I have been doing a few distortion measurements of the drivers in my current project. I have become concerned about the distortion products of the mic itself. The following is a test of the distortion of my HDS Nomex driver driven at 2.83V with mic distances of 4″, 8″ & 16″. The distortion products should be the same % in each, any increase can be directly attributed to the mic.
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As you can see, the 3rd harmonic doesn’t change apreciably. The 2nd on the other hand increases dramatically with each doubling of the SPL.
That distortion looks way too high for that driver. It is a well regarded low distortion driver.
Parts Express recently started selling their own version of the ECM-8000 mic with calibration, have you considered that? If that’s too expensive, then you could always build a few of your own mics for just a few dollars.
I have seen the PE mic and I must say it is tempting. The mic I am currently using is a DIY job, with a DIY mic-pre as well. I must admit that from these tests it doesn’t look to be a very great mic. I may look at a new mic in the future, but it will probably be a step up from the ECM or parts express, perhaps and Earthworks.
In its defense, even at 16″ the level produced by this driver is pretty high. And when you go down to only 4″ there is no reason to think that a little capsule mic like this could hold up without significant distortion. This experiment was to get an idea of how much. Maybe I could try a linkwitz mod on the capsule, but it is harder than it sounds (I wasted a few when I was building the mic before giving up and just wiring it in)!