Hello
I have a hum problem with my ES9018 based DAC.
After startup, the system is basically hum-free. After about 10 seconds the hum (around 100 Hz by ear) starts. It is only hearable when I turn the pot over half, so it is not that bad.
The funny thing is: when I touch the ground pin of a certain regulator in the DAC, the hum is notably reduced. When I touch the regulator very gentle, only a little bit, bet when I touch the regulator more firmly, the hum gets more quiet.
It also works when the regulator is not even powered...
These are the components used:
->USB feed via waveIO
One regulator for the dirty side, one regulator for the clean side after isolation. The reg for the isolator is also the "funny" reg which - when touched - reduces the hum.
->Buffalo III DAC feed from two independent supplies for AVCC and for the rest of the local regs.
-> SEN I/V stage with four independent supplies and floating ground.
-> transformer coupled to preamp.
So, I asume the fact that the hum starts after a certain warm up time, has to do with something charging. Or?
Why is it that when I touch the regulator PCB (at the backside ground pin) for the WaveIO isolator with my finger, that the hum gets quieter? Can I use that somehow?
The regulator doesn´t even have to be powered.
There should be no global ground loops. The USB side is isolated by the WaveIO, the Preamp side is isolated by transformer. All regulator feeds are galvanically isolated (I use 8 independent secondary windings at the moment)
I tried different combinations of connecting the WaveIO dirty side to the chassis and/or connecting the DAC ground to chassis. The hum stays.
Any help is appreciated.
Thanks
FLorian
I have a hum problem with my ES9018 based DAC.
After startup, the system is basically hum-free. After about 10 seconds the hum (around 100 Hz by ear) starts. It is only hearable when I turn the pot over half, so it is not that bad.
The funny thing is: when I touch the ground pin of a certain regulator in the DAC, the hum is notably reduced. When I touch the regulator very gentle, only a little bit, bet when I touch the regulator more firmly, the hum gets more quiet.
It also works when the regulator is not even powered...
These are the components used:
->USB feed via waveIO
One regulator for the dirty side, one regulator for the clean side after isolation. The reg for the isolator is also the "funny" reg which - when touched - reduces the hum.
->Buffalo III DAC feed from two independent supplies for AVCC and for the rest of the local regs.
-> SEN I/V stage with four independent supplies and floating ground.
-> transformer coupled to preamp.
So, I asume the fact that the hum starts after a certain warm up time, has to do with something charging. Or?
Why is it that when I touch the regulator PCB (at the backside ground pin) for the WaveIO isolator with my finger, that the hum gets quieter? Can I use that somehow?
The regulator doesn´t even have to be powered.
There should be no global ground loops. The USB side is isolated by the WaveIO, the Preamp side is isolated by transformer. All regulator feeds are galvanically isolated (I use 8 independent secondary windings at the moment)
I tried different combinations of connecting the WaveIO dirty side to the chassis and/or connecting the DAC ground to chassis. The hum stays.
Any help is appreciated.
Thanks
FLorian