I am also going to take a caliper and measure the diameter id the inside of the rings in both styles. The thickness of the backplate washer should have something to do with the air volume....maybe .001 is to little and .0015 to much. I want to understand this! I keep thinking we should be able to get the capsules to sound great.
Gus,
Yes, it has do a lot. Last couple weeks I went through a lot of experiments, screw-ups, and frustration.
The general observation--the thicker spacer--more bass--less HF.
Could the V67,2001,1006,V69 capsules have a little to much air resistance? so maybe there is just a little to much "drag" resistance between the front and back skins.
In fact, I am thinking quite opposite. In theory, more acoustical resistance should give more uniform frequency response. There is, however, a very fine line between acoustical resistance (air cution between diaphragm and back plate) and air volume trapped between backplates, when response is flat. So far, with spacers I was able to tune the capsule so, that I have whether good bass, or good HF. IMO, more acoustical resistance will help to equalize those two. If I had means of reskining capsule I would try drilling in the backplate more blind holes. It would be cool to see what it affects.
I would be cool to figure this out.
No doubt we will get there.
I believe some of the problems with chinese capsule are that most use smaller dimension holes than German mics. I believe this has some different frequency artifacts than Neumanns for example.
Tim,
I checked very carefully and holes in MXL2001 and K67 look the same.
My U67 capsule has no split in this washer and all Neumann capsules are sealed with Scotch tape.
Mine has this split and no tape. Also, it has a little hole in the front skin, and back skin is warped. Still it sound wonderful. I made the split in 2001 spacer and it sounds like crap.
Do you coat the PET under tension?
As far as I know, the gold evaporated when mylar is already pretentioned in the jig.