Phase 90 Univibe Mod with Switch ??

[solarplexus]

Hi there,

my bandmate wants to mod his phase 90 with a univibe mod (which I already know how) BUT would also like to switch between the stock phaser and the univibe mod with a Toggle switch.  Now... There are 4 capacitors to change the value for the univibe mod... which means I would have to switch 4 parts in one flick...

I am wondering if it is doable with just one DPDT switch with the components on a seperate vero board, or maybe a 4PDT switch, but I don't think it's possible....

Is it ??


Any help / suggestions would be appreciated!

Thanks,

Matt

[Ben N]

If you have room for a daughter board for the caps and a couple of ICs, do it with a CMOS switch. Check GEOFEX for some useful CMOS switching circuits you may be able to modify.
Ben

[jonathan perez]

yeah dude, a 4PDT will do fine!

lots of flying leads.

[Mark Hammer]

Hold up at second base.

Although the Phase 90 does not include gobs of regeneration/feedback or a control to adjust it, it does include a feedback path (this is part of the script/block difference).  Univibes do NOT include any feedback/regeneration, so there is not only the switching of the caps, but the defeating of the feedback path as well.  We're now up into a 5PDT switch and a more complex board.

I realize it may seem like admitting defeat, but I seriously think the ideal solution is a single chassis with a dual board on it, one optimized for phasing, and the other optimized for Univibing, each with their own speed control/setting/range.  This way you can switch between a phaser with one speed, and a univibe with another or bypass the whole damn thing.

[solarplexus]

Thanks guys!

One thing though... I was intending to remove R28 from the feedback path, since my bandmate wants it to stay somewhat subtler.  So there would be no need for me to switch a resistor on / off, or remove all of the feedback path.  I've modded the phase 90 for univibe mod before... it doesn't really sound like a univibe, but I do love the vibe it gives and Ed (my bandmate) heard a recording I did with it and he wants the same sound.

So... what's the verdict ?

[jonathan perez]

how about a pot in place of r28?

[solarplexus]

well he's not a "setting" freak, one knob will suit him just fine.

[jonathan perez]

whoops 

[solarplexus]

So a 4PDT would work ??

How do I use the pinout?

[jonathan perez]

i cant visualize it....BRAIN FART

ill get back to you on that, i need to draw it. in the meantime, someone help this poor soldier!

[solarplexus]

I'm trying to find the pinout for the 4DPT but can't seem to find it anywhere!   

[Mark Hammer]

You mean a pinout for the switch itself, or a wiring diagram for how to do what you want with a 4PDT?

[solarplexus]

Well... a pinout of the switch itself would really help. 

As far as the wiring, if you have any suggestions or ballparks to start with go ahead! 

What I want to do is to wire to a vero board and a switch so that I can place the pcb in the battery compartement and drill a hole near the pot.

[Mark Hammer]

The switch is going to have the same pinout as a DPDT or 3PDT, except with more pins.

The quietest arrangement is to have the caps for the one effect type in series with the caps for the other.  So, for instance, a .047uf (or .05, IF you can find them) cap in series with a .015uf cap, a .047uf cap in series with a .22uf cap, and so on.  From each trio of contacts from the switch, the middle contact goes to the junction between the cap pair (repeated for each of the 4 pairs).  One of the outside contacts goes to the other side of the .047uf cap, and the other outside contact goes to the other side of whatever the Univibe value is for that cap pair.  Step once and the switch shorts out the caps of the one effect type.  Step again and it shorts out the caps of the other effect type.  Once shorted out, its as if the cap doesn't exist and you only have the other one installed.

Some prefer to select between caps, rather than shorting out because it makes more sense to them.  However, this is prone to popping when switching.  The shorting-out method is quieter.

[vanessa]

I'm with Mark on this one and I would go a step futher and say just build a Uni-Vibe. I did Uni-Vibe mods to my Phase 90 and I was not very impressed.   

[solarplexus]

Oh I will definitely build MYSELF a univibe.... but not for my bandmate! 


Would it be possible to build this with just a DPDT ?  (cost effective  )

[sfx1999]

Would it be possible to build this with just a DPDT ?  (cost effective  )

No, but you could use 2 DPDT.

Another possible way is to replace all the internal capacitors with the highest value in the vibe mod, but switch the next 3 stages to the smaller values. You can use a 3PDT switch for that. It will change the stock sound, though.

[vanessa]

Oh I will definitely build MYSELF a univibe.... but not for my bandmate! 


Would it be possible to build this with just a DPDT ?  (cost effective  )

What I should say is I built it and it really did not make an audible difference really. A little warble at best. It was so useless that I wound up pulling the mod from the pedal and putting in Mark's (I think it was Mark) suggestion for vibrato in place of it (much more useful and noticeable).

[Mark Hammer]

Strikes me that the stumbling block here is the desire to convert between circuit types with a stompswitch.  I don't think that is an inappropriate goal, but certainly not one to drive yourself nuts over.  Personally, I can't think of any recorded illustration where someone switched, mid-riff, between a phaser and Uni-vibe.  Especially since the speeds that showcase each effect type are not exactly the same.  So, if you don't HAVE to make the conversion footswitchable, then the toggle option can become quite feasible, the switches cheaper and easier to locate, and the chassis-size requirements less stringent.  It's a piece of cake to stick another toggle  here or there, but dual footswitches require room for the foot and sufficient space to avoid mistaken engagement of the other bypass switch.  So, in that respect, having a single bypass stompswitch, and toggles for conversion is easier and less problematic with respect to layout.

I suppose the other thing to consider as a sort of freebie is that by using one DPDT toggle for two of the stages, and another for the other two stages, you have the option of creating beasts that aren't pure phaser or pure Univibe.  And who knows, your buddy might even like those.

I'm helping my son with a school project at the moment, and I'll give you the same advice I'm giving him atthe moment: Don't make it more complicated than it needs to be.

[solarplexus]

Thanks Mark and everyone else!

As a school teacher myself... I should've known to keep it simple in the first place...