DIGITAL NOISE

[♔Chello]

Chello, thank you for your post about this annoying USB noise. Very informative!
I have the same issue with my Pa5X and ModX connected to a mixer and the MODX by USB. When I disconnect the MODX USB connector the noise is gone. Can the unbalanced audio outputs of the MODX in combination with USB also be a source of noise?
I wasn't aware of the existence of USB-isolators. I'm really curious if they work well. Don't know if there are any disadvantages using USB-isolators.
Worth investigating!

✪mb_pa5x


Many thanks for showing your interest in this topic.
Very few people say anything about it, and perhaps this is because they don't hear it, which could be due to the equipment used or impaired hearing; many people don't hear much above 10kHz, while the problem becomes pronounced at much higher frequencies.

The better equipment and hearing you have, the worse the experience.

I noticed the same thing with MODX as you.
Unbalanced audio outputs should not have an impact, but I haven't tested this.
Something that always helps, however, is to place the PC as far away from the equipment as possible.

The USB isolator I have works well with the DAC - it removes almost all digital noise, but it had no effect on the sound card, which was USB C powered.

I have ordered 5 USB B and 1 USB C isolators which I expect to receive tomorrow morning, and will then test their effectiveness.

There are no known disadvantages to using USB isolators; on the contrary.
The problem with digital noise is because a PC is usually completely unshielded with a plastic case.
Previously I used a 20 kg heavy steel case, and this gave almost no digital noise.

My current one is made of plastic, and is placed close to the amplifiers, which maximizes the problem.
My new amplifier is very well shielded, so that I now have very low noise even at full volume, but I can still hear it well if it is otherwise completely quiet in the room.

I am very excited to see how good the new isolators are, because they are quite cheap and can be plugged into every component in the system.