Bizzare DSP/CPU feedback problem in PTulz ?!?!

S

sushi-mon

New member
Ok, my rig:

Ptool LE 6.8
Mbox 2
PC with 2.8 clock and 512 ram (yes I am going to upgrade the RAM)

My problem:

I was configuring a dual-mono reverb bus last night as an RTAS. So I could have one side of the D-verb set one way, and the other, the other way. I could choose between which side of the "unchained" reverb I wanted and how much I want piped from each audio channel.

3 audio channels, and the 1 d-verb auxilliary input channel. So I am not doing much here.

Everything runs fine, but when I pause play, my CPU usage meters jumps from about 10 percent up to 70-80 percent ! When I press play again, it all falls back down to normal.

After some tooling around, if I give the D-verb no inputs during pause, the CPU meter falls back to normal, if I disable the D-verb channel, everything goes back to normal during pause. So, it seems to be the DSP and/or bus I have configured causing the problem.

So, while the D-verb bus is not processing any signal and lying idol, I am getting some type of idle feedback loop or something. The only way around it seems to be to disable it during pause. This cannot be the way it is meant to be.

Maybe there is some sort of preference to set, that causes all DSPs to be automatically disabled during pause ?

Thoughts ? Help ? A shotgun ?
 
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There were several issues with this back in the past. And which one it is depends on how it's reacting with your system.

First off, is the issue bogging your computer down? I mean, besides the meter in the system usage window...is it inhibiting the way you are able to work? Any errors, or is it just weird that it's doing that? In some versions, this was just a visual glitch and it once you pressed play the CPU level would reset itself with no problems.

In other versions this was a problem with specific algorithms with the D-Verb plugin. Specifcally the Room 2 algorithms and was also more common using Pentium 4 processors. The work around was to use a different algorithm (ie. Hall) or put a random (small) plugin before D-Verb. Dither or Trim should work.

I also once came across this issue and found updating to the latest Pro Tools CS version worked...but I also realized I was having a FSB problem with my motherboard. It was set too low and PT was having problems getting data through the bus.
Hope some of this helps.
 
bennychico11 said:
There were several issues with this back in the past. And which one it is depends on how it's reacting with your system.

First off, is the issue bogging your computer down? I mean, besides the meter in the system usage window...is it inhibiting the way you are able to work? Any errors, or is it just weird that it's doing that? In some versions, this was just a visual glitch and it once you pressed play the CPU level would reset itself with no problems.

In other versions this was a problem with specific algorithms with the D-Verb plugin. Specifcally the Room 2 algorithms and was also more common using Pentium 4 processors. The work around was to use a different algorithm (ie. Hall) or put a random (small) plugin before D-Verb. Dither or Trim should work.

I also once came across this issue and found updating to the latest Pro Tools CS version worked...but I also realized I was having a FSB problem with my motherboard. It was set too low and PT was having problems getting data through the bus.
Hope some of this helps.
Click to expand...

Yes the computer is bogging down, and slowing up, and then errors start popping up, about holding off interupts, etc. It is definitely not just visual.

Funny, I was using the Room 2 algorithm and I have a P4. I will try the options you suggest and see what shakes out.

Please explain "CS" and "FSB" a little more clearly ?

THANKS !!!
 
sushi-mon said:
Please explain "CS" and "FSB" a little more clearly ?
Click to expand...

sorry
CS is Customer Service (or at least that's what I always understood it to be). Pro Tools would release CS updates for bug fixes every once and awhile. Unfortunately 6.8.1 was the first version for the Mbox2 and was ONLY available for Mbox2, so I have no experience with it. Also 6.9 and then 7.0 came out shortly after, so I doubt there were any CS updates.

Also if you are using Pentium 4's Hyperthreading, you need to turn that off.
FSB stands for Front Side Bus and is a physical bus on your motherboard. If you built your own, you'll have to look into information on how to correctly set it in your manual...otherwise, if you bought your computer direct from someone, it should be set properly already.

If none of the recommendations work, you may try installing the lates PACE Interlok drivers. http://www.paceap.com/dldrvr.html
You also might want to look into getting 6.9 or even 7.0. Depending on when you got the Mbox2, you may be eligible for getting 7.0 for free. And if not you should call up Digi and ask them how much the update would be.
 
bennychico11 said:
sorry
CS is Customer Service (or at least that's what I always understood it to be). Pro Tools would release CS updates for bug fixes every once and awhile. Unfortunately 6.8.1 was the first version for the Mbox2 and was ONLY available for Mbox2, so I have no experience with it. Also 6.9 and then 7.0 came out shortly after, so I doubt there were any CS updates.

Also if you are using Pentium 4's Hyperthreading, you need to turn that off.
FSB stands for Front Side Bus and is a physical bus on your motherboard. If you built your own, you'll have to look into information on how to correctly set it in your manual...otherwise, if you bought your computer direct from someone, it should be set properly already.

If none of the recommendations work, you may try installing the lates PACE Interlok drivers. http://www.paceap.com/dldrvr.html
You also might want to look into getting 6.9 or even 7.0. Depending on when you got the Mbox2, you may be eligible for getting 7.0 for free. And if not you should call up Digi and ask them how much the update would be.
Click to expand...

Thanks for all the info !

I went through the set up guide, and I could not find anything about hyperthreading on my P4 following the instructions. Searching for hyperthreading on my PC also brought up no results. So I assumed that my P4 does not have hyperthreading capabilities.

I have an HP Pavilion 7040 series lap top. So, I am pretty sure it is all running just fine.

I am able to upgrade to 7.0 for free, I just have not done it yet.
 
sushi-mon said:
Here is what seems to be the problem, a user at DUC pointed me to this article.

http://phonophunk.com/articles/pentium4-denormalization.php?pg=1
Click to expand...

I didn't know any of the digidesign products had denormaliztion problems. Bummer. Another reason I wouldn't touch the product line!

But, the described problem DOES sound like denormaliztion. It might or might not be "fixed" in a later version of the plugin/software.

Wouldn't you need a dithering plugin AFTER the reverb to stop the problem?
 
Ford Van said:
I didn't know any of the digidesign products had denormaliztion problems. Bummer. Another reason I wouldn't touch the product line!

But, the described problem DOES sound like denormaliztion. It might or might not be "fixed" in a later version of the plugin/software.

Wouldn't you need a dithering plugin AFTER the reverb to stop the problem?
Click to expand...

No, the idea is putting the dither (noise generator) plugin BEFORE the reverb plugin so that noise is always being input into the reverb and it doesn't have to do precise calculations with tiny numbers.

It's more of a combination of CPU and Plugin...not just "Pro Tools specific." As you can see in the example of the above link with Cubase SX2 and a low pass filter plugin.
I haven't experienced denormalization with any of my processors or plugins, so I really can't speak from experience, though.
 
Well, D-verb IS a digidesign plugin. ;) And as I recall, the easy fix is just a pass filter set at like -250dB of something like that. Shouldn't be all that hard to put in a plugin that is having problems!
 
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