Who wants to tackle this idea?

[sonicparke]

What we all need is boutique analog stompboxes with automated pots for total recall.  Keep the analog circuit separate from the automation.  So you could 3 or 4 stomps switches for different delay setting or OD settings or whatever and recall them on the fly during a song.  Kinda like the automation on a Neve or SSL console.

Basically here's why...wouldn't it be too cool to have a seek wah or somehting like that but be able to save 3 or 4 settings and recall them in a matter of milliseconds?  I guess you could buy several of the same pedal but you'd run out of room if you didn't run out of money first.

[Chris R]

does the fender cybertwin do this.. i seem to remember the pots turning when changing settings...  ofcoarse i only played the thing for 15 minutes in a local shop ;p

C

[toneman]

the Sequential Circuits ProFX did this 20yrs ago.
(I still have one)
Plugable modules that were "recognized" by the main controller.
fuzz, flanger, delay, mixer, sync/octave,, a few more that i can't remember.
Escentially, "remembers all settings as  presets".

All the multi-effects boxes do this also.
I mainly know BOSS---GT3, GT5, GT6, ME5  etc.
That's the whole idea.
"Stomp for another preset"

Then there's the Paia Proteus.
A 20yr old analog synth that remembers the positions of 20knobs.
I'm really thinkin' of building "modular stompboxes".
What type of fuzz would U like 2day, sir??

tone

[sonicparke]

I kow all the multi effect boxes do this but the point is for it to be true bypass analaog killer stompbox but with the ability to recall different manual settings.  The best example I can think of is the seek wah.  Not an rp10.

[onboard]

does the fender cybertwin do this.. i seem to remember the pots turning when changing settings...  ofcoarse i only played the thing for 15 minutes in a local shop ;p

C

Yep, the Cybertwin has motorized pots. Pretty ambitious feature for a DIY box....

[puretube]

"dallas" makes digital pots, which in fact are stepped attenuators with little resistors and analog switches in a DIL8 package, the whole thingy controlled digitally with serial "commands".
Smaller than a pot, but more expensive, and not so much a DIY-approach controlling them...

[R.G.]

You're almost there pure.

Use a PIC.

Make the front panel controls be dummy pots read by a PIC. The PIC then interprets the front panel controls from the user, and sets the digitally controlled pots to a similar setting, at the same time storing the set of pot positions in its nonvolatile eerom.

The hard part is recalling a setting. The obvious way is with an LCD screen and more switches, but that's a pain.

Maybe a rotary switch and a "learn" pushbutton would do all we need.

[Nasse]

:? I dont remeber EVER seen an analog stompbox that has presets for more than one or two controls. If analog design wants to survive, I think it is better off someone pros here start make things that have presets.

Single pots might be easier, but how to control dual ones :roll:

Would it be easier to make presets by making the circuit voltage and logig level controlled and add one set of pots which is manually adjustable?

[drew]

If analog design wants to survive, I think it is better off someone pros here start make things that have presets.

I look at it more in the light that digital boxes have quite a-ways to go until they sound as good and are as easy to use as analog pedals


drew
www.toothpastefordinner.com

[Paul Perry (Frostwave)]

A search for "flying faders" will doubtless bring up more on auto resettable pots..

[travissk]

This can get relatively expensive, but how about rotary encoder + ring of LEDs + PIC?

[Peter Snowberg]

Digital pots are problematic from several points.

* Limited dynamic range (most will not let you go over the control Vdd or under Vss, leaving 5 volts of total swing)
* Very low current handling (the wiper resistance becomes a problem very quickly)
* Limited resolution (don't hold your breath if you want dynamic range and smooth control. 32 steps is most common.)
* Limited resistances (does anybody make units with 250K or anything over 100K for that matter?)


I think the best solution is a motorized dual pot with one of the sections used for microcontroller info and the other used for the analog signal path. A 12 bit A/D will give 4096 positions where as most digital pots have 32 steps.

PICs make GREAT servo controllers. Add some E2PROM, a rotary switch for preset selection, a learn button, and a little code, and you have a complete setup with the only drawbacks being the availability of motorized pots in different values and the cost. At least there are no signal quality issues. I don't want to give up quality for convenience.

