Testing microphones

Michael John

Michael John

Junior
Jun 25, 2011
352
9
18
Sydney, Australia
eclipseaudio.com
Hi,

I'd like to make a box for testing microphones. Not something accurate enough for absolute measurements but something good for measuring changes over time and detecting damage. Has anyone done this before? Any tips?

I'm thinking of a box about 1 foot square and about 4 feet long lined with 1" of insulation. A full range driver at one end - say a Dayton RS100-8 - and lots of insulation at the other end, and a removeable panel with a mic clip on the inside.

Cheers,
Michael
 
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Re: Testing microphones

Michael Smithers said:
Hi,

I'd like to make a box for testing microphones. Not something accurate enough for absolute measurements but something good for measuring changes over time and detecting damage. Has anyone done this before? Any tips?

I'm thinking of a box about 1 foot square and about 4 feet long lined with 1" of insulation. A full range drive at one end - say a Dayton RS100-8 - and lots of insulation at the other end, and a removeable panel with a mic clip on the inside.

Cheers,
Michael
Click to expand...

Why does it have to be 4' long? The important part is a way to mount the mics so that all the same type of mic mounts in exactly the same place as the others. This is done all the time testing mics for B'way shows.

Mac
 
Re: Testing microphones

mackerr said:
Why does it have to be 4' long? The important part is a way to mount the mics so that all the same type of mic mounts in exactly the same place as the others. This is done all the time testing mics for B'way shows.

Mac
Click to expand...

Thanks. Yep, I don't have a spot where I can lock things down for repeatability, so I figured a box was the next best thing. I'm planning on the mic clip being essentially fixed and pretty close to the speaker - say under 1' away. The remaining 3' will be almost full of insulation to minimise reflected sound coming back. I'm thinking similar to plane wave tubes for measuring loudspeakers. Maybe this is misguided and overkill.... :razz:
 
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Re: Testing microphones

I do something fairly cheap and easy - with SMAART I plug my Earthworks test mic into the "ref" input, and the mic-under-test into the "measure" input. Put both together as close as possible in front of any decent full-range speaker. Usually the ref mic has to be just a hair in front (closer to the speaker) for delay compensation to be happy (SMAART delay compensation doesn't like ref to be later than measure).

That gives me a messy, jagged curve that still gives a pretty good picture of the mic's response. Then without moving the fixture I try other mics of the same make/model, to see if any deviate significantly from the others.

Yes, this is a cheap test. But you can set it up in your shop without having to build anything.
 
Re: Testing microphones

Scott Helmke said:
I do something fairly cheap and easy - with SMAART I plug my Earthworks test mic into the "ref" input, and the mic-under-test into the "measure" input. Put both together as close as possible in front of any decent full-range speaker. Usually the ref mic has to be just a hair in front (closer to the speaker) for delay compensation to be happy (SMAART delay compensation doesn't like ref to be later than measure).

That gives me a messy, jagged curve that still gives a pretty good picture of the mic's response. Then without moving the fixture I try other mics of the same make/model, to see if any deviate significantly from the others.

Yes, this is a cheap test. But you can set it up in your shop without having to build anything.
Click to expand...

Thanks very much. I just tried this "ref" method with Systune and a dual mic clip and it works like a charm.
 
Re: Testing microphones

Michael Smithers said:
Thanks very much. I just tried this "ref" method with Systune and a dual mic clip and it works like a charm.
Click to expand...

Just bear in mind that you really shouldn't try to save a reference curve for next time. There are a lot of variables every time I set something like this up, such as different large objects in the vicinity. Works best just to look for outliers when testing a batch.
 
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