MIDI Pedalboard Pedal Design

In response to a recent comment I have provided the following layout for my pedal design for anyone interested.

I’m cheating on the pedal a bit and have no forward stop other than the actual potentiometer throw distance so there is the chance I could really do damage if I laid into a pedal. I had planned on adding stops at some point but just left it as is for now.

Dimensions and basic stats for the pedals.
Dimensions and basic stats for the pedals.

Here are some stats on the pedal layout

Pedal

  • Length: 11 5/8 inches
  • Width: 3 1/2 inches
  • Pivot Point: 3 3/4 inches from the heel of the pedal.

Rack/Gear Position

  • The pin that holds the rack gear to the underside of the pedal is exactly 3 1/2 inches back from the toe.
  • As far as placement of the mating gear to the potentiometer I basically placed it to meet the rack when the pedal was parallel with the deck. On my design this means the center point of the potentiometer is 1 1/4 inches from the underside of the pedal

Pedal throw

  • Back of pedal will rest on the deck in toe up position where the underside edge of the top is 2 1/8 inches above the deck
  • In the toe down position the underside edge of the top stops at about 3/8 of an inch above the deck. A simple rubber footer would probably be an effective stop there.

Once you have everything assembled I would recommend sending the midi signal out to something like MIDIOX and testing the throw to find the zero point in the heel position.

Multi-Option Dunlop GCB-95 Modification

This is a writeup on the extensive modifications I have made to my GCB-95 in order to provide a wide variety of sounds beyond the stock pedal.

While I heavily utilize IK Multimedia’s AmpliTube for my guitar rig there are times where I want to use outboard gear as well. After completing my Amplitube MIDI Controller I was literally left with a shell of a Dunlop Cry Baby GCB-95 pedal. I used the gear mechanism from the pedal to prototype the mechanics of my MIDI board then ended up stealing the bypass switch for a power button on a clean amp project.

After a few other projects this (aside from the circuit board and potentiometer not pictured) was all that was left:

When I started this project the intent was simply to get the OEM replacement parts and put the pedal back to stock shipping operations. As I looked at the replacement parts it started to become apparent that the existing circuit board could accept alterations such as replacement inductors and after some more digging online I found countless circuit board modifications to the GCB-95. Most all of the mods appeared to be one-way where the only way to ‘roll back’ to the original stock features was to replace all the parts. In addition, I didn’t see too many people trying to increase options for the inductors so I ultimately decided to combine many of the upgrades into one pedal. I had three primary goals for this project:

  •     I wanted the ability to switch between stock and mod settings
  •     All components needed to fit in the pedal casing
  •     The battery compartment could not be used for additional component storage

It took a few days but I was able to take on the project one phase at a time and ultimately get exactly what I was looking for. As always keep in mind that I am not a road-warrior musician so my projects have silly characteristics like switches sticking out of the side of a pedal that could easily be sheared right off by overzealous stage antics. Before I jump into the how-to I’ll go ahead and give you a look at the final product with a description of the features.

Left side of the pedal with a simple toggle to switch the voicing of the wah sweep. This basically toggles between the stock capacitor and a replacement for a more defined lower to midrange sweep.

Right side of the pedal with three toggles for midrange boost, gain boost, and vocal shaping. The three way switch near the heel provides access to the stock inductor, yellow vintage Fasel, and modern red Fasel inductors.

Two more notes before we dig in. The decision to include an inductor switch was made later on in the build after alot of the circuitry had already been reinstalled. You may want to do all the casing modifications first but if not, be aware you could end up with aluminum dust or shavings in the circuitry. Simply shop-vac or compressed air blast the casing clean in either case to avoid any shorting out of the circuitry. Additionally this mod does NOT send any of the signal to a buffering resistor on switching of the added features so it will most definitely ‘pop’ on switching as the capacitor discharges. You’ll want to throw the pedal into bypass or put down a volume/mute switch on the amp side of the pedal before toggling options… especially if you’re on a live and fully loaded amp.

If you just want to know the changes made, here is the baseline schematic:

Start by removing the wiring harness at top, 1/4 inch jack screws on the outside body, and mounting screw on the lower right of the board. Then remove the board and de-solder each of the following components from the stock circuit board.

