I just built a Midfi Clarinot (http://www.diystompboxes.com/smfforum/index.php?topic=74294.0), and I'm in the middle of a Magnus Modulus (http://www.diystompboxes.com/smfforum/index.php?topic=72527.0) build, so I'm quite focused on PT2399 at the moment. Both these projects, which feature modulated delay time, got me thinking, as did danielzink's Seek Wah clone in the 'Picture's' thread (http://www.diystompboxes.com/smfforum/index.php?topic=36392.9220). So I've got this idea for a PT2399 delay where the delay control is replaced by an eight step analogue sequencer. I'm pretty familiar with analogue sequencers as I've built a few for my modular synth, and I've come up with what I think are some interesting ideas.
There are two distinct parts to Event Horizon, the sequencer made up of a 4022 or 4017, an LFO and some logic, and the PT2399 delay itself. I'm not sure yet if I can run the summed sequencer output directly into the PT2399's pin 6, or if I'll need to use a vactrol or LED/LDR combo.
Running the sequencer would allow the delay time to be specified at each step. It would be possible to set up a chorus type modulated delay by selecting close but subtly different delay times for each step. Wider spaced delay times would allow more complex modulations. It would be interesting to set up delay times which are rhythmically related in alternate steps.
Stepping through the eight steps with the 'Manual' momentary footswitch would allow up to eight different delay time setting to be selected, which would be useful for gigging, selecting the right delay time for each song for example. So it's a delay with eight memories.
Pressing the 'Start/Stop' footswitch to stop automatically resets the sequencer, so when it's pressed again to start it will always commence at step one.
I'm thinking it might be useful to have the ability to override the internal LFO from and external source. Using a simple audio to gate converter the external source could be pretty much anything, from a click track to a drum machine to a microphone inside a bass drum.
It's going to be pretty 'knobby' with eight knobs (I'll use 9mm board mounted) for the eight steps as well as Speed, Feedback and Blend. A switch to select the number of steps, another to select auto or manual advance. Momentary footswitch for Manual Step and Start/Stop and the usual effect/bypass 3PDT.
Until I start breadboarding I can only imagine what it will sound like and how it can be used, but I think it should be cool. What do you think? Obviously, it's going to be a pretty busy breadboard to get all this running, but it should be straight forward enough. Anyone want to throw in any useful ideas that I've missed that wouldn't add too many more components/controls?
I think you're going to need some sort of smoothing pot to ramp between steps. That way you could get reasonable modulation tones or back off the smoothness and get a weird noise pedal.
Quote from: Nitefly182 on April 29, 2009, 12:49:39 PM
I think you're going to need some sort of smoothing pot to ramp between steps. That way you could get reasonable modulation tones or back off the smoothness and get a weird noise pedal.
A portamento control is a good idea and easily implemented as part of the sequencer's summing mixer.
i really like this idea. i hope you can get it to work.
lol...man, Rick, you need to get this thing working and polished up so I can incorporate it into my already-in-progress sequenced wah/tremolo build! :)
I like the idea--definitely. In fact, a portamento control actually sounds interesting for a sequenced wah/tremolo, too...
Cool idea Rick. I haven't tried a sequencer but I've messed about with sample and hold and pseudo random generators hooked up to the Echo Base and you can get some interesting things happening. You can get cool arpeggiator type effects or with loads of feedback something like those mad Jonny Greenwood MAX/MSP sounds.
Thanks Ian - what do you think - can I hook up a control voltage directly to pin 6 of the PT2399? Or is a vactrol needed?
So this will really be a "Seek Whammy"? :icon_wink: That is, if one has a free-running sequencer, and ramping or smoothing between control-voltage changes, AND if there is still data in the RAM sampled at one rate and played back at a new rate, the net effect is to keep shifting the playback pitch of that content.
Mark is most probably right in his post above. Fast speeds will induce seasickness. It's a very cool idea, anyhow, and I will follow this post closely. I've been planning to make a sequencer for the control jack on my A/DA flanger soon.
LARS
I was actually just thinking about a sequenced delay this morning. I really like the idea. I have a nice compact breakout board for the sequenced wah and it could probably be ported to another design.
A more usable effect might be to use the sequencer to adjust wet/dry mix or regen levels, or maybe even a low-cut aspect of the wet signal. That would keep your pitch stable, but introduce cyclical changes in how the delay sounds.
That being said, there is a big difference between a free-running sequencer yoked to a delay, and a stepped set of sequential control voltage changes used like a non-random access set of saved patches.
