With this kind of bias, the cathode is on ground without a resistor.
... And the tube is running at maximum gain, which I'm not 1000000% sure is what you want, in a mic...
Will the circuit shown in the image work correctly and is a 0.01 MF capacitor needed (marked in red in the image)?
C800G = cathode bias mic?Filtering the heater supply? Didn't the C800G employ a couple of 1F supercapacitors in series for that?
One could probably get away with a single one here, filtering the gate bias alone.
Yes, with a fixed bias, the difference is audible, and I like it.Keep at it though - in my experience a fixed bias tube mic is a audible change (and awesome) but is so difficult (due to H+ filtering) there are not many builds (vs C12 clones).
As picture ?If you do manage the fixed gain - get rid of 1000 pf to the capsule!
Switch the grid connection to the other side (that currently goes to ground). The tube grid (at ~ -1.5v) can provide the capsule reference. The backplate can stay connected to the polarizing voltage (~60v).
YesAs picture ?
It's clear.Yes
I would get rid of the trimmer in the final build also (replace with two resistors instead). Find the resistances you need and then swap them in for the trimmer.
strange. Does your capsule have a membrane on the front and back? The 'backplane' is the metal center, it is not the membrane on the back, if you have a dual sided capsule. You are just swapping the connections of the bias and grid.I tried to connect the capsule according to this scheme and I got a quiet and bad sound ..For some reason, the sound from the back of the capsule is louder than from the front.
Just for long term durability. You can use a trimmerAnd how can the trimer interfere, will it somehow affect the sound?
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