# using Room EQ Wizard



## raulgalimidi (Feb 26, 2010)

Hello, can somebody orient me on how to measure live frequency response using a condenser mic M-Audio ? I downloaded the free version but cannot seem to find how to change from reading the soundcard towards reading from live mic.
thank you.
r.


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

Look for the tab that says “Spectrum.” That’ll switch the program to real-time analysis.

How accurate do you need the readings to be? You won't get the best accuracy without a calibrated mic. Using just any mic you will get readings that are a combination of the mic's response and the signal's.

PS – welcome to the Forum!

Regards,
Wayne


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## raulgalimidi (Feb 26, 2010)

Hello Wayne, I appreciate your response. I am a new user trying to understand room acoustics and select treatment for project studio for music production. I will be using a Neumann M 147 Tube Condenser Mic and I have now an M-Audio Nova Large Diaphragm Condenser Mic. with which I was trying with. I appreciate any other suggestion, Regards,
Raul.


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

For accuracy, it’s best to have a calibration file for your mic that can be loaded into REW. You can make your own calibration file if you have a manufacturer’s response plot of the mic(s). However, mics with small capsules (such as the Behringer ECM8000) are generally preferred for room measurements.

Accuracy is primarily for when you’re measuring speaker’s frequency response. Since you’re mainly interested in readings relating to acoustics, you’ll primarily be concerned with RT-60, ETC and waterfall readings. With those you can probably fudge on having a mic with absolute accuracy.

Regards,
Wayne


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## raulgalimidi (Feb 26, 2010)

Thanks again Wayne. Would I need to do calibration routine for soundcard? I have done all the steps but keep getting a lower than usual signal under -43dBF... I am not sure I am getting live readings yet. My setup is a Digidesign Mbox digital interface with the condenser mic on its left (mono-phantom) input. Mbox output left and right go to active 40 watt speakers. On calibrating soundcard routine I plugged one of these outputs on front right input with microphone turned off. You think I will get there?
I do have the frequency response plot for microphone in a jpg.


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

The sound card calibration is accomplished by looping a cable between the line input and line output. No mic pre amps should be used. Also, make sure any monitoring functions are turned off.

This thread will show you how to create a calibration file for your mic from a frequency response plot.

Regards,
Wayne


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## timba-n-tango (Apr 4, 2010)

Wayne, 

I see a number of folks use the RS SPL meter and its generic calibration file for REW. Is this reasonably decent or should I be buying a Behringer mic with calibration? I really not in this very deep (audio addiction), just a hobbiest interested in testing and getting more info. I do want to test and adjust a sub I will be getting soon, and would be interested in the response of my main system.

At this point I plan to use a laptop, behringer UFO202 sound card, and RS SPL meter.


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## JohnM (Apr 11, 2006)

raulgalimidi said:


> My setup is a Digidesign Mbox digital interface with the condenser mic on its left (mono-phantom) input.


If your mic is connected to the left input make sure you tell REW to listen on the left input in the Soundcard Settings.


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## JohnM (Apr 11, 2006)

timba-n-tango said:


> I see a number of folks use the RS SPL meter and its generic calibration file for REW. Is this reasonably decent or should I be buying a Behringer mic with calibration?


The RS SPL meter is fine for sub calibration and positioning etc, its weaknesses are further up the frequency range (above 2-3kHz) where there is typically a significant hump in the frequency response centred on about 5kHz.


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## timba-n-tango (Apr 4, 2010)

Thanks John, and thanks for REW! I will continue on.

Do the cap fixes for the RS meter happen to fully fix the 5K hump?


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## JohnM (Apr 11, 2006)

timba-n-tango said:


> Do the cap fixes for the RS meter happen to fully fix the 5K hump?


No, they are aimed at giving the meter a broader response at the upper and lower extremes, flattening out the C weighting curve's roll off at low and high frequencies. The external mic mod may give a flatter response though.


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## timba-n-tango (Apr 4, 2010)

Sounds good. I think I will take the RS meter back and get a calibrated ECM8000. Then I can play with the entire system response without having doubts.

Thanks.


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