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My first multichannel "ground loop less" DIY amplifier !


May 5, 2022
Paris, France

I build loudspeakers cabinet for more than 40 years, I play with electronic crossover for 30 and I try to assemble amplifier board for more than 20.
From the moment more than 2 channels have been made, I have never reached "zero noise" amplifier because of "hum" and "buzz"...
The famous ground loop syndrome :confused:

And then, I decided to build a last 2.1 chanel for my son. The parts:

Now, I can't hear any buzz, my ear sticked to the speakers; just a normal slight high-pitched noise. Finally ! :)

I achieved this goal thanks to 3 factors:
  1. only class D amplifiers (I tried AB gainclone or similar for a long time)
  2. qualitative SMPS from Connex Electronic: it is not cheap but essential (note I first tried a very noisy aliexpress 36V SMPS)
  3. independent power supply for each PCB, which is particularly important for the BT module


Two features:
- volume knob via miniDSP (digital control) particularly useful when RCA input is used;
- automatic switch between BT and RCA input via the excellent LQCS module (really helpful!).


Right to the amplifier, my last DIY cabinet made for my niece.


OK, it is not a perfect back plate, but I don't own a drill press...

Now I'm confident :cool: I plan to build another 2.1 system for my daughter, around an excellent 3E Audio EAUMT-0100-3-A I bought used (because discontinued TPA3251).
I will use exactly the same setup (only one SMPS300RS) in a smaller Galaxy case.

PS: my similar main HTPC system is, also, groundloopless because I removed an auxiliary (unused) PSU... noisy!
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