Modularized planning

[sleepybrighteyez]

I have really enjoyed looking at the multi-fx boards you guys have built. It has me thinking- how can I design my pedals in a modular way, so they can be easily used on their own, or placed into a strip mall of fun goodness? I'd like to have jacks on the board (maybe on the board itself like i've seen some switches?) but also have a cable hookup (just two wires bound together, not a huge ribbon cable) to route the audio from one pedal to the next in a larger enclosure. Same thing with power supply- I'd like to have DC jacks as well as a small power connector so all the 'modules' can run off the same supply. The main idea is that I want to be able to easily pull FX from the strip, and use them on their own. I've even thought about the possibility of leaving the top of the enclosures with the modules (so you wouldn't have to unscrew the pots and switch, etc), and only removing the bottom (lid) for cable access. But then I thought about shielding, and well, I guess it needs more thought. I just wanted it to be very easy to swap the roles of the pedal.

[earthtonesaudio]

If you think about the basic needs for most effects, you have just signal in/out, power and ground.  All of that, plus switching and LED indicators, can go on one board, which could be common for every effect.  (Look how companies like Danelectro do it, they have jacks and switch on a common board, and 4 conductors running to the unique effect board.)

If you standardize the number of controls it can be even easier.  Just mount the effect board using 3 pots or whatever you choose, then connect to a common switch/jack board using a 4-pin connector.  You could standardize drilling templates that way.

[R.G.]

Read Geofex, http://www.geofex.com for mutliple articles on modularization.

[petemoore]

  Other than being a bit more demanding 'up front' in terms of what to use for connectors, which circuits share potvalues [and effect order position] well...lots to think of...mounting the boards well but not permanently.
 Once past the initial hurdles with less coaching, I'd say a good run after that is quite likely, as long as the drawbacks [ie which circuits aren't easily 'fitted' to the format...whatever else you discover] are not bothersome or can be worked around in some other way.
 Like switch to decide potvalue for "X" effect that Needs an odd value or odd taper pot...
 I just opted for the box to box build technique like everyone else, after finding a few incompatibilities and being stumped a bit by the required  'up front' thinkings.

[Mark Hammer]

I'd show you what I did, but I'm blocked from accessing photobucket here at work so I can't show you any pix (if someone has the link and can show it, I'd be much obliged).  In a verbal nutshell, though, here's what I did.

I made myself some small "frac-rac" chassis.  The box is wood, about 6" deep, front to back, and just under 18" wide when you factor in the thickness of the wood.  I bought some angled aluminum from the hardware store to use as my "frame".  Three pieces across the front of the box were enough.  The whole thing is about the size of a shoebox...for size 15 feet.

As luck had it, and partly as the kick in the pants to do this, I stumbled onto some nice black anodized faceplates for 25 cents each.  These are 2.5" x 4" and have holes in the corners that were countersunk for a nice flush screw fit.  It's not as much space for mounting controls as a 1590BB might provide, but since I wasn't going to use a stompswitch, or need space between the stompswitch and pots/toggles, that actually provides me a fair amount of panel space; enough for 4 pots, or 3 pots and 2 toggles.

So, the gist is that I have a bunch of identical-sized face-plates that are screwed into a kind of cross-brace attached to a larger box.  My boxes are both (I made two) able to hold two rows of 6 modules each (24 modules "on duty" at any time).  The inside of the wooden chassis is shielded with copper shim stapled to the box.  The outside has some tolex/naugahyde covering.  Each box has a bipolar (+/-9v) supply so that single battery and two-battery circuits can be accommodated.  A red/black, or red/black/green wire combo runs from each circuit board to the common power distribution point.  You could use a plug/socket arrangement for fast connection; I chose to use screw terminals and tinned wire ends.

Although the 2.5 x 4 panel space means that no single circuit board can be larger than that (or else it won't be able to fit through from the from-side access), the fact that the 6" depth means you don't butt up against a stompbox cover like on a pedal means you have the freedom to "stack" several boards that size on top of each other with spacers.  So, if you wanted to make yourself a flanger or delay or anything of similar complexity, you could stick the input/output stages and LFO on a board closer to the front panel so that wire leads could be short, and have the clock and BBD/filter stages on a secondary board behind it.

