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#1
09-06-2005, 09:13 AM
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G5 and 002 (noisy firewire bus)
So, here's one worth talking about...
I have a digi 002 rack (connects via firewire) and a G5. It occasionally develops this really stubborn high pitched squeal, chirp, etc sound that is directly related to processor load (sometimes it gets worse when i'm taxing the processor, sometimes I'll open up programs to load the processor so that it stops). I've done research about it, digi points to an article where apple acknowledges the issue, and points to issues with the power supply. Offers swaps, etc. Which I've heard has fixed the issue. Also, Apple tech support will try to suggest "audio grounding issues", it's not an audio cable, this is not 60 cycle hum. BUT, i do understand that their is potential for issues to be passed through the jacket of my firewire cable. A friend/coworker of mine suggested that the processor could actually be generating RF into the firewire bus due to its speed. So, in that case, it sounds like a topographical error in the circuit design of the motherboard. It is worth noting that I have a friend, same issue, he lifted the grounds on things and said the issue went away, and that was on an maudio firewire interface. So again, this is not a Digi issue, but a G5 issue of some kind. It is also worth noting, that I am not running everything on a furman or the like, though I am running a 2 outlet power conditioner. I plan to do so soon. If/when I do, is there a potential that the problem will getter better, or even worse? This is long winded enough. Any thoughts, similar experiences, etc? 
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#2
09-06-2005, 01:18 PM
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I have the same setup (G5 dual 2.0+002R), and I get the same, steady, high-pitch whine when I fire up the 002R.
I'm powering it all from *both* a Furman AR1215 voltage regulator *and* a Monster 2500 conditioner (kinda redundant, but I kept the latter for its power-up sequencing) and I still get the whine. The sound isn't too loud or distracting at my listening position (002R off to my right, G5 under the table), but it is a nuisance for any same-room recording. I did have a separate G5 noise issue, a pulsing beeping sound, that was cured after installing the developer tools, opening something called CHUD (ha), and disabling 'napping'. It was processor-related. I actually haven't used the 002 since doing that though--maybe it'll help the whine too.
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#3
11-15-2005, 01:03 PM
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UPDATE!!
http://docs.info.apple.com/article.html?artnum=86523 New Info!.
As I said before, apple attempts to chock it up to stupid customers not knowing difference between fan noise and noise induced over firewire bus. Also, they attempt to chock it up to poor audio signal flow (grounding issues). ...We're not stupid, we know it's processor/disk related. And for christ's sake it's not 60 cycle hum. ***(edit) I should note that my issue is regarding FW digital/RF noise that the above author seems to have rectified w/ CHUD tools (did nothing for me) rather than the acoustical noise that blnkbnkr seems to be experiencing at present. They ultimately say, if none of these troubleshooting suggestions resolve the issue, and you have a dual 1.8 -2.0 G5, (there's a limited run that are eligible) we're eligible for power supply replacement through an auth. apple service center. I called Comp USA here in chicago, the guy was supposed to be getting back to me about it, as it was the first he had heard of it, but no response as of now. I think I'll call and bug him today. Interesting point is, as you'll see in my original post, at one point Digi sent me copied text from an old Apple press release that had since been deleted acknowlidging the issue. BUT, now, as you see at the bottom of that page it was modified 9/1/05. To add that "we'll replace if..." tag. Last edited by clineaudio; 11-15-2005 at 01:54 PM.
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#4
11-15-2005, 01:39 PM
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This is very interesting...
I just posed something in another post about this... My setup varies a little, but similar problem... I have a dp1.8gh G5, a MOTU 828 mk1. I just got a pair of Wharfdale Diamond 8.2 powered monitors. Anytime my firewire harddrive spins up or when its working I get a noise through my speakers the exactly corresponds to the noise the harddrive makes itself. Its not overwhelming but its annoying. Whats interesting is that I never heard anything like this before I had these powered monitors. Before I was using Event 20/20's and a Hafler power amp. Maybe its a crappy power supply design in the power amp of the Wharfdales thats not filtering out whatever interference the G5 is sending on the firewire bus. For me it doesn't do it when the internal hardrive spins, just the firewire harddrive. But regardless the G5 shouldn't be sending that noise. Its got to be a firewire related issue. Is everyone else experiencing this with firewire hardrive, firewire interface, and powered monitors? Whats interested is that I am get the noise even with the master volume all the way down on my mixer. So its probably an interference thing with the power amp on the monitors. Maybe, who knows? Regardless its annoying.
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#5
11-15-2005, 01:51 PM
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exactly the same set up for me as wel 909one, had a freind w/ the same situation. interface, fw drive, dual g5. He got around it by lifting grounds on his monitors oddly enough. Seems to me to be RF induced into the jacket of the FW cable, due to drive spin, or maybe even processor cycling.
The fw drive thing seems to make sense, too, though my logic may be flawed. Being that the noise I often hear is sweeping up to around the 7k range (7200 rpm drive)...am I crazy? I have an internal SATA drive for most of my audio work though, so my external drive is oftern just idling. This may explain why I only intermittently hear said noise, because my drive is only sometimes in use. Maybe we should try yanking the external drives and see if it goes away. Is it possible that if we have interface in front FW port, drive in back, or vice versa that we're getting a voltage difference over the FW jacket, since the FW drive is AC powered as well? Secondly, I've started to run my interface off of the front port on the G5, and it seems to improve the noise issue.
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#6
11-15-2005, 01:58 PM
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Quote:
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#7
11-15-2005, 01:58 PM
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Yeah, this is absolutely some type of back EMF from the power supply, not a grounding issue. If I had to take a rough guess, I'd say that using a power supply with a different (possibly higher) switching frequency would get rid of it. Just a guess, though.
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#9
11-16-2005, 04:20 PM
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Quote:
 lol! you owe me a new keyboard!on the topic at hand. it could well be a fan issue but on the external harddrive itself. certain firewire harddrives have small built-in fans that run intermittently, some of them are kind of fritzy and make other computer items run kinda fritzy as well when they run. eh just throwing something else out to see if that might also be the cause.
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#10
11-17-2005, 12:11 PM
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I've talked to an Audio rep at Apple, as well as a tech at CompUSA, basically, since they're not listing a serial number at the end of that document, just a general "dual 1.8 to 2GHz...for customers who are dissatisfied" it gets tricky. Surely this was a semi-intentional way of skirting the issue by Apple; though, you could also chock it up to uncertainty on their part--as in they know it's an issue on units in this range, but not all of em.
It essentially sounds like I'm going to have to attempt to duplicate the issue in front of an apple tech (the Apple rep suggested the AppleStore here, rather than CompUSA, as the direct tie to the manufacturer may be able to get the ball rolling faster). Sucks, means I have to transport the G5, a pair of monitors and my interface somewhere on the off chance that I can get it to happen there. As I said, fortunately (or unfortunately in this case), it doesn't happen ALL of the time.
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