Topic: Would this work for a matrix? (may help lots of people if so!)

[morst]

This would help most if you are using two different decks for the first time. Recording a test signal at the start and end of a continuous track will help with the time stretching aspect. What this will not help with is determining the relative delay between the sbd and aud sources. That is mostly determined by the distance between the mics and the source as modified by the local speed of sound which is dependent on air pressure, temperature, and humidity. Roughly .88ms/foot give or take a room full of sweaty dancers! 

[joemango]

I agree.  In order to get the time alignment aspect exactly right you'd have to record a "slate" sound from the mic source on both decks at the beginning AND end of the recording. 

Using a drum click at the start is great but it has the natural room delay between the two decks.  The slate method at the end of the recording will not have this inherent delay.  So you'd have to offset one of the sources by the room delay time and THEN make your time base adjustments.  You're actually adding more math to the equation your way.   What might be better would be to go to the stage before they shut off the PA and fire a gun or knock over a mic stand   But then you're dealing with possible law enforcement action.  Not good.

Considering you are being given a SBD patch, you may have the ear of the sound engineer and may be able to get his/her cooperation in producing some sort of pop or click through the PA that you can use as a timing mark on both sources.  They may have a talkback mic that can be used for this purpose. Or you could start rolling early and use the house music at the start and stop of the show as a benchmark.  Or wait until just before the set starts and use your method to make a start slate and an end slate, but you risk missing the start of the set and/or pissing off the engineer by trying to get to your SBD deck too close to the start of the show. 

But marking only one end of the recording with a synched signal won't help much I'm afraid.