Quote from: frequencycentral on April 29, 2009, 01:31:34 PM
Thanks Ian - what do you think - can I hook up a control voltage directly to pin 6 of the PT2399? Or is a vactrol needed?
I don't think you can just hook the CV up to pin 6. I'd use a vactrol or a transistor like in the Echo Base.
Quote from: Mark Hammer on April 29, 2009, 03:09:14 PM
A more usable effect might be to use the sequencer to adjust wet/dry mix or regen levels, or maybe even a low-cut aspect of the wet signal. That would keep your pitch stable, but introduce cyclical changes in how the delay sounds.
That being said, there is a big difference between a free-running sequencer yoked to a delay, and a stepped set of sequential control voltage changes used like a non-random access set of saved patches.
I know this think would have the potential to be really chaotic--but...my first thought was to have a control to mix the delayed signal well below the dry signal. You could have crazy pitch-bending craziness in the background of your dry signal, but it wouldn't be complete chaos--you could get it to move at a standard rate...I'm imagining a kind of crazy ring-mod...
Quote from: slacker on April 29, 2009, 03:11:37 PM
Quote from: frequencycentral on April 29, 2009, 01:31:34 PM
Thanks Ian - what do you think - can I hook up a control voltage directly to pin 6 of the PT2399? Or is a vactrol needed?
I don't think you can just hook the CV up to pin 6. I'd use a vactrol or a transistor like in the Echo Base.
Yeah, I just measured the voltage at pin 6 of my Clari at both min and max time, there very little difference, a few millivolts. So a vactrol it is!
A current sink is faster and more linear.
I just bought a couple of 2399...I believe this idea will find its way, after all you're much more into sequencers as I am, Am I right Rick?! (no, I'm left) <---Sorry for being stupid.
Stay tuned!
Quote from: Renegadrian on April 29, 2009, 03:53:59 PM
......after all you're much more into sequencers as I am, Am I right Rick?!
Damn right, I'm mad for them. Here's a couple of 'soundscapes' i did a while ago just using modular synths/analogue sequencers. No keyboard, no drum machine, no overdubs, just loads of wires and knob tweaking.
http://dl.getdropbox.com/u/967492/Modular%20One.mp3
http://dl.getdropbox.com/u/967492/Modular%20Two.mp3
I don't know how useful this would be - for example, the delay speed constantly changing would be all out of whack with the sequencer resets, the echos would randomly change pitches and speed up/slow down - It sound like a noisemaker to me.
Give that, I want to see a vid of one! Step on it!
Did you ever get this working, Rick? I have an old Rebote PCB that I've never built, thinking about trying it.
I didn't see this when it was new, but around the same time I pretty much made the same thing - I just hooked The Tone God's Vanishing Point to an optocoupler, aand put the LDR side where the PT2399 expects the time pot. Works exactly as you would expect. One thing to note is that the PT2399 has a slope in how fast it can change its time parameter - so at high sequencer speeds, you don't get instantaneous pitch change, more like a burbling random vibrato.
Quote from: frequencycentral on April 29, 2009, 01:31:34 PM
Thanks Ian - what do you think - can I hook up a control voltage directly to pin 6 of the PT2399? Or is a vactrol needed?
I made a similar circuit! I used an NPN as a ground pull on the 2399's time pin. the NPN modulated by whatever source.
Right, that's how Slacker's done it in his Echo Base, but actually if you look at the Magnus Modulus it seems to be the case that you really can pump CV into pin 6.
See here:
http://www.diystompboxes.com/smfforum/index.php?topic=81668.msg677026#msg677026
And here:
http://www.diystompboxes.com/smfforum/index.php?topic=87813.msg743112#msg743112
I think I'll revisit this, because as I remember there were some really interesting and unique sounds available here. Using a CV or the transistor method would of course dial back the inherent portamento a bit - then we can add a dedicated portamento control just with a variable lowpass on the CV signal.
I dug out my hideous perf board version of the sequencer I made last year, and hooked it up to an Echo Base PCB, soldering the LDR across the stock time pot, disabling the modulation.
It's a lot of fun. Pretty weird. I put the opto across the time pot to limit the excursion to a safe range. My optos have a max resistance of 500k, and previous experiments have shown me that this much resistance makes the 2399 lock up and stop making sound - what I read was that you need to refresh the DRAM with a clock cycle within a certain time range, otherwise it just forgets what's stored in the memory.