Since my plan was to use non-dedicated solid-state switches for "in-progress" loop bypassing, the modules themselves only have a mini-phone jack for in and out (rather than bulkier and costlier 1/4" phone jacks), plus a DPDT toggle for configuration and comparison purposes.  This lets me run a bunch of patch cables from the master switching module to a series of effect modules, and turn each one on and off individually.  The fact that the in/out/bypass for each module is so compact also frees up more panel space for controls....and legible legending.

The overall system is pretty dang flexible, ridiculously cheap, and takes up little room.  In my case, I use pre-made faceplates of a pre-determined size.  In your instance, you could easily get yourself a sheet of 12 gauge aluminum, bring it to a local sheet metal place and get them to cut you blank "slugs" of whatever size you wish.  So, maybe you kind of like the tall and slender format that MXR used for their modular units.  You could get them to cut something like that for you.  In my case, I mount the circuit boards parallel to the faceplate.  In the MXR case, the circuit boards are mounted perpendicular to the faceplate allowing them to be much larger.  A faceplate of 6" height, coupled with a mounting system that lets you attach circuit board at 90 degrees to the faceplate would easily accommodate just about any PCB you'll find in the DIY world.  In my case, I often have to perf things, but that doesn't mean you have to. As well, I use machine screws that require a screwdriver, but you could use thumb-adjustable screws like on true pack cabinets, and thread the mounting bracket on the cabinet properly, instead of being lazy and using self-tapping screws to do the labour.  I might also point out that it is worth your while to make/buy many more faceplates than you need, so that you CAN pull this one out and insert that one instead.  I have to say that it is nice to be able to think of all those fuzzes as simply another $6 expenditure each, and have a whack of them to yank or insert at will.  When you think about how much it would cost to have 1590B boxes for every damn distortion with all those jacks and stompswitches and battery snaps and status LEDs, that is a lot of machining and a lot of expense.  I used a faceplate that cost a quarter, 20 cents worth of screws, a $1.50 toggle, and two 60-cent phone jacks to do the same thing.  My legending was a paintpen and no painting or powder-coating was required.  It would not surprise me in the slightest if you could find some small metal-fabrication shop that had the remains of a sheet of colour anodized aluminum sitting around because it was too small for a "normal" job that they would be happy to cut up for you.

In the MXR chassis you see a sort of master bus/bypass on the left.  The individual modules plug into a bus at the back which routes ins and outs to that spot on the left.  In my case, I was content to let mini patch cords with phone plugs do that for me since the boards were all going to be a nonstandardized size and shape.  However, my system DOES have some modules of nondedicated switches (as mentioned earlier) and nondedicated splitter/mixers.  The switch modules mount in the rack package, but have a jack for connection to a remote foot-control unit.  So, I can plug my guitar into the splitter/mixer module, run two outs to a pair of individual series of effects, and run the last one back to the mixer.  For that matter, I can nest them so that splitter output A goes to some effects and then to another splitter, before returning to a mixer.  Stick some CMOS switches in there at different points, and there is pretty much nothing you can't do in the way of massive sonic changes at a foot-press.  I hadn't thought of it before, but now that I'm writing this, I think it is time to plan a remote panning-control module for foot-controlled morphing.

Finally (and I really DO have to get back to work), it IS possible to design a modular system that makes use of the guts of existing commercial pedals without necessarily destroying them or making them impossible to re-sell.  You can simply take the pedal guts out of the chassis and attach it in some nondestructive way to your modular panel, saving the original stompbox and assorted parts away in a baggie for later use.  Naturally, you have to plan out your faceplate size and a number of other things in advance so that you can take advantage of any pedals you might already own.

[frank_p]

Is That what you were talking about Mark ?



