clean blend / optional buffered bypass

[thunderaxe]

hi all,

i'm interested in the idea of adding a clean blend to an existing distortion effect, and i'm also wondering if it's possible for it to double as an optional buffered bypass.

i feel pretty certain that i'm going to go with a dual op-amp setup, with a buffer up front and an active mixer at the back, though i'm not sure yet if the mixer will be like r.g.'s panner that goes from 100% dry to 100% wet:



or just a purely additive one:



i do have two questions for the forum though:

1) are there particular advantages and disadvantages to placing the input buffer before or after the split? should i buffer the input right off the bat and then split passively into clean and distorted paths, or split first and then place the buffer in the clean path? the first stage in the distortion circuit is a non-inverting op amp boost of +10.4dB with a 15hz high pass, which should serve as the buffer for that path if i go with this option.

2) the way i envision doing the optional buffered bypass -- and if there's a better way of doing this please let me know -- is to have the 3PDT stomp switch still switch between on and bypassed like normal, but a second toggle switch changes whether the bypass path is true bypass or sending the signal back into the effect, and then out the end of the clean blend path before the clean/distorted mixing section. the question for me is whether it's possible to get an isolated clean signal to the output through this method without the distorted signal "leaking" backwards through the mixer and into the clean signal. i've attached some crude concept diagrams of the switching scheme that will hopefully make my idea clear:

[knutolai]

1. You will find that some distortions sound different if you feed it a signal from a passive guitar pickup versus the output of a buffer. I suppose that depends on the distortion circuit in question.

Some further light reading:
https://www.muzique.com/lab/imp.htm

2. I would advice going for a dry/wet mixer between clean and distortion. If you want buffered bypass wire your stomp switch such that the mixer pot is "overridden" to minimum (dry) on bypass.

Make sure that the clean and distorted signal are in phase before doing the mixing or you may have phase cancellation somewhere along the potentiometers travel.

Here's a project I did that might be relevant to you:
https://khcdn6e06e6406e.b-cdn.net/wp-content/uploads/2024/03/KNIV_schematic_v3.1.pdf
https://pladaskelektrisk.com/product/kniv/