Speaker for Mic Measuring

[Marik]

Hey Gang,

As the subject states, I am looking for a full range speaker to measure microphones. What would be the flattest full range 300Hz--20KHz. The flatter, the better, even if that would be 500Hz-20K.
Having said that, I would not mind the straight line from 100Hz or even lower...
Are there any contenders there?

Thanks, M

[454Casull]

You want to use a speaker to calibrate a microphone?

[Marik]

Not to calibrate. As reference mics I have here B&K4133, 4134, Gefell MK202, 221, etc.
I make microphone capsules and will need to take their plots.

Thanks, M

[Elias]

Hello,

I think it's better to shoot a pistol than to use a full range element

- Elias

[scott wurcer]

Originally posted by Elias
Hello,

I think it's better to shoot a pistol than to use a full range element

- Elias

Close I used a spark discharge, which is actually a doublet (+6dB/octave) to make this plot. I used it to measure the flattest capsule I had, the CP3 pin-point omni from Nakamichi. If I had a calibrated B&K I'd bet with averaging I could get +-.5 dB or better match. I used nothing but a good soundcard and Audition/Cooledit2000.

My measurement is the red offset by +10dB.

[adason]

Marik,

why does it have to be fullrange? Can't you use one of Zaph's 2way designs? Some are exceptionaly flat from 100Hz to 10kHz. No fullrange can compare in flattness with well designed 2way, especially wizzer-coned ones have too much wrinkles in hights.

ed

[Marik]

Originally posted by scott wurcer


Close I used a spark discharge, which is actually a doublet (+6dB/octave) to make this plot. I used it to measure the flattest capsule I had, the CP3 pin-point omni from Nakamichi. If I had a calibrated B&K I'd bet with averaging I could get +-.5 dB or better match. I used nothing but a good soundcard and Audition/Cooledit2000.

My measurement is the red offset by +10dB.

Thank you Guru Wurcer
I remember seeing somewhere (was it on micbuilders site?) a paper on the topic. Do you have it handy?

Originally posted by adason

Marik,

why does it have to be fullrange? Can't you use one of Zaph's 2way designs? Some are exceptionaly flat from 100Hz to 10kHz. No fullrange can compare in flattness with well designed 2way, especially wizzer-coned ones have too much wrinkles in hights.

ed

Well, yeah, but I'd rather go with a point source and also not to deal with crossover artifacts. Of course, the wizzers are out of question.
The last I looked some time ago there were some 3"-4" wide range aluminum cone jobbies with some serious break-up modes. Now I see there is some new stuff, so just was wondering how far the modern technology went since then...

Best, M

[hifiZen]

Scott's got it. Just understanding the fundamental physics involved, a spark will give you an extremely precise and very wideband impulse, from a small omnidirectional point source. No real tweeter (let alone whizzers) could even pretend to match this. Not by a mile. Well, maaaaybe a plasma tweeter. Maybe.

I imagine there are several caveats to setting up the spark gap and power source correctly to get the impulse you want. But it should be fairly easy to get excellent results once it's functioning.

Of course, a spark will only cover the treble. A stick of dynamite should go much lower, and test the reliability of your mike at the same time.

Seriously though, the low end could be filled in with data from a decent cone driver.

[FrankWW]

Why not just pop a balloon?

http://www.youtube.com/watch?v=zSGPN...eature=related

[adason]

http://www.parts-express.com/pdf/264-848s.pdf