The Sennheiser MD211 N with Pleiades V6, or V1 with Freed transformer?

This is after wandering how the excellent MD211 N microphone will sound with a military quality input transformer which has a core of variable inductance index with frequency. Would it produce flat frequency response from singer's brain to listener's brain. See today's post on this Freed input transformer.


See also last 2 days posts for more details of the setups used.


Initially the MD211 N was connected with this signal path, setup:


Male voice singing When I Fall in Love - MD211 N at 1-2in - Pleiades V1 (Freed input transformer - CV2269 electrometer tube with 60MΩ from 1.2V to grid, AAA battery for both filament and anode, anode RC coupled to Canford red 1/4in high Z to low Z transformer) - Sony TC-D5 Pro - Sennheiser HD580


Great sound, very natural. Big. Full bass but not bass heavy. Silky smooth treble, perhaps lacking some sparkle but so natural. Balanced mid range with no exaggeration. The slight treble loss might also be due to the high 1:30 turn ratio of this transformer or the high internal, anode resistance. But perhaps it may be an additional factor on why it sounds so natural.


Next setup:


Male singing voice - MD211 N - Pleiades V6 (Nuvistor 7586, 6MΩ from anode to grid, Cc=22nF, 3 AA batteries for both heater and anode, a 10Ω in series with heaters) - Sony TC-D5 Pro - Sennheiser HD580


When the excellent Altec 4722 input transformer is used the sound is nice but bass heavy.


When a Pleiades 100Hz, (333mH) is cascaded after the mic the sound is more natural and less bass heavy. Some mid peak.


When another such Pleiades filter is cascaded the sound becomes thin and mid peaky.


When the Pleiades (130Ω,40mH) gentle slope low cut filter is only included between the MD211 and the Altec 2269 transformer the sound is exceptionally nice. But it is a more bright sound that the 1st setup. Perhaps different values are needed for further experimentation with Pleiades (R,L) filters. (140Ω,42mH) has been already found better, see previous posts.


Perhaps the best choice might be the fullness of setup 1 with some more sparkle.


The gain with the Pleiades V1 is low. The Sony TC-D5 gain setting has to be at max. But what a nice sound.


It is amazing what an AAA 1.2V battery can be do with the CV2269 with this wonderful microphone and the Freed transformer which makes the total system or setup flat from singer's brain to listener's brain.


Reference:


http://euroelectron.blogspot.com/2018/07/the-use-of-microphone-transformers-for.html



Pleiades V6 schematic (the RC coupled to output transformer Pleiadss V1 headamp is similar but perhaps simpler and smaller, just 13mA current consuming for filament!)





Photo of the Pleiades V1, the bias is negative but less so
http://euroelectron.blogspot.com/2015/10/pleiades-electra-13v-electron-tube-pre.html