Also mentioned previously: the Gigrig  (with switchable effect placement)

http://www.thegigrig.com/acatalog/TheGigRig_Pro-14_BLack.html

If you are searching at R.G.'s GEO site look for :  FX-bus  (if I remember well)

[iaresee]

I've been turning over an idea for a few months now after seeing Marks setup.

If you take a standard true bypass strip that people like to sell for way too much money, and use something akin to a dsub connector, you could have a modular system. With all the on/off toggles up front, and all the boxes at the back, with the toggle -> box connection being made through a short run of cable and some dsub connectors or something like that. Lets you swap order, effects, and what not. But keeps your switches all in a row. You can deliver power through it as well. Couple it with something like that little hookup board that was being offered by one of the guys  here and it'd be pretty easy to do. And borrowing an note from Mark's design I'd make the switches momentary and use a Wicked Switch implementation with a toggle on each switch to select momentary or latching operation. That lets you have some effects set to be "punch in" type effects.

Hmm...sounds like a pretty cool system actually. Flexible. But neat. You get to make effects without having to worry about input/output jacks, power jacks and bypass so you can squeeze 'em down a bit in size. You can even get fancy and make modules that let you do things like swap two effects relative to each other and deploy those modules at will, on a whim, amongst your effects in the system already.

I guess what I'm describing is a cross between Mark's approach and the FX Buss idea.

[Mark Hammer]

Sound advice.  I think the usefulness or wisdom of any of the approaches would depend on a) what you need, and b) where you are in your building skills and pedal acquisition.  If you have far more than could ever fit on a pedalboard (and Ian can attest to that first hand in my case), and are in a position to build stuff in a common format, then a modular rack-like thing can be a best path to pursue.  It can allow you to stick a large amount of processing power in a small space.  If you have a fair amount of stuff already that you either can't, or would prefer not to, adapt but it can all fit on a pedalboard of reasonable proportions, then a more flexible switching control centre like what Ian describes seems like the more sensible solution.  The Carl Martin Octaswitch is a nice example of that.   In the 80's, before there were digital multi-effectors, Boss used to have a programmable control unit that let you pack a pile of their pedals together as if they were sound modules, and program in combinations that could be saved in memory.  And if that weren't enough, our very own Dean Hazelwanter developed a very nice system that would accommodate 8 pedals.

The overall objective is clearly "sound management".  In my instance, I have a thing about obscure parallel combinations of things, and stereo, so the patch-panel approach I use starts to put me in roughly the same ballpark as modular analog synth users.  But that's not everyone's interest or need.  For many, the need is simply to have one series signal path, be able to shut a bunch of things off or turn them on in one simple motion, or change up the order just a bit, or add a new pedal, without having to completely redo the whole pedal-board.  In those instances, simply being able to plug a pedal into a bus, without having to work out the whole strategy of where the heck it could go on the pedalboard so that you could step on it when needed, is a real step up in functionality and convenience.

Some folks, of course, will need something that permits treating the pedalboard like synth patches.  Bar bands that cover top 40 tunes would be the likely customer, and MIDI control would be the likely route.  As powerful as the system I described might be at being able to create sounds, it comes up far short in terms of being able to manage them as smoothly.  In my case, the "memory" is in the patch cords.

[iaresee]

If you have far more than could ever fit on a pedalboard (and Ian can attest to that first hand in my case)

Hehe...one of the shots from the party perhaps is in order here?

and are in a position to build stuff in a common format, then a modular rack-like thing can be a best path to pursue.  It can allow you to stick a large amount of processing power in a small space.  If you have a fair amount of stuff already that you either can't, or would prefer not to, adapt but it can all fit on a pedalboard of reasonable proportions, then a more flexible switching control centre like what Ian describes seems like the more sensible solution.  The Carl Martin Octaswitch is a nice example of that.   In the 80's, before there were digital multi-effectors, Boss used to have a programmable control unit that let you pack a pile of their pedals together as if they were sound modules, and program in combinations that could be saved in memory.  And if that weren't enough, our very own Dean Hazelwanter developed a very nice system that would accommodate 8 pedals.

