DIY Tube Microphone Part 3

Next is drilling the enclosure and wiring up the PSU boards.

On the left is the power switch, below that is an LED to indicate power.  On the right top is the 5 pin XLR which goes to the mic and below it is the 3 pin XLR output to the preamp.  On the far right you can see the audio transformer.  I scored a couple of vintage Jensens on Ebay.

I put a mic on each side of the box with a separate power switch and light for each mic.

Front of PSU

Back of PSU

I also had to make some tube mic cables.  Since tube mics require their own power supply, a regular 3 pin XLR won't cut it.  These require 5 pin.  I made them out of star quad cable.  See this post about making cables.

 How do they sound?   At first, they didn't work, but I had some conversations with the good folks at the Yahoo mic builders group, (especially Ricardo) and I was able to diagnose the problem and fix it.  It had to do with the wiring of the tubes in the microphone.

After I got them working, they sounded great except for  some minor hum or buzzing, which was really annoying.  I solved that problem by shortening all of the wiring in the PSU, keeping the audio cables well separated from the AC lines and some general clean up.  Result:  zero noise, pure tube goodness.

I am going to use these to record drums, hoping to get some vintage RVG drum sounds.  I will post something when I have it.

Update: see Sounds page.  The drums were recorded using these mics.