Assuming it is built in an enclosure or XLR adaptor.
From mic in pin 2 to mic out pin 2 a resistor.
From mic in pin 3 to mic out pin 3 a same value resistor.
In parallel with each resitor a capacitor.
By choosing values very high pass (shelving) can be obtained. Or gentle low cut ect.
The Haden BBC books shows 500Ω for the resistors and 2μF for the capacitors.
(It had been tried a long time ago with the Grampian ribbon GR1 /L, the sound was not quite as expected, a possible cause could be the fact that the mic is 25Ω so different values should have been tried, or that different mic source distance should have been used.)
It is also possible that for some reason inductor filters sound better than capacitor ones. Great examples of such filters can be found on the Olson paper including one with an inductor in series with a resistor. L or R,L filters are seen connected in parallel with tapings of the ribbon microphone internal input transformer.
See also the Pleiades (R,L) gentle slope low cut, high pass filters with inductors and resistors. Such filters are inside AKG D1000, (possibly inside Senheiser MD421, MD441), and inside the Electro-Voice 642 academy award winning microphone etc. See datasheets at www.coutant.org.
References:
High Quality Sound Reproduction - Hadden - page 63 - BBC
Ribbon Velocity Microphones - H. F. Olson - JAES - June 1970, volume 19
No comments:
Post a Comment