"alice" microphone (XM8500) mkI
Surfing the web looking for infos and diyers I've found many pages about a microphone called "alice", built around a chinese electret capsule, the Transsound TSB-165A.
Almost all of the built mics used and anclosure made of metal pipes: aluminum, copper, brass.
I realized that that would be the most difficult part and a small error or flaw in the construction might have caused also some waste of money. So I decided to use an existing microphone enclosure to be filled with my own built electronics. The cheapest mic I've found is the Behringer XM8500, made of solid metal and available online for about 20 bucks.
I've found also a video on YouTube that shows the Behringer XM8500 compared to a more expensive Shure SM58 http://youtu.be/Tj3Us76vK6E.
I started opening the Behringer: there's a rubber ring that looks like a shock mount inside...
This is the capsule before my "treatment".
I removed the round foam pop filter and with a pair of dikes I made many cuts around the upper part of the capsule.
The diaphragm can be seen after removing some bits of plastic.
Now all of the border has been removed and the capsule is exposed. The two white felts were inside the lower part (the one that fits inside the metal body of the mic) and will be scrapped.
This is the part of the capsule to keep, the black plastic enclosure, everything else is trashed.
Unfortunately the XLR plug was also glued to the body of the mic so its removal was very difficult: both the screw and the connector were destroyed in the process.
The electronic part is the same circuit you can find on every site about the "alice" mic, a circuit similar to some vintage Schoeps. I've used two ceramic caps because of the lack of space. Please also notice that the 1Gohm resistor and the FET are soldered on the board: this is because initially I was thinking about a much smaller enclosure, with the capsule soldered on the circuit board. All of these quirks will be solved in the next version of the microphone!
A sheet of thick paper was placed on the inside to prevent short circuits, maybe a not very elegant solution: another issue to be solved in the next release.
Now the board is inside the body, a new XLR connector has been soldered and screwed to the bottom and all of the parts of the mic are assembled with the exception of the capsule.
And this is with the TSB-165A suspended with a small rubber ring: I'm looking for a more cleaner solution to be used in the next version.
Below the finished microphone, indistinguishable from a real Behringer XM8500!
I'll upload some audio files as soon as possible.