# Soundcard/pre-amp for using with REW



## svm88 (May 7, 2011)

I am going to start using REW to do some measurements of my new speaker project with minidsp and are looking for a good solution for soundcard/pre-amp for the mic. Since I also may need a small mixer for other use I though of buying a cheap USB mixer like Behringer 1204USB Xenyx. Can this be used with REW as soundcard/pre-amp for mic? 

I cannot post a link because I do not have more than 5 posts here yet... But this mixer is selling for only 139USD inc shipping on ebay. 

All answers are very appreciated


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## EarlK (Jan 1, 2010)

There's no history here of that unit being used, either successfully ( or not ) . 

You would be the first guinea pig . 

I think it should work ( my opinion is based on Behringers history of using the builtin USB drivers that ship with host computers OS / but then, I've been wrong before ).:innocent:

Are you a gambler/tweaker ? :boxer: :devil:

<> EarlK


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## Wayne A. Pflughaupt (Apr 13, 2006)

EarlK said:


> ...but then, I've been wrong before ).:innocent:


Well, I’ve yet to see that... :hail:

Regards,
Wayne


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## svm88 (May 7, 2011)

Okay  

It will be frustrating if it do not work, but I think I will give it a shot and see how it works out.


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## Theresa (Aug 23, 2010)

I haven't done much measuring but with a cheap microphone phantom power supply the Realtek 889a on my motherboard's microphone input works. I don't use that sound "card" as it doesn't sound very good but for measuring it seems to work fine. My Asus Xonar Essence STX is excellent sounding but it's microphone input is very noisy. Just a tip for those having a 889a on their motherboard.


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## EarlK (Jan 1, 2010)

Earl said:


> ...but then, I've been wrong before ).
> 
> 
> Wayne said:
> ...


You're too kind / but really,, it's a very tattered jacket upon closer scrutiny .

:dontknow:


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## rbcollins (Aug 5, 2011)

svm88 said:


> Okay
> 
> It will be frustrating if it do not work, but I think I will give it a shot and see how it works out.


So did you purchase one and try it? I just received one today but haven't yet worked out a method to do a calibration of it as an external sound-card


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## rbcollins (Aug 5, 2011)

Update: this unit appears on the PC as a USB soundcard with a MIC unless you use the ASIO drivers. Only then does it appear as a "line-in". Line-in receives whatever audio is playing through the "Main" output on the mixer. The sound-card audio going to the mixer is the "2-track/USB" channel on the mixer board. So it appears you'd need to loop the "2-track/USB" channel on the mixing board over to the "main" in order for it to loop back on itself. The board included a button to send "usb to main" but unfortunately when you do this it cuts off the output to "line-in" via USB effectively breaking the loop.

I was able to send "2-track/USB" to the control-room output and then loop that back to "MIC1-LINE_IN" to send the audio back to the the USB sound card line-in on the PC, but control-room/phones doesn't appear to the a line-level output since it has a volume control. It did pass to do a calibration in REW this way, but the graphs looked suspect to me compared to ones done on my PC soundcards in the past. They didn't look as bad as when you use a mic input on a laptop for instance, but still not typical.

The next thing I'll try is using "Virtual Audio Cable" to loop the USB output and line-in on the laptop directly (i.e. no physical cable loops) to see if that will measure freq response accurately or not of the USB sound card.

The board works fine with my Behringer mic and will be great as a consolidated USB sound/card and phantom-power mic input if the sound-card itself can just be calibrated with REW.

Oh, and this board was only ~$125 new online, so good price-point for an all-in-one solution.


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## rbcollins (Aug 5, 2011)

Update: I got it to work finally. To calibrate the USB device, use the ASIO drivers and set the input and output to the Behringer device. Then connect the Control-Room Right output to the channel-1 LINE-IN input. Press the 2-TR/USB Source button to send the USB audio to the control-room/phone outputs and max the volume on the control room knob. Then I set channel 1's mixer volume to 0, main volume to 0, and the channel-1 gain to about -5db. Run the REW calibration and you should see the test-tone sent out the Behringer USB device and then received back on the same device. Tweak the mixer levels to get your -12db signal as normal for any other sound card calibration. I'll post the resulting JPG later, but it appears to be a very flat response in this board. I'll take some readings tonight and post actual REW results as well.


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## rbcollins (Aug 5, 2011)

Update - It turns out it works better using the headphone jack instead of the control-room output on this unit for me so that you can use all stereo cables (which I had lying around) when doing the sound card calibration. 

So final procedure was to attach the head-phone jack to the MIC1-Line_In, Set the Headphone volume to 50-75% range, Press the red "2-TR/USB" Source button to send the audio to the phone jack (don't use send it to MAIN). Set levels as listed above as a starting point and then tweak them during the calculation tone playback to get your desires FS level.

Attached is a graph showing the final result.


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## EarlK (Jan 1, 2010)

( RB ) Thanks for the update on this product ! I originally missed it, as I was out of province for work reasons ( & offline, & ignoring Forums ) .

Anyways, it's good to know that it can be calibrated ( one way or another ).

<> cheers


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## SAC (Dec 3, 2009)

Many would simply prefer to spend less for the same functionality versus the coast of a pre-assembled kit featuring a mic-preamp, calibrated mic and interconnects.

But for about twice what it would cost you to assemble an equivalent kit yourself, if you are willing to spend ~$250USD for someone to assemble the interconnects, preamp and a calibrated mic into a kit that you can easily do for about 1/2 the amount,_ go for it. _ 

And (unless one simply requires higher compliance) it appears to be a substantial unit. 
The benefit of either assembling the part yourself, or buying a pre-assembled kit is that either approach affords you the advantage of still using a more capable platform, such as REW or ARTA, than is offered by such platforms as either XTZ or Omnimic!

However, an issue that the kit does not address, and where I would suggest that most folks seem to have the most problems, is not in assembling the mic and pre-amp, but rather in understanding the secondary software configuration of the I/O and of routing the signal through their receiver in order to achieve both sub and speaker output.

Additionally, at least in the realm of hobbyist applications, the tendency is to look for the least expensive but not necessarily the best performing setup. Whereas in professional use the tendency is toward significantly better phase linearity in both pre-amps and mic - a good example is to compare the performance of the Duran Audio Axys pre-amp - that literally has a level of performance that cheaper pre-amps cannot approach - a level that is useful for many more critical applications where the intrusion of the platform as a limitation to what can be measured is not desired. Additionally, with multiple input supported platforms, the trend seems to be to begin moving beyond the bandwidth limitations of USB and Firewire to Ethernet connectivity.


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## SAC (Dec 3, 2009)

duplicate. please delete.


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