"Manual" Phaser?

[trad3mark]

Hello all!
I was listening to some of that "Mewze" band this evening, and it got me thinking about the idea of a manual phaser. I don't quite understand entirely how a phaser works, but, if, for example, you set up some sort of wah foot control, could you make a manual phaser easily enough? I know there's fake phaser circuits, but what about one based on a treadle that can be "phased" manually via the treadle?

[kvandekrol]

I asked the same thing a few months ago - see this thread for some more reading material:

http://www.diystompboxes.com/smfforum/index.php?topic=88776.0

Right now I'm building a Bad Stone phaser, which has this exact control by design. The EHX production version didn't have an external jack to control the manual pot with an expression pedal, but that's a pretty simple mod that mine will have. There was a group buy for the boards a couple of months ago, but unfortunately I believe they are all sold out by now - so it won't be quite as easy to build one, but the Bad Stone is definitely a circuit worth looking at for this.

I would be very interested to see if there is any way to incorporate this sort of control into another more common phaser, though.

[kvandekrol]

Also check out this, which goes into more depth on how to do this to a Phase 90:

http://www.diystompboxes.com/smfforum/index.php?topic=43933.0

[merlinb]

what about one based on a treadle that can be "phased" manually via the treadle?

It should be extremely easy to add this functionality to a typical phase like the Phase90. The treadle jack would simply interrupt the LFO, or alternatively it could reconfigure the LFO opamp to buffer the DC voltage that is controlled by the treadle.

[Rodgre]

Merlinb is right. I have at least 3 commercial phasors that do this trick, most recently acquired, a Maestro Fuzz Phazzer which has no LFO at all.

You should be able to take any phasor circuit which has or allows for a depth control for the LFO (i.e. be able to turn the amount of sweep down to zero) and apply some kind of control voltage to the point where the depth control feeds the phase shift circuit.

Since not many (but some) commercial phasor pedals have a depth control already, you should be able to compare the LFO in a schematic to any similar LFO from a flanger that has a depth/width control.

2 of the commercial phasors that I know which allow for pedal-controlled sweep (and again, not the rate, the actual sweep, which sounds similar to a wah) both use LDR/lightbulbs to do this. (Morley Power Phasor and Maestro Fuzz Phazzer).

One of my favorite phasors is the Boss RPH-10 microrack series phasor.
http://www.modezero.com/boss-rph10.htm
It not only has a front-panel "Manual" control for this function, it has an external "Modulation Bus" input, which lets you plug in a CV pedal to sweep the phasor (and do all sorts of great multi-wave/random sweeps by combining 2 or more external LFOs/CV sequencers to sweep the phase).

Roger

[Mark Hammer]

Modulation buses let you do all sorts of interesting things.  I used that CV input to add envelope control to mine.
http://hammer.ampage.org/files/RPH-10-a.jpg

No reason why envelope sensitivity could not be used in conjunction with foot-pedal control.