Icepower 50Asx2Se input buffer preamp buzzing.

[Gaspar74]

I have built an amplifier with a single 50ASX board, I was using a Dac as preamplifier into it. Im trying to add a Preamp board into the amp to act as input buffer. Its a Ne5532 preamp board marketed to use to amplify Bluetooth signal for external speakers etc. When I wire it up I am getting noise from both channels. The board is capable of being powered by 12-35v dc. I am currently using a seperate DC supply to feed it 12v as Im not sure the Auxillary on the Icepower is adequate. Here us the Preamp Board/

https://a.co/d/hJnlz7U

Any ideas whats the issue possibly? Im going from RCA LEft and right to L R of 3 pin connector input, and both grounds Ive got running to center pin of 3 pin input of PCB, I reversed it for the output and that goes into the Source input of the Ice board., Center pin being ground of the output of preamp and I tied it to pin 2,3 of 7 pin connector to icepower board.

 

[rwortman]

Many possibilities. Your separate power supply for the preamp board may have a different ground potential than the amp resulting in ground current noise. That board has a fair amount of gain. It isn’t just buffering. I would take my oscilloscope, look at the nature of the noise, where in the signal path it appears and go from there.

If you don’t own basic test equipment you have a conundrum. One has to get pretty lucky to build electronic gear and never need to troubleshoot it.

 

[voodooless]

I’m pretty sure the AUX power is fine. I use a cheap board with balanced converter to a bridged version of the amp and it runs fine on the AUX. The board I use has additional regulation, so you can probably keep yours as well.

Also, recheck your wiring. That brown GND wire is really close to the amp output GND. Best to keep the output wires away from the inputs. The output wires could probably also use a few more twists.

 

[Gaspar74]

I’m pretty sure the AUX power is fine. I use a cheap board with balanced converter to a bridged version of the amp and it runs fine on the AUX. The board I use has additional regulation, so you can probably keep yours as well.

Also, recheck your wiring. That brown GND wire is really close to the amp output GND. Best to keep the output wires away from the inputs. The output wires could probably also use a few more twists.

It draws 600ma which is too high for the Aux supply. I tried all variations, including removing from Chassis, its not what I had expected so IM ditching this as a potential buffer. Thanks for all feedabck.

 

[voodooless]

One single buffer drawing 600mA? That’s curious…