DIYish PSU for Altec M11 Coke Bottle Microphone.

[thecr4ne]

I could really use some advice on this power supply project. If you're willing and able, please have a look and provide feedback.

I got a pair of Altec Coke Bottle mics without power supplies. I decided I'd try to modify existing chinese tube mic PSU's to do the job. I got a pair of the t.bone retro tube II PSU's from Thomann, swapped the power transformer with something from Aliexpress, recapped the PSU board with higher voltage rated caps, added some zeners to get the B+ voltage to 300V, and cut the ground trace to reference the filament voltage to +150V instead of ground. Swapped out the 7-pin XLR for the correct Cannon 8 pin connector, changed the pattern select switch to function as the High Pass switch. Built cables with original cannon connectors and Sommer octave tube mic cable.

I created a thread about this in the Microphones section, but didn't get much traction. Link is to the last post on that thread, which includes a schematic of where I left off. I thought I had gotten to a place where things should work, but I got no sound when testing the mic. I set the project aside and haven't picked it up in a while, but would like to get back to it.

https://groupdiy.com/threads/diy-psu-for-altec-150a-m11-coke-bottle.85598/post-1130227

 

[thecr4ne]

Here's the schematic for the M11 PSU. I also forgot to mention above that I added a switch to select either the standard polarization voltage, or a lower 60V in an attempt to use the Cardioid capsules from the Altec M30 with this as well.