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Old 24th February 2009, 06:34 AM   #1
Marik is offline Marik  United States
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Default Speaker for Mic Measuring

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
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Old 24th February 2009, 07:04 AM   #2
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You want to use a speaker to calibrate a microphone?
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Old 24th February 2009, 02:28 PM   #3
Marik is offline Marik  United States
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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
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Old 24th February 2009, 03:34 PM   #4
Elias is offline Elias  Finland
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Hello,

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

- Elias
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Old 24th February 2009, 04:02 PM   #5
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Quote:
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.
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File Type: jpg spark.jpg (98.3 KB, 167 views)
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Old 24th February 2009, 04:17 PM   #6
adason is offline adason  United States
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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
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Old 24th February 2009, 08:33 PM   #7
Marik is offline Marik  United States
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Quote:
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?

Quote:
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
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Old 24th February 2009, 09:27 PM   #8
hifiZen is offline hifiZen  Canada
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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.
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Old 24th February 2009, 10:50 PM   #9
FrankWW is offline FrankWW  Canada
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Why not just pop a balloon?

http://www.youtube.com/watch?v=zSGPN...eature=related
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Old 25th February 2009, 03:06 AM   #10
adason is offline adason  United States
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http://www.parts-express.com/pdf/264-848s.pdf
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