friends, PLEASE help me figure out how to do this one ;)

[pinkjimiphoton]

so in one of my multiple pipe dreams, a vision came unto me of a Potentially Cool Idea

in a nutshell, and i can't remember seeing this done anywhere yet, tho i am not too bright and haven't looked in depth,
but

is there a way to use an envelope follower circuit, something simple like maybe tim escobedo's phunqgnosis and have that control the speed parameter of a modulation pedal instead of it's more normal pot?

would the system need to be split so its preamped and conditioned  to feed the audio and control parts of the circuit?

i was thinking something where the harder you play the faster the speed goes... or even put a switch on the thing to reverse it so it would go SLOWER the harder you played.
to me, either one seems like a world of possibilities that probably frankly ain't too hard for anyone other than my fuzztarded self. i'm a good monkey. i can solder and put things in holes, i'm NOT afraid to let the magick smoke out of stuff, but this is a little beyond my paygrade, which is usually being a solder jockey or BREAKING sound waves in horrible ways via germaniumy goodness n $#l^...

to me, it seems the ability to control the speed of an analog thru hole kinda effect via your pick attack sounds like it would work killer with tremolo, flanging, chorusing, but especially phasing and echo.
with phasing, particularly if ya get that chewey formanty sound happening you can play with the "fore and aft" of the sound somewhat.. having it sound like it comes from behind your audience can really freak them out some (as you ludwig phase II buiders have probably discovered).
a delay that varied time by your pick atack could be cool too. but tremolo and stuff i think would be the coolest.

too much LDS 52 at berklee there spock? or do ya think it's doable and is it worthy of pursuing?
i am bot a grahshoppah always.

so opines, facts and factoids, even ludicrous humor welcomed.
finally got some downtime so been getting my build back on.

thank you bros and sistrens

bottom line.. envelope control of effect parameters like depth, speed or time feasible or folly? what say ye?

[Kipper4]

Sure it's doable monkey.

[blackieNYC]

If you can turn it into variable DC, you can light up an LED/LDR. Any pot can be replaced with an LDR in some manner. 
Just a smidge beyond that is a VCA/LM13600 kinda thing.
Or a transistor or FET. The LDR, being a resistor itself, is easiest to grasp. To me anyway

[rutabaga bob]

Much as I would like to help, old Photonic One, this is way out of my league...maybe I'll just hang around and dust the furniture or something... 

[balkanizeyou]

there have been a lot of envelope-controlled modulation effects posted on this forum (tremolos, phasers etc), Kipper4 and duck_arse specialize in this kind of thing. Together with duck_arse I've designed an envelope-controlled delay but haven't posted it here, because who the hell needs an envelope controlled delay anyway. I think you should look for them to get a basic idea of how those things work.

Anyways, the simple way to do this is to rectify the signal, smooth it out a little with an RC filter and then use it to drive your favourite voltage-controlled resistor (LED-LDR combo, FET, BJT or whatever) to control the "rate" resistor in your LFO.
Depending on the actual LFO used things can get tricky - translating the input waveform to an envelope (or "CV") is a cakewalk, getting the CV to control the parameter you want may not always be as easy as it looks, but it's a good idea to take a look at how our fellow DIY-synth guys implement the CV-control. They have some cool tricks up their sleeves (and they love the TCAs)

[R.G.]

Yep, it can be done - worse yet, like many of my "new ideas", someone has.

There was a buildit article in the UK magazine, Electronics and Music Maker for a tremolo with loudness controlled speed, although I think it speeded up with louder notes. I can find the article if needed.

There was also the vibra-magic idea on geofex, a rehashing of an old Thomas Organ idea, where the transient of a note's start ... stopped ... the oscillator on a tremolo, and it started up again gradually, so notes appeared to have tremolo fade in on longer notes. I can point that one out if that's any help, as well.

[PRR]

On a real (modular) synthesizer, EVERYTHING is controllable.

I am so glad I no longer work near one.

[bluebunny]

Sure it's doable monkey.

You're being too modest, Rich.  Didn't you recently post a couple of projects that did exactly this?

[deadastronaut]

+1 im sure rich was doing this too...envirotrem wasnt it?

[bluebunny]

Yeah, here you go:

EnvoTrem and Whirly Bird (phaser).

[Mark Hammer]

I did it to my P90 phaser build.  Whipped up a little daughter board with a simple envelope follower, and tapped the output of the input buffer stage on the P90.  The envelope follower makes an LED glow, and the LED changes the value of a photocell that runs in parallel with the Speed/Rate pot on the P90.

