St. John Smythe wrote:
Scott Dorsey wrote:
There's no room inside there for the magnet assembly, though. The actual
element on the D-104 is pretty tiny.

The one in my parts drawer is about 1-1/2" diameter x 3/8" thick. Aside
from the dimensions, wouldn't a ribbon need an open back?

It would help. You could build a baffle behind the ribbon to make it a
cardioid or omni, but that would require more space inside.

St. John, whose ribbon experience starts and ends with RCA 77 and 44 series

You can make a ribbon assembly smaller than that these days, but the problem
is that the field needs to be uniform so whether the ribbon is fully forward
or fully back it's bathed in the same flux. This means the pole pieces on
the side need to be pretty deep. You can make them less wide by using
modern rare earth magnets but it's hard to reduce them in size and get an
even field, without making the ribbon smaller. Then, if the ribbon is
smaller the output is reduced.....

I think a Beyer assembly might just barely fit. The Shure SM33 assembly
won't.
-scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."