Computer Noise in Audio Path - But Not in Mixcube (As Much) Jan 17, 2020 0:43:09 GMT
Post by Hexspa on Jan 17, 2020 0:43:09 GMT
Hi. Everything was fine until I cleaned my computer's fans. I did that then hooked my UPS battery backup through an extension cord (is this really bad?). Now I get a whine that's correlated to computer activity but only in my Yamaha speakers. Sometimes it's in the Mixcube but usually not.
I was using a Behringer Xenyx 802 as a monitor controller but, since setting up S/PDIF loopback, I tore out all my cables and the mixer - mostly unbalanced cables - and currently I'm hooked up directly from the interface to the Mixcube with a single balanced cable. This singular cable is also the one I'm using for my 'noise removal' tests outline below. I have tried a different cable but still the same basic result.
The mixcube has a ground lift for pin 1 on the audio cables. When there's noise that helps but even when there is noise it's very little when compared to the Yamaha's which scream. I've tried every combination of plugs - one outlet, star configuration, etc. but nothing works. The only thing I haven't tried is plugging the UPS back into the wall because I'd really rather not.
The Mixcube and the Yamahas are both going into a Monster Power 600 along with my interface which I've tried with both FireWire bus power and with a power supply. I even tried disconnecting the molex power from the PCIe FireWire card. To me, it seems like the noise is coming through the FireWire card because when I disconnect it the noise disappears. This isn't a 60Hz hum, it's digital whine.
The Monster Power, with all the audio stuff, is on one plug, and the UPS with all the computer stuff is on the other plug on the same outlet. I've tried different outlets, putting the computer on the Monster and the Monster on the UPS. Always noise; sometimes better, sometimes worse. Having them in parallel like this is the least worst. There is no noise in the headphones.
I feel like it's either the PCIe card or the interface itself. Hopefully, it's not the motherboard but I'm really just guessing at this point. The interface is over 10 years old so this isn't really a shock but it's still unwelcome, of course.
So, I'm at a loss. I was planning to replace this interface anyway. Hopefully, a USB-powered one connected directly to the motherboard will give a different result. It's a very strange problem. I should mention that the interface's PSU stopped working at the same time as this. My electrical qualifications are virtually nil so I feel completely unqualified to tackle this issue.
If anyone can point out any glaring flaws, I'll be happy to listen. In the mean time, got any recommendations for an at least 4 line-out USB interface that doesn't cost too much and preferably has software loopback? As much as I want to avoid going with MOTU again, I just might since the M4 is only $220.