Using Pleiades Filters with Ribbon Microphones

A great way to use a ribbon mic is to have 3 transformers in the signal path.
One in the mic itself.
One in the microphone preamplifier
And a Pleiades step up autotransformer in between.


For example an effective 1:42 turns ratio with a 1:7 in the preamp and a 1:6 Pleiades can be created using less than a millihenry primary inductance.


A 1:6 Pleiades was yesterday first used  on a 25-50 Ohms Grampian ribbon mic.
Only 6 turns primary was wound on Magnetec excellent smallest size Nanoperm toroidal core giving 0.6mH.


For next to lips mic distance even <0.6mH could be used.


The Pleiades low cuts and electromagnetically damps the ribbon making crystal clear voice capture at 1in using 0.6mH. Getting as much voice with least possible thermal noise and low cutting ambience too.


Next experiment will be with even less turns; 5?, 4? in the primary.


It is very refreshing  to hear this way a ribbon mic for closest vocals after some 20 years of experiments.

:
The Magnetec core is so good it may be able to handle directly a very high turns ratio of the order of 1:40 or perhaps more.


Some more Pleiades filters may be available in the future on eBay by aetoulis.


Possible next experiments will include lower cutoff and a 2nd pole defined by the value of the source resistor bypass capacitor.