Mine's smaller! Musings on the lower size limit for guitar effects...

[earthtonesaudio]

With the popularity of 1590A pedals, and seeing people cram obscene amounts of junk into them, I can't help but wonder how much smaller is possible...?

The main size restriction, to my mind, is the 1/4" audio cable.  You could use 1/8" or 2.5mm jacks, or even a stereo 1/8" jack wired as a splitter, but that's just cheating.  So if you keep the full-size, mono, 1/4" cables, that takes up a certain amount of space inside an enclosure.

The next thing that most stompboxes need is a footswitch (otherwise what are you stomping for?).  But clearly the "blue" 3pdt is not the only choice.  You could probably get away with a tactile pushbutton and some supporting hardware (like the GEOFEX "pancake" switches) and really shrink things down.

Next is the controls.  Even a simple booster needs at least one external control knob.  Sure, everything could be internal trimmers, but in a live situation you might as well break out the soldering iron and change fixed resistors.  Maybe the walkman-style pots could be used, where the edge of a rotary dial sticks out just a little from the enclosure, or something even more compact and functional that I can't think of.

Then there's the power supply.  Some people have used watch or camera batteries, but most go for adapter power.  The main thing here is the size of the jack used.

Finally, the circuit.  SMD anyone?


I bet you could cram a couple 5-knob delays into something half the size of a 1590A if you really, really, really tried.

[Ice-9]

I have seen on some effects before where the pots for the controls are actually trims, the knobs themselves have a spindle on them with a flat that pushes into the trim.

[iaresee]

I have seen on some effects before where the pots for the controls are actually trims, the knobs themselves have a spindle on them with a flat that pushes into the trim.

Like this?



Definitely saves some exterior surface area. Not sure how much smaller those are in the box.

[Taylor]

I really don't get this trend. One important limit that you've overlooked is how much space you need between stomp switches in order to activate one without the ones on either side. Putting 3 1590a stomps next to each other, I don't see how one could reliably turn the middle one on in a performance. So, if you then have to space them apart enough to fit your shoe in there, what's the point in making them so small?

I get the fun of an engineering challenge, and if that's really all there is to it, then I'm happy for you guys for doing such difficult stuff. But to me it seems like it's antithetical to the utilitarian needs of a performing musician - presumably the person that these little effects are intended for in the place, right? Who needs tiny pedals if you're in an apartment?

Lastly, this may be because I live with 4 artists and live in the middle of an art school campus, but I feel that the smaller you make something, often, you diminish its perceived importance. Big paintings command more attention, and add to the perceived value of a piece, so they generally sell for more. I think that, coupled with the more mainstream electronics manufacturing world, where companies crank out tiny mp3 players that are super-cheap, can make tiny effects seem to be worth less money to a consumer.

Well, to me, anyway. I like big effects. But I may be in the minority.

[Mark Hammer]

It is possible to get those cute little latching PC-mount DPDT switches for use with actuators/plungers.  I've used them and they're sweet and small.  You can still get status-indication with a DPDT under some circumstances.

Ah, but see here:  http://www.diystompboxes.com/smfforum/index.php?topic=75895.0

[Ice-9]

I have seen on some effects before where the pots for the controls are actually trims, the knobs themselves have a spindle on them with a flat that pushes into the trim.

Like this?



Definitely saves some exterior surface area. Not sure how much smaller those are in the box.

No not quite like those, they are actually trims that you would use internally, but the knob is designed to push into them, i will have a look see if i can find a picture. You can even buy smaller SMD ones, reliability would be a problem i would think.

here you go. here is a link to a similar preset/trim, instead of a using a screwdriver to turn them the knob is moulded with a flat spindle that push fits the preset.

http://www.maplin.co.uk/Module.aspx?ModuleNo=6499

[caress]

i completely agree with taylor here... 
i like em big

[kurtlives]

^I'm with ya too.

Little tiny pedals just seem like an easy way to break a knob or pot off while trying to hit the switch.

I know personally when I play live I don't want to gingerly walk over to a pedal and carefully place my foot on the switch then let go. I want a decent sized enclosure so I can stomp without fear of totally stepping on my pedal. Hell my size 13 shoe is about twice the size of those little 1590A boxes.

Despite not liking the little pedals, I have a lot of respect for the guys who have the patience to build them.

[Ice-9]

+1 i also like pedals that are robust and gigable, but reading the first post this is an exercise just to see what can be done in the smallest size box, which my para boots would probabaly crush the 1st time it was used.

[R.G.]

There are two limits, neither of them having to do with the electronics or how small they can be made. Given the attention of a suitable team of chip-monkeys to translate the circuit into a valid design-rules floorplan, I could put most effects on a bit of silicon. It would cost several hundred thousand dollars, and involve some design compromises because of having to follow the maker's design rules for compatibility to the fab process, but it would work. You can put the full circuitry of most effects in between six and 24 nano-acres* of silicon surface with today's technology. Probably less since things have moved on since I was current, but this should be comfortable.

