# Help for a newbie with REW...



## sub_junkie (Apr 14, 2009)

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


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## brucek (Apr 11, 2006)

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


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## busahaya03 (Aug 25, 2009)

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?


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## brucek (Apr 11, 2006)

> don't mean to thread jack


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

brucek


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## sub_junkie (Apr 14, 2009)

brucek said:


> 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.
> 
> ...


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


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

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


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## sub_junkie (Apr 14, 2009)

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


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

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

Regards,
Wayne


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## sub_junkie (Apr 14, 2009)

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...


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## brucek (Apr 11, 2006)

> 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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## sub_junkie (Apr 14, 2009)

Yes, I did want to measure the HPF of the Mic2200. I didn't know if I have to hook the 2200 up the sound card, and run that through my EP2500, then to the sub to get the correct response I was looking for...
I didn't know I could just hook up the 2200 to the sound card. How would it be able to measure where the HPF was set for just the 2200?

Thanks and sorry for the confusion


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## brucek (Apr 11, 2006)

> I did want to measure the HPF of the Mic2200


Re-read my original post.

You insert the Mic2200 into the loop of the soundcard. That's it. It stands alone as the device under test. No amps, no speakers, no mics, just the Mic2200.

As stated - first measure the response of a loopback cable to be sure its flat, so that when you measure the device, you'll know that you're getting the response of it alone.

Line-out of the soundcard to line-in of the device, and line-out of the device to line-in of the soundcard. Fuss with the levels and Measure.


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## sub_junkie (Apr 14, 2009)

Ok, now I get it :T
What kind of connectors do I use to hook up the 2200 to the sound card? XLR (for the 2200, at least I think that's what it uses) to RCA with the RCA going to the sound card??


Thanks again for the help Bruce and Wayne.


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## brucek (Apr 11, 2006)

> What kind of connectors do I use to hook up the 2200 to the sound card?


At the soundcard, use 1/4" TS connectors, so that the interface will revert to unbalanced. Then at the soundcard, you have to split out the standard 3.5mm stereo jacks into right and left so that you can gain access to the right channels of line-in and line-out.

brucek


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## sub_junkie (Apr 14, 2009)

How would I split the standard 3.5mm jacks? Just by using a additional addaptor thing? I wish I already knew this stuff so I wouldn't be asking so many questions :bigsmile:


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## robbo266317 (Sep 22, 2008)

Yep, just get a splitter to suit your connectors.


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## brucek (Apr 11, 2006)

sub_junkie said:


> How would I split the standard 3.5mm jacks? Just by using a additional addaptor thing? I wish I already knew this stuff so I wouldn't be asking so many questions :bigsmile:


Yes, an adapter or adapter cable........Read and become familiar with the REW HELP files and the REW Cabling and Connections Basics.

Also note the REW information Index and the Download Page..

brucek


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## sub_junkie (Apr 14, 2009)

Aright, those threads helped me a lot. Now that I saw that diagram of how to wire everything up, it's much easier to understand.
Would it be possible to have the person that I would be buying the MIC2200 off of set the HPF on 13.50hz for me so I wouldn't have to get a new sound card? Or does it change when shipped (possibly?)? I might have a sound card on my desktop computer that has the needed line in and line out needed for REW so I could do it then, but otherwise, it would probably be better for someone else to do it for me becuase I might not set it up right for the needed HPF...

Thanks again for all of the help


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## brucek (Apr 11, 2006)

> Would it be possible to have the person that I would be buying the MIC2200 off of set the HPF on 13.50hz for me so I wouldn't have to get a new sound card?


I think that obtaining a soundcard that can be used to setup your own HPF and later used to measure your system with REW would be a good idea.

brucek


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## sub_junkie (Apr 14, 2009)

That's what I was thinking. But, I wouldn't be able to get a soundcard until around Christmas, s I wouldn't be able to set up the MIC220's HPF until then, and I don't want to wait until Christmas to get the EP2500 up and running :bigsmile:


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## brucek (Apr 11, 2006)

> I wouldn't be able to set up the MIC220's HPF until then, and I don't want to wait until Christmas to get the EP2500 up and running


You may be making this a bit more difficult on yourself than it needs to be.

The MIC2200's HPF is variable from 12Hz-320Hz. Press the LO-CUT switch and turn the frequency dial counterclockwise and you know you're good to 12Hz. Simply turn it up a bit from there and you're good.

brucek


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## sub_junkie (Apr 14, 2009)

Ok, I didn't even think about that :T
That will make it easier, definitely. Will going over Xmax a little bit around 9hz be noticable?


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## brucek (Apr 11, 2006)

Usually when you get that low the natural rolloff of your electronics combined with the absence of any signal will suffice. That's one of the main attributes of an LLT design, in that it doesn't usually require a HPF.

brucek


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## sub_junkie (Apr 14, 2009)

Hmm. It would be nice to save about $70 on a HPF, but my revceiver doesn't have a stong enough Pre-Out channel to power the EP2500. 
So, what your saying is the EP2500 won't provide 2000w around 12hz or so (which is what I had thought...) ? That's where my Mal-X hits it's Xmax limits before distortion...


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## brucek (Apr 11, 2006)

Well, I don't know if an EP2500 would provide an actual 2Kwatts at any frequency, but its response is reported down only about 0.5dB at 12Hz, so that's not an issue. It would usually be the receiver that suffers from some low end roll off. I am a bit confused about what you're asking, there's a big difference between 9Hz and 12Hz...

Perhaps you would be best served by asking these type of questions in the subwoofer section. 

brucek


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

Yeah, between 9 and 12 Hz is not much numerically speaking, but on the frequency spectrum it's fully half an octave. Shifting things up higher will get you a better perspective - imagine the difference between a 90 Hz and 120 Hz crossover.

Since you're using an outboard amp I imagine this is a DIY sub? We have a forum for those, too, you might want to check it out.

Regards,
Wayne


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## sub_junkie (Apr 14, 2009)

What I had meant is without running a HPF, my Mal-X would hit its Xmax limits at 12hz. With running a HPF at 13.50hz, it is right below its Xmax limits at 9hz, so if the HPF is set at 12hz, then raised up a little bit, I could be right at that or above.
But, what I was getting at was, if the EP2500 didn't put out 2000w (or 1950-1900w) at 12hz (which would be where the sub would hit its Xmax limits would be without a HPF) I could possibly set the HPF lower, or not even need a HPF at all.

Would there be a way that I could test the Receiver's low end roll-off just by connecting a voltage meter (or something; I don't know what to use) to the Pre-Out channel?

Thanks again for the help, and sorry for the confusion.

Edit: Oops. I didn't see the second page before I pushed the post button.
Going from 90hz-120hz Xover is quite a bit :bigsmile:
And I got my box dimmensions and everything that I needed (and some) for building a DIY sub. They were a great help over there and I appreciate it. I would probably have bought a Klipsch $400 sub if I hadn't come here, and now I have one that is much much better :T


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