ampage Tube Amps / Music Electronics	For current discussions, please visit Music Electronics Forum.

ampage archive

Vintage threads from the first ten years

Tube Phase Shifter

:

11/30/1996 11:59 PM
Steve Morrison	Tube Phase Shifter I'd like to hear some thoughts on the possibility of building a phase shifter with vacuum tubes. Any ideas?

12/3/1996 5:21 PM

I have a tube version of the Univibe in the works at the moment. Will that do?

I'll drop an announcement when I have something that could be built. Right now it's shaping up as a single rack space unit with six 12AX7's in it.

It's no great trick to make a tube phase shifter, the old transistor circuits work just fine when adapted to tubes. You just can't use the stock opamp circuit for tubes (well, not and also be economical of tubes) because a tube doesn't have a noninverting input with high impedance. Otherwise, they offer some advantages over the transistor circuit used in the original Univibe.

The Magnatone amp line all included what reduces to a phase shifter, using a varistor for the variable resistance element for the phase shift.

4/23/1997 5:07 PM

This is probably on the same line as R.G.'s
The op amp method's mix's sweeped amounts of
opposite phased signals together in the op-
amp. With a tube you can mix varying amounts
of the signal developed across the cathode
resistor ( like a cathode follower) with the
segnal developed across the plate resister.
Make the cathode resistor large, but you will
never want equal amplitudes mixed together.
I made a little 4 stage phaser using fets
instead of op-amps and fets as the variable
resistance. It was only 4 stages because
I was testing it, but 4 stages is still good.
Hope this helps, E-mail me if you want.
later- eth

Page 1 of 1