DrFrankencopter

Have hi-res U-87 pics...need host!
« on: September 19, 2004, 02:56:33 PM »
Hi guys,

I just disassembled my U-87ai to check out what's inside. I snapped a few pics too and figure folks here would be interested. PM me if you're interested in hosting these.

FWIW, the PCB is a U-89 PCB that is only partially popuated (interesting). Very fine gauge wiring is used to interface tothe XLR connector (much thinner gauge than I'd use). Resistors leading from the capsule appear to have a glassy/glossy exterior. I wonder what they're composition is? Neumann have used a really cool method for assembling this mic, with a pair of rails that hold the capsule module on. Press the rails together and you can pull the head off the mic, revealing a connector for the head assembly. A metal plate seperates the two circuit boards, which is a good idea considering there is a DC/DC converter circuit on there. Most compents inside look like run-of-the-mill good quality stuff (Wima and Elna caps)...nothing really esoteric other than the custom injection molded switch assembly.

C110 looks like a good candidate for upgrading. It's an Elna electrolytic that couples the circuit to the O/P transformer. An EL cap here is not too bad given that there is likely a nice DC bias given the single ended supply voltage, but I figure there is sufficient space to shoehorn a good film cap in there which should help open up the high end a bit, and maybe tame a little of the harshness that I hear in this mic. I'm going to have to sit and think before I do any other upgrades though...anyone have any suggestions?

BTW: here's the best schematic I've seen:

http://www.omnipressor.com/MicSchLib/u87ai.gif


Cheers,

Kris


 

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