REW Forum

**sub_junkie** · **08-30-09, 12:23 PM**

I am thinking about getting the Behringer Ultragain MIC2200 and using it as an HPF for 13.50hz. I would probably have to run it through REW to make sure that it's set correctly and so my sub won't go over Xmax. I just don't understand how to run REW to make sure that the HPF is set correctly...

I have a Dell Inspirion B130 with everything stock on it, so I would probably need a bettersound card. I have a desktop computer that was used for light gaming, but it recently crashed. I don't know what sound card it has and if it would have the needed inputs and outputs for REW.

Would I just match the graph that I got from REW with my graph from WinISD to see the frequency response with the HPF set correctly?

I'm not fully understanding how this stuff works so I will be reading up on the threads here, hopefully being able to understand it better.

Thanks for any help

**brucek** · **08-30-09, 01:10 PM**

Any computer soundcard that has a line-in (not mic-in) and a line-out will suffice fro REW.

Measuring a piece of line equipment to obtain its response is quite simple.

First you connect a single cable from the right channel line-out to right channel line-in of the soundcard and run the soundcard calibration routine. Save the file it creates so that REW has it loaded.

Then without removing that loopback cable, do an REW response measurement from 0hz to the upper frequency you require - probably 200Hz in your case. Before measuring the loopback cable you must first run the Check Levels routine and the SPL calibrate routine.

The response of the loopback cable should of course return a perfectly flat line response from 0-200Hz (if you created the soundcard calibration file correctly).

Now simply insert the line device you want to test in place of the loopback cable. The response you measure will be the frequency response of the device.

brucek

**busahaya03** · **08-30-09, 01:17 PM**

Hello, don't mean to thread jack, but I'm having a funky response from my soundcard cal, I posted this in my own thread but I'm not sure it made it up on the boards, is a 20Hz to 20kHz; with a flatness of +8.1, -0.2 reasonable?

**brucek** · **08-30-09, 01:19 PM**

Quote:

don't mean to thread jack

Post a graph in your own thread and we'll certainly look at it.

brucek

**sub_junkie** · **08-30-09, 01:33 PM**

Quote:

brucek wrote:

Any computer soundcard that has a line-in (not mic-in) and a line-out will suffice fro REW.

Measuring a piece of line equipment to obtain its response is quite simple.

First you connect a single cable from the right channel line-out to right channel line-in of the soundcard and run the soundcard calibration routine. Save the file it creates so that REW has it loaded.

Then without removing that loopback cable, do an REW response measurement from 0hz to the upper frequency you require - probably 200Hz in your case. Before measuring the loopback cable you must first run the Check Levels routine and the SPL calibrate routine.

The response of the loopback cable should of course return a perfectly flat line response from 0-200Hz (if you created the soundcard calibration file correctly).

Now simply insert the line device you want to test in place of the loopback cable. The response you measure will be the frequency response of the device.

brucek

Ok, now I'm starting to understand it better.
For a sub amp, do you mean the right line-out going to the sound card would be basically the RCA cable that you would use to hook the amp up to your receiver?

Thanks for the help

**Wayne A. Pflughaupt** · **08-30-09, 03:45 PM**

Normally, you'll connect the sound card's output to an input on your A/V receiver. However, it's fine to connect it straight to the subwoofer input, if you prefer.

Regards,
Wayne

**sub_junkie** · **08-30-09, 03:47 PM**

Ok. Would it make any difference in connecting the input to the amp's input instead of the receiver's input?

**Wayne A. Pflughaupt** · **08-30-09, 03:53 PM**

If it's an amp that's driving your subwoofers, then yes.

Regards,
Wayne

**sub_junkie** · **08-30-09, 04:53 PM**

Yep. What kind of connection would I use to hook i up to the sound card? Just an RCA cable, right? I haven't looked at sound cards in a long time...

**brucek** · **08-30-09, 04:53 PM**

Quote:

Ok, now I'm starting to understand it better.
For a sub amp, do you mean the right line-out going to the sound card would be basically the RCA cable that you would use to hook the amp up to your receiver?

Wait a minute...............

You asked how to measure the HPF of a line device (a Mic 2200) - not an amplifier that feeds speakers.

DO NOT attempt to do what I outlined above with a power amplier, if that's what you're alluding to.

Let's start again... what is it you want to do?

brucek

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