Bo Deadly
Well-known member
Here's a Neumann KM84 PCB I just did for an MXL 440 donor body but I think the board would work with a lot of other mics:
Here's the zip of gerbers I submitted to OSH Park. It should work equally well with other fabs.
SQ-KM84-0.9.0.zip
This is the stock KM-84 circuit. No changes other than adding a trimmer for bias.
Although in this particular build I used a K47 capsule. And I used a 2SK170 (instead of the usual 2N3819) so I changed the trimmer to 5K and associated bias resistor to 1.5K. And I left out the 47R resistors (there are solder jumps for this) so that I could use 47u / 330p LC filters on the outputs (I didn't put these on the board because they need to be right on the pins to stop RF from getting in).
Sounds good (although I thought the MXL sounded fine too). Here is the response:
and just for comparison the response of the original MXL 440:
Clearly the response is flatter (superior capsule?). Schoeps style circuit is quieter and has less distortion though.
Here's the zip of gerbers I submitted to OSH Park. It should work equally well with other fabs.
SQ-KM84-0.9.0.zip
This is the stock KM-84 circuit. No changes other than adding a trimmer for bias.
Although in this particular build I used a K47 capsule. And I used a 2SK170 (instead of the usual 2N3819) so I changed the trimmer to 5K and associated bias resistor to 1.5K. And I left out the 47R resistors (there are solder jumps for this) so that I could use 47u / 330p LC filters on the outputs (I didn't put these on the board because they need to be right on the pins to stop RF from getting in).
Sounds good (although I thought the MXL sounded fine too). Here is the response:
and just for comparison the response of the original MXL 440:
Clearly the response is flatter (superior capsule?). Schoeps style circuit is quieter and has less distortion though.
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