Chuck -
You could do worse than to get another one of these mics and keep it unmodified as a reference. It's only a $50 mic. I would also make a reference recording with the unmodified mic with better source material under more controlled conditions, even if it's just you speaking into it. No offense intended but the source material in your wav files is pretty poor. Also, you're making a number of major changes to the mic and you're not working very methodically. Make a list of the components you swap (I don't see before and after values in your schematic, just after) and make a test recording of each modification against the reference mic with each change of components. You could also take the capsule from the unmodified mic and test it against your mics with circuit modifications. Once you take a Dremel tool to the capsule your changes are unrecoverable.
Those small yellow ceramic caps are all screwed up on them. The values don't match at all. I'm going to have to re-cap both of them. It looks like the person that assembled them just used any yellow capacitor they could find in each microphone.
C3 and C4 on one mic are .22uf and .47uf. On the other they are both .047uf!
It is good that they put the larger values, but...
The caps at C1 and C2 are screwy too. But, all the resistors are right.
QC is not too good on these mics.
It's stories like this that convince me you're better off spending more money on a mic where the manufacturer does better QC. Either that or have something like an Oktava MK012 modded by someone who basically guts the electronics and puts in all new components.
Just a suggestion.
Yeah, actually, I did document everything I did as I replaced components. I made a spread sheet with all the pre-mod component values and as I replaced components I added the new values to the sheet. I didn't note that on the schematic. I even tested the mics every time I changed something. But my tests consisted of listen to ambient noise & snapping my fingers in front of it, just to make sure they worked. I should have used a more full spectrum test source. I'll do that nest time.
Yeah, and I just purchased a pair of the KAM i2 mics on eBay for $68!
They are the MXL clones and come with omni and cardioid caps. I was thinking the same thing as you, that I need a reference to work from. When they arrive, I will make some controlled full spectrum recordings before opening them up. I'll be much more methodical this time.
As I said, It's learning experience. I'll figure it out eventually.
Yeah, and on that source material. They were set up way in the back of the venue. I had my C-481's ceiling mounted FOB. I just made the recording in the back to see how the moded mics did in a loud environment against mics that I am very familiar with.
Thanks for the input.
If I get the first pair to work right I'm thinking about donating them to the venue, as they don't have a good pair of condensers for drum overheads. They treat me very well there. So, I may be able to do something good for them.
