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-   -   SPDIF Question (http://duc.avid.com/showthread.php?t=168436)

Doog 05-22-2006 08:13 AM

SPDIF Question
I recorded a Kurzweil PC2 keyboard through it's digital out into my 002 console through the SPDIF IN. The session is set at 24bit/48kHz. The Kurweil does not have an external clock input, and I don't have a separate clock so I have the Hardware Set up in protools set for RCA = S/PIDF, Clock Source Internal, and Sample Rate 48kHz.

Everything seemed to record fine, but I recently discovered that my Bass Pod Pro has a digital SPDIF output also and I would like to record it this way also. This caused me to investigate both and led to 2 questions. (I have been using my 002 and PTLE for quite a while, but always with analog inputs - I would like to use the digital inputs more in the future)

1) - The Kurzweil manual says the digital audio output is 48kHz linear PCM, and that the bitrate is adjustable including 16, 18, 20, and 24bit. The default is 16bit which is probably what we recorded at. Should I rerecord with the bitrate at 24 to match the rest of the session. Will I have potential clock issues with the clock set to internal? If so, what would they sound/look like?

2) With the Bass Pod Pro there is an option for an external clock input, or 44.4kHz or 48kHz settings. Output is 24bit. I don't have an external clock and I don't want to mess up the rest of the session. Should I set the 002 for internal clock and set the pod at 48 to match the 002? I have not tried recording with the pod yet and won't be able to for a couple of weeks so I was hoping to get some thoughts on the best setup.



daeron80 05-22-2006 08:33 AM

Re: SPDIF Question
When recording from the Kurzweil and Bass Pod, set the 002 clock source to RCA (S/PDIF), and set the Bass Pod to internal clock. That way, PT will use the clock of the device it's recording from, and receive the data bit-for-bit. Be sure to return the 002 to Internal clock afterward; otherwise, any other audio you recorded would be done using the instrument's clock. In all likelihood, the 002 clock is superior to the Pod's and as good as the Kurzweil's.

OTOH, you might try tracking a few things using the Kurzweil's clock and see how you like it. It might be lower jitter.

Doog 05-22-2006 10:12 AM

Re: SPDIF Question
If I use the POD or the Kurzweil clock with PTLE set to Clock Source S/PDIF and record several instruments for a demo or a base line framework track (guitar, drums, scratch vocals and either the Bass Pod or the Kurzweil), then does all of the analog input get converted using the external clock? If so, when I unhook these and go back to the internal clock and mix will I have pitch and time issues when bounced? All of my session are at 24 bit/48kHz.

Also, I just went back and listened to the Kurzweil track orginally recorded using the digi internal clock. It is loaded with clicks and pops. My second question is - I recorded a midi track at the same time, is it effected by the clock issue? Can I pump the midi track back through the kurzweil and record it with either through an analog input or through the S/PDIF channel with the clock source set to S/PDIF. If this is done will the popping be gone and everything good, or did I screw up the MIDI also by using the Digi internal clock?

Thanks for your help,


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