Fostex M80RP with various Pleiades (R,L) gentle slope high pass filters

2 Danbridge air cored inductor box type D13A connected in series anti phase in order to hum cancel
and
1 Danbridge resistance box type DR4/ABCD
were used to create a variable Pleiades (R,L) microphone filter.


The Fostex M80RP used was measured with the Escort LCR meter ECL-120 to have an ac impedance of 680Ω.
(DC should not be used as it can damage a ribbon mic)


The microphone was wrapped with very thin food wraping membrane so that singing distance of even 1in can be tried.
The difference between membrane and no membrane turns out to be subtle. Perhaps this has to do with the fact that even at the highest frequency the sound wavelength is much longer than membrane or membrane much much thiner....


(70ω,40mH) nice for 1in
((100-140)ω,60mH) nice for 3in
(140ω,40mH) nice for 3in more HF less mid
((70-170)ω,80mH) nice for 6in resembles AKG D190 with Pleiades (130ω,40mH)
((90-140)ω,100mH) nice for (10-12)in