Change SR on an existing session?

[GrievousAngel]

This may be JR question, but how do you change the SR on an existing PT9.0.6 session? I 'recorded in' a live mix off of my Mackie SDR2496 ADAT multi-track which was tracked at 24/96 (48x2). I used my LYNX AURORA16 + LT-ADAT option for the interface via a AES16e. With ther PT session at 96KHz, I must set the AEs16 at 48KHz to playback properly! Any idea why? I understand ADAT MUX, etc. but maybe I am missing a few key concepts.

Thanks,
William

[cwsand]

Not sure exactly what you're experiencing, but you can't just change the sample rate of a session. You can use "Save Copy In" and create a new session at the new sample rate and Pro Tools will import and convert the audio files to the new sample rate. Or you can create a new session at the new sample rate and import session data to import and convert your audio files.

[GrievousAngel]

I'm from a Nuendo background and I think you allowed to change SR IF you were not in play or record mode. The reason I asked this was that the initial recordings were done on a ADAT multitrack @ 96KHz (48KHx X 2) and then recorded into PT at 96KHz. All OK except I always have to change the SR in my LYNX AES16e interface to 48KHz to aget proper playback speed. I was thinking about changing the PT SR to 48KHz just see how it plays back.

With ADAT MUX you have to run 2 tracks at 48KHz each to get 96KHz SR. Who can explain what going on in a ADAT MUX recording such as my session? Why do I have to run 48KHz on my LYNX AES16e and 96KHz in PT in order to properly playback the ADAT Mux tracks? Am I making sense?

Again thanks,

William

[cwsand]

That sounds really strange but it sort of makes sense if the Lynx uses 2 tracks at 48k to record all the bits. So the actual sample rate is 96K. If you want to work at 48k just convert it to a new session.

[GrievousAngel]

By design, ADAT s/mux uses 2 ADAT channels at 48KHz to achieve 96KHz. Example if recording ADAT signals at 96KHz (often referred to as 48x2), the number of available channels are cut by half.

My confusion lies in the LYNX AES16e, why it requires to run at 48KHz to playback at proper speed, while PT9 is set to 96KHx SR. I'm missing a detailed concept of how s/mux is actually working from the standpoint of the AES16e. PT runs at 96KHz and so does the ADAT multi-track which plays back at 96KHz (48x2). Only the AES16 requires a 48KHz SR, which is of course the middle piece of gear, (i.e., ADA converters).

Later,

William

[Top Jimmy]

Since the S/MUXing happens at the Aurora, there's no reason why the AES16e should be set to 48. If you mistakenly tracked the original tracks in while the AES16e was set to the wrong rate, it would make sense that you have to continue with that wrong rate. I would start over making sure all settings are proper before attempting the transfer again.

[GrievousAngel]

Top Jimmy,

You might be correct. I will do it all again. Understand though, that the AES16e is the clock master and the Aurora16 is slaved to the AES16 by selecting AES A clock source. The Mackie SDR2496 recorded the source at 96KHz (48x2) and plays back with the 48x2 LEDs active, so the SDR2496 ADAT source is without doubt correctly at 96KHz (48x2). PT9 session is set to 96KHz as well.

Do you use LYNX gear? How would you fly in the ADAT live recordings? I can use the SDR2496 USB option and copy the music files directly onto my DAW computer, instead of playback / record into PTs via the Aurora16. Would that be a better approach? I was thinking that re-recording via the better Aurora16 converters would improve the sound quality, but . . . I even considered running the SDR2496 analog outputs via an analog mixer then into the Aurora16. What do you think?

Later,
William

[Top Jimmy]

I think the USB option to be the most foolproof. Transfering via analog is not going to improve what you've already recorded. Serial DA/AD conversion has always been a no-no with digital audio. If you do transfer again, the clock master should be the SDR2496. Clock the Aurora to the incoming ADAT, and clock the AES16e to the incoming AES/EBU. This will assure a proper digital transfer, i.e. an exact copy of the original track. Then, once the transfer is done, you can return the AES16e to being clock master.