L1 – The stock inductor. Save this component. IMPORTANT! … mark the component in some manner which helps you recall the position BEFORE you remove it. For instance you cannot see it here but I put mark on the side of the inductor near the area of the board that has L1 printed on it. This told me where the bottom right corner of the inductor should go. This will help you know how to correctly wire the inductor later.
R5 – Resistor controlling vocal shaping. Toss this.
R1 – Resistor controlling midrange. Toss this.
R9 – Resister controlling gain. Toss this.
C5 – Capacitor controlling the ‘sweep’ of the wah sound. Toss this.

This leaves us with a clean board:

Next we’ll work on the casing a little to hold 4 DPDT (Double Pole, Double Throw) miniature toggle switches.

The smaller the better when it comes to these switches because there isn’t alot of space in the casing.

The right side of the pedal is best for multiple switches given that when the potentiometer is placed in the housing there isn’t too much clearance on the left side. You’ll want to be ultra aware of the switch body size and proximity to the 1/4 jack mount flange (shown left) and rubber foot mount (shown right). Aesthetically your best bet is to mark the mounting position of those two holes first, then simply split the distance between them for the middle switch. The pedal base is cast aluminum which is very easy to drill. I recommend using a punch to set the center for drilling and starting with a smaller pilot hole to ensure the larger bit doesn’t travel when you start drilling the final mounting holes. For the sweep capacitor switch on the left side, simply match the position of the hole closest to the 1/4 inch jack to keep clear of the potentiometer base.

Outside shot of the housing showing the mounting holes running parallel with the top of the pedal base.

A quick fit-test to ensure the switches are not going to give us any issues.

Note the ample clearance between the circuit board and how the switch leads are just inside of the cut out area (rounded rectangle) for the gear assembly. Smaller switches that stay inside that area won’t interfere with the potentiometer.

Now remove each switch. Solder 2 leads about 6 inches long to the center terminals on each switch then getting the leads on the resistors and capacitors as close to the external terminals on the switch as possible, create the following switch combinations:

  • Switch One (Midrange): 2 six inch center leads with a 2.2kOhm (R-R-R-Gold) resistor across the terminals on one side of the switch and a 1.5kOhm (B-G-R-Gold) resistor across the opposite terminals of the switch.
  • Switch Two (Vocal Shaping): 2 six inch center leads with a 47kOhm (Y-V-O-Gold) resistor across the terminals on one side of the switch and a 33kOhm (O-O-O-Gold) resistor across the opposite terminals of the switch.
  • Switch Three (Gain): 2 six inch center leads with a 270Ohm (R-V-B-Gold) resistor across the terminals on one side of the switch and a 390Ohm (O-W-B-Gold) resistor across the opposite terminals of the switch.
  • Switch Four (Sweep): 2 six inch center leads with a 0.01uF capacitor across the terminals on one side of the switch and a 0.022uF capacitor across the opposite terminals of the switch.

Remember to mount the components as close as humanly possible to the terminals (note the image above) because you need to ensure they will not make contact with the mechanical components on the gear side of the potentiometer or the leads on the opposite side.

Now remount the toggle switches in the case and shape the leads to run as close to the casing walls as possible before falling between the 1/4 inch jacks and inductor space. I should point out here that I didn’t pay too much attention to the placement of the toggles with respect to the original resistor and capacitor values. It would probably be a good idea to put them all either towards the toe end or heel end of the pedal so when all switches point in the same direction you know you have reverted the pedal to ‘stock’ mode.

Cut another pair of 8 inch leads. Trim all toggle leads to as short a length as practical to keep wiring runs as short as you can and hook up the toggle leads and spare 8 inch leads as follows:

  • Switch One (Midrange): Solder leads to R1
  • Switch Two (Vocal Shaping): Solder leads to R5
  • Switch Three (Gain): Solder leads to R9
  • Switch Four (Sweep): Solder leads to C5
  • 8 Inch Leads: Referencing the image above solder the leads to the two holes on the left inside the inductor outline. Basically look to the right of R5 and connect to the two leads inside the larger circle but just to the left of the larger drilled hole in center of that circle. Leave the opposite ends loose for the time being.

