understanding the difference in work Phase 90 & PH-1R

[POTL]

Hello everyone, I'm interested in the implementation of the phaser at PH-1R.
If on MXR we see a simple jfet solution and a resistor parallel to it, jfet is controlled by the LFO and changes its internal resistance, thereby changing the parallel value of the jfet resistance and the resistor and changing the frequency of the notch filter.
BOSS use a similar solution, but we see 3 additional elements
1) drain gate resistor
2) source gate resistor
3) a capacitor in series with a drain gate resistor
I was wondering what advantage this connection provides, this does not eliminate the need for transistors, but for some reason it is.

[teemuk]

Feedback. Reduces distortion.

[Mark Hammer]

The additional components around each JFET provide a degree of immunity to distortion; at least at low signal levels.  Mike Irwin - my personal phaser sensei - related to me that the simpler arrangement provided by the Phase 90, results in accumulating distortion in the FET as signal amplitude increases.  Our mutual buddy, the brilliant and diligent Osamu Hoshuyama (http://www5b.biglobe.ne.jp/~houshu/synth/) had posted a drawing contrasting the impact of four different ways of configuring the FET, including the PH-1R format. 



The more complex arrangement around the FET in the PH-1R (and the Phase 45 as well), holds off that distortion until a higher threshold is reached, at which point there is a large increase in distortion.  Mike indicated to me that he preferred the former to the latter.  I should note, however, that although he would dabble in guitar FX, his primary interest is synths, where much higher signal amplitudes are used, and the notion of "tripping" a dramatic threshold may be a source of audio risk, rather than a desirable effect.  Osamu's drawing suggests that the more complex circuit, while holding off distortion at more modest amplitudes, impairs faster tracking.

[POTL]

The additional components around each JFET provide a degree of immunity to distortion; at least at low signal levels.  Mike Irwin - my personal phaser sensei - related to me that the simpler arrangement provided by the Phase 90, results in accumulating distortion in the FET as signal amplitude increases.  Our mutual buddy, the brilliant and diligent Osamu Hoshuyama (http://www5b.biglobe.ne.jp/~houshu/synth/) had posted a drawing contrasting the impact of four different ways of configuring the FET, including the PH-1R format. 



The more complex arrangement around the FET in the PH-1R (and the Phase 45 as well), holds off that distortion until a higher threshold is reached, at which point there is a large increase in distortion.  Mike indicated to me that he preferred the former to the latter.  I should note, however, that although he would dabble in guitar FX, his primary interest is synths, where much higher signal amplitudes are used, and the notion of "tripping" a dramatic threshold may be a source of audio risk, rather than a desirable effect.  Osamu's drawing suggests that the more complex circuit, while holding off distortion at more modest amplitudes, impairs faster tracking.

Thanks for the detailed answer, it's really useful, I've never heard of boss clipping problems, but mxr owners definitely have problems with hot pickups.

[PRR]

[4] is sweet.

[Mark Hammer]

Sam is a smart dude, and a heckuva nice guy.  I hope we meet again some day.  Here (L->R) is a pic from 2002 of former forum member, the late Peter Snow, Sam, me, and missing-in-action Mike Irwin, at a get-together in my basement when Sam was a visiting scholar for a year at one of the universities here.  You will note the pile of 8-Tracks in the lower left-hand corner, and VHS tapes on the other side of the pic.  I think the book that Peter is holding is one of the Japanese effects books that Sam brought for us to see.