My Oktava 319 CF tube mod.

[k brown]

Long before Oktava came out with their tube mic, I did this with a 319:

Modded the body for a more '47-ish' appearance, re-mounted the capsule on a rubber post, removed the res discs, removed all the switches and electronics and put in it a slightly different version of the C-37A cathode follower. So, like the Sony, all that's in there is the tube and three resistors. Out of a box full of NOS 6AU6s, I culled a reasonably quiet Mullard with fairly low microphonics.

Also shortened the head basket a bit, flattened the top mesh cap, rounded off all sharp corners, and filled the space on the back of the shell where the switches were, with auto body filler. Adding that mass did so much to kill any ringing, that it didn't need anything further.

Since the rattle-can paint job looked like, well, a rattle-can paint job, I gave it a couple of coats of brown-tinted ('for dark wood') floor paste wax. Helped a lot; gives a nice soft sheen that no paint on it's own can provide, while also warming the silver color slighly.

Captive cable, and built-in swivel mount were intended to approximate the appearance of a '47 with the swivel adapter attached.

 

[Recording Engineer]

I’d buy one! SO COOL!

 

[mrgrooves666]

Very nice job you did there, how does it sound? Curious

 

[k brown]

Well, funny thing is - I also did one with the electronics replaced with a very simple constant-current loaded 2SK170BL circuit, and they sounded exactly the same. Same with two pairs of MK-012; one with a 5840 CF, the other with the same 170BL circuit - couldn't tell them apart either (all were transformerless).

I also built an Ampex 350-clone mic pre and a Pultec MB1-clone; they were my best pres for several years, but since upgrading to better SS pres, I've left them behind, too.

Hard-driven plate-load tubes and high-color transformers can be magic for rock, jazz, world music - but I do almost exclusively classical, so I want clean and real.

Fun projects at the time, but don't really get used anymore.

 

[McIrish]

Very cool. The 319 is a pretty nice sounding mic stock. I have three that I removed the resonator disc and upgraded the electronics. I too was wondering if a tube might put it into another category. I guess not. Nice work though.