Now remount the board to the casing with the single screw to the lower right.

Now it’s time to mount the inductors. Above you’ll see the stock black inductor and the aftermarket red and yellow Fasel inductors. It took me a little time to figure out how to jam these things in the pedal along with that massive switch but here is what I ultimately ended up doing.

The heel of the casing is practically the only place that all three inductors and an additional switch can be placed. After staring at this void for awhile I realized that just below that battery foam is a totally unused screw mount. This image was taken right after that discovery because there was also a much longer screw protruding from the nut just to the right of that mount point. Take a pair of pliers, grab that screw end and give it a couple of to and from tweaks. It will snap off right at the nut base.

Now find yourself some sort of non-conductive material and cut it to cover a majority of the void in the heel of the casing. In this case I used a semi thick sheet of plastic from some kind of binder. Those lightweight 1/2 inch vinyl binders with snap rings come to mind. The key is to just find something that a sharp wire or component lead will not easily puncture.

Next you are going to need a really short 6-32 screw… the same length as the one that holds the circuit board in place. If you can’t find one short enough just run a nut onto a 3/4 or longer 6-32 screw then using a hacksaw or bolt cutters, lop off the additional length. Running the nut back off of the screw will re-cut any damaged threading, making it easy to use the screw on the mounting hole.

Now find yourself a 1 3/4 inch square circuit board (set with copper solder points on the opposing side will help) and test fit the board using the mounting screw. This particular board came from Radio Shack and just happens to be a perfect fit all around… with the exception of that top notch which I will now explain.

As mentioned in the start of this post one of my requirements was to ensure I didn’t intrude on the existing pedal functionality… that included the battery compartment. The Dunlop Wah has this funky clip on the battery compartment that ends up taking up some real estate and just happens to run right along the line of that mounting screw. So using some nibblers and a file, I removed enough material to ensure the battery clip would still fit as expected.

You don’t need much clearance here… just enough to prevent the battery clip from pushing down the newly mounted circuit board.

And here is where things got tricky. You see the black inductor? It’s ever so slightly too tall to clear the bottom of the pedal… it sticks out if you look from the side so the bottom plate cannot be put on the pedal. If you look on the OEM circuit board between the 1/4 inch jacks you’ll see that there is a big hole drilled in the board.

The OEM inductor has a flange at the bottom. You’ll need to drill the circuit board to allow this flange to slide into the board. It will help get the clearance you need. Now for the next problem. The Fasel inductors mount vertically taking up even more room than the OEM inductor.

Using a pair of needle nose pliers gently (and I do mean GENTLY) bend the terminals right at the edge to move them into a 90 degree position. Do this for both the read and yellow Fasel inductors. You need to be super careful here because if you snap off the terminal you’re done and if you look on the opposite side of the plastic mount you’ll see just how thin and fragile the inductor wire really is.

If you did it right, the Fasel should now mount horizontally on the circuit board.

Temporarily Solder the inductors in the following configuration, keeping the OEM aligned the same as before. Remember I marked the lower right corner earlier which means I mounted this with the lower right corner mark towards the bottom right of the heel and picture in this photo. Now we move on to the switch. Notice from the previous picture how long the terminals are on the switch? Notice how close the lower mounting hole is to the rubber foot mount? This is going to be tight. Start by using wire cutters and trim off to the top half of the switch terminals. If you notice you’ll see additional mounting holes close to the body that we can use. We need that real estate or the battery will either not fit, or will shor the contacts on the switch.

Measure the height of the switch using a ruler or caliper.

Now pick a drill bit just slightly larger than that.

This step is a little tricky as you have to look at the inside and outside of the casing to get it just right but place the switch in the leftmost throw and set it on the body where if you were to drill through and place a nut on the backside, it would not interfere with that mounting post. The Dunlop is painted with powder coat so it’s easy to scratch. Scratch a mark at the outside edge of the switch then carefully move the slider to the far opposite throw point and make a mark on that outside edge as well.

I got a little carried away here but scratch a line parallel to the top of the pedal body then punch three holes at points where the drill bit will meet the left top, top, and top right edges of the mark from a dead center drill on the punch marks.

