140mH input transformer

The 16H to 140mH Pleiades output transformer for V6 was connected as input transformer for V4.


So the microphone is connected to the 140mH input. Step up ratio is aproximately 1:10. The magnetic Nanocrystalinne tape wound ring core is the Magnetec Nanoperm 070.


With the MD21 the sound was somewhat bass heavy. So possibly the MD21 need less primary turns, ie a transformer primary of less inductance.


With the D130 almost correct balance. (Some s problems).


635a was natural,


The M55 was thinner on bass as expected as it is 500Ω. Natural sounding. Smooth high frequency.


The M 55 sounded with full and natural sound with the Candord input transformer which has an input inductance of aproximately 413mH. What a microphone!


The MTL F-96 sounded natural. On its own it is bass heavy for close vocals. The 140mH primary inductance compensated giving a natural balance to listener's brain. Again polarity was very important. It sounded confused. By when the tip of its mini jack was connected to return pin (3) of the female XLR and ground to the live pin (2) of the female XLR input the sound was clear and beautiful. This was done without the use of crocodile cables. By opening the XLR female and joining the metal parts of the 2 connectors without touching them.


The Pleiades V4 electron tube pre preamplifier was connected with just 3 AAA batteries. Measured potential at various points: Vb=3.4V, Va=3V, Vg= - 8mV


When the input of the V4 was short circuited there was almost complete silence.


When the short was disconnected there was some nice sounding hiss. When the input transformer was connected with crocodile cable it was still there. When the microphones were connected to the primary, hiss almost disappeared and ambient sound could be heard. The polarity of the secondary connection (ie to which trasformer output terminal is the grounded crocodile clip connected) played again a tremendous role to the sound, rf problem?


Setup:


Male voice at 1in - Microphones - Pleiades input transformer - crocodile cable clips - Pleiades V4 - Realistic disco mixer at mic input - Sennheiser HD 580