rtas problems in ptotools 7.0 (g5 tower). help!

[mattpreston]

hi there

anyone experienced problems with RTAS plug-ins under Protools HD 7.0?

the system is as follows: Mac g5 dual processor tower, osx 10.4, protools 7.0, HD1/HD Accel, eventide clckworks bundle, sony oxford reverb

the problem:

am testing out some guitar amp simulation plug-ins with a view to purchasing some for my Music Department (college). we have a very stable protools HD system which is used every day and has hardly ever crashed or behaved strangely. however, the one time i experienced problems was when i was mixing a track and used Amplitube LE as a RTAS plugin. normally we use TDM exclusively. i kept getting a strange, high pitched constant digital buzzing noise upon stopping playback.

today i have been evaluating the various different software packages (pod farm, ampeg SVX, amplitube 2, amplitube metal and Overloud TH1) and am very impressed by the quality of TH1 and Ampeg SVX (and also some of amplitube). the only thing is, there seems to be some instability as a result of using these plugins. the various glitches were:

on changing amp models during playback occasionally the audio would go very bizarre - almost like it had some strange digital distortion/ring modulator effect on it. this disappeared upon stopping the track and restarting it again.

when using a mono>stereo version of a plugin (either TH1 or Amplitube) one side would disappear. this could be sorted out by changing the output of the channel to a different output and then back again, but then the plugin on the next channel along the mixer (also an RTAS one) would lose one side instead.

occasionally i was getting CPU messages (running out of..) and spikes that stayed pinned to the top until i restarted playback.

could all these problems be simply down to over-taxing the native CPU? this was happening at one point with only 2 RTAS plugins running (1 ampeg and 1 TH1) and the average CPU was only about 30 percent, but it was flickering up & down quite a lot. the sample buffer in protools is set to 256 and plugin delay compensation is switched OFF (as i had heard that it can cause more problems than it solves...and up until now we had not really been using RTAS stuff anyway).

anyone else had issues with protools 7.0 and RTAS plugins? especially CPU hungry ones

i am thinking of increasing the buffer size to try to accomodate the additional native CPU use, but i am slightly confused about this:

if i increase it right up to 1024 i presume i will really need to enable delay compensation (a student changed the buffer to this setting by mistake once and the channel using an RTAS plugin lagged behing the others by miles). will this affect the latency of the TDM bus during recording? i'm presuming not, but any tips welcome (or potential pitfalls of delay compensation, if indeed there are any...)

[DigiTechSupt]

Try changing the number of CPU's in the playback engine to '1' and let us know if it helps at all.

[mattpreston]

Originally Posted by DigiTechSupt

Try changing the number of CPU's in the playback engine to '1' and let us know if it helps at all.

thanks mate - just read the other thread and there's some useful info in there too. will try it tomorrow. am praying it sorts things out because these plugins sound so awesome, but i dont want to cause my students problems.

have you ever heard of the problem i described where one side disappears on mono>stereo plugins?