microphone frequency plot ... how to advice please.. :)

[ToobieSnack]

hey peeps

i'm getting some decent results with some new ribbon mic designs and i was wondering:

how can i go about obtaining a frequerncy plot for my mics?
any macintosh programs for this?
white noise? pink noise? reference mic? RTA?
could i use my jz-1 as a reference mic? any associated math involved in matching process?
I have a MOTU DAW for audio input to the digital world.

if i were to want to take it to a lab what would i look for in the yellow pages?

could a local college/university help with this?

any other suggestions?

as always your kind comments help and suggestions are sincerely appreciated.
later
ts

 

[rodabod]

You really need the right equipment and acoustic conditions to make accurate tests, I believe.

My University has an anechoic chamber for doing such tests. You might want to get a measurement mic like a B+K or Behringer for making tests.

However, I sometimes just make simple tests micing a monitor speaker and recording a frequency sweep from Cooledit / Soundforge. You can then make a plot using the same software or Cubase SX. It is handy for a/b comparisons, plus you can use FFT plots on some of these programs (should you wish to use them).

 

[omeiko]

Do you think this could work? Record a sine sweep with a flat measurement mic (dpa) and then record same sweep with your ribbon. Then sum the recorded signals so that the other one is out of phase. This should cancel out the effect of the room and the speaker and show the difference between the measurement mic and the ribbon.
I haven't tryed this yet and it might not work at all.

Okko

 

[rodabod]

Yes, this would work in one sense - but remember that most ribbon mics are fig. 8.

If you had a really bassy room or generally bad acoustics, each mic would be affected differently because they would pick up more or less room sound.

An anechoic chamber or a very dry room (studio) are a good solution.

Remember to watch out for proximity effect too.

 

[Guest]

It's afar more complicated world than it might seem and not only do you need the reight test environments, you also need the correct processees. Your proposed sinewave test will probably have you chasing your tail before you know it.
If you have a real anechoic chamber it's the quickest way to obtain a general idea of what the mic is doing, with an unspecified test environment and an FFT you'll still really be measuring all of the test environment components, unless you know how to and have the resources to eliminate them, which is no small feat.
regards,
D.Bock
Soundelux Microphones

 

[bcarso]

A large open area on a day with no breeze and no extraneous noises, with the mics well above the ground. Of course the likelihood of finding that anywhere these days is slight, hence the anechoic chambers.