Phase 45/90 Hybrid

[tatou]

So far I've built a MBP Phase 45 clone (Smoothie) and a GGG Phase 90 clone. I like them both, but sometimes I want one sound and sometimes the other, so I'm tempted to make a more versatile hybrid for my pedalboard. In particular, I'm thinking of the following controls:

• speed knob (duh)
• toggle switch between 2 and 4 stages
• toggle switch for feedback (like MBP's NomNom)

If both toggles are off, it's like a Phase 45. If they're both on, it's like a Phase 90. But you could also have a 2-stage phaser with feedback, or a 4-stage that's clean.

Has anyone tried this? Does it seem like the full 4-way versatility would be worth it?

As for designing this circuit, I could either start with the Phase 90 schematic and add the toggles as bypasses, or start with the Phase 45 schematic and build in 2 more stages + toggles. I'm not sure I fully grasp the subtle circuit differences (e.g., the LFO seems different), so I'm not confident about the best place to start. For example, I don't *think* there are power supply issues to consider if switching between 2 and 4 stages (1 and 2 opamps), but not 100% sure. Any advice is appreciated!!

Related question: Is there a reason that the feedback current goes into the second stage for MBP's NomNom , when it seems like it goes to the first stage in the original Phase 90?

[jimilee]

I built a 2 in one with a 45 and a 90. If you use them at the same time you can get a cool tremolo effect. But, seems to me, if you use a 90 and a 2 stage bypass, you won't have to reinvent the wheel. Sounds like an awesome project though.


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[tatou]

OK, I guess I'll just try prototyping a Phase 90 with 2-stage bypass and see how that sounds. Thanks!

[solderfumes]

I built something like it with 6 stages, switchable to 4 or 2.  I like the different textures, but I rarely use all 6.  I put in a feedback control, and found that I preferred to use the Smoothie LFO and its method of using the JFETs.  The JFET circuitry feels smoother to me.  I can't remember why I picked the Smoothie's LFO, but I remember using an oscilloscope to see that it had either a larger range of rates or a larger amplitude.

I don't think there should be any power supply issues. 

[solderfumes]

Wait sorry I used the Nom Nom's (Phase 90's) LFO.

[tatou]

Cool, thanks for the input. When you say "feedback control," do you mean a toggle, or a pot that controls the amount of feedback?

As I've ruminated on this idea more, I've thought of doing that and also adding a mix knob (speed, mix, and feedback pots, plus a 2/4 stage switch). As a fan of simplicity, I worry that that's over-tweaking. But it has occurred to me.

[solderfumes]

I put in both, actually -- there's a toggle that chooses between feedback to the first stage, feedback to the second stage, or no feedback.  I'm all about overkill!  If you don't care about choosing the stage, you could actually implement using a no-load pot, which is easy enough to make yourself, and which I wish I had thought of at the time.

I put in a mix pot as well, and that's fun too, but yeah, not for everyone.  What may be more useful is a depth control, which is pretty easy to implement -- is it in the GGG documents?