Weird noise through my amps to do with hard disk...

sebovzeoueb · Post by **sebovzeoueb** » Mon Jan 08, 2007 10:56 pm

This is weird. I currently have no monitor speakers, so I output sound through 2 guitar amps and a keyboard amp just for general listening to music purposes. During the christmas holidays I acquired an external hard drive. I get back to my student room and plug everything in, and when I turn the amps on I get a horrible screech. Through unplugging various things I've managed to establish that the noise is going from the hard drive to my amps (which are plugged into the audio interface) through the firewire of my computer. The hard drive is going into the Firewire 800 and the audio interface into the Firewire 400. Any ideas about this?

sebovzeoueb · Post by **sebovzeoueb** » Mon Jan 08, 2007 11:02 pm

Oh, and do you reckon daisy chaining might work, rather than using the two firewire ports? (although I would then only get Firewire 400 for the hard drive)

sebovzeoueb · Post by **sebovzeoueb** » Tue Jan 16, 2007 1:51 am

does no one know about this? I was unable to find anything on the internet. I assumed it was just a guitar amp problem, but I tried running my computer through a PA and the noise was there, although to a lesser degree than my amp noise. My hard drive is a Formac Firewire 800, and the problem seems to be the firewire ports: even with the MOTU Ultralite switched off, if the amps are connected to it they pick up my hard drive noise... Please, if anyone has any ideas on this, let me know, I have tried powering my audio interface not off firewire but off mains, any other suggestions to random things like this I could try?

Clearscreen · Post by **Clearscreen** » Tue Jan 16, 2007 2:13 am

could it be a ground loop problem?
eg http://www.epanorama.net/documents/groundloop/
off the top of my head i can't think of any other way for the hdd to affect the audio... you don't have the mic on your computer turned on an causing feedback?

MrYellow · Post by **MrYellow** » Tue Jan 16, 2007 3:18 am

Could well be a ground loop......

The HD powered externally? Not Firewire power?

Could be your firewire ports are being earthed in more then one spot.

i.e. The drive or sound card has an earth from external power as well as the
laptop. Instead of all devices connected to the laptop using the same earth.

-Ben

Aunt Acid · Post by **Aunt Acid** » Tue Jan 16, 2007 5:35 am

I have a similar problem using an external drive and a PowerBook.

When daisy chained to a Presonus Firepod the problem goes away so that would probably work for you.

sebovzeoueb · Post by **sebovzeoueb** » Tue Jan 16, 2007 9:20 am

Thanks, I will check all this out, yeah, my hard drive is running off external power, I can't power it off the firewire. Well, thanks for the tips, I'll see if I can resolve the problem.

sebovzeoueb · Post by **sebovzeoueb** » Tue Jan 16, 2007 9:29 am

There may well be a ground loop, but I am in student accomodation, and I have access to one plug, and I can't really avoid the use of extension cables etc... not sure what I could actually do to help this. I have tried daisy chaining the audio interface to the hard drive, but the problem is still there, I have yet to try the other way round (I need another firewire 400 cable), but I'm getting a distinct feeling I may be stuck with this problem...

sebovzeoueb · Post by **sebovzeoueb** » Wed Jan 17, 2007 2:32 am

I have got a firewire cable and daisychained, although not perfect, this does significantly reduce the noise (turning on the hard drive is still pretty loud, but then it calms down into a background hum). I think my system is probably usable for just listening to music etc. now, although I have yet to test the performance of this set up. I suppose I am not getting the full power of my hard drive due to the fact it is now going through firewire 400, plus daisychaining must mean that the two devices are sharing the firewire speed, therefore making it slower... I have also heard of issues involving the MOTU Ultralite and hard disks not being properly detected or something. Anyway, I will now test this setup and see what the differences are.