Weird digital blips

[Dennis]

All -

I wrote on this topic a while back...and after reading the 24 bit glitches, thought it might be worth another shot.

I have a Glyph drive, and whenever I record a session directly onto the drive, hard drive activity gets recorded onto Pro Tools. You can see the light of the Glyph...whenever it blinks, there is a slight "pop" in the distance.

I'm not quite sure what this is...they are not plugged into the same power strip...AND, whereas before I had the Glyph sitting on top of the 888, they are now separated.

SO, I've been recording directly onto my Mac HD...and then transfering the file to the Glyph once all recording is done. Is this bad for my mac? Does anyone else have this problem with the Glyph?

Dennis

[BDWillis]

Dennis — Like to help, but guess I need more info… 1) What's the actual drive mechanism inside the Glyph enclosure? (Glyph simply builds a power supply/fan, etc. into a case with their name on it, as do virtually all drive vendors). 2) Is the drive on the Mac's external SCSI bus, a SCSI accelerator card, or…?! 3) What's your system configuration (which PT card(s), Mac model, accelerator cards, RAM, PT software version, etc. - significant because, for example, beige G3s have a slower external SCSI bus speed than many earlier macs, which could be a factor…) 4) More obvious: have you tried a different SCSI cable? (I've been bitten by this one before, with nearly new cables .) It's conceivable that there could be a grounding problem inside the drive enclosure causing the blips, but it's usually easy to eliminate other causes before sending gear in for repair.

As for the power strip, the whole rig should be powered from a single source in order to avoid grounding conflicts. Ideally, you'd want to power the entire PT system from an uninterruptible supply (APS units very highly recommended for this). You'll be feeding RF filtered, spike-protected, brownout/blackout-protected power to your rig, and you'll be very pleased when the lights suddenly go out & you have 10+ minutes of battery backup to save your session, shut down & find your flashlights by the light of your Mac monitor!! — it's happened to me several times… and compared to the cost of a PT system, $150 ~ 500 for a great, stable AC supply is CHEAP! Also, you shouldn't have a problem setting the drive at least CLOSE to the 888, if not on top of it — all this stuff is very well shielded.

BTW, I have a Glyph enclosure with two hot-swap 9 Gig Seagate Cheetahs among the tools/toys in my PT rack, and have run ProTools systems off of APS Uninterruptibles for over 6 years, and have no complaints about either. Good luck; curious to get your details.

Warmest Regards,
Brian

[Dennis]

Brian -

thanx SO much for your post...

Here are my specs:

G4, Pro Tools 24 Mix|Plus, external SCSI bus, 256 RAM, Glyph is 9 Gigs (I'm not sure what you mean by drive mechanism...)

Here's another twist to the story that I might have discovered yesterday. Since I'm aware of the problem, I've tried on several occasions to record into the Glyph and listen back closely. I've recorded successfully (so I thought) when I hear no blips. But then, I think it occurs AFTER I close and then launch Pro Tools again...that's when I seem to hear the hard drive activity in the session I just recorded. I just hear this faint disturbance, almost pulse-like since it occurs each time the hard drive light monitor blinks.

It's DRIVING me NUTS!!! Am I doing damage to my G4 by recording to that hard drive? I can mix when I transfer sessions over...but I just can't record straight into the Glyph.

D

[BDWillis]

Dennis — Thanks for the details; they bring up a couple thoughts & (of course) more questions. First off, you're not doing any harm to the G4's internal drive by recording to it. Though it's a cleaner system when your recording drives are external, it's not essential.

One thing to consider: backing up! If something does happen to your internal drive, you're in trouble if you don't have some kind of backup. At the VERY least, burn 2 CD-Rs of your critical data, i.e. system folder & any other essential folders on your desktop. (use some GOOD media, like Mitsui silver, for example - write 'em in Toast) and stash them away in a fireproof safe labelled with dates & at least a cursory contents list. That way in a panic situation, you have something to reload & start over with.

As to the Glyph drive, it's very likely a Seagate "Barracuda" (7200 rpm) or "Cheetah" (10,000 rpm) mechanism. Both are excellent - your drive's documentation should tell what's in there.

Regarding the blips: are they actually audible while the program material is playing? Or do you have to turn your monitors up & lean in (loud enough to where if the music came on, you'd be replacing drivers…!!) and listen to silent portions of the session. Are you able to see the blips when zooming in on the recorded waveforms? Or is this just a playback phenomenon from that drive? It's interesting that they don't become obvious until you close the session and open it back up… I'm still wondering if it's a poorly shielded SCSI cable that's to blame.

First thing I'd try is change that cable out. If you get the same noises, try to get access to another external drive, and hook IT up in place of the Glyph. Go through the exact same procedure of recording to the drive, closing and reopening the session, and see if the blips are still ocurring. If so, then it may have something to do with the external SCSI bus; a SCSI accelerator card could be the answer. If you can't recreate the blips, it's possible that it's some grounding issue in the Glyph drive.

I'm also wondering about the proximity of your PT gear to the audio cables feeding the board & monitors… also wondering what quality of cable those might be - how well they're shielded.

In any case, IF it's something that's NOT actually being recorded to disk, and doesn't show up in your mixes, and is low level enough to where you have to crank up your monitors & search for it to know for sure if it's there, but it caught you're attention one day and you want to make darn sure it's not a technical nightmare waiting to explode, you may have what we sometimes refer to as a "Spock" (Star Trek reference here…) "The difference that MAKES no difference IS no difference!"

Good luck with this - curious to hear about the SCSI cable/drive swap attempts.

Warmest Regards,
Brian