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3 posts since 22 Aug, 2017

Postby rodrigonader; Wed Sep 20, 2017 7:58 pm Behringher B2 as Room test Mic

Is there any way that I could use my B2 (omni mode) as a room measurement mic?
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10491 posts since 8 Mar, 2005, from Utrecht, Holland

Postby BertKoor; Thu Sep 21, 2017 12:56 am Re: Behringher B2 as Room test Mic

From http://realtraps.com/art_microphones.htm
People often ask which affordable microphones I recommend for measuring their rooms. Best is a condenser microphone having a small diaphragm for an extended high frequency response.
With the B2 having dual large diaphragm instead of single small diaphragm, plus:
SoS wrote:rather than being ruler flat, the mic has a presence peak at around 12kHz

To me that disqualifies it as usable for measuring your room.

But you could order a Behringer ECM8000 (affordable proper measurement mic.) Then compare it and return it :-P
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2291 posts since 17 Apr, 2005, from S.E. TN

Postby JCJR; Thu Sep 21, 2017 1:36 pm Re: Behringher B2 as Room test Mic

Bert makes good points.

IMO a bump or rolloff above 10 kHz isn't necessarily a deal breaker. Many inexpensive measurement mics have some frequency irregularities, but if a calibration file can be found for use in programs such as Room EQ Wizard, it will work ok anyway.

My cheap dbx measurement mic is fairly flat but has a healthy bump above 10 kHz. It isn't lab calibrated but I found a generic cal file and my elderly ears roll off up there anyway.

Some individually lab-calibrated mics are not too expensive nowadays. They don't do any modification to the mic-- They just individually measure each mic and supply a matched cal file for use with measurement software.

Bert's observation about dual large diaphragms is right-on. Even with a cal file a dual diaphragm large diaphragm omni will probably have issues at least for nearfield multiple speaker measurements.

Measurement mic diaphragm is typically about a quarter inch diameter. Measurements can include left speaker only, right speaker only, subwoofer only, all speakers at once, etc. Some even advise against all-speakers testing but in my ignorance I like that.

Testing all speakers turned on, even with the quarter inch diaphragm one needs to position the mic as precise possible, equidistant between left and right speaker. I try to get the mic spacing to less than a quarter inch difference distance to left speaker vs distance to right speaker. With a generic mic stand and boom it is fiddly getting the spacing that close, at least for me. Usually requiring several loops of ruler measurement, nudge, ruler measurement, nudge, etc. But sometimes get lucky and achieve good spacing right away.

If the spacing is not near-perfect, you get extreme comb filtering in the both-speakers measurement. If the spacing error is small the comb filtering is just in the highs. With additional spacing error the comb filtering extends down into the mids.

I don't know but suspect that dual large diaphragms might show comb filtering regardless how carefully you position the mic.

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