C12a mod to remove cathode follower?

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the one very annoying thing is that i wound both mic transformers identically, although within the panic of trying to fix this hum i have resulted in rewinding one of the transformers to a 3:1 but didnt record what or how i wound the other one.
luck would have it that i still have the windings on a bobbin, so if i gingerly put them back, everything should be fine.
i did record the ohms and inductance and i have the other one to compare so its not a complete loss but still annoying!!
seems i love learning the hard way!!!
 
well i can give a quick run down here no problem, i need to write this down anyways:

so for these C12a it needs a small bobbin nickel lams, i chose these of ebay:

https://www.ebay.co.uk/itm/334340331691
you get two.

mobys U11 is 1.8:1 ratios so i thought id go either 2:1 or 3:1
pretty sure i used 0.1mm guage for PRI ans SEC
i have a hand winder with a little attachment screw which is able to hold this small bobbin.
start with the secondary as it going to be the most winds
sec = 1800 turns
tie off the wire and solder, make sure to do even layers applying a bit of tension so it all gets on the bobbin nice and neat.
i then test the winding and write down the DCR, in this case its 168R
then i cut some masking tape and wrap just enough round that winding so i can do the next winding.
next is PRI A = 200 turns, then tie off once done and solder, then test 22R and cover with tape.
Next is PRI B = 365 turns, then tie off once done and solder, then test 46R and cover with tape.
i then attach and solder any winding joins and then cover with tape and put in a mumetal case or i make a mumetal encolsure for it.

so my transformers for these c12a turned out like this
SEC = 168R inductance = 64H
PRI in series = 68R inductance = 6.3H

and thats how i roll, or rather wind!!
 
That's about as sacrilegious around these parts as putting a Schoeps FET circuit in a U47 . . .
I agree, C12a reason to exist IS it's cathode follower topology... have you heard it on a loud source (e.g: drum overhead...), with it' snappy, infinite headroom response? Only C12a and Sony C37 can do this, why butcher a fine engineered vintage mic? Il you want a plate loaded mic you have tons of (not so expensive) different models...
 
I agree, C12a reason to exist IS it's cathode follower topology... have you heard it on a loud source (e.g: drum overhead...), with it' snappy, infinite headroom response? Only C12a and Sony C37 can do this, why butcher a fine engineered vintage mic? Il you want a plate loaded mic you have tons of (not so expensive) different models...
Did you read the whole thread or just the title?
 
or i make a mumetal encolsure for it.

Hey Spencer. Are you annealing your enclosure after you've built it? What construction methods are you using? From what I understand, cutting, bending, even hard knocks can reduce the magnetic field screening properties of mumetal, but they can be restored with appropriate heat treatment.

Perhaps folks with first-hand knowledge of this could chime in.
 
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