http://diystompboxes.com/sboxforum/viewtopic.php?t=7580&postdays=0&postorder=asc&start=0
In particular:
- variable Rate
- variable Resonance
- variable Sweep Width
and the intensity and depth using a one chip circuit?
I am thinking of trying the color switch to sweep width control mentioned here and was wondering if there were other cool things I am missing.
Mnay thanks!
Shad
maybe this can help:
http://diystompboxes.com/sboxforum/viewtopic.php?t=18102
I'm not sure whether the additional chip to facilitate adjustable sweep width was ever pursued. As Ton correctly links to, a variable resistor feeding the Iabc inputs of the OTAs (3080, 3094, or 13600/13700) will reduce the input current and the amount of sweep in the Ross Phaser. However, for reasons I didn't quite understand, doing the same thing in a Small Stone resulted in a speed change, even though it had no impact on LFO speed in the Ross.
I will point out that the simple adjustable width thing on the Ross is far from foolproof. Playing with it last night, it really seems as though the added series resistance does not do the same thing as a conventional depth control on your standard 2 op-amp triangle-wave LFO. Instead of simply scaling down the overall wave amplitude, it seems like the lower part of the LFO waveform gets "chopped" at increasingly higher and higher points, so that at minimum intensity (which in my case is 100k resistance in place of the 10k) the unit behaves like there is essentially no sweep except for an intermittent triangle-like "blip" superimposed on a steady amount of phase-shift.
I will emphasize that *small* amounts of sweep-width reduction still sound natural, and are helpful for achieving a suitable sweep-width compensation when you adjust speed, but greater amounts of series resistance produce something that does not sound quite as natural.
So, while the Ross Phaser lends itself more to this bonehead simple intensity/width adjustment than the Small Stone does, in neither case does it mimic what you get if you simply stick a voltage divider on the triangle-wave output of a standard op-amp LFO.
Certainly you CAN still add a variable regeneration amount control to a Small Stone and simply use the existing "color" control as a full/half-width sweep control. That alone will open up the tonal options since it is otherwise impossible to get modest sweep width with high regeneration or wide sweep width with little regeneration. Hell, even the MXR Phase 100 at least gives you 4 settings combining these parameters instead of the Small Stones 2 settings!
I'll have to get back to digging up the one-chip solution Mike suggested.