Take care,
-Peter

[Bluesgeetar]

I hope I don't make a fool of myself here.  Here goes.  Aren't pots just resistors?  Maybe find a setting you like and measure the pots current resistance.  Put all the values on a rotary switch with Carbon comps or carbon films and use some type of foot job liken to the old Maestro effects to switch to your desired setting.  And maybe have a stomp switch that clicks back to the standard twist pots.  Please be gentle.  Design is not my cup of tea or strong point.  I could expand on my idea but I am already starting to get a headache.

[Mark Hammer]

The dividing line, it seems to me, between workable and problematic emulation of "programmable" pedals, is the role[/] of the pot.  Bear in mind that a *physical* pot can have a variety of different roles.  It can act as a simple variable resistor.  It can act as a voltage divider where the specific resistance values of the two legs are semi-critical.  It can act as a voltage divider where the values are non-critical.  It can also act as a complementary mixer, where two signal sources come along each pot leg and exit the wiper, with balance set by resistance ratio.

Some of these are easy to emulate by simple solid-state switching schemes, others less so, and others so tricky that there is no point in trying anything other than fully digital.  The extent to which a given design/pedal depends on easier and harder-to-emulate pot functions would determine how easy it would be to "fake" programmability.

The easiest case would be one where all physical pots involved simply serve as variable resistors.  So, imagine I have a two op-amp diode-clipper distortion.  The gain of the first stage is set by one variable resistor, resulting in some degree of clipping, and the output level is set by a second variable resistance in the second op-amp stage which would determine clean gain in the recovery stage.  It would be a piece of cake to have two pairs of pots for "preset" one and preset two.  Going betwqeen them is as trivial a matter as using a DPDT toggle or stompswitch, which is what a number of companies already do.

You could up the ante a bit by having more than two variable resistors in each setting (for example, include a RAT-style tone control) and more than two preprogrammed voices/combinations.  The Quad Sequential Switch idea, in an old POLYPHONY article I posted at my site (hammer.ampage.org) addresses this nicely.  A 4017 counter can be used to sequentially step through a series of settings, with each 4017 output enabling a set of 4016 or 4066-based CMOS switches.  The switches either complete or lift the connections made with the pots.

I have a Japanese schematic for a chorus/flanger project that uses the same BBD chip for each but provides different settings for each function.  A BOSS-style momentary switch alternates between them.  The flanger function provides slower overall LFO rates and enables the regen function.  The chorus setting lifts the regen and shifts the LFO range and rate setting.

The bottom line is there are some useful compromises between one-trick ponies and full programmability.  Things like PICs and digital pots are making the days of these other more cumbersome arrangements draw to a close, but there is still a little life left in them.

[Johan]

If anyone ever has the time to trace the Sans-amp Tri-AC... it has that funktion...three stompchannels with programable sounds...
http://www.tech21nyc.com/  

Johan

[Transmogrifox]

I HAVE had some success with a "pseudo-resistor" accomplished by a pulse-width modulation scheme, similar to the MXR envelope filter idea.  I haven't played with it enough outside of a distortion pedal to know how hi-fi it is, but it seems like a reasonable way to make multiple adjustable features, then the preset storage could be done more easily in a simple cheap microcontroller if you are one with the knowledge and equipment to do it.  

Volume control is the easiest to do with this pulse-width chopper type idea.

[petemoore]

Modular Rack And Ratio'd pinions.
 Old school...
 use treadle activated slide pinions...one for multi switching...one or more for multi dialing.
 Modularize the intended ckt's so the pots are driven by a rack gear using different size potshaft gears for different ratios of potshaft articulation...sprung so you can easily adjust the center, 'on' and off' settings [some resistors may added to or around ther pots for further tuning.
 and end up with a large box, or Dr. Suess's emaculation for articulation Special !!!
 I was wondering what I wouldnt be able to do with all that junk that replaces all the pots I'm not seeing in the puter boards during salvage detail...though maybe someone would find a useful purpose for those 'push button pots' [electronically controlled pot displacers...I like the old monitors that had pots all over the place.

[David]

Hey, people!

Remember that circuit snippet that Joe D. had on his web site that implemented the up / down pushbutton functionality?  That could be of use here, too!