Using diodes LEDs to bias tube in mics ? & capacitors in mics & other mic ????

[Gus]

You could try a voltage doubler and then a RC(s) into regulator circuit and maybe a RC after the regulator circuit to clean up the DC of a 3 term regulator (if you use one).
What is the current rating of the 6.3VAC transformer that you are using?

 

[Gus]

If you want to use a LED to bias. This is what I did
First find an LED with the correct voltage drop
Then check how much the voltage changes within the current range the LED will work at some LEDs voltage drop is more constant with current changes

As noted by o3misha LED alone often does not sound good even bypassed with a cap.
I added current to the LED from the heater supply with a resitor
say the tube is operating at .5mA I would add about 5mA by selecting the resistor value

The Square microphone uses LED bias

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[vitopower]

"You could try a voltage doubler and then a RC(s) into regulator circuit and maybe a RC after the regulator circuit to clean up the DC of a 3 term regulator (if you use one).
What is the current rating of the 6.3VAC transformer that you are using?"

Thx Gus. 2 x 6.3V 2A.
Looks like your suggestion fits the one lo-res PSU pic I've found. I'll try that route when I can get the parts.