tube ribbon mic design

[mus1k_freak]

Hey did some quick searching but didn't see anything, is there any designs floating around here for a tube ribbon mic? does the tube circuit have to be after the transformer? just wondering cuase I don't see much about tube ribbons, seems like it would be a fun project

 

[micaddict]

The vast majority of dynamic mics, moving coil and ribbon alike, are passive (no preamp in the body).
I guess that's the reason you don't see many tube ribbon mics.

There have been some exceptions on the transistor side lately, though. Active ribbon mics that is.

Hmm......... perhaps I'd better leave this to the experts.  :-\

Carry on. 

 

[emrr]

Its not a simple one. 

Ribbon matching side of transformer is extremely low Z.  A fraction of an ohm. 
Tube matching side of transformer is high Z.  30-50K reasonable range for this application. 

That turns ratio is beyond what many companies will touch.  It's extremely problematic to get quiet full range audio at these limits. 

Talk to Samar Audio about the transformer requirements.  I don't know that Mark will even agree to wind that. 

There are some vintage ribbon mics that have 30K or higher output impedances, which will have this sort of transformer, but they are exclusively lower-line product intended for PA usage, and have lesser response ratings.  You could get one of those and turn it into a dedicated mic with tube preamp, or run it into a tube DI type preamp (straight to grid).

 

[mus1k_freak]

Ah yea that's what I figured,  I was thinking of putting a tube buffer stage with unity gain probably a 12at7 after the transformer.  Though I'm not sure how productive that would be  guess you'd at least get some harmonic distortion out of the tube stage.  Would be a easy build maybe I'll throw  together and see if it's any good