Topic: Do I need to use a digital delay when running an on-stage matrix?

[carrington]

Planning on taping some shows this weekend on-stage.  I was thinking of running a matrix...I have a Mackie 1202 4 channel mixer that I just got.  I have access to a digital delay, but I'm not sure if I'll need it.  Any info?

Also, what's the best way to run/set up the matrix with the mackie?  I understand that I would go 4022>mp2 + SBD >Mackie>MMe, but how do you set the gain, mix the 2 feeds, etc.

Thanks for the help,
C.

[Marc Nutter]

Hi Carrington (and All),

I suspect this is late for the shows you were planning but I hope it helps for the future.

While you may hear arguments that you can get away without using a delay line to align a console signal with an ambient pair of microphones, be aware of the following:

Without proper alignment tools, like SmaartLive, see http://www.siasoft.com , it is nearly impossible to set a digital delay properly.  If you are in an isolated room monitoring the sources, you may be able to hear well enough to make a good decision but don't expect to achieve it on your headphones in the same room as the music is playing.  You can use an estimate based on distance and speed of sound but you will only come close.

An offset of 1mS (about the time it takes for sound to travel one foot) in either direction will cause comb-filtering starting at 500Hz.  This means that from 500 Hz on up, you will have a -24dB or greater null in the frequency response at 1000Hz intervals.
While our ears are more sensitive to frequency response peaks than they are to nulls, this deep combing is quite audible.  

The most audible effect of misalignment is brittle high-end, edgy mids, scratchy/thin vocals, and potentially weak bass response. It won't be anywhere near as easy to identify as the echo caused by delay beyond 30mS.  For those who have workstation, take the time to align something properly, then insert a delay on one stereo pair.  Gradually increase and decrease the delay to hear the effect of the offset.

I have addressed this in greater detail in our forum
http://207.36.59.179/cgi-bin/yabb/YaBB.cgi?board=software;action=display;num=1044386172

Generally, my sentiment is that "matrixing" without a measurement tool, or without a DAW, is the best way to take two really good recordings and make one mediocre one.

Happy Recording,

Marc