So the circuitry is not the limit. What is the limit is what has already been alluded to - it's the humans that will (more accurately, will NOT) use it.
Humans won't use a device that is too small for them to work the controls on. It takes a major paradigm shift to get people to use different controls. The ipod, even given it could be made, could not have been sold a few decades earlier, because the idea of tiered menus with rotating selectors was so foreign before humans in general used computers for a long time that no one could have used it. Devices with knobs closer than about 0.5" aren't usable for anyone, and aren't usable except close up in your hand by anyone. Certainly not on a floor mounted stomp switch. Human eyes, hands, fingers and experience limit the smallness of controls.

The other thing, also mentioned is the idea that you ought to get a whopping big whatever for your money. The idea of paying more for a smaller (whatever) goes against the grain if the customer does not understand what's inside. This was noticed early, back in the 60s if not further back. Stereo dealers noticed that customers would surreptitiously heft the tuners, amplifiers, preamps, etc. and often bought the heavier one, regardless of the relative prices and sound quality. Some makers resorted to putting weights into their hifi stuff.

* The nano-acre is the unit of chip measurement we used when laying out processors. A square mile (5280ft x5280ft) is 640 acres. One acre is then 43560 square feet. An acre expressed in square inches is 144 times this, or 6,272,640 square inches, and a nano-acre is then this number divided by ten to the ninth power, or 0.00627 square inches. A 5mmx5mm die is 6.18nAcre.

[earthtonesaudio]

Good comments everyone.  I suppose if it's so small you can't use it, then there's not really much point, eh?

I'm just interested in how small you could make something while still retaining the necessary functions, and what changes would need to be made to accommodate such an effort.

[Taylor]

Well, I don't want to discourage anyone from trying to go smaller with effects. I think it can be a very interesting problem to pose, and the solutions can have benefits even when you're not aiming for a tiny box.

[R.G.]

I'm just interested in how small you could make something while still retaining the necessary functions, and what changes would need to be made to accommodate such an effort.

Here's how to determine that.

1. Assume the actual operational pieces that do the work, power it, etc, everything that is something a human does not actually touch or interact with directly, can be as small as you like. Head of a pin, or 1mm cube, or one atom. Or zero.
2. Now, with the hypothetical device small enough to be ignored, layout your controls. Use the smallest real pots, knobs, switches etc. that you can find in anybody's catalog at any price. Draw/and or mock up the unit. Modelling clay or Sculpey fakes stuck into cardboard will do, but make them actual size.
3. Try it out. Would you use that on stage? If no, you're too small. If yes, then a sample of one human thinks it's OK, and you've noted at least one point in the distribution.

Here's another test. The ipod condenses a marvel of controls into a few simple sensors. Assume your effect is inside the ipod.How well do those controls work for using an effect in a real-world gig?

I have seen working miniature machines, guns, etc. made by miniaturing nut...er, enthusiasts.    Some are so small they have to be seen with magnification to be appreciated. It is possible to make a working effect so small that you'd need a magnifying glass to work it. Is that useful?

No, it can't be used by an average guitarist in an average gig. The controls are too tiny to be worked while playing guitar.

[newfish]

The number of angels dancing on a pin head is not in question.

What's at stake here is that none of them can find their ultra-mini-pico-sized-fuzzbox.

[Mark Hammer]

Small boards does not necessarily mean small pedal.  That conserved space could be put to use for patching purposes (insert loops and such), for more sensible or practical layout of controls, or even for multiple 9v batteries.

[enquiryband]

I really don't get this trend. One important limit that you've overlooked is how much space you need between stomp switches in order to activate one without the ones on either side. Putting 3 1590a stomps next to each other, I don't see how one could reliably turn the middle one on in a performance.

try a triangle pattern, not a straight in-line pattern? one in front, two behind?

[Sir H C]

I have always thought about fabbing an IC with some fuzz and other circuits using MOSIS ( http://www.mosis.com/ ).  Some of the older processes are pretty cheap, and probably can get 100 ICs for under 10k. 

I always thought, if you make it small enough, then much like the iPod you could put a bunch of pedals into one control rack/device and instead of emulation, you get that real BBD and all that in a boss pedal size.  That could really be cool.

[Thomeeque]

 Generally I agree with most of arguments against this trend (when it gets to extremes like feeding PT2399 based delay by watch batteries ), on the other hand speaking about ergonomics, I'd say that most of e.g. danielzink's 1590A stompboxes have no problem (and some of these giants do ).

[StephenGiles]

Sorry, but a complete waste of time and energy. Bigger is better!

[iaresee]

I always thought, if you make it small enough, then much like the iPod you could put a bunch of pedals into one control rack/device and instead of emulation, you get that real BBD and all that in a boss pedal size.  That could really be cool.

Lexicon did pretty much this exactly in their older MPX G2 rack unit. It was a rack unit with an all-analog front end. Analog versions of a TS, Muff, Fuzz Face, etc. could be selected and controlled as easily as the digital effects in the box. And they are very, very, very good sounding circuits.

I covet an G2 very much.

As to why you'd want to build smaller? Well: consider using these as modules, not as standalone stomps. I've recently switched a looper and have traded off the last of my 3PDTs. My builds now will all be: always on, no bypass. I don't need to be able to toggle the effect on/off now at the effect. So I can either use the extra space I gain to cram some more pots or something into each circuit, or I can put the circuits into smaller boxes.