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Discussion Starter #1
Thanks brucek for answering my previous post so quickly. I thought that ASIO drivers might be the problem. I put this on a new thread and title so maybe more folks would read it.

I've installed a music venue that I need to voice ASAP; it's my main reason for researching these RTA programs. We're using a Peavy PV20-USB mixing board for the two channel house sound and two channel stage monitors, with Behringer EQs in each channel. Windows immediately recognizes the board as a USB sound device without loading any drivers or anything and I'm able to record and playback to it from a laptop with no problems so it must use a WDM driver. I'm assuming that it should do the trick with REW. I've got an ECM8000on the way and can plug it into one of the phantom powered mic channels on stage for EQing the monitor system, and take it out into the audience area with a long cable for doing the main system...

Oops!, I think I just realized that what I was planning to do won't work after all since the only output from the board to USB is the final mix, not individual channels. OK, so I'll use a little Sound Blaster SB0270 that I have, connect it to the laptop, run it's output to a line in on the board for the sweep or pink noise signal to the system, then pull only the ECM8000 mic channel off the board using the insert jack or effects out jack (keeping it turned off from the main and monitor systems) and run that to a line in on the Sound Blaster. That way I'm getting phantom power and preamplification from the board without having to have a separate preamp.

Sorry about getting so long-winded here, but I thought I'd leave in all of that first part I was typing, just in case anybody else had thought along those same lines.

Anywho, if anybody has followed me this far, am I getting way off base here, or do you think this would work? Has anybody here done anything like this before and do you have any advice? This place I'm doing is pretty far from home and way out in the sticks so I need to have everything I need when I go back, and I can't spend a lot on preamps and power supplies and stuff (cables, I've got or can make).

Thanks, Mike
 

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I would think it should work. You will have to do a soundcard calibration that includes the full in/out path. The soundcard cal routine and subsequent loopback cable measure will tell you if it's going to work or not. Note any deficiency in the mic preamp won't be included in the soundcard cal routine, but that would be quite minor in its effect.

brucek
 

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Yeah, it'll work, depending on what you're trying to do with it. Naturally if you're taking front of house measurements, you'll have to keep the other mics muted; otherwise they'll all be feeding a signal to REW via the USB. Might want to keep any other channel you have something plugged into muted as well, in case they're adding residual noise. Direct feeds from backline amps can be noisy, as you probably know...

I assume for "EQing monitors" you want to EQ for feedback, which means the stage mics need to be active. Typically the monitor signal is fed from an Aux send, which is isolated from the main output. But muting the mic channels (again for the purposes of letting the ECM 8000 feed REW) would mute them in the monitors as well; an easy work-around would be to simply pull the main sliders all the way out, all but the ECM 8000's channel.

Naturally, if you intend to use REW as an RTA during a performance, you should probably use a separate sound card...

Note any deficiency in the mic preamp won't be included in the soundcard cal routine...
That can't be accomplished by looping the mixer's XLR output to an XLR input?

Regards,
Wayne
 

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That can't be accomplished by looping the mixer's XLR output to an XLR input?
Well, you could, but I think using the mixers XLR input path wouldn't be the same path used during the measure routine when he's using the line in on the board from the line-out of the soundcard. I was trying to avoid any response differences so the soundcard cal would be as accurate as possible (save for the mic amp itself).

I also figure that the mic path might be a bit too twitchy because of the high gain of the mic amp itself.

Anyway, these are things for Mike to consider...

brucek
 

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Okay, I see what you mean. I think maybe you're thinking of the common REW set up using a mixer like the Behringer Xenyx connected to a soundcard?

In this case, the Peavey mixer is the sound card, since it has a USB output. So the in/out loop is XLR, and by default will include the mic pre amp.

The only potential problem I can see (and I'm just speculating here) is if REW expects to see a line level signal for soundcard calibration. If so that could be a problem because in the calibration loop for a mixer like the Peavey, the signal level is variable, giving the wide range of adjustments available between the input gain knob on the channel strip and main output slider. IOW, if REW expects a certain signal level for the soundcard calibration, matching that level with the Peavey could be a challenge.

Maybe John can check in and let us know something about this.

Regards,
Wayne
 

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Discussion Starter #6
I assume for "EQing monitors" you want to EQ for feedback, which means the stage mics need to be active.

Wow, I'm getting a lot of help and ideas here. Thanks! Actually what I meant about EQing the monitors was that I wanted to check for any resonate peaks on the stage with the cal mic (I'm getting sort of a boominess that I'm just guessing at and trying to eliminate with the equalizers) and then I would ring out the system for feedback with the stage mics live.
 
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