Before you start checking mic response curves, read how Earthworks does it.
http://www.earthworksaudio.com/wp-content/uploads/how-earthworks-measures-mics.pdf
http://www.earthworksaudio.com/wp-content/uploads/how-earthworks-measures-mics.pdf
Just have it done. They vary a lot more than you think. Once I had one done, I did a "close enough" on my second one and my home made Panasonic. I did not pay the extra for phase response as at that time my design work was not that complex. Wish I had but it is a lot more money.
You can't use ANY published frequency response of a speaker at home. I would suggest doing a lot more reading, like "Testing Loudspeakers" By John D.
You can't use ANY published frequency response of a speaker at home. I would suggest doing a lot more reading, like "Testing Loudspeakers" By John D.
You could read up on reciprocity calibration.
Use a headphone element as the auxiliary transducer and measure a tweeter.
Basically measure any tweeter with your mic and the headphone element (used as a mic) then measure the headphone element (used as a speaker) with your mic. There is some math, but you get a primary calibration. I have done it (very roughly - mics sitting on a table) using a cheap radio shack dynamic omni microphone instead of a headphone transducer - the results weren't great, but promising enough to try it again with a more elaborate setup.
Use a headphone element as the auxiliary transducer and measure a tweeter.
Basically measure any tweeter with your mic and the headphone element (used as a mic) then measure the headphone element (used as a speaker) with your mic. There is some math, but you get a primary calibration. I have done it (very roughly - mics sitting on a table) using a cheap radio shack dynamic omni microphone instead of a headphone transducer - the results weren't great, but promising enough to try it again with a more elaborate setup.
My project to measure the F.R. of our Microphones is based on the purchase of a pair of Ribbon Microphones - which don't have their F.R. Their Base Noise level is too high as well. They use Phantom = they have some cheapo Chinese amp and mic Xfmr. I'm going to replace all that with FAB Microphone Xfmrs - thus making them Passive Microphones - turning back the clock - so to speak. I shall do a 'Before/After' conversion test - hence all this desire to master HOLMImpulse programme. Once mastered I shall test all our Microphones. Age isn't kind to Humans or Microphones - and I'm finding that out in a big way! But, for the HOLMImpulse I need help, I fear! Thanks. Michael UK
Immeasurable thanks for this Article, Kevin. A great friend of mine had 11 Earthworks Microphones: QTC1's,TC30's,TC40's,Z30Xbc's. Sadly he died but I purchased his SPS422 and a pair of Schoeps BLM's (which include the Mic.Pre-amps as used in their Colette systems). This article gives very conclusive evidence and is enormously helpful in understanding the principles involved in the use of Measurement Microphones - and that the speaker sound source must NOT be enclosed in a box. . . . All makes sense! Michael
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