RTA with two inputs running together

Damian

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Apr 26, 2017
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Hello

Is there anyway of setting up REW for two inputs. Ie reference input and mic input?

I am wanting to use this in a live scenario where I take a split off FOH out and use that as my reference trace and then have the mic be another trace to see the difference in signals?

Thx
 

KeesH_TNe

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Sep 8, 2017
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"Simple" home-made amps./speakers; in-/outdoor.
No, that type of 2-channel monitoring isn't in REW yet.
Severely delayed, but despite..
I also would be highly interested in that feature being available. It would allow to quantify the place-to-place correlation in a room, which, if properly used, should(!) provide extra information on e.g. the location of a strong absorber or reflector (and so room uniformity) and how this effect propagates throughout the room.
Also, it allows precise measurements of the transfer function using two NON-calibrated microphones (assuming those to behave decently smooth over frequency) by simply doing two measurements with the two microphones interchange position. Many more application can be guessed .....
 

MasterLufier

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Sep 3, 2017
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Yes, multichannel measurements it's so good, but not cheap, and needed good audio interface and much same microphones.
 

KeesH_TNe

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Yes, multichannel measurements it's so good, but not cheap, and needed good audio interface and much same microphones.
MasterLufter, I agree and disagree.
Agree: more-than-one-channel is very powerful and widely applicable. And the interface is important, but not to the utmost. So here I tend to be more optimistic.
Firstly, going beyond N=2 inputs might indeed get costly, also when it comes to the interface. However, as most audio-grabbers are stereo, the case N=2 is well within reach (financial-wise). And, secondly, one also does not really need two close-to-identical (and/or well calibrated) microphones, as long as these two are reasonably smooth in their transfer characteristic (both amplitude and phase). Note that we are not interested in anything like absolute SPL's but just in relative values, i.e. ratios. So, to do the 2-channel measurement one needs in practice 2 runs, with in the second run the two microphones being interchanged position as good as one can! Take the average of the two outcomes, and that (to first order) compensates for the differences between the two microphones, thus providing the ratio between the two SPL's at the two locations at hand.
Conclusion: I like a 2-channel option in REW ......, even if it would be a non-free option!
 
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