Stereo Voodoo Vibe; how to?

[Bernardduur]

Hey all!

I have build my Voodoo Vibe but got tired of using it with two amps just normal; I would love to make it true stereo, so with outputs that are 90 degrees from each other.

Thing about the unit + schematics
Note that the schematics are not completely right;

Any thoughts on how to make this unit true stereo?

[petemoore]

  This is a bump.../ '?'
    make it true stereo, so with outputs that are 90 degrees from each other.
  Here we go with the dual phaser questions..and not to detract from more technical help on how to actually accomplish this..what prompted your decision to have 90 degree phase offset ?

 

[Bernardduur]

I never thought on a dual phaser;

I have made my Small Clone stereo; true stereo. And with this both my amps do a different thing when they are fed with the stereo signal. I read somewhere that they are in phase apart by 90 degrees. When I plugged in my Voodoo Vibe I felt it lacked the whole stereo experience with two amps; they just broaden the spectrum, they don't offer real stereo.........

Therefor my question. Dual phaser thus.... I'll need to read upon that

[dbell76]

the link doesn't work anymore, anyone has the schematics please?

[Mark Hammer]

Basically, wat you do is this:

1) Get yourself a pair of dual op-amps or a quad op-amp.  I imagine a TL074 or any other low-noise equivalent will work just fine.

2) Make two of the op-amps into fixed phase-shift stages, one lag and one leading.  So, for example, you could use the Phase 90 stages as models to work from.  Instead of having the FET, you just have the cap between previous and subsequent stage and a fixed resistor to ground, such that where the phase shift is located does not change with the LFO.  One of the stages will have the cap and resistor in the mroe frequently-observed position, and the other stage will have their positions reversed.  So, the cap will go to ground and the fixed resistor will go between stages.  When the resistor goes to ground, that provides for increasing phase shift (up to 90 degrees) as you go higher in frequency.  When the cap goes to ground, that provides for increasing phase shift (up to 90 degrees) as frequency goes down.  If you stagger the cap values a bit such that the two stages don't provide more than 90 degrees shift at any given frequency when summed, you will have your desired 90-degree shift.  I reckon (though I could be wrong) that a sensible place to start s to make the cap to ground 4x the value of the cap between stages.

3) One of the op-amps becomes a simple unity-gain invertor; 10k to the invertng input, 10k feedback resistor.  You can use a DPDT to bypass the inverting stage and decide what sort of "stereo" you want.

4) The fourth op-amp section sums what comes from the added fixed phase-shift stages and from the original clean output.

That's it.

[R.G.]

Hey Mark. Tell him about Hilbert dome filters.

[Mark Hammer]

I would....if only I knew what they were (maybe I do but just don't know them by that name).  So.......back over to you, RG.

[puretube]

Dome (with a capital "D", as in: "Robert B. Dome" - B. for: Byron)

[Eb7+9]

Hey all!

I have build my Voodoo Vibe but got tired of using it with two amps just normal; I would love to make it true stereo, so with outputs that are 90 degrees from each other.

Thing about the unit + schematics
Note that the schematics are not completely right;

Any thoughts on how to make this unit true stereo?

split the cells in two groups and run each side by the same drive circuit duplictaed twice but stick an inverting op-amp stage on the LFO signal after the first op-amp to run the second group on ... this will cause the LED intensity on one side to go in the opposite of the other ... just make sure the LFO signal has same amplitude and offset and it'll work fine ...

good luck

~jc