Inconsistent Tempo/Playback slows down,speeds up
 

Hi everyone,

I'm running Pro Tools 8.0.1cs2 on a powermac G5 dual core 2.3ghz, OS X 10.5.8. The problem is the playback cannot hold a consistent tempo, so if I'm trying to create a drum loop, whether it be audio or midi, fully quantized or not, I can't retain the groove, rhythm. I can see the fluctuations clearly in the main counter or big counter, bars go slow then fast, and it seems completely random, even on a completely blank brand new session. I'm not getting any error messages. I'm not sure if this like a sluggish playback that catches up at various points or what. Any advice greatly appreciated, if you need any more info, please let me know.

Also I'm on a digi 002, lacie extreme triple interface external HD for recording, everything connected 6 pin firewire. Internal clock on PT. No third party plug ins, just what came with Pt.
I've tried:

- reinstalling OS and pro tools
- repairing disk permissions, repair disk
- changing firewire cables
- different h/w buffer settings, sample rates, all kinds of preferences
- trashing prefs

Re: Inconsistent Tempo/Playback slows down,speeds up
 

How much RAM on this G5? Is this a new issue or has it always behaved like this? If a new issue, what's changed (software additions, updates)?

Bob

Re: Inconsistent Tempo/Playback slows down,speeds up
 

Hi Bob,
I've got 4gb of ram. I'm not really sure when it started, I just know I noticed it a couple months ago, because I've been very focused on creating tight drums, and realized I can't create a loop that is consistent. When you watch your main counter time, does it remain completely constant or do you notice, especially if your watching the smallest increments, that it fluctuates at all?

Re: Inconsistent Tempo/Playback slows down,speeds up
 

I have changed my main hard drive about 6 months ago, but it is the exact same model as the original hitachi that came with the G5, but it seems to be working fine.

Re: Inconsistent Tempo/Playback slows down,speeds up
 

The only times I've seen fluctuations could be traced to heavy system loads, or to inappropriate Setups.

4 Gb RAM isn't a lot, depending on the specific VIs in use, and the number of them running. What do you have instantiated, including any that are in Bypass when you see this behavior? If you show Windows>System Usage, what kind of loads are indicated?

What are the settings in use for Buffer Size and Number of Processors? If you aren't actually recording, does it behave better at the highest Buffer? Have you set the number of processors to one less than all available?


Bob

Re: Inconsistent Tempo/Playback slows down,speeds up
 

Did you reinstall PT, etc., or migrate?

Re: Inconsistent Tempo/Playback slows down,speeds up
 

This is happening on brand new sessions, no instruments at all. Happens no matter what buffer size, and yeah I've tried it on one processor, same thing. I reinstalled everything OS and PT. I've tried disabling blue tooth, airport.

Re: Inconsistent Tempo/Playback slows down,speeds up
 

Well, it seems like you've done a good job researching and correcting as far as I can see. At this point, I'm leaning toward something unusual about your rig, so apologies in advance....

The wiring is MAC>LaCie (fw400)>002 (fw400)? No other Firewire devices at all?
The LaCie is formatted per the Avid spec? No RAID?
Do you have anything connected to the Ethernet port?
Which video card is in the machine? How big is the cache?
One monitor or multiple monitors?
I assume that PT is the only running app, aside from Finder?
Wired keyboard and mouse?
You've checked the installed plugins against the Plug Compato list?

And just to confirm, a new session with no tracks at all exhibits the twitchy counter? If you make a click track only, does it play OK or unevenly? Is the playhead traveling smoothly or jumpy?

You get no error messages at all?

Sorry for the barrage, just looking for non~obvious causes.

Bob

Re: Inconsistent Tempo/Playback slows down,speeds up
 

Well, actually no, I have it configured where the g5 connects to the digi via front panel firewire 400, and the g5 connects to the Lacie via backpanel firewire 400. I thought that was the right way. No other fw devices.

The Lacie is mac os extended journaled, no raid

Nothing in ethernet port

Video card is Nvidia GeForce 6600, I'm not sure the cache size, I see VRAM(total) 256mb.

I have two LCD monitors.

Just PT running.

Wired mouse, keyboard is bluetooth, but I've had it disabled while trying to work this out, and will be getting a wired one.

No plugins other than what came with PT8, which is supported by OS and G5.

Yea, blank session twitchy counter. Click behaves the same way a kick drum would be if it was there, somewhat random sounding. And now I zoomed in real close to the playhead traveling and it's not smooth.
Don't be sorry, any ideas helpful.

Re: Inconsistent Tempo/Playback slows down,speeds up
 

OK then. I'll check back later. Any other ideas from the Peanut Gallery? Bueller?

Bob