Random Delay Time Stompbox?

[fattcamp]

Hello all. Last year I got very into making stompboxes and well on my way

with my home-made modular synth. I moved at the end of the year and found

myself stuck in a small apt without the ability to do alot my pedal making

and whatnot. I'll be back in business soon and wanted to take on a delay

project. I've seen odds and ends here and there related to this but would

like some opinions or methods of achieving success with this idea:

I'd like to create a delay pedal with a random delay time option. I've been

looking at other pedals such as the Pefftronics SB-101 Super Rand-O-Matic

and random number generators and whatnot, but don't seem to be what I'm

after. If you look up "jonny greenwood" on youtube there are 2 videos near

the top of the list related to Max/MSP (software made by cycling74). These

videos suggest 100% wet mix, infinite feedback, random delay times (for

random lengths of time) that are quite sporatic. Very glitchy but still the

original sound of the guitar rather than synth sounding or bit-crushed. And

no, I'm not just trying to copy johnny. I think the sound is insane and not

necessarily useable too often, but would be a fun to play with... and could

turn this into a module for my synth down the road.

These videos have someone side stage manually tweaking or possibly

programmed into the program but I'm trying to achieve this in a pedal. It

sounds super complex but when you break it down it shouldn't be. It's just a

delay with a random delay time with the standard feedback/time/mix knobs.

Anyone able to shed some light on whether this is a losing battle or able to

be achieved my modding an existing diy delay or commercial product. thx all.

Bye for now

Dave

[earthtonesaudio]

Not sure.  You could try this:
replace the delay time pot with a LED/LDR pair or some other optocoupler, and find some sort of random generator that will drive an LED.  Either vary the current going to the LED or something like pulse width modulation if that works better. 

Just my 2 cents.

[caress]

Not sure.  You could try this:
replace the delay time pot with a LED/LDR pair or some other optocoupler, and find some sort of random generator that will drive an LED.  Either vary the current going to the LED or something like pulse width modulation if that works better. 

Just my 2 cents.

this is probably what you need to do.

the glitchy johnny greenwood thing is max.  it's recording his guitar live and storing the sound in a buffer, then randomly playing back (probably randomly reversed/pitch shifted/etc... too) the sound.
not possible in an analog domain.

check out the tyme safari by the harvestman:  http://www.theharvestman.org/1973.htm
it seems he built this as an alternative to using buffers in max...  it could probably do what you wanted if you had some random voltage sources controlling the various parameters on the module and maybe some other effects....

[Paul Perry (Frostwave)]

How I'd try is to have a number of delays operating a the same time - with different delay settings - and randomly switch between them.
(there are some hints on random switching at geofex, I imagine.)

[zeppelinchld]

this is a cool idea it would b like a seekwah except it would be a seekdelay

[Austin73]

could you not use Tone Gods vanishing point to control delay time?

Not sure how it would work but I'm sure some of the Boffins would!

Aus

[fattcamp]

I'm basically looking for a very simple setup for this. I don't really want to have to create a massive project if avoidable. I'd like to keep this in the standard stompbox format/size. Sounds like an lfo/sample and hold would be the way to go. I'm aware of what cv's are as I'm making a modular but not understanding how that would play into the lfo concept in a stompbox. Can anyone shed some light on this? I'd preferably like to have a simple mod on say.. a rebote 2.5 digi-delay for the delay time knob. If there was something i could put in it's place or adding to the signal path. It would be awesome to have the original pedal but be able to switch on the random option and just adjust the mix/feedback as normal.

[caress]

check out the echobase thread.  insert an lfo/s&h where the lfo on the schematic is.  that's it...

[levon]

It defiantly sounds like a sample and hold that is being triggered every bar for a few beats.

Ableton live has an effect like this called the Beat Repeater.

