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| Re: Digital noise [message #105841 is a reply to message #105840] |
Fri, 19 November 2010 00:17   |
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Hmm, I don't claim to be an expert on this but looks to me like you're having the same noise issues I had with my dual G5 - although it certainly didn't sound to me like traditional ground noise that's exactly what it turned out to be. We hear ground loops in audio gear as 60 cycle hum because that's the frequency of AC but inside your computer it manifests as much higher frequencies. There was a particular high-pitched whine associated with my graphics card that worsened when i'd, say, click a dropdown menu, and in my case it turned out to be a bad batch of power supplies with a grounding issue in that production run of G5s which Apple fixed under warranty (probably won't be the same problem with yours though).
Inspect the new fans, try unplugging them one at a time if it's feasible and safe (careful not to cook your computer!) and see if you hear any difference, check for anything that looks like it might have been jostled. If you have a DI or some other means of lifting the ground on your Emu then give that a shot. IMO it's unlikely to be PARIS - it may be old but they really got that stuff completely right, it's remarkably over-engineered re: ground/shielding/noise. Keep us posted.
PS: both your Emu and PARIS going into your power amp separately increases the possibility of weird loops. Consider the merits of having PARIS be the only card connected to the power amp and routing your Emu into PARIS through a pair of spare MEC inputs - maybe two of the channels of ADAT, or the SP/DIF ins. I'd bet that would have a good chance of eliminating it. Only downside is leaving PARIS on all the time like you would with a mixer (although that's what I do over here - PARIS goes weeks between reboots sometimes).
"... being bitter is like swallowing poison and waiting for the other guy to die..." - anon
[Updated on: Fri, 19 November 2010 08:28] Report message to a moderator |
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| Re: Digital noise [message #105842 is a reply to message #105840] |
Fri, 19 November 2010 19:22 |
Wayne
Messages: 206
Registered: July 2008
Location: Las Vegas
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Senior Member |
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Could be a multitude of things.
If all was well before the fans, then it's got to be the fans. Either they are noisy fans (electrically) or maybe the PSU.
I wondering if the new fans are pulling the power supply to it's max.
When I was upgrading my PSU I went to a site to determine the power needed. To my suprise when I entered my USB components, each USB component pulled 50watts. I don't believe it but it how the PS vender determines usage.
So if your running two sound cards, USB stuff, video card, DVD and/or CD player/burners, extra fans, floppy drives, multi hard drives, etc, you can see you can use up 400 watts real fast.
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| Re: Digital noise [message #105843 is a reply to message #105840] |
Fri, 19 November 2010 19:36 |
Wayne
Messages: 206
Registered: July 2008
Location: Las Vegas
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Senior Member |
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If you don't hear it with the headphones, I'm wondering if during your rebuild you crossed power cables over and around your audio cables or speaker wires. Things like that can induce noise into an audio chain and you may not hear it until after your stereo amp power output transformer.
Also, I've had bad luck patching my DAW or Paris to a stereo system when it's on a different A/C leg in my house, ie, power outlet on opposite wall in the room.
I've been taught to keep my DAW and MEC and outboard gear on the same A/C leg in my house. When I do, no noise.
And lastly, grounding. When I run my laptop (cakewalk while away from home) and I connect it to a mixer and power amp, even when on the same power outlet, I have to take a wire with alligator clips and ground the laptop to the power amp. This is mostly a Dell laptop problem when connected to it's power supply. If I run the laptop on battery . . . no noise. Point is, it's another way to get noise.
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