Starting my second Neovibe build soon. Thinking of some mod ideas...

[Nitefly182]

OK so I built a stock Neovibe a while back and it turned out pretty nice. This time around I really want to up the speed of the LFO and possible smooth out the lamp operation to the sweep is a little less aggressive and more natural.                         

So far I know I can lower the value of the caps around q11/q12 (I believe its just one pair of caps)

I also think I read somewhere that bumping r49 up to 47k makes the sweep a bit more natural as well.

Im wondering about a few other things:

Can I replace the two mixing resistors with a 200k or 250k pot (cant seem to find a 200k) and have a mix pot instead of a switch between vibrato and chorus? Would a 250k still work or would that make it difficult to get a good thick sweep?

Has anyone added a pot in place of r49 as a smoothing control so you can have the harsher and mellower sweeps with the turn of a knob?

I've searched around but haven't seen a whole lot else mod wise. Ill probably add the pulsing LED mod by cutting the one trace and adding an LED and resistor. I might also use a switch to change between two rate pots for a pseudo leslie type thing.

Any other cool mods to the Neovibe circuit you guys have done?                   

[JOHNO]

For the mixing pot I think R.G recommends a 50k pot with a 82k resistor in series with lug 1 and lug 3.

[Nitefly182]

For the mixing pot I think R.G recommends a 50k pot with a 82k resistor in series with lug 1 and lug 3.

In series with both lugs? Would that be bridged across the pot ?

[JOHNO]

No that would be parallel heres how i did mine

[Nitefly182]

Impressive. Could you post more details about how you pulled off that expression build? Maybe some more photos as well?

[JOHNO]

Its just an old cry baby shell i had lying around

It has no volume control, all i did was to put 100k resistor to ground as mentioned by john lions on another thread.
You can see it in the first pic, its the one that sits horizontal at the top of the board.
To set up the pot i just ran wires from where R35,R36 resistors go to the pot which has the 82k resistors soldered onto it and the pot wiper goes to point N on the layout and I left the vibe chorus switch out. Also its not true bypass, I used points I and X on the layout to short the LFO to ground like the original. If it was good enough for Jimi Hendrix its good enough for me. The LFO shade is made from a piece of copper shim plate cut to R.G's specs and soldered at the corners to keep it together. I layed the LDR's flat on the board as i found the sound alot smoother that way.

[John Lyons]

That looks good Johno!
I need to make myself another Univibe clone.
I'm going to use a different layout this time and incorporate some tweaks here and there with trimmers.
I've got other things on my plate for now though.

Don't forget these soundclips by SteveB
(see post made recently)
These are the pinnacle as far as I'm concerned.
http://www.sbkustoms.com/music/fx/Neovibe.htm

Lots of Univibe mod stuff here.
http://www.lynx.bc.ca/~jc/pedals.html

john

[JOHNO]

Thanks a lot John but with out help from you guys it would not have ever happened.

[Nitefly182]

Im thinking that instead of switching between a pair of rate pots, it might be wiser to switch in and out an extra pair of caps in the LFO control so that I can double or halve the rate of the lamp and thus the rate of the vibe. Would I just use a switch to add in the extra caps in parallel or would it be series. Im not actually sure how I would pull off that switching now that I think about it... Any ideas?

[Nitefly182]

Im looking at my first build and trying to figure out the two caps that are controlling the LFO rate. Between the schem and the board it looks like c19 and c22 but Im not sure. Can anyone confirm that those are the two caps controlling LFO speed?

edit - just tried c19 ans c22 and that dropped the depth significantly with no effect on rate.

[SteveB]

OK so I built a stock Neovibe a while back and it turned out pretty nice. This time around I really want to up the speed of the LFO and possible smooth out the lamp operation to the sweep is a little less aggressive and more natural.                         

So far I know I can lower the value of the caps around q11/q12 (I believe its just one pair of caps)

I also think I read somewhere that bumping r49 up to 47k makes the sweep a bit more natural as well.

Im wondering about a few other things:

Can I replace the two mixing resistors with a 200k or 250k pot (cant seem to find a 200k) and have a mix pot instead of a switch between vibrato and chorus? Would a 250k still work or would that make it difficult to get a good thick sweep?

Has anyone added a pot in place of r49 as a smoothing control so you can have the harsher and mellower sweeps with the turn of a knob?

I've searched around but haven't seen a whole lot else mod wise. Ill probably add the pulsing LED mod by cutting the one trace and adding an LED and resistor. I might also use a switch to change between two rate pots for a pseudo leslie type thing.

Any other cool mods to the Neovibe circuit you guys have done?                   

Are you using reflected light or direct light? When I used direct light, I had to increase the value of R49 to get it to sound like I wanted. With relected light, R49 is back to 4.7k. I guess you could use a 50k pot for this, too.

I also adjusted the lamp bias to sit around 390 ohms, measured from lamp driver emitter to ground. Increase the bias for more mellow phasing. If that is still not enough, turn down the intensity control.

Try different colors & types of material for the reflected surface. This has been covered before, but it does affect the sound. Of course the distance from the reflected surface to the photocells changes things, too.

Use a linear pot for the intensity. The parts list calls for an audio taper, but the scematic & layout shows linear.

Lower the values of R42 & R43 to increase the faster speeds.

I think the mix trimpot thing is a waste of time, IMHO. Use 2 100k's & be done with it.

I have seen some clones that use a blend pot instead of a chorus/vibrato switch.

Steve

[Nitefly182]

I just used a pair of 100ks for the mix in my first build and it certainly wasn't lacking but Im building in a slightly bigger box this time around so Ill have room to leave some pots inside the box if I need to. Ill probably put one in for the mixing and the lamp setting so I can tweak easily by ear instead of swapping a ton of components.

[mr_fender]

I used a 200k mix pot in place of the chorus/vibrato switch on mine.  It works well.  Set to full dry, it goes a little crazy (buzzy), but full wet = vibrato and about half way = chorus.  I like that I can vary the mix to get different shades of vibe as well.  The Neovibe circuit sounds fantastic, but I can see how some would want to mod it.  It takes a bit of tweaking to get desired sounds since the speed and intensity controls are quite interdependent.  I used a mirrored metal box for mine with the LDR's mounted flat.  It has a great swirl.  I'm curious how a different and more tweakable LFO would respond in the circuit.  I've built a tremulous lune and it's LFO seems to be very good.  It's got very broad speed and depth ranges and both are quite independent of each other.  It also has a variable wave shape and adjustable duty cycle as well.  Is the output of the Univibe LFO a pure sine wave?  I don't have an oscilloscope to check it.  It seems like any LFO that is capable of outputing the same waveform would work just as well.  Any thoughts?

[omarvolta]

To speed up the lfo lower resistors 42 and 43(both 4k7). I think I put two 1k8 and it worked just as I wanted. This is info that I got somewhere in this forum. Peace...