This, rather then a “Bug” or “Workaround”, is a look at the Delay Compensation Engine in ProTools HD 8.

Likely a residual “Belief” amongst many engineers, stemming from previous versions of Pro-Tools TDM, where perhaps the delay compensation engine was problematic… The statement, “Once you’ve started to mix, and insert plugins, especially a mix of RTAS and TDM plugins, you need to ALWAYS open, and run your sessions, using the same exact HW Buffer size… Otherwise the delay compensation engine will NOT be performing accurate calculations, and your mix won’t be phase coherent” is a thing of the FAR past.

This is a post, putting ProTools 8 HD’s Delay compensation engine to the task, of recalculating a complex mix, with RTAS & TDM plugins mixed on EVERY track, Controller written automation on several tracks, several paralell compression Aux’s, as well as mult’s with different plugins - All NULLING with the original buffer (64), when changing the sessions buffer to 128, 256, 512, 1024, and ONLY causing a problem at 2048, when the delay compensation engine is “Out of range” and turned red.

I’ve had this argument with several engineers, and after sending a link to this video, posted on a forum, have not only changed the minds of my arguing friends… have received reports of controlled tests, showing the SAME competency in the delay compensation engine, as far back as PT HD 7.4, on 3 different systems.

So… our collective conclusion, is that this has been solid for a while, and that it hasn’t been necessary to maintain identical buffer settings, through the life of a mix, as long as you are not out of range.

If anyone is running earlier versions then 7.4 TDM, please do this same test, and write in with the results, and your version number, and we’ll document problematic versions here, as well as “Where it seemed to be fixed”