_________________________________________________
| |
( _|_
) L ___ C
( |
mic in | | mic out
< <
> R1 > R2
< <
________________|____________________|____________
Pleiades high, low pass wave filter schematic
R1, R2 can be variable for variable steepness slopes.
For a 200Ω mic a typical potentiometer value of R1 may be 300Ω.
R2 should normally be higher.
L together with the mic impedance defines high pass turnover point.
C together with mic impedance defines low pass turnover point.
The wave filter should sound great are it is a minimum component signal path, with no active devices with feedback such as op amps etc.
The inductor is preferably wound on a ring tape wound magnetic core to avoid alternating magnetic field noise pickup. A ring shape creates a very efficient closed magnetic circuit where minimum magnetic flux leaks out and minimum magnetic flux leaks in.
See also improved Pleiades filters.
The objective of the use of the Pleiades wave filter is flat frequency response from producer's brain to listener's brain. [Lowe, Morgan].
The wavefilter can be connected to a microphone input transformer.
A low noise head amp may follow such as Pleiades V6. It consists of input transformer, EF183 electron tube, output transformer, 4V battery for both heaters and anode.
Pleiades concepts and schematics are open source.
References:
Improved Pleiades Filters - euroelectron
Pleiades V6 schematic - euroelectron
Flat frequency response from brain to brain, Sound Picture Recording and Reproducing Characteristics - D. P. Lowe and K. F. Morgan - J.S.M.P.E.
Bibliography:
Motion Picture Engineering
Elements of Sound Recording - Frayne, Wolfe
Feynman Lectures in Physics
Conceptual Physics - Hewiit
Electromagnetism - Grant, Phillips
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