Phase 90 univibe mod?

[vanessa]

I recently saw a mod for a Small Clone that gets Univibe like tones from it.
It may be just me, but I have always felt the MXR Phase 90 sounded closer to a Univibe. Where the Small Clone was a little more "spacey" sounding.
The Phase 90 sounded like it needed a little more "warble" and a tad more grit to it to get a Uni- 'vibe' to it.
Has anyone every modded one to give it more of a Univibe 'vibe'. And if so what could you do to make it "warble" and grit?

:roll:

[petemoore]

Yes, I socketted the phase staging capacitors Vanessa.
 Using Uni-vibe specs [U.Vibe is also a 4 stage phaser] as one extreme of capacitor uf valueing, trying those 'highly staggered values'...
 Using all same values on all four stages [.1uf on 4 stages, .047uf on 4 stages etc.] as the other extreme...trying that for a time too.
 Using 'everything inbetween' and even 'in excess of' the two extremes at one point or another...
 I settled on somewhere close to, but not as extreme as univibe's capacitor staging values.
 Warble is nice, but may become too 'lumpy'.
 You could always add an SPDT or DPDT and switch values on a stage or two. Even a SPST could change a stage  value by adding/subtracting a cap. SPDT ?? I've never done it....now I'm thinking about doing it again !!!

[vanessa]

That does sound about right. Maybe just one cap value might do it. Just to throw it off a bit to give it that warble thing a little bit more. Also it would need something to give it a bit of a more low-fi vibe (no pun intended!). It needs a tad of distortion. If you had a switch to switch in the Uni-Vibe side I wonder how that could be done. Maybe a diode to cause some clipping?

Also I also think the Phase 90 is like a Uni-Vibe on steroids. It needs to be mellowed out a bit. I wonder how that could be done.

[Ed G.]

I played a phase 45 clone a while back and was floored. I think this is what you are looking for. It had that tone, plus at high speeds it got a cool leslie-esque warble. At slow speeds, stuck in front of my bsiab, I easily copped the Jimi/Trower vibe thing. I'm going to build one next.
I think matched jfets make a difference.
Also, the DOD Phasor 201 is the same circuit, with different components.

[vanessa]

I like the phase 45 but it's a little weak as far as phase shifters go. I do like it please don't get me wrong. For a phase shifter I really like the phase 90 the best. It has a real fat vibe. I just wanted to see if anyone tinkered with one to try and get a uni-vibe tone out of it. I want the phase 90 but it would be cool if at a flick of a switch it could do a half way decent uni-vibe tone.
What got me going on this are a love for my phase 90 and a love for my uni-vibe but a hate to have to bring them to shows and practices. I wined up just taking the phase 90 as I can get a uni-vibe'ish thing going and then I do all the rest. And seeing that Small Clone mod makes me jealous.

[petemoore]

Yupp, they're all a little differnt.
 EZ Vibe...Luschious !!1
 Phaze 90...Beautiful tone, Love My 'little Phibe 90' build [1 knobber with UV cap mods].
 SS phazer...with foot treadle speed control in Vox Wah case he hee...
 6 stage phazer A 'la Geo...Yeahh
 I do like the PHaze 45, definitely less pronounced phase sounds [coole]
 Here's one...phase 45 into a 4 stage phaser....mess with BOTH the speed controls LOL...one before one after FF...both before etc. WILD !!!

[ESPm2M]

this is from a previous thread of mine. hopefully you or someone else will find it useful as I find it to be relevant here...

by Mark Hammer

1) Possible to "Univibe" a P90? Yes. You can do this to essentially any 4-stage (and sometimes two-stage) phaser. The cap values in the actual Univibe design are not "magical" in any sense, but they distribute the phase shift more evenly across the spectrum, and that's a big part of what delivers the characteristic sound. Something close to the values you see in the Univibe should get you something close to that sound. Many folks have swapped the cap values in Small Stones and Ross Phasers for the Univibe values and gotten excellent results.

2) "Drying out" a P90. Two broad approaches to wet/dry mixing in modulation pedals. One is to provide a means to vary both wet AND dry balance/level. That is the method shown in the GIF linked to. The other approach, which I personally tend to opt for, is to vary wet level only in continuous fashion, and use a switch to cut out dry on an all-or-none basis. Why? Lifting the dry signal entirely creates another kind of effect. Having SOME dry signal dilutes that particular effect, and while it provides another musically-valid sound, most folks (myself included) don't find a lot of use for it on a day-to-day basis. In contrast, most folks can find a reason to trim back the effect intensity by reducing the wet content. Fortunately, that's a much easier task to accomplish.

Leave the 47k resistor coming from the output of the first op-amp in place as is. Change the 47k resistor from the last phase shift stage to a 39k resistor, and wire up a 250k pot as a variable resistor between the free end of the new 39k resistor and the mixing point at the base of the transistor. This new arrangement will let you go from just a little more wet than dry, through the perfect 50/50 balance to noticeably less wet than dry. It won't achieve NO wet signal, but then that's what the bypass control is for isn't it?

Variations: Where the cancellations happen most can be influenced by sticking a small-value cap between the output of the last phase shift stage and the 39k resistor. Try a .01 to .033uf cap and see if it appeals to you.
There may be insufficient space to install another pot and knob, in which case a 3-position SPDT toggle (centre off) can do the trick nicely You can stick in a 270k fixed resistor in place of the suggested 39k and 250kpot and use the toggle to connect each of two parallel resistors. With no parallel resistance, you have minimum depth. With a 180k resistor in parallel, you have medium depth, and with a 56k resistor in parallel, you get max depth. That may well be enough for your needs.
If you want, you can stick in an SPST toggle (or if you have the room, stompswitch) to disable the dry signal by lifting one end of the 47k resistor. That will score you vibrato. If you need it, you can wire up a DPDT stompswitch or toggle such that when the vibrato function is engaged, an LED indicator comes on to indicate effect status.