Also, by using this arrangement, the time pot acts like a depth pot when sequencing. Turning this down to a sensible level gives some funky but usable-to-normal-people vibrato/chorus sounds. I don't have it set up, but it would be possible to add a manual step mode like you see in ZVex's Ringtone. This would allow you to save n delay time presets, n being the number of stages in your sequencer. So you could use this as a regular delay pedal with presets, in addition to the funky sequencing.
Any chance of a sound sample? I'm really curious as to what this sounds but still have to wait a few weaks for my p2399's to arive.
I'm going to try to do some. I may do a PCB for it, as it's surprisingly versatile and pretty unique. I might even add the ability for the modulation to control feedback amount as well - then you'd really have crazy stuff happening.
I'm very glad my bump had such a positive reponse!
My Echo Base PCB is (hopefully) somewhere over the Atlantic right now...
Quote from: Taylor on December 12, 2010, 06:29:10 PM
I'm going to try to do some. I may do a PCB for it, as it's surprisingly versatile and pretty unique. I might even add the ability for the modulation to control feedback amount as well - then you'd really have crazy stuff happening.
woot! I vote for an extra CV input in parallel or that can insert and replace the seq CV.
- Strategy
You mean an extra CV that is also controlling time in parallel? How would you use that, out of curiosity?
Inject an LFO for more madness but to lend a random, non repeating aspect to modulation
Or have it switchable between onboard SEQ and external voltage source so not nec. both at the same time
but I am definitely silly enough to do compositions using multiple voltage sources. It is great for getting into babbling brook type effects where there is pattern with degrees of variation
- Strategy
I wonder if another useful, possibly more generally musical, effect would be seq modulating feedback, to create rhythmic delays. I used to have a great VST plugin called Metal Mickey which was IIRC an 8 step sequencer controlling delay time and/or feedback. It was great - I'll see if I can dig it out for inspiration
Edit: here it is: http://www.kvraudio.com/get/677.html
Screenshot pretty much explains whole thing.
Quote from: tombola on December 16, 2010, 03:13:35 AM
I wonder if another useful, possibly more generally musical, effect would be seq modulating feedback, to create rhythmic delays. I used to have a great VST plugin called Metal Mickey which was IIRC an 8 step sequencer controlling delay time and/or feedback. It was great - I'll see if I can dig it out for inspiration
Edit: here it is: http://www.kvraudio.com/get/677.html
Screenshot pretty much explains whole thing.
Yeah, I was thinking that would be cool too (mentioned it above). It's a pretty easy mod to add, so I will probably do it.
I think I probably won't put a CV in on the board, but it's the kind of thing that would end up in the mods sections of the PDF that accompanies the project. It would be useful for synth guys but not so much stompbox guys.
I was thinking about getting echobase pcb, is there a CV input mod published in the documentation?
So, for Event Horizon, consider a clock input, a way to control the internal clock with pulses from outside, so people can sync the rhythm to drum machine triggers, square wave LFO, etc.
OK, I know, more synth oriented than pedal oriented...
Strategy
Well if this is turning into a project I guess I'll sign up. I really enjoy your projects Taylor, everything is well thought out, nice boards where components fit, clear instructions. I can stuff the board one night and play it through the breadboard the next. It's like knitting or meditation, I get a cool effect without any effort, kind of a rest between my own projects.
Hmm, perhaps I should make my PCBs harder and messier, so as to be taken more seriously? :D
I don't know if I have it in the doc for the Echo BAse, but the top of the LFO depth pot pretty much acts like a CV input. If you disconnect the LFO from there, maybe run it to a switch so you can have onboard LFO or a CV in jack. Then just connect whatever source there. May need some tweaking to get it in the right range.
What sort of box and form factor would people want to build this in? 1590b ZVex-style? I personally don't like tiny boxes with tiny knobs, being a somewhat Lurch-shaped man myself, but that's just my preference.
I should also say that "Event Horizon" is a sweet name, but it's Rick's, so I would use something else.
I'd be fine with a BB or larger if necessary. Sideways oriented boxes bother me. I'm definitely in for at least one board.
Quote from: Taylor on December 17, 2010, 03:15:33 PM
I should also say that "Event Horizon" is a sweet name, but it's Rick's, so I would use something else.
I've been watching this thread develop with interest. Coincidentally, I just bought a bunch of 9mm 100k lin Alpha pots, and I have 4017's in stock too.
