Bluetooth audio receiver noise...

[diy1995]

Hello,
I had intergrated bluetooth audio reciever in old Contec boombox (thumbs up that old plastic low power japanese radios from 90s,that some of them sound much better than you would expect ).

It plays good, but I have problem with background noises, high pitch noises, that remind me on old dial up modems. I can tell that it`s releated to the data transmission, it reacts to pairing, connecting, it`s louder when it`s connected...

I tried it with different amplifier and seperated power supply, so I ruled out problem with radio and common psu...

I extracted the bluetooth module from Xplore car radio and that radio didn`t had any background noises either...

What could I try to do?

Thank you for help

 

[diy1995]

I had fixed the issue by adding 10000uF capacitor from vcc to gnd, noise isn`t completly gone, but it`s good enough.

 

[Pano]

Good to hear you've mostly fixed it. I've had a lot of trouble with noisy BT receivers, sometimes hiss and whine, sometimes mains buzz. An isolated power supply for the BT usually fixes the buzz, the whines and hiss I've not been able to fix.

 

[Hugh Jazz]

Same for me. I can get fully noise free BT but only when the device is independent - e.g. in its own case, battery psu, and it outputs spdif to a DAC. Otherwise, I get varied levels of noise with different BT receivers - some are very quiet and others sing their own little digi-song in the quiet passages. The variance in quality is astonishing for something that should, by now, be a mature tech. I would investigate further but BT is, for me, convenience so I'm not going to spend an indefinite amount of time fault finding. I think that's really the responsibility of companies like CSR, JL, etc. who churn out these devices.

 

[diy1995]

UPDATE... noise sometimes come back... as loud as it was without added power supply capacitors... I know that isolation transformer would fix this, but it's a garage radio and I don't mind it so much to throw even 1euro in it.
So acording to my researches fix is do add insulation transformer to signal line or to power supply...