and very susceptable to stray garbage.

High-gain audio amplifiers (ALL guitar amps) must be shielded to get best noise/garbage performance.

If it works OK except for this, box it up.

[lml]

Thats some great info. The other thing I get is over drive at high volume, but I guess thats normal in a 5v 1watt amp.

Ill try the other schematic to see if its better. thanks to both.