Treadle vibe/phaser

[Kipper4]

On the breadboard now. Just experimenting.

image deleted see my next post

[Fender3D]

shouldn't dry signal (220nF I cap) go to IC4b inverting input (via 10K)?

[Kipper4]

Sorry Yes Fender3D

It's the wrong image anyway Heres what is really on the breadboard.

[duck_arse]

there's something very wrong with your I cap wiring. Q4 base seems to be connected hard to the output. I'm off for a listen .....

[Kipper4]

yep sorry again guys theres a 100nf cap between the Q1 source and Q4 base.

[Fender3D]

I'd add a mix/buffer @ output, just in case...

Even a simple thing just like P90

[Kipper4]

Thanks Fender.
Theres more to come hopefully. I'll update as progress is made.
I'm already happy to have made this work so thats a positive.
Stay posted.

[Kipper4]

Theres room for improvements still such as fenders excellant suggestion and you guys can keep this coming.
Heres ver4 schematic (or something similar)

[Mark Hammer]

Intended more as fuel for the fire than as rain on the parade, the traditional tradeoff in modulation is that faster modulation rates want less sweep width.  Indeed, many would argue that the reason for including a Depth control at all is simply because the range of speeds is so wide that no single sweep width works for all speeds.  MXR and EHX, as well as so many copiers, went with a single fixed sweep width for the earliest phasers, that was deemed as an acceptable one-size-fits-all solution.  Actually, I'll correct that.  The Small Stone cleverly built in a change in both speed range and sweep width to the Color switch it included.  But it wasn't continuously adjustable.  While two allpass stages is not going to get you boy-yoy-yoing vibrato, one may still feel some sort of compensation for faster speeds is needed. 

Sometimes, that is provided by the properties of the LDRs themselves.  That is, the LDRs may be sluggish and not respond to faster changes in luminance, such that slow speeds get you full sweep width, and fast speeds get you something much less than that.  The old CLM6000s were sort of like that  Unless one can make some very specific recommendations for LDR, in a DIY circuit like this, there is no assurance that faster LFO speeds will be accompanied by a suitable change in sweep width.

Which leads me to the following suggestion.....

Make BOTH your speed and depth set by some combination of LDR and parallel resistance.  Your foot treadle, now controls the resistance of two legs of a pot in reciprocal fashion.  Heel down, the current limiting resistance for the Rate LDR goes high, slowing down the LFO.  At the same time, the current-limiting resistance for the Depth LDR goes low, brightening it and increasing the LED luminance on Vact-11B and 12B.  Toe down, the Rate-LED current-limiting resistance goes low, speeding the LFO up, but the Depth-LED current limiting resistance goes high, reducing the luminance and making that Depth setting higher resistance.

Admittedly, its a lotta LEDs and LDRs (four of each) but it could get you a smooth treadle functioning that automatically adjusts width as you go faster.  Naturally, it would require  tinkering with the value of resistances in parallel with the Rate and Depth LDRs, so as to achieve a pleasing and musical transition from heel to toe down, as well as wise choice of the physical pot controlled by the treadle, and any resistances in parallel with each of those pot legs to achieve the desired change in LED luminance.

One perk, in addition to automatic depth/width compensation is that any potential noise from momentary discontinuities in the LFO circuit would be absent.  The only moving part is associated with control of luminance of the additional LEDs.

[Kipper4]

Cheers Mark.
I'll reread this a few times to get a fair grasp of it.
I guess the second output of the treadle could be used as a variable resistor for the depth of one side of the effect. (2 phaser stages).
Its far from perfect and pretty far from what I would like to achieve.
I was kinda hoping to get that interactive wow and flutter effect you get with a leslie cab.
Also It might seem like a lot of vactrols too, I'm certain i can trim down the amount of leds by half by making discrete 2x ldr per led vactrols if I ever build it.
I might even change direction and go for 4x series phaser stages with 1x led controlling 4x ldr all with the speed controlled by the treadle lfo.
I'll go look at the small stone meantime.
Thanks for the fuel.

[Mark Hammer]

The Small Stone will be an unproductive distraction, since it uses an OTA-based LFO, which is not relevant here.

[Kipper4]

At the moment I'm running all four phase stages in series and it sounds ok.
It does have some issues.
The op amp non inverting output make up gain stage (gain of 5) isnt helping. Creating some noise.

Its a bit thumpy. I suspect lfo tick?

If I play hard it seems to unbias the input? solutions sought please.


The clean feedback path is ac coupled to the output mixer (series 1uf) after the I cap.
I'd like more control over the amout of clean gain. How best do I achieve this?

Further thoughts.
I'm considering using the volume pedal to control the speed of both lfo's simultaniously but both lfo's would have the speeds offset a little.
I thought I'd put different sized series resistances IC4A output and IC1A output (ref last posted schematic)
The reason for the speed offset is because thats how it sounds best to my ears, When the speeds are similar but not the same.

Thanks for taking the time to read this and any help will be appreciated
Rich

Edit. I forgot to ask how do I put some small caps (eg 50pf) in the phase stages like some of the op amp phaser stages ergo the bi phase?

[Kipper4]

Update oclock. Well just gone midnight really.

News just in.
I cant use a single volume pedal with two lead on the outputs to control the speed of two independant lfos.
Unless I wanted a junky effect.
Basically one of the lfo's stalls for a bit, jumps back into life, and the output of the lfo also is way stronger than normal. Suggest a rush of currant given that my retina are burning.

This might work as a dance dj's effect with built in laser but as a rotobox its near useless.
Back up a bit and replan.

It'll be kipper time before I know it.

Wheres Duck at? Surely it must be sun up in the Antipodese.

[Kipper4]

I guess If you had an old wah shell or busted volume pedal you could swap out the pot for a dual gang pot and do this ^ though.

Have the feedback path on a switch and go Vibe or phaser......

[Kipper4]

"Edit. I forgot to ask how do I put some small caps (eg 50pf) in the phase stages like some of the op amp phaser stages ergo the bi phase?"

Do I just put them in parallel with the 4M7 resistors?

[Kipper4]

Having investigated the treadles limitations.
I decided to go a little more tradtional but keep the dual lfo.
Heres ver 7 with demo to follow.
Of course you could simplify it by only using one lfo to drive a discrete vactrol, 1led driving 4x ldr bunched around the led,

[Kipper4]

Please note although the drawing say ver5 the last post is in fact ver7

Demo

[Ben Lyman]

Rich, that is the coolest thing ever!
I might have to repost my ad for "Wanted: Broken Wah Pedal"

[Kipper4]

Sweet man. Glad to inspire.
One could do a depth mod on the treadle pot to go between totally dry through phaser to full vibe.
By hooking up clean pot to the treadle.

Option 2
Speed on the treadle.

Option 3
Depth on the treadle.

Note a new feature the 100pf caps which I haven't tested yet for oscillation with an overdrive pedal behind it.
Because I had an issue without them.

SteveO say you have 3 vibes already.

[Kipper4]