48v phantom supply in tube circuits

can i do this for phantom supply ?

if zener fails it wont be good, but is it dangerous ?

30K is calculated from http://www.electronics-tutorials.ws/diode/diode_7.html
edit : not sure if i calculated correctly....
(5w zener)

You need more than that.  There's a thread about this somewhere, think I detailed what I arrived at to get correct current at 50V.  Short answer is you burn a ton of current and have big big power resistors. 

still searching your post ... mean time. how big r we talking about ... 50W resistors ?  200W ?

In your case you have 30W at the resistor so you probably want one rated for 50W and need an ideal zenner for it to work, since that doesn't exist you'll need a little bit more current from start. The zenner should be about 10W to work at about 50% at idle and you will want at least 5% at max load, so you need only 10% more current, so 33W resistor, 5.5W at the zenner. Those are, let's say 40W more you need at your HV power supply, for the extra cost on the transformer you could probably afford a small 40V, 25mA transformer. Ah, all this is for a single microphone, if two or more mics goes from this, multiply...

JS

Easier is doing a voltage multiplier from an AC filament winding. 

i think i am gonna go  with a small  50 VAC transformer.
thank you
kambo

Your plan wastes up to 3.5 Watts.

In a mike-preamp, 3.5 Watts may be as much (maybe more) than ALL the tubes put together.

Put a 120V:12V transformer backward across your 6VAC source to get 60VAC which will rectify-out about 85V which can make a solid 48V supply.

PRR said:

Put a 120V:12V transformer backward across your 6VAC source to get 60VAC which will rectify-out about 85V which can make a solid 48V supply.

Click to expand...

I've done this and it works.  No need to re-invent the wheel!

i am trying to have universal solution  for my self...  and my vacuum tube love...
every single sircuit requiring different trx... its easy to adjust voltage on B+ ...
i think 30VA 6/12v transformer is my best bet for heaters...
i wanna stick with 12 v heater where possible for less current and heat...
but, where i need to use 6 v heater, with 6/12 trx i will have double amp on 6 volt parallel  winding..
not regulated, just diode, cap-res-cap  filter...

PRR said:

Your plan wastes up to 3.5 Watts.

In a mike-preamp, 3.5 Watts may be as much (maybe more) than ALL the tubes put together.

Put a 120V:12V transformer backward across your 6VAC source to get 60VAC which will rectify-out about 85V which can make a solid 48V supply.

Click to expand...

You're right, I think I miss it for just an order of magnitude...
JS