K4005B K4006 K8084 buzzing

I have the K4005 en 4006 installed in a wooden box of a subwoofer for a while. Originally i used it with a pot between the input and amp. This worked perfectly but I wanted bass and trebble control. So I bought the 8084 with a 2*12v trafo 300mA.
I also installed it in the box and connected the input and output directly with wires instead of the cinch.
At first I had a humming, but then I replaced the trafo more away from the kit. This helped but there is still a buzzing with higher freq left. The buzzing gets higher when volume is higher. With continuously music you can hardly hear it but quit passages (example classical, soundtrack or radio talking) are annoying.
What can I do to resolve this?

Without being able to measure, we cannot tell if it is hum (50 or 100Hz) or a buzz caused by oscillation of the amp.
Most likely, it is hum caused by a hum loop you’ve created somewhere in your wiring.
Hum loops can be avoided by using one single GND point, e.g. at the ‘0’ of the power supply.

the sound left is defenitely a higher frequency, only to be heard in the satelites attached to the subwoofer.
the humming is as good as gone, sometimes it returns and then leaves again, what exactly do you mean with wiring one single gnd to the 0? Must a attach a wire from the 0 of the trafo(s) to the earth pole of the power supply?

Please: english or french (see forum rules).

For us, it is hard to determine where the problem is coming from, without being able to check and measure your assembly.
Do you get the same behaviour when you short the inputs?


I have tested it andwhen I short the input the buzzing stops.

Could you please also let me know what you mean with: using one single GND point, e.g. at the ‘0’ of the power supply?
thank u

Most likely, the problem is related to connected equipment.
Is there a tuner in your system which is connected to the cable ?
This could be the cause of troubles. Try disconnecting the cable to check.

As for the second issue, it is important to avoid ground loop i.e. ground wires that meet at both ends.
Therefore, it is recommend to have a single point where all ground wires meet at one end.
This point should be chosen as close as possible to the ‘0’ of the power supply.
For further reference regarding star grounding and ground loops, please check the internet.

I have rewired the input and the satelite connections. Now power cables run at one side and music cables at the other side.
There is now hardly any buzzing left, except when volume and treble are at maximum. Of course not with music (I think my ears otherwise will start to buzz :open_mouth: ).
This is now acceptable for me.
thank u for the support