Pleiades (R,L) microphone filters on PA systems

At your risk.
Take all safety precautions including hearing protection.
Any voltage or current can be dangerous.


Public address systems may benefit too when using a suitable Pleiades (R,L) gentle slope low cut filter. Suitable values of Rrsistance in series with Inducatnce (and the resultant in parallel or across preamplifier inout or mic output) can be used for approaching the ideaL of flat frequency response from singer's vocal chords or even brain to listener's brain [Lowe, Morgan].


On PA work, same as on pop music vocal production, the human voice is made louder that it's acoustic natural SPL so our brain perceives more bass [Lowe, Morgan] or even more treble.


The class A (electrons flowing all the time) Bouyer ST 3 amplifier had been used for demonstration and experimenting which has a gentle low cut and high cut:
https://www.doctsf.com/schema/d46004/ref=29391#lg=1&slide=0


Nevertheless the sound from most mics tried left much to be desired. They sounded mid or bass heavy as if someone is singing in a bad acoustically bathroom..
By inserting as an example a Pleiades (130Ω,40mH) high pass filter, the sound immediatly cleared up becoming artistically usable. Experimentation is needed for most suitable values of R, L according to mic used, it's output impedance etc.


Mics used:
Sony F96 high Z
Sony F96 high Z specimen with more bass, mid heaviness
Shure SM63
Shure VP64


Signal path:


Male singing voice at 1 to 2 in - omnidirectional moving coil mic - Pleiades (R,L) filter - German XLR to 1/4in step up transformer - Bouyer ST 3 - Pleiades linoleum Auratone 5C type monitoring speaker with 5in Tesla fullrange drive unit - bedroom - singer's ear, brain


Speech has not been tried yet on this setup. It is expected that a Pleiades filter may not be needed as bass exaggeration is more apparent on singing. Counter to intuition some music applications such as a vocal may need less electronic bandwidth for flat bandwidth from record producer's brain to listener's brain.


Playing: Broken Wings - Mr. Mister
https://m.youtube.com/watch?v=nKhN1t_7PEY


Reference:


Sound Picture Recording and Reproducng Characteristics - D. P. Lowe, K. F. Morgan - Journal of the Society of Motion Picture Engineers