Double sweep phaser

[StephenGiles]

I was listening this morning to a Lampinski recording of Jean-Luc Ponty at the Leroy Theatre, Pawtucket, RI on 13 October 1978 - were you there???

On one of the tracks there was a synth being played through a phaser of some kind where the sweep was followed by a trailing sweep maybe half a second behind. Bearing in mind this was 1978, when music electronics was still in it's infancy as we know it today, I wonder how this was done?

My immediate thought was that a quadrature oscillator being utilised in some way  - perhaps he was even using a Bode Barberpole Phaser. Simpler than that perhaps is the use of 2 phase shift networks in parallel, a single LFO being fed to one, and a delayed version of the LFO fed to the other, then the resulting phase shift networks mixed together.

Whatever the method, it was one of the richest phasing sounds I have ever heard. I'll drum up a sample later.

[Strategy]

My guess would be Mu-Tron biphase, you could set the phasers in serial or parallel. There IS a DIY project for this too - big pcb's though, google "Marc Bareille" + "synth DIY"

- Strategy

[StephenGiles]

http://www.4shared.com/audio/O2EWu7wW/Jean-Luc_Ponty.html

Here is a short sample of the sound I heard.

[Mark Hammer]

I actually get something like that with the 4+4 stage Ropez I made.  Believe me, it wasn't intentional.

I'm wondering if the effect occurs because one of the quartets reaches some maximum point in the sweep where the other quartet continues just for a bit.

[StephenGiles]

I actually get something like that with the 4+4 stage Ropez I made.  Believe me, it wasn't intentional.

I'm wondering if the effect occurs because one of the quartets reaches some maximum point in the sweep where the other quartet continues just for a bit.

Or could it be a by-product of unmatched FETs perhaps?

[StephenGiles]

Now I think of it, didn't the old ETI phaser produced that effect using 4049 gates was it?

[Rodgre]

Sounds very Mu-tron to me.

Roger

[Mark Hammer]

I actually get something like that with the 4+4 stage Ropez I made.  Believe me, it wasn't intentional.

I'm wondering if the effect occurs because one of the quartets reaches some maximum point in the sweep where the other quartet continues just for a bit.

Or could it be a by-product of unmatched FETs perhaps?

Not bloody likely - it uses OTAs.

[PRR]

> a synth being played through a phaser of some kind where the sweep was followed by a trailing sweep maybe half a second behind. Bearing in mind this was 1978, when music electronics was still in it's infancy as we know it today, I wonder how this was done?

Hmmmm. In many ways, "we" know less today than we did in the 1970s. While some of my recollections are colored by strong drugs, I know we knew tech-tricks which are generally forgotten now. Many things are very much easier today, true. Especially in Live Performance (which narrows the answers to your question). But there is little which can't be done via razor and tape or an analog computer (Moog, ARP).

I can't listen right now, so I'll just blather.

On a real synth (not the homogenized pre-packaged bumph of the 1980s), a "trailing sweep" can be a constant voltage offset on a second VCF.

A half-second delay is, of course, a tape machine with an extra head (or two tape decks).