The trick is to:
a) Have a parameter you want to control that consists of a variable resistance, and not a voltage divider.  In the case of the P90, speed is a simple variable resistance.
b) Have an LDR whose max resistance is much greater than the variable resistance you want to control, so that it can have no impact on fixed settings when not using the envelope to augment that parameter.  In the case of the P90, the speed pot is 500k, and the LDR is probably around 5M or more when dark.
c) Have an LDR whose min resistance is less than the pot resistance.  I think the LDR I used drops to 10k or something like that when the envelope is strong.
d) Have the sensitivity of the envelope follower up high enough that it can easily respond to changes in picking.

[stringsthings]

Way back when, Craig Anderton's EPFM had an envelope follower circuit that you
could hook up to the phase shifter circuit.  I made it and it sounded pretty good.

[midwayfair]

RG Keen's Vibra-Matic.

Also the Blue Warbler, the first version of which was based directly on that. [toot toot] I only set it up to increase the speed but you could make it decrease the speed, too. Jimi, if you want I can see if I have an extra PCB for the 2-stage version, which you're welcome to.

[Kipper4]

Take a look at this too Jimi

http://www.diystompboxes.com/smfforum/index.php?topic=107812.0

[pinkjimiphoton]

holy cow, Rich and DA have gotta lot done, i was clueless...
i'd say great minds, but hey, if i'm in on it... a day (year) late and a dollar short!!
i gotta gig tonite of course, so i am gonna catch up on yet MORE reading...
the trem is exactly as i envisioned.

yes it needs a fuzz front end. lol

i can't wait to check the phaser out.

but not entirely sure if it's doing what i expected. i kinda envisioned it as every note triggering the effect at whatever velocity you play it at.well.. maybe bad word... whatever dynamics you play at.

but this is insanely cool!!! well done you guys, and thanks to EVERYONE for the wealth of replies!!

talk soon and again, thank you.... perhaps humble simple hippy can realize one more sound echoing in the abcesses of his mind

[digi2t]

Maybe the envelope section could be grafted onto the Mr. Multi, or Foxx Guitar Synth LFO?

Now how cool would THAT be?!

[pinkjimiphoton]

what i kinda envision is a simple stand alone board that can be grafted into almost any existing pedal.

so you could say, add it to your fav flange or chorus or vibe or echo or ludwig phase II or whatever and control it just from your touch.

the peds in this thread are gorgeous sounding but i think i'm misunderstanding somethings and am wondering if maybe i could explain it better.

these are cool, cuz they speed up or slow down based on the envelope of the guitar... but what i think i was trying to describe was using the attack velocity of your picking to control the spped, and have it stay constant, not ramping up and down as in the video examples.

i mean... hit it softly and say ya gotta really fast modulation. hit it harder and it slows down.  so you could actually set the tempo of the effect by your picking attack.

similar, but subtly different i think from the way it's being implemented here.

in the case of these circuits, i think the idea would work better for depth exactly as you guys are doing for speed now.

but i was kinda looking at using the initial  attack to set the speed. having the envelope of the guitar shape how intense it is would be wicked cool and is cool,,,, but i think i explained my self wrong.

if i whack it soft, i wanna be able to make it go one speed... whack it harder, a little faster. whack the living bejesus out of it have it go fast as possible (or as fast as ya set the normal control, anyways...) or vice versa.

so i think this is a good starting point. i hope i described it a little better.

to me, using the envelope to shape the modulation  is cool, but i think i need to know if it's possible to trigger it at different threshold levels?

me widdle bwain hurts

[midwayfair]

Jimi, these do what you're describing, just not all of what you're describing. The problem is, circuits are dumb, guitar playing is complicated, and what you are asking for essentially requires an intelligent pedal.

An envelope takes your signal and converts it into a control voltage. The control voltage then controls a device elsewhere in the circuit that acts as a variable resistor (usually). How hard you play, and how much voltage it needs to do its thing, is the threshold. It has to do its thing for a certain amount of time and can't start until a certain amount of time has passed (these are attack and decay). Mark's GEOFEX article on envelope effects is a good place to start for understanding how they work with a filter circuit if you aren't already super familiar.

You can make an analog envelope always do something when you play in a particular way -- and as long as you, the guitar player, can absolutely guarantee that you will play the same note twice and only at intervals that give the envelope circuit time to recover, you can repeat that effect. If you want it to go fast when you play hard, you can make it do that. If you want it to go slow when you play soft, you can do that.

What you can't do is have it stay at the new speed forever until you do something else. The envelope's going to drain off and leave you with the preset speed control setting.

For that, start thinking digitally. And not necessarily programming a chip to do what you want, though that might in the end be what's required to avoid a million components. Thinking digitally is breaking everything down into switches. 1 or 0. On or off. Yes or no. Big enough or not. See where this is going? You can set up a circuit so that if you play hard enough, it'll set a switch at a slow or fast speed setting and stay there.

What's the biggest problem? Guitar notes are dynamic, less so when you've got a fuzz going, but really, really dynamic. The initial transient coming from your pickups might read over 2V on a multimeter, while the tail end that you still hear might be 1/1000th of that. You can only realistically set it up so that you play bigger and it switches to something, and maybe lengthen the time it takes to "listen" again to a couple seconds. If you want to set it up so that it switches when you play soft, eventually you're going to stop playing notes, and suddenly your signal's really small, so you're back at a small setting.

Ultimately, you need something smarter than your average envelope. You need a device that can detect the size of your signal, compare it against a set of cases, and switch to speed settings you've predetermined until another case is detected, and it needs to be smart enough not to be checking all the time.

Now, you COULD start writing out pseudocode at this point

if signalSize = x, set speed to 1Hz
....
except when I want it to be .1Hz ...
Or maybe .5Hz because this song is faster ...

Or you could just use a tap tempo controller or treadle and engage your feet to perform the action you want in a predictable fashion.

Add-on board for basically any LFO effect: http://madbeanpedals.com/projects/Tapanatorator/Tapanatorator.pdf

[anotherjim]

I'm thinking the key to what Jimi wants is in the manner of envelope detection.

Usually, the pick attack is strongest so pumps up the DC envelope rapidly, but the sustain portion of the note barely keeps the DC from dropping back to zero. For an envelope sweep, that's what you want, while it looks like Peak Hold Detection is what Jimi is after.

The highest level (peak) from the pick attack is remembered until another pick attack. The target control is always set to the amount determined by the current peak reading - or average of the peak reading!

The simplest (could be too simple) I imagine is similar envelope circuity as the usual diode rectifier/charge-pump types. The envelope cap is bled very slowly so it doesn't follow the note decay down too fast. It might even have a second RC to further slow (average) the envelope. Juggled right, it could be a fairly steady measure of pick attack. I doubt it could precise enough for tempo control - you could control it, but not so you can consistently match to a tempo.
You will probably need some panel controls - sensitivity & decay. Might work with internal presets if your setup is consistent.
The bleed rate of the envelope is the tricky thing. Bleed too fast and the control gets swept by the envelope. Bleed too slow and it takes a while for softer picking to take effect. Choose the lesser weevil.

[pinkjimiphoton]

thanks for the explanation Jon,
yeah i see your point.

i use a cheap pos dano autowah. absolutely love it. by varying my pick attack, i can basically have it give me whatever tone i'm looking for. i thought it would be neat to do the same but control other parameters.

i guess if hearkening back to my old analog synth days of yore, i'd need just the A section of an ADSR to do what i was talking about. seems like a lot of effort
just thought it would be cool to trigger stuff and trigger speed or depth/intensity changes right from the touch of the player.

i look forward to trying both of these circuits that rich and da worked up once i get my bench clear of the present projects...

one of which is your cardinal tremolo project, FINALLY, after what... 2-3 years? 4? man... time flies.

my plan is to mount it in a crybaby shell ((which just came in yesterday ) so i can control the speed with my foot.
really getting sick of hauling around my univibe AND a foot controller when i can probably get close to the same result built into one treadle.

tthanks for the linky to bean's project too

but i still think it would be cool to be able to trigger this away from the pedalboard... say you're on your 100 foot guitar lead (you DO have a 100 foot lead, don't ya??? <g>) out in the crowd's face and decide ya wanna make something sting so ya hit it hard and trigger... whatever...

i realize DSP is the way to go probably... but i wanna do something analog and simpler. i like the paths being blazed and they are most definitely leading lights, but i think the path i seek may diverge some.

i don't want the notes to be shaped by the envelope. i just want the attack from the envelope to trigger different parameters i guess.
and in that case, i assume how fast/hard you hit it would be as you say inconsistent, but that's part of the quirkyness i think i may be looking for.

and dude... we're talking me... so ya KNOW there's gonna be fuzz before it. at least one.

(speaking of, on ebay they now sell these 1590a pedals cheap outta china... they have a 26$ npn germanium fuzzface that is @#$%ing BRILLIANT and has replaced my DA on my live board and saved me a LOT of weight in the process!!)

anyways... as always, thanks for the replies. i am digesting information. i think most is above my paygrade still, even tho i've been messing with stuff now for literally years.

thank you all for taking the time to help and teach me, and to show me how to teach myself, which i think is the most brilliant aspect of aron's forum here.