Drill pilot holes first with a 1/8 inch or smaller bit. This will help keep the larger bit from traveling too far on the final sizing run. After the pilot holes have been drilled, switch to your selected bit and open up the slot by drilling into each pilot hole.

You’ll need to use a smaller file at first to knock out the ‘points’ between the holes.

Once you have gained enough space, a larger file will fit and definitely speed up the job. Check your work often with both the caliper/ruler and actual switch to ensure there is clearance for the throw on all sides.

Once you are happy with the clearance place the switch on the outside of the body with the slider pointing in. Hold firmly while ensuring the slider moves effortlessly down the channel then make to registration marks in the mounting holes and drill for the mounting screws.

As you can see the final mounted switch with trimmed terminals and short screws/nuts will keep clear of the 9volt ‘zone’

Wire all inductors as indicated in this schematic:

The completed mod. Note the black wire ties used on the inductors just to help add stability and wire ties across all added wiring to keep things clear.

Everything works great so far. As mentioned earlier this mod does NOT send any of the signal to a buffering resistor on switching of the added features so it will most definitely ‘pop’ on switching as the capacitor discharges. You’ll want to throw the pedal into bypass or put down a volume/mute switch on the amp side of the of the pedal before toggling options… especially if you’re on a live and fully loaded amp.

In an upcoming post I’ll show the features of the mods with some sound samples, etc.

AmpliTube Guitar MIDI Pedalboard Project

I recently finished up the first part of a guitar pedalboard controller I’ve been planning/working on since about November of 2010.

Completed Guitar Pedalboard
Completed Guitar Pedalboard

Keep in mind that I never really intended to post a How-To/DIY on this project and because of that I’m missing various details on how some things were done. At a certain point I just started photographing everything as I progressed. Overall there are plenty of photos and descriptive info to foster ideas if this is something you want to take on. My only advice is to take your dear sweet time. This was just about the most challenging project I’ve taken on in the past few years and is evidenced by the 6-7 months of development it took to get to where I am today. That said… it passed the all important “smoke test” the first time I plugged it in, so taking your time on this stuff is a good thing.

The purpose of the pedalboard is to send MIDI messages to my Presonus Studio One digital audio workstation running AmpliTube 3 from IK Multimedia. AmpliTube can receive MIDI commands to turn on and off guitar pedals and alter parameters like volume, gain, wah-wah pedal filters, etc.  There are plenty of midi controller pedals out there (IK even makes a line) but with what I wanted I knew I would end up in a wiring mess and alot deeper in the hole cash-wise for this adventure. Since I only play in my studio I wasn’t overly concerned with building the pedalboard like a tank, I just focused on good design and general ruggedness.

My first stop was trying to figure out how to even tackle the electronics aspect of this. I asked a horde of music hardware vendors if anyone made some kind of black box you just plug a bunch of expression pedals into and then it all runs to a simple MIDI output. To my knowledge, nobody (commercially) makes such a simple little beasty. Pressing on I got into the idea, and alluring underworld,  of DIY MIDI… USB controllers using joysticks, programming your own joystick to MIDI drivers, etc. All way too much for something I just wanted to have fun with.

After alot of searching I finally discovered Doepfer Electronics in Germany, producers of MIDI keyboards/controllers galore and one great lineup of OEM/DIY controllers. They have plenty of them to choose from but ultimately I selected the Pocket Electronic as it offered up to 16 buttons or Potentiometers (sliders/pedals) running a MIDI in/out pair (which could be daisy chained)… just enough for the design I had in mind. I got the board from Doepfer’s US Distributor, Analogue Haven, based in California.

Pocket Electronic
Pocket Electronic

This is where I started design-wise in November of 2010:

Guitar Pedalboard Design
Guitar Pedalboard Design

The original design (sorry, not alot of light near the whiteboard) was to include 1 analog pedal with an insert, 5 midi pedals, and an array of switches to send signals, reverse pedal polarity (up becomes down), etc. The pedals were shaped like feet and all of the wiring was to run out of the back of the unit.

Early Prototype
Early Prototype

This early prototype of a pedal was tossed together by myself and my good friend Jeff. I traced my Cons and we used whatever was in the garage to toss together the initial concept. If I remember correctly the first pedal was the rack and pinion from a telescope, curtain rod, potentiometer, a bracket from those western-style swinging doors, and some screws/plastic tubes and brackets. Crazy… but it worked long enough to give me hope, then it broke. Good enough.

