Treadle vibe/phaser

[snap]

That 2nd ph
asestage gets loaded quite a bit!

[Kipper4]

Please elaborate Snap or anyone else.
Do I need a resistor between phase stages?

[snap]

you need a higher impedance after the point where LDR and cap unite.

[Kipper4]

So a bigger blend pot? or bigger R38.
I thought the op amp impedence was basically set by the 1M to Vb.

[Fender3D]

I thought the op amp impedence was basically set by the 1M to Vb.

Inverting op-amp's input is a virtual ground, then its impedance is set by R38.
R26 keeps +input "open2 allowing you to feed another signal on + input.

What snap says is your Vact+R21 is affected by Blend+R6

[snap]

I thought the op amp impedence was basically set by the 1M to Vb.

Inverting op-amp's input is a virtual ground, then its impedance is set by R38.
R26 keeps +input "open2 allowing you to feed another signal on + input.

What snap says is your Vact+R21 is affected by Blend+R6

Well, yes, R21 doesn`t care *that* much though, but the combined, phaseshifted signal at the vactrol/cap-output is very "fragile" and screams for being buffered somehow.

[Kipper4]

Ok thanks so It would be more stable with a buffer after the 2nd phase stage output and before the blend pot.
It's still on the breadboard I'll stick a bjt buffer in.
Cheers

[Kipper4]

Thanks Guys for the advice. It is defeinitly worth the extra parts.

[Kipper4]

Demo time

[duck_arse]

nice to see the winky led in shot, I find it provides more information about what I'm not/hearing in clips. sound good.

when you say "switch to antiphase", what is it you are doing?

[Kipper4]

Just this

[Fender3D]

Just this

Why don't you use a 10K pot instead of R19?

[Kipper4]

Won't that misbias the transistor and add some horrible noise to the signal?
If not. What does it do?
It had'nt occured to me that was even an option.

[armdnrdy]

It looks to me like a trimmer for R19 will allow you to adjust the "wet" output.

[Kipper4]

Oh I'm following now.
So an A10k lug3 to emitter, lug 2 to capK, lug1 to gnd.
The transistor is always working the same as the 10k series resistor.
but the pot put signal to output amp or not depending on rotation.
Works great on the breadboard too.
Thanks guys one part less.
Back to the layout.
Thanks
Larry this thing has so few pots it's nice to have the wet dry pot outside of the box.

[ElectricDruid]

R19(10K) and the Blend pot (25K) in parallel gives a 7.2K result, so replacing R19 with a 10K pot does adjust things a little.

I doubt it matters though, so go with it. Just thought it was worth mentioning.

HTH,
Tom

[Kipper4]

The only issue I have with this now is that when phased and dry sigal both go to the non inverting input theres a certain amount of dare i say it phase cancellation.
IE It's a lot brighter.
Now do i try to combat this with a low pass filter on the phased signal when it goes to the Non Inverting input only (extra cap to Gnd after R21) or some other solution.

It sounds ok if i just roll the guitars tone pot back a bit. And still sounds different enough to the opposite mode to say theres a definite change of sound and feel.
Suggestions please.

[Kipper4]

Quick fix schematic. New low pass filter with cap H1
note theres a new value (4u7) timing cap in the lfo.
different value resistors going to the output amp. All now 33k.
and different phase stage mix control as suggested by you guys Q1
Thanks a bunch fellas

[Fender3D]

note theres a new value (4u7) timing cap in the lfo.

I didn't noticed it before...
I think it should be BP (or non-polarized)

[Kipper4]

I dont have non polar.
Its life may be limited i guess.