The L in series with R Pleiades filter may be used for compensating Fletcher Munson and voice effort curves otherwise even a world class ruler flat omnidirectiona microphone may sound bass heavy on soft singing voice reproduced at high acoustic intensity.
With the use of an LR filter in parallel with an omni mic voice coil we may approach flat frequency response from producer's brain to listener's brain. See yesterday's post.
If a directional mic is to be used we may need to also compensate for the proximity effect. Assuming it boosts bass at 6dB per octave starting below a mid frequency we may need an additional inductor in parallel to cut bass at 6dB per octave.
So we may need (La in series with R) and then Lb in parallel with this. Then the total in parallel to the voice coil or amplifier input.
Values are to be found by listening.
A Pleiades programable filter can be made with variable switchable components, variable resistor etc. Like a Pultec. Make up gain should not normally he needed as these are filters subtracting only what is not wanted.
Reference:
Flat frequency response from producer's brain to listener's brain, Sound Picture Recording and Reoroducing a Characteristics - D. P. Loye, K. F. Morgan - J.S.M.P.E.
After them a Pleiades V6 head amplifier should be used anyway in order to have a health high output low noise signal comparable in level and why not on quality with a VF14 Neumann U47 microphone or amplifier.
See yesterday's post on MD211 with V6 Nuvistor 7586 electron tube.
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