Two-stage all-pass vibrato circuits, Tri-Vibe (RunOffGroove) and ESP v2

[fryingpan]

The Tri-Vibe is a nice OTA design, with maybe weak vibrato but a very nice rotary speaker effect. The ESP design uses LDRs instead (so much higher headroom, slower maximum rate though) and instead of having the three modes, it has an "effect" potentiometer mixing the clean signal with the wet signal. What is the difference in implementation between the two? (Meaning, the three modes as opposed to the mix control). The Tri-Vibe goes from no dry signal (Vibrato), to a 47k series resistor on the dry signal path when in Whirl/Phaser mode (so a 1:1 ratio between wet and dry) and a 100k resistor in Swirl/Rotary mode (so a 2:1 ratio). AFAICT, this could be replaced with, say, one of those pots with bypass at minimum (you know, when it "clicks"), of an appropriate value of course, with the same end result, right? Also, one could double the phaser stages to have a stronger vibrato effect?

[fryingpan]

Here are the two schematics:

http://www.runoffgroove.com/tri-vibe.png

https://sound-au.com/p206-f1.gif

modulator circuit for ESP V2:

https://sound-au.com/p206-f2.gif

[ElectricDruid]

The Tri-Vibe is a nice OTA design, with maybe weak vibrato but a very nice rotary speaker effect. The ESP design uses LDRs instead (so much higher headroom, slower maximum rate though) and instead of having the three modes, it has an "effect" potentiometer mixing the clean signal with the wet signal. What is the difference in implementation between the two?

I think you've spotted all the differences already, tbh. As you've pointed out:

1) Phase shift stages based on OTAs vs LDRs
2) Different approach to mixing wet/dry signals (passive crossfade vs active mixer)
3) Different LFO design, only partly driven by necessarily different drive of OTAs vs LEDs.

The Tri-Vibe goes from no dry signal (Vibrato), to a 47k series resistor on the dry signal path when in Whirl/Phaser mode (so a 1:1 ratio between wet and dry) and a 100k resistor in Swirl/Rotary mode (so a 2:1 ratio).

These three modes are pretty tidy, I reckon. It covers the basic stuff you might want without bogging things down in more options. Note that the equivalent positions on the ESP design are all in one-half of the pot's rotation. There's no equivalent on the Trivibe to the mostly-dry settings you can get on the ESP.

AFAICT, this could be replaced with, say, one of those pots with bypass at minimum (you know, when it "clicks"), of an appropriate value of course, with the same end result, right?

Yep, lots of ways this could be done. Classic wet/dry mixer, as shown here, is another:

https://electricdruid.net/two-stomplfo-projects-ptwobble/

Also, one could double the phaser stages to have a stronger vibrato effect?

Yes, why not? "Noise" is the only reason - it'll build up the more stages you add, which is particularly an issue with the low signal levels in the OTA design.

HTH