Marik
Pro Microphone Design
OK folks,
Today I went to local GC and got ECM8000--just to play with it and to see what it's capable of. Of course, before the listening, the very first thing I opened it up. I swear, I remember seeing somewhere on forums a picture of its PCB with tiny transformer. The picture on the box also shows a transformer. I got quite a shock--you know, when you expect something for sure and it's not there. It was not in mine! Anyway I don't care much for that, as you can imagine which quality it should be considering $39 for the whole thing. I opened the capsule (I had to put some strength). I heard rumors, and it indeed suspiciously looks like Panasonic WM60:
http://www.panasonic.com/industrial/components/pdf/em07_wm60_a_dne.pdf
I 'reversed' schematics. The input stage is on BC118 (silicon transistor), and output on A1349--I could not find any documentation, but it looks like two transistors in one body. The crutial signal path capasitors are surfice mounts , and the board is full of other 'goodies'.
As for the mods.
The very first thing is capsule itself. The Panasonic (as many other electrets) has a built in FET. This FET is responsible for the noise and low SPL. The easiest way to go is to make a 'Linkwitz mod'. Originally, the FET is hooked up without source resistor. The mod is to hook it as a source follower, which reduces noise and increases SPL to 140Db.
There is another capsule--WM61 which has about 4Db lower noise, but also lower SPL. However with Linkwitz mod the SPL is still at very respectable 134Db. The ultimate solution would be disassemble the capsule, cut off the internal FET and instead, use 2SK170, selected for high transconductance. I will probably have to order some Panasonics and play with them.
Tomorrow I will start serious listenings, measurements, tweakings, recordings, etc. I will also try to use Oktava 012 pre (I will have to modify it a little to make it work) to see if and how much difference it makes.
So, Gentlemen,
If you are interested and don't get bored, please let me know and I will keep you posted on the progress.
Today I went to local GC and got ECM8000--just to play with it and to see what it's capable of. Of course, before the listening, the very first thing I opened it up. I swear, I remember seeing somewhere on forums a picture of its PCB with tiny transformer. The picture on the box also shows a transformer. I got quite a shock--you know, when you expect something for sure and it's not there. It was not in mine! Anyway I don't care much for that, as you can imagine which quality it should be considering $39 for the whole thing. I opened the capsule (I had to put some strength). I heard rumors, and it indeed suspiciously looks like Panasonic WM60:
http://www.panasonic.com/industrial/components/pdf/em07_wm60_a_dne.pdf
I 'reversed' schematics. The input stage is on BC118 (silicon transistor), and output on A1349--I could not find any documentation, but it looks like two transistors in one body. The crutial signal path capasitors are surfice mounts , and the board is full of other 'goodies'.
As for the mods.
The very first thing is capsule itself. The Panasonic (as many other electrets) has a built in FET. This FET is responsible for the noise and low SPL. The easiest way to go is to make a 'Linkwitz mod'. Originally, the FET is hooked up without source resistor. The mod is to hook it as a source follower, which reduces noise and increases SPL to 140Db.
There is another capsule--WM61 which has about 4Db lower noise, but also lower SPL. However with Linkwitz mod the SPL is still at very respectable 134Db. The ultimate solution would be disassemble the capsule, cut off the internal FET and instead, use 2SK170, selected for high transconductance. I will probably have to order some Panasonics and play with them.
Tomorrow I will start serious listenings, measurements, tweakings, recordings, etc. I will also try to use Oktava 012 pre (I will have to modify it a little to make it work) to see if and how much difference it makes.
So, Gentlemen,
If you are interested and don't get bored, please let me know and I will keep you posted on the progress.