This has probably been schemed up by smarter cookies than me.

[Devius]

How about an envelope controlled fuzz for bass.
Thoughts? Ideas?

[Mark Hammer]

Explain yourself, lad.  What does the envelope control?

[Gurner]

Explain yourself, lad.  What does the envelope control?

Working on the limited info available to hand ...I'd say 'fuzz for bass'.

[Devius]

The filter would control the amount of fuzz into the signal. Simply put, instead of bwow wow it would be growl growl.
I don't know if it is even possible, however if it is I thought I would pick some brains and find the appropriate avenue to explore.

[WaveshapeIllusions]

That'd be cool. For bass, you'd want a clean signal as well. Mix them in an inverting opamp and use an LDR for the fuzz input resistor. Playing harder mixes more fuzz in. I'd use a resistor in parallel with the LDR to limit the maximum value.

For extra simplicity, you might not even need an envelope follower. Just gain the signal up way high and use LEDs as the clippers, preferrably ones with a low forward voltage.

Shoot, I might have to breadboard this.

[Devius]

Thats more or less what I had in mind. I would like a guitar version as well but I wanted to make something special for a friend of mine that would be quite unique.

[darron]

it's difficult to describe i guess. envelopes usually trigger depending on volume. fuzzes already have the 'fuzz' go up as the pick intensity and volume goes up (:

[Devius]

Now, this is probably laden with more problems than I could fathom... I think, in a way, it captures what I want it to do.
I would like to toggle fuzz to clean AND clean to fuzz if you understand what I mean.

[kodiakklub]

what about an EH bassballs or autowah but controlling fuzz? maybe you could adapt the bassballs circuit....

[Devius]

Thats what I want to do.

[Mark Hammer]

I suspect devius wants somethng that is like the Toadworks Enveloope: http://www.toadworksusa.com/manuals/Enveloope.opman.p1.pdf
http://www.emusician.com/news/0766/toadworks-enveloope/146412

This product was sadly ahead of its time, and is no longer in production.

[Devius]

That would basically be it in a nutshell. So much for a unique original idea.
I still want to make it though.

[Mark Hammer]

I think it is a terrific thing to make, and has uses well beyond what prompted the thread.

Essentially, what you are looking for/at is an envelope-controlled mixer/panner, that will blend seamlessly between a dirty bass tone and a clean one.  BUt this sort of thing could also be used to morph between a wide array of sounds, and doesn't have to be just clean vs something else.

[Devius]

Okie dokie. You wouldn't happen to have a schematic in that magic hat of yours, would you?

[Devius]

Take it to the next level. A phase shifter that would shift between phases of different effects. A phase blender if you will.

[Mark Hammer]

Okie dokie. You wouldn't happen to have a schematic in that magic hat of yours, would you?

Nope, wish I did, but it shouldn't be too hard to whip something up that is functionally equivalent.  Imagine a mixer, where the relative level of each of the two inputs is dictated by their respective input resistances to the mixer.  The envelope follower drives two LEDs, one of which gets brighter with higher input signal, and the other of which starts out bright and gets dimmer as you pick harder (i.e., a normal and inverted output, up and down drive all at the same time).  The LEDs set the LDR values, and bob's your uncle.

[brett]

Hi
one of the easiest methods of making a mixer/panner is to apply the envelope voltage to the gate of a MOSFET. The MOSFET can either change the signal in-line resistance or bleed some of the signal to ground.
cheers

[Devius]

Would that require 2 op amp stages from the input buffer, one inverted and the other normal? Would those same op amp stages have the same components, just pins swapped?

[Mark Hammer]

After pondering this a bit, it got me thinking about an envelope-controlled, or rather amplitude-controlled, switch; essentially a flip-flop that responds to peaks above some threshold.  Hit a string or two hard, and the flip-flop state changes, and hangs in there until the next similar peak, at which point it switches state again.  Everything in between is processed in either A or B mode, whatever happens to be in those to modes.

What I'm trying to get past here is the problem of A/B/A transitions happening in ways that are a little too "busy" or frequent.

I'm guessing there is inevitably a comparator here, to trigger the flip-flop with a preset level?

[~arph]

I am actually in the process of cooking up something similar:

https://dl.dropbox.com/u/1849818/published_images/envelope-blend.png

It's not 100% verified, but it basically blends in an effect on the decay of the note. If you want this to follow the original envelope instead you should reverse the envelope going into the inverting opamp that drives the led for the LDR. One could accomplish this by making the Q1 buffer inverting.

I'm using a window comparator for the max and minimum level detection plus some hysteresis to prevent unwanted triggering.

I'll post this as a project when it's done.