ProTools HD; delay beyond compensation

[CygnusX-1Bk2]

Hey, I love the way this thing sounds! Very smooth. Great for drums, which was my primary interest.

This is not a huge deal because I am using Redline Reverb as a send effect, but I feel that it is worth reporting. I am running ProTools HD 8 on a PowerPC MacPro G5, OS X 10.5.7, with dual 2.5's and 2 GB RAM. This is an HD 2 system, 96 I/O hardware with the playback engine set with a H/W Buffer of 2048, 2 RTAS processors at 90% CPU, ignore errors unchecked, 128 voices (4 DSP's), 44.1 kHz session, Delay Compensation set to Long, Disk buffer level 2, Large cache and Plug-in streaming level 8, optimized. My audio tracks are being output to different busses, depending on the instrument, which are summed to other busses for group "master" busses (not Master Fader but Aux Inputs). In one case one instance of Redline Reverb is inserted on a parallel bus and in another case another instance is inserted on an aux input from a send from the "master" bus. In each case Redline is the only plugin on that channel. In both cases Redline Reverb is delayed beyond the inherent compensation, with Delay Compensation view enabled in the mixer. The signal is delayed by 4164 samples which is beyond the auto delay compensation. The maximum user offset compensation is 4095 samples. The RTAS CPU usage is around 15%.

Of course because I am using this as a send effect, the mix is fully wet. I have not yet tried Redline as an insert. When I turn the mix knob to fully dry there is noticeable slap effect, which goes away when removing the plugin from the track.

I should also note that I am using TDM compressors and EQ's on other tracks. I have not tried using all RTAS effects. Redline sounds much better than the TDM verbs that ship with PT and other RTAS verbs that sell for much more.

Thanks!

[dj!]

Glad to hear you like what you're hearing!

As for the latency issue, the problem appears to lie with Protools itself since Redline Reverb has no inherent latency, neither as an insert or as a send. 

Do I suppose correctly that you have Redline Reverb inserted (directly or indirectly) after a TDM plugin?  In that situation Protools adds a latency of about twice the HW buffer to all following plugins--in your case 2*2048 = 4096.  (Where the additional 4164-4096=68 samples come from I'm not sure.)  You shd be able to reproduce the same latency with any RTAS plugin inserted in Redline's slot.  FWIW I have contacted Digidesign for an insider's explanation, am waiting to hear back from them.

BTW thanks for the extreme detailed report, that's extremely helpful in troubleshooting issues like this.

Thanks & take care,

-- dj!

[CygnusX-1Bk2]

Technically yes, because some of the bussed tracks have TDM plugins inserted before being routed to the sum busses where Redline is the only plugin. I kind of figured that was the issue. Looks like I will have to use the RTAS versions of the other plugins to test out latency that way. Because reverb is a delay effect and I am using it as a send this is not a huge problem.

Any chance of a TDM version?

I work in game development and am a former tester. Details matter!