The first thing I struggled with were the mechanics of the pedal itself.. specifically the issue was driving the potentiometer via the pedal. I went through a few designs then ultimately opened up my old Roland volume pedal (uses a sliding mechanism) and then the Crybaby Wah pedal (uses a rack and gear assembly). Preferring the Crybaby engineering because it seemed a little simpler to engineer, I was set. Finding a source for the Crybaby parts took some time but I was very happy with the service from NewOldSounds.com. I ordered a set of racks and gears then played the waiting on shipping game.

Pedal Design
Pedal Design

The pedals were the first thing I built. Ignore the nails and gizmos all around the above image… we’ll get to that later. The pedals are simply just 3 inch wide oak from Lowe’s. I cut two three foot sections into foot long pieces then routed off the sharp edges with a 45% bit.

Near the top of the pedal you can see the pedal racks. I cut then filed pieces of aluminum channel (again Lowe’s), added a hole for the rack pin, then screwed them to the board and mounted the rack via the pin insert.

The pivot point of the pedal is a really crazy design but this is what happens when you start with one thing, get too far in, and have to make it work. The base of the assembly is aluminum channel which is screwed to the board with countersunk nuts on the top of the pedal. Within the channel (at the ends) you can see nylon grommets which have been cut to fit inside the channel. Through the grommets is a length of 1/4 aluminum rod. The rod has a setscrew which keeps it from pivoting in the grommets. Working our way out you will find a 1/4 washer, 1/4 clear tubing to help pressure fit the pedals together, another 1/4 washer, then finally a 1 inch nylon grommet. I can probably imagine nine better ways to do this now … live and learn.

Mounting Layout
Mounting Layout

Back to the nails. The blocks are oak which has had holes (the same size and the nylon bushings) drilled through them at a 90 degree angle then four mounting holes at the corners of the blocks. They were all placed on a curtain rod then run through the table saw to give them the angled edges. The pedals were then placed on the pedalboard at even intervals and the blocks spaced between the pedals. The nails were simply tapped in to provide marks ensuring a proper lineup for each block when I drilled the mounting holes.

Mounting Holes Revealed
Mounting Holes Revealed

Holes were then drilled in the board then working left to right, each block was temporarily mounted followed by a pedal until all blocks were in place. No photos exist of this, but obviously I put some non-skid tape on the pedal faces. This is just the standard black no-skid stuff you can get at Lowe’s.

Pedals Temporarily Mounted
Pedals Temporarily Mounted

Finally, the end blocks were capped with an oak dowel and set screw.

End Block
End Block

Now to backtrack for a moment. You may remember that oddball pedal design and mention of some clear tubing. The reason for the tubing is to allow for adjustments in the placement of the pedals so they glide effortlessly between the blocks without touching. There was alot of troubleshooting to get that to work. Basically if the left side of a pedal was rubbing the block, I needed to pull everything and put a longer spacer. Then that may change the pedal next to it, and so on. So this was a tedious chore to finalize and one day I’ll change the design, but it works now and that’s enough for me.

After the pedals were working well I marked the location of each rack gear, labeled each pedal and block, then pulled the whole thing apart (again… this design will never be repeated!)

Marked Locations for Gear Area
Marked Locations for Gear Area

Ok so on to the gear and potentiometer. The Crybaby Wah pedal has the rack gear as shown earlier which marries up at a 90 degree angle to a gear on a potentiometer. I needed to find a way to mount the potentiometer, keep it from rotating, and also take a little abuse from the constant up-down action of the gear. So here is what I came up with:

Potentiometer Assembly
Potentiometer Assembly

The frame is 90 degree aluminum stock with a mounting hole and (to the right) a ‘stop hole’ for the little tab that sticks out on potentiometers. This holds the pot in place without rotation. The potentiometers were 2 inches long and here is where I got fancy. It’s hard to see in these photos but there are two problems with standard potentiometers and the Dunlop replacement parts. First, the gear has a very shallow D shape that is not common and second, there is a snap ring on the end. I don’t  know how I decided to do it this way, but before assembly I put the potentiometer in my drill press, just like it was a bit then threw the switch. Using a hacksaw I was able to cut a thin notch for the snap ring. I then raised the blade about 1/8th of an inch and cut a little deeper to score a cutoff for the post.

