High SPL mic?

[Amphiprion]

I am looking for a (hopefully inexpensive) microphone to do some subwoofer distortion measurements. Specifically, I am looking to feed band limited (20-100Hz) high amplitude noise to a sub and measure the distorted output signal as free from reflections as possible. This will probably be done outdoors and as close to the cone as the mic's range dynamic range will allow (I would like to be pushing the cone close to max excursion). What is the max SPL that condenser microphones like the ECM8000 can handle? Are there any inexpensive microphones that can handle more? Are there any caveats to recording 120, 130, 140db+ sounds? Any help would be appreciated.

[JonMarsh]

The "real" condensor measuring mics have 200V power supplies and special attenuator assembilies, and can measure those kinds of SPL's reliably. Got a couple like that- a 30 year old Bruel and Kjar, and an ACCO Pacific. These are true instrumentation mics.

The ECM is an incredible value, but doesn't have the kind of electronics or screw in attenuator assemblies that would make those kinds of measurements possible. I'm not familiar with any amplified mic that will do that reliably. Some dynamic mics might hold up to the abuse, but distortion generated by the microphone would be another factor, same as occurs with over travel in a speaker.

[ThomasW]

Here ya go.....

http://www.zzounds.com/item--AUDTR40

[Amphiprion]

Yeah I've heard that dynamic mics are not so good for measurement. Do you think universities might have that sort of thing (the high amplitude capable condensers) onhand? I'm not too far removed from college and could go bother some folks, assuming the people I knew are still around.

If I tried to do a true 2pi measurement (as true as possible, anyway - sub mounted in a shallow box facing up in the middle of a basketball slab outside) would I really need to worry about getting the mic as close as possible to the sub, or could I just take 1 or 2m measurements? That would kill the need for a high SPL mic.

Also, are there any other good ways besides random noise signals to generate loads of data re: subwoofer nonlinear distortion? I mean I need craploads, the standard nonlinear distortion tests that you can run in praxis etc won't nearly generate enough data.

[Amphiprion]

Yeah Thomas you guys measurement budget is a little bit beyond mine, well at least til I get employed. Under $200 isn't too bad at all though, it's just that I'm more or less broke

[ThomasW]

There's no such thing as a low cost high SPL mic. You can have low cost, or high SPL, but not in the same package.

[Amphiprion]

It's like smart, sexy and sane women then.

[RobP]

Audio Control has a 180db mic, I know its reliable but do not know how acurate it is.

[ThomasW]

Audio Control has a 180db mic, I know its reliable but do not know how acurate it is.

It's specific for use with their RTA (or the mic preamp they used to sell). I have one of their RTA's and it's a dinosaur compared to TrueRTA.

[RobP]

It's specific for use with their RTA (or the mic preamp they used to sell). I have one of their RTA's and it's a dinosaur compared to TrueRTA.

Didnt know it was specific to that RTA. Their RTA's displays do make a nice Christmas ornament. :lol

[Dennis H]

Kim Girardin makes a high-SPL version of his mic; <3% distortion at 140dB. His standard mic is <3% distortion at 128dB. But his mics like a different preamp from the ones the Behringer likes; RCA connector and lower phantom voltage.

http://www.libinst.com/hispl.htm