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Discussion Starter #1 (Edited)
not sure about my graph, but maybe someone can tell me if it looks ok, or my room has problems.

This measurement is done for my home studio room. size is 12' x 9' x 6½' celing.

using yamaha hs80m speakers, motu 828 audio interface, apex220 mic, no EQ.

the max reading that I was getting from the mic, at listening position, was around 68db and my speaker was cranked all the way up. Couldn't go up to 75db.
speakers are placed 3' away from the wall.

Question:
when taking a measurement, both speakers have to be hooked up with a Y cable from the right audio interface or it doesn't matter. either 1 or both can be hooked up.

thanks for the all the help guys in helping me getting the program working for me.
 

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Hi djruss,

First, set the graph limits to 45-105 dB and frequecy to 15 - 200 Hz.
What reading did you get on the SPL meter.
Normally you measure one speaker at a time to see how they interact with the room.
Do you have a calibration file for your mic? Also make sure that you calibrated your sound card.
 

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the max reading that I was getting from the mic, at listening position, was around 68db and my speaker was cranked all the way up. Couldn't go up to 75db.
When you reference the 68dB, do you mean using the REW SPL reading?

If so, you've missed the fact that when you use a mic instead of an SPL meter, you need to first establish a real reference of 75dBSPL at the listening position with an SPL meter (of any kind).

Once the approximate level is set, then the REW SPL meter must be matched to this letter by running the Calibrate routine.

brucek
 

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Discussion Starter #4 (Edited)
Hi djruss,

First, set the graph limits to 45-105 dB and frequecy to 15 - 200 Hz.
What reading did you get on the SPL meter.
Normally you measure one speaker at a time to see how they interact with the room.
Do you have a calibration file for your mic? Also make sure that you calibrated your sound card.
oppps!!!!!! I knew I messed up somewhere. :doh:
I don't have an SPL meter. I was taking the reading that was showing up on REW software.

now when you say calibration file, you mean the one I made with the loop connection (right output to the right input of the sound card) in the settings menu, under calibration > clear cal > measure > make cal and then saving the file. if, so then yes I did that and here is the jpg of it.

Mic calibration file ? don't know what you mean by that one. If it means having the same loop connection but this time clicking on the measure icon in rew and then clicking start measuring, then I have also done that with the loop connecting and here is the jpg too.

Do I have to get as SPL meter or I can use the one displaying in the software.
Also, the calibration files are made using the loop connection or the mic connected to the audio interface.

Bruce, I forgot to meantion that I had the mic on a stand and 3' away from the left speaker when doing this.
if I don't have an SPL meter, what SPL reading I should be seeing in REW. or that is not good to do. It's better to get an spl meter.
Sorry for so many questions. things are getting a little bit confusing to me. Still trying study this program but very interesting to work with.
thanks guys for all the help.. will have to do this again.
 

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Your sound card calibration looks Ok.
A lot of people here use the Behringer ecm 8000 as thay have a file of it's frquency response that they plug into REW to compensate for the mic.
So, when you have the soundcard calibrated and the mic calibration file set, all you are measuring is the speakers & amp/equalizer.
If you don't have a SPL meter then just set it to a level that isn't excessivly loud and pretend that is 75 dB. I would try and get a meter though.
What make/model is the mic.
That's about the limit of my experience with REW.
BruceK is the REW Guru and should let you know if I have given you any wrong info.
 

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if I don't have an SPL meter, what SPL reading I should be seeing in REW.
REW's SPL meter doesn't have a reference of what 75dB actually is, or any other reading for that matter. So, you must match REW's SPL meter to some actual reading. The Calibrate routine accomplishes this.

If you don't have an SPL meter, make a guess. Hook up your mic, run the Check Level routine at a reasonable level, and when complete, run Calibrate and set the REW level to 75dB.

You also need to find an apex220 microphone calibration file.

brucek
 

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Discussion Starter #7
REW's SPL meter doesn't have a reference of what 75dB actually is, or any other reading for that matter. So, you must match REW's SPL meter to some actual reading. The Calibrate routine accomplishes this.

If you don't have an SPL meter, make a guess. Hook up your mic, run the Check Level routine at a reasonable level, and when complete, run Calibrate and set the REW level to 75dB.

You also need to find an apex220 microphone calibration file.

brucek
thanks guys for the responds ... I tried searching for the apex 220 mic cal file but can't seem to find it. I read that a cal file can be made for that mic. I do have the print out sheet of the mic's freq.

Brucek, do you know how can i make a cal file for my mic, so it's better to gvie it back to the store and get a ecm8000. Problem is, they dont have the ecm8000 in stock, and it will take about 3 to 4 weeks once ordered to come in. Didn't want to wait that long, so I bought this one. .
 

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do you know how can i make a cal file for my mic
Yep, it's easy if you have a printout of its response over the bandwidth you want to use (i.e. 15Hz-20000Hz). A generic file isn't as good as having a mic calibrated professionally, but it's fine for home use.

What info do you have on the mic?

brucek
 

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Yep, it's easy if you have a printout of its response over the bandwidth you want to use (i.e. 15Hz-20000Hz). A generic file isn't as good as having a mic calibrated professionally, but it's fine for home use.

What info do you have on the mic?

brucek
hi burcek.... here is a scanned copy of the printout that came with the box...

Sorry burcek, for zipping the jpg up, cause the file size was big and the max limit is 200kb for jpeg.
 

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here is a scanned copy of the printout
It would be easy to create a cal file from this printout (even with its large vertical scale), unfortunately they have cleverly omitted the important range from 15Hz-50Hz. This is where mics usually drop off rapidly and require the most compensation from a cal file to render them flat for use with REW.

If you could find an ECM8000, then we have the generic file on our download page.

brucek
 
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