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I've been working on a version of this with a different LFO and a JFET input buffer. Sounds wicked good!

why do you need an input buffer?

madbean wrote:I've been working on a version of this with a different LFO and a JFET input buffer. Sounds wicked good!

I just tried it out, sounds good to me. Starts getting a little wilder at lower settings, but tonalwise just the typical buffer clarity increase.

I'm boxing this up this week. It might find it's way into my rig...

Krefu wrote:

madbean wrote:I've been working on a version of this with a different LFO and a JFET input buffer. Sounds wicked good!

I just tried it out, sounds good to me. Starts getting a little wilder at lower settings, but tonalwise just the typical buffer clarity increase.

I'm boxing this up this week. It might find it's way into my rig...

ummm, where'd ya get the layout?

sprayfe wrote:ummm, where'd ya get the layout?

I imagine he made it himself. You could probably just take the vero layout, widen it by 3/4 columns, move all the existing components across and use those extra columns to stick a simple single FET buffer infront of the first transistor.

You could try this: (please note it's unverified) -

Niiiice ... Does anybody knows if I can roll it with the 2N3904?

Nocentelli wrote:

RnFR wrote:I would highly suggest a buffer on the input though. I think it will liven things up a bit.

(In theory) would having a buffered (non-true bypass) pedal in front of it have the same effect?

I made mine without the buffer, using the smaller layout on page 4 so it would fit in a 1590a. It sounds fine to me, no volume drop, and if there is any tonesuck/whatever, any mellowing of the high end (if that's what happens) probably fits fine with the vibrato effect. However, I do play with buffered pedal ahead of it - Still no idea whether this has the same effect as buffering the circuit itself - Anybody?

After building it up on a pcb, I still can't decide if I like with a buffer or not. Using a buffer at the input seemed to make the effect more noticeable on the higher strings, but I kinda like the swampier sound without. Also I wasn't getting unity gain to my ears so I bypassed the 2.2k transistor at the input and that helped a little bit. Putting a booster circuit at the output made it distort for some reason. I'm going to try an opamp buffer instead of transitor JFET next.... may even put a buffer/no buffer switch when all done.

i built mine without the buffer, came out fine....seems to be unity gain, maybe even a slight boost. could be cuz i subbed a couple resistors maybe?
i love this thing, it's permanently on my pedalboard now!

pinkjimiphoton wrote:i built mine without the buffer, came out fine....seems to be unity gain, maybe even a slight boost. could be cuz i subbed a couple resistors maybe?
i love this thing, it's permanently on my pedalboard now!

Ya know, I just checked out the Bigfoot website and listened to some sound clips and made me realize mine doesn't sound nearly as intense.... maybe still need to experiment with LDR/LEDs instead of the cheapo, out of spec vactrols I have laying around.

Mine is built with a 1Mohm LDRand a super-bright blue LED, and the effect is plenty deep enough at max depth. When I was breadboarding it, it didn't seem very deep, then I accidently moved the LED/LDR position a fraction of a hair and it became much deeper, so alignment is critical.

Nocentelli wrote:Mine is built with a 1Mohm LDRand a super-bright blue LED, and the effect is plenty deep enough at max depth. When I was breadboarding it, it didn't seem very deep, then I accidently moved the LED/LDR position a fraction of a hair and it became much deeper, so alignment is critical.

i used a jumbo white led, about 3/16ths away from the ldr (about 500k dark) sealed in shrink wrap. i think distance is the key, if the led is against the ldr, it doesn't get a chance to "fade" enough to be as effective. if ya play around with it, you'll find a sweet spot most likely. mine works great, it's like a pitch bending univibe tonally, and the pitch seems to wobble almost like the original eh clone theory. it's seasick and wonderful, and my most used modulation pedal now.

I saw a stock magnavibe but it has a tremolo mod switch...where in the circuit that tremolo mod switch?

I believe the Magnavibe version with the trem switch is an older version, and the newr one are vibrato only. To get trem, you need to disconnect the LDR leg that junctions with Q1 emitter and connect it direct to ground: this reduces the output somewhat, so you'll need to compensate by reducing the value of Q1 emitter resistor - check out Madbean's Quadrovibe to see how he achieves this. As always, I'd advise breadboarding it first to find a suitable value.

thanks..

hi all

Really keen to try this vibrato out - would also love to add a switch for Tremolo mode, basically to keep some space on my pedal board.
Shall be using the version 3 vero layout https://www.freestompboxes.org/download/ ... &mode=view

would i need an spdt or dpdt?
to be honest am quiet new to building pedals - how would i wire a switch into this version.


Thanks for your help

If you look at madbean's quadravibe project he uses a DPDT to switch both the LDR from emitter to ground, and switch the emitter's resistance to ground from (normal vibrato) 6k8 to a preset level to compensate for the volume loss:
I'll have to play about with the breadboard to try this mod out. I could alter my vero appropriately to accomodate this trem mod if you're into vero: I do love the sound of this vibrato, but it doesn't have quite the speed range I might like, so i'm not sure how useful it would be as a tremolo: It does a good job vibrato for my tastes, though. I've though about using a different LFO, because I've no idea where to start trying to slow it down...

Hi Nocentelli

embarrassingly i don't actually know how to read schematics - could you draw me a rough diagram of the switch and wiring etc
also on the subject - do you know of any good books on how to read circuits?

thanks for your info - do let me know how it goes with your breadboard mod.

Something like this should work:
The dpdt switch at the bottom has six lugs, though only five are used. If you look at the schem and layout side_by_side, you'll see the LDR connects the junction of two 220n capacitors to the switch lug A2: from here it is either connected to Q1's emitter (with leg with an arrow in schematic) via A1 for vibrato, or to ground via A3 for tremolo. At the same time, the emitter is connected to a 6k8 resistor then down to ground, and in trem mode has a parallel resistance to ground through the trimmer, reducing the total resistance and presumably raising the gain of Q1: