Envelope modulated delay?

[Peter Snowberg]

I just wondering if any effect has utilized a delay modulated by the envelope of the current input signal? I know the famous Roland JC210 has some feedback from the speaker to the chorus LFO, but I don't know the effect.

Thanks!

-Peter

[drew]

The weird and possibly somewhat rare (no idea how many were made) Rocktron MX-3 delay unit has envelope-modulated delay time. I never found much of a use for it... but... since you're asking, maybe you can!


drew
toothpastefordinner.com

[Paul Perry (Frostwave)]

I had a try at an envelope modulated trem. The problem is, the envelope you get from the detector circuit, probably isn't the envelope you wish you had, for the effect in mind. Maybe a triggered envelope is more to the point, depending on playing style.

[mikeb]

No commercial FX that I know of ... I've been working on one one and off for ages now, but can't ever get myself happy with the response to the guitar signal. I think Paul's idea about the triggered envelope has some merit.

MikeB

[bwanasonic]

I think it might be more useful for short chorus/flange range delays. I know the ADA Flanger has some kind of envelope response, but I don't remember how it works. I think for long delays you might want it to behave more like velocity response on a keyboard rather than envelope following.

Kerry M

[puretube]

the Roland Jazz-Chorus functioning is explained in their patent:

the envelope modulates the depth;

with no signal at the input, the LFO-sweep is muted, so there will
be no audible noisy "swirling" in playing pauses.
As soon as the guitar gets louder, the delay-modulation comes
back into effect, according to the signal strength.....



//www.puretube.com

[Mark Hammer]

The envelope can be used to control the delay in many ways:

1) to control the actual delay time

2) to control modulation rate in a modulated delay (E-H Polyflange)

3) to control recirculation

4) to control mix/level

Although I am personally not aware of any commercial products that do this, I always wanted to see some sort of implementation of something like Anderton's "Pluck Follower" with a delay line.

One of the difficulties of delays is that repeats can clutter up your sound if the notes are not spaced far enough apart.  The Pluck Follower (which appears in something like issue 7 or so of DEVICE; http://hammer.ampage.org) sums trigger pulses, yielding an overall control voltage that reflects how many notes one is playing at the moment.  Speed up and the CV goes higher, slow down and it declines. Somethng like that would permit you to adjust the relative mix of the dry/wet signal such that as you start to slow down more delay signal is introduced, and as you speed up, it is gently faded out so that "audio note clutter" is reduced.  Of course, that would require a lot more than a simple half-wave rectifier to accomplish.

Probably the most sensible and easily implemented use of an envelope follower with a delay would be to control amount of recirculation.  For things like flangers, increased resonance nicely complements what it is people want to achieve when they strum harder and softer anyways.  perhaps more importantly, recirculation is often done via a single variable resistor in many designs, and even when it isn't there is usually a trimpot on-board to set maximum resonance.  It's a piece of cake to stick an LDR from a simple half-wave rectifier-driven optoisolator in parallel with that variable resistance and increase recirculated signal as you strum harder.

[puretube]

just had a gorgeous brandnew idea while reading the above post...........

thank you Mark, for the inspiration!!!

[Mark Hammer]

You're most welcome.  It better not use any of those g*****mn tubes or I'll NEVER be able to build it!  :wink:

Given the time delay between where you are and where I am, I guessing its going to be a long night.

[Peter Snowberg]

Thanks for all the replies, and a special thanks to Mark for taking the time to not only explain, but to explore possibilities as well.

-Peter

[idlefaction]

ain't it funny how loads of people get the same idea at the same time across the globe?

i've been posting about making the delay time on my PT2399 voltage-controlled recently - with the hope of modulating it with an LFO to make a chorus, and also (dun dun dunnn!) using the envelope from my envelope filter.  :-)

no luck as yet but gez sent me a neat idea using a MOSFET which i haven't tried yet:
http://www.diystompboxes.com/sboxforum/viewtopic.php?t=1653

hth...

[R.G.]

It might be well to generalize all of the preceeding stuff into making an envelope controlled fader.

Pluck harder (or faster as in Andertons Pluck Follower) and you get varying fade between two channels. The advantage is that you can then use two *anythings* to fade between, not just dry/wet or amount of effect.

An interesting one that comes to my mind is a fade between mild crunch distortion and hyper-sharp razor distortion or octave up screaming. Play gently and you get soft distortion, strum harder and the pick attacks get really distorted, fading to soft.

I think you could do this with one LM13700, CA3280, or NE570 chip and of course the support junk to detect the trigger event and modulated the fader.

I can even see how you might do it with a PIC 8-)

[drew]

There are lots (or at least some) voltage-controlled panners in analog synth land. Normalize the output of your envelope filter, send it to a VCA, invert it and send to another VCA... I think to have "constant-volume" perception you have to have some exponential or logarithmic character to the CV sent to the VCAs, but that might not be a problem here.

I'm sure there is a simpler solution if you're not concerned with precision, etc... how about something similar to a balance control, with the two halves of the balance potentiometer replaced by vactrols, and the normal/inverted envelope sent to the LEDs?


drew
toothpastefordinner.com

[J. Luja]

I'm sure there is a simpler solution if you're not concerned with precision, etc... how about something similar to a balance control, with the two halves of the balance potentiometer replaced by vactrols, and the normal/inverted envelope sent to the LEDs?

I breadboarded a something very similar to this about a year ago and it works quite well actually as long as the LDRs are fast enough -though a slow attack is usefull too (best to have a panel mount control for this)

I mean to get this one in a box one of these days...
clean fade to chorus is nice but distortion fade to octave up alone is worth the cost of admission

-Jeremy

[Peter Snow]

Hi RG,

I think what you are describing was mostly addressed by Bill Berardi's FuzzStain circuit in Electronic Musician 1987.  Never built it, but it looks interesting.

Cheers,

Peter

[Peter Snow]

... Thinking more about it,  the FuzzStain circuit worked in the opposite sense - strum harder and the fuzz decreases - pick single notes and the fuzz becomes harsher.  The idea was to switch from lead to rythym without needing two different settings on your fuzz box.  Similar idea tho'.....