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Discussion Starter #1
I am trying an experiment. Is there any way to get REW to accept input from LEFT and RIGHT channels at the same time and perhaps sum them?

Or, will I need to do the summation of L/R on a Binaural MIC set via hardware (summing amplifier) and then send the summed signal to LEFT or RIGHT channel in REW?

Ge0
 

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If they're standard electret condenser mics that use the standard 15-48 volt phantom voltage, then the Behringer XENYX 802 would be fine. You need a mic preamp anyway to bring the mic level up to line level for use with REW.

You will require a calibration file for the mic to use with REW.

brucek
 

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Discussion Starter #5
If they're standard electret condenser mics that use the standard 15-48 volt phantom voltage, then the Behringer XENYX 802 would be fine. You need a mic preamp anyway to bring the mic level up to line level for use with REW.

You will require a calibration file for the mic to use with REW.

brucek
Thank you for coming through once again Brucek. I could use this sucker to sum my mic channels to a single channel plus have extras. All this for less than I could probably build my own for (assuming time is worth money that is :)). The Behringers summed mic signal would feed into my M-Audio Mobile-pre. I would have one channel on the Mobile-pre for MIC and another channel for loopback to set my timing reference. Not the most elegant solution seeing how there will be two boxes and an excess of cabling, but, should work just fine.

Ge0
 

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I would have one channel on the Mobile-pre for MIC and another channel for loopback to set my timing reference.
I assume you mean that the "MIC" channel you're referring to the line-in of the Mobile Pre?

and another channel for loopback to set my timing reference.
Why do you need the timing reference? The preferred method using REW is to create a soundcard calibration file and then only use the single calibrated channel with the other channel left open and unused. It's more accurate and easier to use REW this way.

brucek
 

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Discussion Starter #8
I assume you mean that the "MIC" channel you're referring to the line-in of the Mobile Pre?
Yes of course. Perhaps I should have been more clear.


Why do you need the timing reference? The preferred method using REW is to create a soundcard calibration file and then only use the single calibrated channel with the other channel left open and unused. It's more accurate and easier to use REW this way.

brucek
Good question. I want to factor out the variable latency through the preamps & operating system when taking impulse response measurements. This is for the purpose of accurately measuring (and compensating for) arrival time differences between individual drivers. In case you are wondering, I don't have a conventional speaker system. I'm just getting started with REW and am not sure if it supports this functionality. I previously used software called ARTA that did. But, that software is lacking in key areas and is no longer under development. REW seems new, refreshing, and has endless possibilities...

Ge0
 

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Discussion Starter #9
Doesn't summing binaural mics kinda defeat their purpose?

Regards,
Wayne
Good question Wayne. I am not using the binaural mics for their conventional purpose. Rather, I am attempting to take a shortcut in making frequency response measurements using the Localized Sound Power Method as devised by Dr. Earl Geddes for use in an automobile:reading:. I believe this can help me in my application.

The localized sound power method takes response measurements over a number of locations surrounding the listening area. The measurements are then averaged to get a response plot that covers a wider area than the point source measurement taken via the conventional method. That way if you move your head or shift your location slightly the balanced frequency response you hear won't collapse. I'm trying to cut down on measurement time by performing the averaging via hardware vs. numerous measurements taken that are then summed in software.

Call me ignorant, but, I strongly believe that using binaural mics is the way to go when making measurements vs. using a single point source MIC on a stand. Placing the mics in your ears takes into account the effect of your head and how you interpret frequency response.

Why go through all of this? All I can say is because I can. Musical playback has never seemed so lifelike to me since I have started implementing this method. At the end of the day, that is all that matters.

Ge0
 

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I want to factor out the variable latency through the preamps & operating system when taking impulse response measurements. This is for the purpose of accurately measuring (and compensating for) arrival time differences between individual drivers.
Yep, understood.

I'm trying to cut down on measurement time by performing the averaging via hardware vs. numerous measurements taken that are then summed in software.
To take eight quick measurements with an omni mic in REW and then push the Average button is fairly quick. Your method only averages two spots. I doubt you can better REW in that regard. :)

brucek
 
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