I always thought those Boss boards were pretty cool. The ME-X and the ultra-rare SCC700 took, to a commitment-phobic person like me, the right approach to programmable effects selection.

Now I've got this modular thing in my head. You can even build modules that would let you patch in third-party effects, complete with a 9V tap to power them, that didn't have the special dsub connector. Hmm...what a nice way to build the more I think about it. You wire up a 4-switch strip once and then all the pedals you build you just test on that strip.

[Mark Hammer]

Now I've got this modular thing in my head. You can even build modules that would let you patch in third-party effects, complete with a 9V tap to power them, that didn't have the special dsub connector. Hmm...what a nice way to build the more I think about it. You wire up a 4-switch strip once and then all the pedals you build you just test on that strip.

Yep.  In many respects, the ideal is to go beyond my little black frac-rac boxes and make one's pedal modules be part of a rack system.  In other words, you have a normal 3u or 4u or whatever 19" wide rack chassis.  One or two vertical "units" of space are reserved for the modules, and a horizontal brace bar or two or three goes across the front of the chassis so you can attach modules to them from the front.  meanwhile a rear panel permits interfacing with any rack unit or table-top unit you can stick in the chassis or on top of it.

If you want to go completely nuts, incorporate a module or two with the "station-switching" idea, where a rotary switch on the front lets you manually reassign effects or even groups of them in a different order.  Naturally, one would expect to find a patching system on the rear skirt complementing this.

I've mentioned several times in past a rackmount setup I made for myself 20 years ago, based entirely on Anderton circuits (and now owned by someone in the Canadian Maritimes I gather).  It had a built in 2-out active splitter, 2-in-1-out mixer, two nondedicated EPFM CMOS switch modules (hooked up to a remote foot control with duplicate latching and nonlatching switches), and bypass toggles for all the assorted effects circuits included.  All of this was connected via an RCA jack/plug patch-panel along the rear skirt.  You could patch anything you wanted into anything else and route whatever you wanted to the switch modules.  It also let you incorporate external devices, as long as you had an RCA-to-1/4"-phone cable.  That's where I learned how to use "input kill" with delays; by using my rack unit and its switching capabilities in combination with a table top analog delay unit.

One way to conveniently distribute power to stompboxes via a master system is to make yourself some shunts for the battery connectors.  That is, you clip the connector top off dead 9v batteries and solder a connection between the male and female portions of the connector.  When you put that on the pedal's battery snap in stead of a battery, you turn the path from the ring lug on the input jack to the circuit board into essentially a straight wire connection, and now have a direct line to providing +9v (or whatever you want) to the circuit board via a stereo plug to the input. If you have a bunch of stereo phone jacks on the rear panel of your master unit, that will let you have a bunch of send-return loops that power and carry signal without too much of a rats' nest of wires.  The caveat is that you have to be absolutely unswervingly religious about plugging everything in first before any power is applied or else you risk damage..

[sleepybrighteyez]

Thanks for all of the advice guys, I really appreciate it! I really like the rack method. That seems to make more sense than what I was originally thinking of. I like the routing possibilities of that kind of setup. I'm all about the parallel fx chains. I'm interested in learning more about the 'hub' that all the modules would connect to (instead of a serial linear connection through the strip), and how to control the switching/routing.

[R.G.]

http://geofex.com/Article_Folders/FXRack/fxrack.pdf

[Mark Hammer]

Yep.

[frank_p]

Yep Yep,
  but to keep the idea of Alex:
you could put the pots (and other switches) on the channel.  Then you could find a connector (that would be more than a four pin one) to plug everything that is "outboard" of the module.

One thing that would be interesting is having something like those adapters that they put on 2.5in hard-drives IDEs.  the plate of the module could be placed on one edge and hinged to the other side (thus, making all of the contacts in the connector).  Than only one machine screw would be needed to "clamp the module in place.  The idea would be to have no controls at all on the module (only cheap electronic parts that you are experimenting with and a standardised connection so no time would be lost on wiring all the pots and switches...

Eh...  Just brainstorming.