Noisy USB Problem

Hello everybody,

I recently found a very interesting problem I had in my sound system.

As I told you in one of my reviews, I got a power regenerator for my system in which I plug my Burson Conductor and Audiobyte Hydra-X. It only has 500 W and I thought not to overload / stress it with my computer and other electronics.

PowerInspired AG500 Review

A month ago I got a new DAC for testing. I used the Conductor just as amplifier and the external dac was connected on RCA in to it.

First I used Hydra with the external DAC and everything went well. When I inserted the usb from the computer into the external dac, I got noise into my headphones, even though the rca input wasn’t selected on conductor yet. And it wasn’t subtle noise, it was like on the radio between two channels. I tested it with 3 usb cables but with same results.

I thought it was something wrong with the DAC. Well…last week I got another DAC and got the same result. I have tested other DACs in the past without this problem. I realized it was a problem in my system. I immediately thought it was the Conductor. I panicked and did a fast test on my laptop to find out that the problem was just with my desktop. I was relieved. This is one of the few hobbies where when something breaks people say “thank God it’s just the computer” :)) .

Ok but this was a recent problem, so something changed in my system. I realized that my old Nvidia Geforce 8800 GTS passed away almost one month and a half ago and I started using my HD4000 from my I7.

My 2 monitors were now inserted directly into the motherboard. Maybe they induced the noise into the usb.

OCD kicked in and I wanted to find out the cause of the noise issue so I started to perform some tests.

1. Tested every cable inserted in my computer

I started taking out every component from the motherboard. I remained just with the usb from the external dac,  the power cord and the 2 monitors.

I said…ok.. what now? I took out the power cable and the noise was reduced to 50% but still very present and annoying. I took out the power from the external dac as well. So now, only my Burson Conductor was plugged in but still I had very present noise in my headphones.

It was already 4 in the morning and I couldn’t believe my ears:

glasses

I then took out the 2 monitors out of my motherboard and the noise stopped completely. This is how I reached the conclusion that there must be something that the monitors and the computer power cable must have in common. So this is how I got to phase 2 of the test.

2. Started pulling out every component from the power outlets in my extension cords.  

The annoying part here was that every time I pulled out a component from the outlet I heard it clearly in the headphones…and that just because of the usb input.

Solution

I had 2 extension cords that I used with my computer and my electronics, so I reconfigured the monitors and computer to be in the other extension cord and and switched the wall socket for the extension cords and … surprise, almost all the noise was gone!

This really showed me what influence can a usb port have in your entire system. Remember that my Burson Conductor and the external DAC were inserted in the power regenerator. This didn’ stop the noise from USB though and this ruined the whole sound.

Somehow the other electronics inserted in the same extension cord interfered with each other and that had a very powerful impact in my system.

Hydra made me ignore this issue for a month as it has the USB completely isolated from the computer as it doesn’t use the 5V from the computer and it takes the power from it’s clean battery. I cannot help wondering if the data line was affected in any way.

The sound seems more clear now overall and I listen to lower volumes now, but I cannot say with certainty yet.

I will try to find a power conditioner for my computer and the monitors and see how that goes.

This may be just a ground loop but I never thought the impact would be so big just because of the USB port.