Remove noise from TDA amplifier

[Jacques321]

I've soldered the TDA7386 with all necessary components (as advised on datasheet) onto a circuit board and it works fine when connected to a source, except for the fact that it generates quite a lot of noise. The noise is not audible when I connect my phone to the amplifier at full volume, but it is clearly audible when just connected to a wire or to my phone at a lower volume. If I connect nothing to the input terminal (that is to the capacitor that goes to pin 11/12/14/15) there is really no noise at all, but the longer the wire is that goes to the source the more background noise there is. I want to use this amplifier for my computer, so it my not have any audible noise, so how can I fix this? Maybe I'm using the wrong type of capacitors for C1-C4, I'm using film capacitors?

 

[shrtrnd]

Somebody here might find something you can do to your circuit electrically, but here's something you can try in the meantime:
Shield your circuit and input leads from outside electrical interference noise.
You may just be picking-up RFI from outside sources (you're not working under a fluorescent light are you, they generate a lot of electrical noise)
Good luck.

 

[BobK]

Are you using shielded cable for the audio in?

Bob

 

[Jacques321]

Somebody here might find something you can do to your circuit electrically, but here's something you can try in the meantime:
Shield your circuit from outside electrical interference noise.
You may just be picking-up RFI from outside sources (you're not working under a fluorescent light are you, they generate a lot of electrical noise)
Good luck.

Listening to the sounds on the wikipedia page of RFI (https://en.wikipedia.org/wiki/Electromagnetic_interference) it doesn't really sound like that, I switched all my lights of and nothing changed and other amps in my home don't make any noises

Are you using shielded cable for the audio in?

Bob

No, I'm not. I use normal wire from input to RCA jack that connects to a RCA to 3.5mm cable that goes to my phone. I'll try some shielded wire, thanks.

 

[davenn]

No, I'm not. I use normal wire from input to RCA jack that connects to a RCA to 3.5mm cable that goes to my phone. I'll try some shielded wire, thanks.

That is quite important

 

[Jacques321]

So I removed the cables and jack that originally connected to the inputs (top picture), cut the RCA to 3.5mm cable and soldered it directly to the board (bottom picture). And now I have absolutely no noise at all, thank you guys!