[soggybag]

I have been trying to whip up a Sample and Hold that will run off 9V. Here's a thread with a circuit posted here a while back.

http://www.diystompboxes.com/smfforum/index.php?topic=65644.0

[fattcamp]

Wow. First off, thx all for the continued replies. Always loved the help provided here. All fingers seem to point to the lfo, but 2 things....

1. there's no lfo on the rebote 2.5 delay.
2. an lfo and sample and hold will just choose random notes rather than random delay times won't it? I'm not looking for a traditional s&hold synth style effect. I'd like the pedal to randomly choose say... 300ms and and repeat with a 100% wet mix and max feedback for a random amount of time... and then say.. jump to 30ms and repear the same for a random amount of time. I'm trying to achice random delay times for random amounts of time.

Am I just mis-understanding this or would the lfo/s&h possibly achieve this?

('m also wanting to preserve pitch being played on the guitar).

Again.. I hate to use this example, but the youtube search for "jonny greenwood" has 2 max/msp patch videos and I'm essentially trying to achieve as close of a sound to that as possible. random delay times for random ammounts of times just jumping around like crazy. This has to be able to be done.. just how much work is another story.

[caress]

2 options here, IMO...

1.  buy that harvestman module (i sound like an advert...) it basically does what that max patch is doing... (you still need the cv to control it though)
2.  build the echobase - http://www.diystompboxes.com/smfforum/index.php?topic=60662.0 - and insert an lfo/s&h where the lfo currently is. 

the sample and hold doesn't change your pitch, it sends a random voltage to x.  x in this case is "...a PNP transistor in series with the delay time pot. It took quite a bit of experimenting to get this working nicely but I think it's a neater solution than using a LED/LDR combo."  use a switch to cut your dry signal out, leaving only delayed signal, and you're all set.

[paperhouse]

check out the echobase thread.  insert an lfo/s&h where the lfo on the schematic is.  that's it...

i suggested that in the echo base thread but designing it is way out of my league. if someone could do a revised layout with that i'd build it though 

[caress]

a good starting point...  http://www.musicfromouterspace.com/analogsynth/singlechipsampleandhold/singlechipsampleandhold.html
you can just use a max1044 or 555 chip to get the +/-9v

it would have to go in a bigger box, but no problem.  actually, i've perfed this and it only take up a square about 11x11, although you could easily get it smaller...

[slacker]

Adding a S&H to the echobase or any other DIY delay could give you a similar effect.

You'd have to make the S&H slow enough that it only changed voltage every few seconds otherwise it would sound more like a traditinal S&H filter circuit. To really get anywhere near the effect you'd also have to make the LFO driving the sample and hold random as well. That way you could get random delay times that changed at random intervals, if you just used a traditional S&H circuit you'd get random delay times but they would change at a regular interval.

On the echobase the switching can be controlled electronically, so in theory you could use an LFO of S&H to turn the delay on and off as well.

Doing all of that might get you somewhere near that effect, but the pitch would change when the delay time changed because there is no way to clear what's in the delay loop when the delay time changes. Could sound interesting though.

A much easier way to get that sound would be to heavily mod a Boss DD3. As it uses electronic switching you could in theory add a random LFO to turn the effect on and off and mod it so the delay time was controlled by another random source. Or just use an expression pedal to control the delay time and randomly stamp on the hold switch, or get an assistant to tweak the pedal for you

If anyone wants to mess around with this, but is having trouble making a sample and hold circuit you could use a pseudo random circuit instead. These are much easier to make especially using a single supply and sound enough like a S&H for most things.
Check out Geofex for an example from Mr Keen http://www.geofex.com/Article_Folders/LFOs/psuedorandom.htm#Pseudorandom%20LFO or Ken Stone's Pycho LFO http://www.cgs.synth.net/modules/psycho_lfo.html.
I used a version of these circuits in my Slackfilter http://www.diystompboxes.com/smfforum/index.php?topic=45148.0. Basically on the schematic the part using the 40106 is the random LFO.