I have a somewhat weird question (hopefully not too weird).
I work with an audio system. It includes a wave generator, a (33500B series Keysight) wave generator, an amplifier (2003 op-amp based circuit, will be replaced with LM1875 circuit in the future) and a speaker (H1283 Seas Prestige). I use BNC cables between the system components.
Here is my problem, I have background noises (even when the generator is on but not outputting any sounds).
I noticed, that the best thing to reduce this noise is me touching one of the system components (not speaker but wave generator, audio amplifier or the metal ends of the cables).
I am not sure why is it so. Is it because I am a huge capacitor?
Anyway, here is my question: (Since I can not hold the boxes while applying the experiments…):
What is the simplest action I can apply in order to create a similar effect to me touching the system components?
I already tried:
- Attaching a metal mesh (to create a "Faraday cage" effect).
- Attaching parts of the metal mesh to components of the audio box.
- Connecting the boxes to an external ground.
- Connecting the grounds of all the boxes.
All these things helps a little. But nothing has the effect of me touching the boxes.
It "sounds" like a ground loop or an impedance mismatch, but if everything is properly grounded, then a ground loop seems unlikely, but then again, if everything were perfectly grounded, then you touching anything should have no effect. In either case, a ground loop isolator should help significantly.
Although they are not very expensive, be aware that there are different ground loop isolators for audio signals and video signals, so be selective when shopping.