Once the post was cut off I then filed the rough end and while in a vise, carefully filed just enough of the rounded post off to form the shallow D to mate with the gear. Then I did that whole process over and over for the rest of the pots.

Nothing Quite Like Garage Machining
Nothing Quite Like Garage Machining

It was time to mount the potentiometer assembly. Using my marks from before I measured the space needed for the gear and 90 degree angles then knocked this out with a jigsaw:

Potentiometer Mounting Hole
Potentiometer Mounting Hole

The left side is for the pot body, the slots are for the 90 angle facing and the open area is for the gear. Using the 90 degree stock and this ‘slot’ allowed for a good bit of contact surface area and added strength.

The Potentiometer Assembly Just Slides Right In
The Potentiometer Assembly Just Slides Right In
Underside Shot Of The Rack Mated To The Gear
Underside Shot Of The Rack Mated To The Gear
All Pots In Place
All Pots In Place

After cutting then staining the board and pedals, the assemblies were screwed into place followed by remounting the pedals. Starting to look like something, isn’t it?

Assembled Pedals
Assembled Pedals

In order to hold the rack against the gear, and to keep the pedal positioned when your foot is taken off, Dunlop uses a greased wire grommet pushing up against the back of the rack. Ok… good enough for me.

Wire Grommet Mounted to Stock Aluminum
Wire Grommet Mounted to Stock Aluminum

Only three major tasks left in the construction phase.

Angled Housing Box Built Around Board
Angled Housing Box Built Around Board

I found an old modwheel while cleaning up… couldn’t resist. The handle is off an old sink. Why not? Looks great!

Mod Wheel
Mod Wheel
Footswitches Added
Footswitches Added

I added a series of footswitches for various purposes that I’ll outline later. Some momentary, some on/off. I got all the switches from AllElectronics.com. For whatever reason these footswitches vary wildly on price and All Electronics seemed to have the best deal and their site gave me the most confidence. I also got the 5 PIN din plugs and 1/4 inch jacks through them.

This is where things in this post will speed up. Wiring this beast took about 2 days and if you want to learn about that, opt for reading the manual with the board. Instead of soldering  to the ribbon cables that connected to the board I opted to use a series of terminal strips. My thinking was that I’ve never done this before and I didn’t want to have to undo alot of stuff if I made mistakes. This turned out to be a wise choice as I made about a half dozen mistakes that were easily corrected by unscrewing a few terminals and switching wires.

Wireapalooza In Effect
Wireapalooza In Effect

Some of the things to point out in my wiring:

Audio Wiring
Audio Wiring

The first pedal is an audio pedal and serves as a passive volume control. There are three audio jacks for in, out and insert in the chain. there is an a/b switch for the insert along with a master kill switch and a momentary kill switch for stutter effects or just temporarily muting the line. The exposed copper wire feeds through all the pot mounts and is grounded to the MIDI board as well. I’m currently using a pretty mismatched pot for the audio. It is degrading the signal but in a way I like. It almost gives my guitar a semi-weak vintage pickup sound. I trying to figure out a way to allow that with an upgrade potentiometer before I change it. If I need to hot-rod the guitar I currently just run it right to the audio input of the DAW.

Midi And Power Hookups
Midi And Power Hookups

Another early design decision was to put all the inputs on top of the pedalboard. I decided to also run two cropped MIDI cables to 5 Pin DIN connectors instead of mounting the board in such a way to allow direct plug in of the cables. I did this for two reasons. First, I didn’t want to break the board with general wear and tear plugging in cables and second, since multiple OEM units from the vendor can be daisy chained, this design allowed room for a second board and easy connectivity. In this show you may also be able to see the MIDI panic button near the DIN plugs. There is also a power switch just to the opt out of view.

The Final Board
The Final Board

And there you have it. One 6 month long, but worth it, ordeal. I’ll be posting some follow up videos on how the board interacts with AmpliTube 3 along with an overview of the various board functions.

Go forth and create!