I want to build a tube mic preamp. Any recommendations?

[ruffrecords]

oh thats really great - thanks so much Ian - that circuit is pretty similar to what i was talking about - do you know offhand what that resistor value is?  9k6 gives us 5mA if we follow the same thinking of maintaining a more constant current flow…

would this work over 16 channels tho? would it be too much? that would mean there would be at least an 80mA draw off the phantom power tap…

Can't remember the resistor value but I suspect it was about 10K. For 16 channels you PSU has to be designed to supply all 16 at once so it is no different if the phantom on a channel is on or off.

I really have no concept of what  i need to keep in the bank for this stuff…

For the phantom power power you can use my phantom power PCB available via my white market page. The largest expense in tube mic pres is in the iron. Good input transformers are in the $75 region and output transformers will be in the region of $40. Notice the little 6 into to has no output iron. For simple systems you can get away with unbalanced outs.

i'd love to hear about that variable HPF - is that helios inspired?
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thanks again Ian.

The HPF was specified by the original client who was going to use the mixer for on location recording of classical music. There were 3 frequencies with a 6dB/octave slope and a couple with a 12dB/octave slope. The main idea was to cut rumble from this like air conditioning systems I think.

Cheers

Ian