distortion/clipping with DOD 201 phasor

[fallingfurther]

hello, this is my first post.  I just picked up an 80's version of the DOD 201 (the yellow one), which is supposedly the exact same components as the 70's ones.  It's a great, subtle phaser, but I'm getting some distortion with it.  I use a Gibson '57 classic plus bridge pickup.  I've tried adjusting the trim pot, but it still clips at all the useful settings.  Is there any way to give more headroom?  Maybe something like the R-28 mod for the Dunlop Phase-90's?
Thanks, Louie

[Mark Hammer]

FETs are prone to distortion under high signal-level conditions.  Though "barebones" phasers like the DOD do not do so, some phasers include a small network between the drain and gate which can reduce distortion, or rather increase the signal handling capacity so that distortion occurs less often.  You can see it illustrated here through the graces and expertise of Osamu Hoshuyama.  Most phasers, including the DOD use version #1.  The part you are interested in is illustration #2.  The implementation of the simple RC network shows up in phasers like the one from Korg, several from Ibanez, and the Mr. Multi, among others.  The MXR Phase 90 does NOT use such a network.  Since this is intended to improve signal handling by FETs, as you can imagine, there is no need for such a network in either LDR-based phasers like the Biphase or MXR Phase 100, or in OTA-based phasers like the Small Stone, Ross, or Moog Stage Phasers.

 

[markphaser]

Whats the difference between slow tracking and Fast tracking?
What is slow tracking? what is fast tracking?

Why would the FET distort?

The FETS input is the ouput of the LFO voltage so how would it distort the FET and why would it?