Pleiades (R,L) filter or two omnidirectional microphones connected out of phase while singing to one of them?

There are errors on this post. See part 2:
https://euroelectron.blogspot.com/2019/12/pleiades-rl-filter-vs-2-omni-mics-out.html


Signal path:


Male singing voice at high register - mic - Pleiades (130Ω,40mH) filter - Sony TC-D5 PRO II on one channel - Sennheiser HD580 (signal to one earphone).


Or


Male singing voice - 2x Beyer M55 out of phase - military transformer - Sony TC-D5 PRO II on one channel - Sennheiser HD 580 signal to one ear


The ingenious trick by Lou Burroughs (Electro-Voice) clearly wins. (Later addition: on latter auditions of recording it did not, see part 2).


It is described in his book, Microphones.


Bass or mid bass or mid heaviness disappears together with ugly room ambient noise. One is left with a very clear and bright vocal.


Before trying this trick many good quality microphones were tried today while making a demo of the song Πως θα Ηταν.
A Pleiades filter of (130Ω,40mH) was connected to each mic for reducing bass heaviness to listener's brain.
The following mics were tried:


AKG 190
Nice by mid bass heavy


Fostex M80RP
More treble but bass heavy


Shure SM63
Treble but bass heavy


Shure VP64
Loud but less treble and some bass, mid heaviness


Same for the Shure RadioShack omni microphone


Same for the 600Ω Beyer M55.
Nice but somewhat bass heavy


Then 2 Beyer M55 where connected out of phase to each other to a military transformed used as a hybrid adder (mixing is an incorrect word as it means in electronic engineering multiplication of 2 signals and not addition). The output from the transformer was connected to one channel of Sony TC-D5 Pro II similarly to previous mics. The 2 omni mics were held with the back of each touching the front of each.
Excellent sound.
No bass heaviness, mid bass heaviness, boxiness etc.


Results were confirmed by listening instead of to Sennheiser HD 580 to also the linoleum Pleiades Auratone 5C type monitoring speaker with a Tesla 5in fullrange drive unit connected to Sony Tac-D5 headphones output.


A very smooth sound and it sounds professional. On most of these demos male singing voice was recorded together with Yamaha PSS-14 keyboard used for string chords.


Speaking voice sounds very thin but singing male voice sounds just right. Wish I knew this trick when starting playing with electron tube small reel to reel recorders. They always sounded mid bass heavy and I didn't know it was my brain creating the mid bass heaviness.[Lowe, Morgan]


Later addition: A lower value of R or L may do the trick. Or using the Pleiades (130Ω,ω40mHΩ) with the Pleiades V6 booster amplifier with the CV2269 electrometer tube or other electron tube at low anode current so that a second low cut filter is created, see older posts.


Reference:


Sound picture recording and reproducing characteristics - D. P. Lowe, K. F. Morgan - Journal if the society of motion picture engineers