I would be flattered if you were to use the "Event Horizon" name.
OK, cool, well Event Horizon it is. Don't know if you intended a nod at "Vanishing Point" or not, but it's got a very... Bladerunner-esque feel to it in any case. I'm terrible at coming up with names for circuits.
I think I will try to either send CV straight into pin 6 ala Magnus Modulus, or use a transistor as in the Echo Base. The optocoupler approach works, but it would be nice to have more instantaneous changes possible.
The feedback sequencing control will have to use an optocoupler as an OTA or similar would just be too complex to add. For simplicity's sake the same sequencer controls for time will control feedback (with a switch so you can have time sequencing, feedback sequencing, or both). Since this tends to the experimental end of effects, I think that's an ok compromise and will still yield some pretty crazy sounds.
Quote from: Taylor on December 17, 2010, 08:44:47 PM
The feedback sequencing control will have to use an optocoupler as an OTA or similar would just be too complex to add. For simplicity's sake the same sequencer controls for time will control feedback (with a switch so you can have time sequencing, feedback sequencing, or both). Since this tends to the experimental end of effects, I think that's an ok compromise and will still yield some pretty crazy sounds.
Wow, awesome!
Quote from: Taylor on December 17, 2010, 08:44:47 PM
I'm terrible at coming up with names for circuits.
Here are some imaginary pedal names. Now, design circuits specifically to fit the names.
The Cubist
Stay Puft
The Slider
Mossy Channel
Motion Detector
The Percolator
- Strategy
Cool, I will try to use those, though there's already the ol' Harmonic Percolator.
So I'm thinking about knobs. :P I started thinking about the knobs I'd want:
8 sequence step time knobs
1 sequencer speed
1 glide time
1 feedback amount
1 depth
1 mix
So that's 13 knobs... It would also have a sequence/random/step footswitch, a toggle for sequence or manual mode, and a rotary or 2 toggles for time/feedback/both sequencing. I have no problem with that, but it occurred to me that that might be too many for some folks. Anyone want to weigh in on what seems superfluous enough that it should be a mod instead of a stock feature? It matters because, with this many knobs, there absolutely have to be onboard pots on this. So I have to consider how it will be built before I can really do the PCB for the most part.
I already have an enclosure drilled for 12 pots...what's one more? :)
How difficult would it be to make some of the pots optional? The biggest issue would probably be space saving. Do you have an idea of what size enclosure you'd want to fit this into?
Right, the enclosure and pot configuration are all entangled. I mean, if this was just for me, I'd probably design it for a 1790NS. I'd either do it landscape orientation, with the 8 sequence pots in a row and the others in a second row, or else I'd do it portrait style with 3 pot rows.
But, I know people around here like their tiny boxes. I'm 6'1" or so, so to me the little 1590b Zvex kind of thing is too tiny to adjust or to stomp accurately. But that's me. I can say for absolute certain that 13 pots, even 9mm ones, will not fit in a single row across a 1590b. Which means that we can't use the horizontal mount 9mm pots like Zvex does - I'd have to design for vertical-style pots, and these are not as available in the 9mm size (though I think Small Bear is supposed to start carrying those). So it leads me towards the 16mm pc-mount pots.
I guess the decision is between 1590bb and 1790ns, and portrait vs. landscape. I could make any of those 4 setups fit.
As far as optional pots, probably one or some would be, but I'm not sure what people find the least useful out of those controls. The difficulty of making lots of things optional with these PCBs is that then it's more complicated to figure out what you're supposed to leave out for the configuration you want, and people end up leaving out parts they need for the pedal to work. I like o make things easy to build, both for the benefit of people building the boards, and to cut down on my email overload.
Doesn't Markeebee work in biometrics or something? I wonder if he knows off the top of his head the diameter of the average human finger...
When I was mulling this over I was thinking a toggle for auto/manual advance, and manual advance momentary footswitch, a mode switch for 2/4/8 steps, and a manual reset momentary footswitch.
I even did a panel layout for it, for 1590BB, but on reflection a 1590JJ would be more suitable.
(http://dl.dropbox.com/u/967492/Event.jpg)
I likes this :) carry on
:icon_cool:
I have my sequencer controls in a circle, so board mounted pots are out for me. Planning it for a 1790 is probably for the best, given the number of features.
1790, all the pots. I'm no designer so only time, tweeking and mods will show me the pots I don't use. I may also be forced to use off board pots, simply because I have so many.