How to measure other speakers with REW using XMC USB input.

[ansat]

In the other two tutorials I showed how to use REW with the XMC using the USB input and the EMM microphone. We used the XMC's bass management to get REW's measurements to the subwoofer. You can however measure all speakers using REW and the USB method.


Using the USB method - REW sends the full signal to both the left and the right front speaker at the same time. We will use sound modes in the XMC to send the signals to the speakers that we want.

Here is the method that we used to use get the REW signals to the subwoofer.

You will need:
1. a measurement microphone (the emotiva emm-1 will work great)
2. REW link
3. a long usb connection to the XMC

Step 1 - plug sub(s) the XMC left subwoofer out.
Step 2 - Configure the XMC as the following (you will need to have speaker preset 2 clear of any PEQ or distances) In preset 2, configure your mains as small speakers and set the xover to 200hz (do not set this any lower) and configure the sub(s) to mono.
Step 3 - Plug in the usb connection to the back of the xmc and to your computer (drivers should start installing)
Step 4 - Plug in the XMC microphone to the computer
Step 5 - Open REW and click on preferences. Your "Output Device and Output" will be Speakers (#-usb2.0..)  set the default output to SPEAKER. set the "Input Device and Input" to microphone (#-C-Media). Check the "Control output mixer/volume" and set the "output volume" to 1.0


Step 6 - either turn off or disconnect your main speakers at the amplifier. (your subs need to remain powered on)
Step 7 - change the input on the xmc to USB stream and set the speaker set to Preset 2 and surround mode to Direct.

To measure your mains, Set the speakers in preset 2 to Large and the Surround mode to Direct (or stereo if you want to play with the PEQ on the XMC). Then unplug the speaker that you do not want to measure.

To measure your mains with an active crossover to the sub, set the speakers in preset 2 to small and set your desired crossover point. Set your Surround mode to Direct.

To measure your center, rears and surrounds, set your the preset 2 to large (or small if you want an active crossover) and set the surround mode to all channel stereo. you will need to unplug all speakers that you do not want to measure.   (NOTE : in all stereo the sound will not be as loud as the subwoofer measurements and the mains and you might need to turn up the volume up a little. If you need the same SPL for all speakers, then you can use the all channel stereo for the front measurements as well)

There is an easier method out there to swap speakers, but that requires additional setup and a HDMI connection from the computer to the XMC.  I have made a couple of posts on how to use the asioforall drivers and an HDMI on this forum or you can just google it and there is a ton of info out there.

As always, your questions are welcome.

Thanks,
Tony