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I have a 45 tube SET amp system with Horns in a dedicated 2 Channel system. I build some custom crossovers for it and my plan is to use REW to see if it looks as good on paper as it sounds. Or can the crossover be tweaked. I currently have Klispch Bass Bins and Tweeters with Altec 1005B horns and 288-16K drivers. They are crossed over at 400 hz and 6K hz. - I think - or that is what the formula said with the Cap values and inductor values I'm using.

I have an Extech SPL meter and have downloaded and read the REW help extensively. My plan is to buy a Creative external Sound card that has been mentioned and take some measurements. Am I on the right track in what I am trying to do?

Suggestions Welcome!
 

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Am I on the right track in what I am trying to do?
You would require a calibration file for the Extech meter. Most Extech meters appear to be of good quality, so I suspect it's full range, but you would require a cal file to compensate for the upper and lower end. If you were just checking the crossovers, I suppose you could get away without it.

brucek
 

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You would require a calibration file for the Extech meter. Most Extech meters appear to be of good quality, so I suspect it's full range, but you would require a cal file to compensate for the upper and lower end. If you were just checking the crossovers, I suppose you could get away without it.

brucek

OK, I am confused a little here. I though that I just calibrated my SPL meter in the REW program. If I need to get a file, where might I get one?
 

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I though that I just calibrated my SPL meter in the REW program. If I need to get a file, where might I get one?
Both the soundcard and the meter require compensation for their inadequacies.

The soundcard is taken care of by running a routine that measures the response over a loopback cable and a calibration file is created.

That obviously isn't possible for the meter, so a calibration file is required to be loaded into REW. There are a few ways to get a calibration file. You can get the meter/microphone calibrated at a lab. You can use a generic file that we supply on our Download Page if you are using a Radio Shack, Galaxy or Behringer meter/mic. You can create a file from a frequency response chart over the bandwidth supplied on the chart.

Read and become familiar with the REW HELP files and the REW Cabling and Connections Basics.

Also note the REW information Index

brucek
 

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Did your SPL meter come with a calibration curve?

I didn't look it up, but someone mentioned you have a nice one...the really really nice ones always come with a frequency response (and polar response) of the microphone's performance.

If you were creative, you could get by with a super jagged and unknown meter frequency response, but it would change how you interpret the measurements (and require some extrapolation).
 

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Did your SPL meter come with a calibration curve?

I didn't look it up, but someone mentioned you have a nice one...the really really nice ones always come with a frequency response (and polar response) of the microphone's performance.

If you were creative, you could get by with a super jagged and unknown meter frequency response, but it would change how you interpret the measurements (and require some extrapolation).
I have an Extech Model 407727 - I don't think it came with a curve.

I can't even buy the Creative Sound Card anymore! - Seems like it's out of production.
 
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