MIDI Footswitch

Andy has a Line6 Bass Pod and needs to control it with his feet. He needs to be able to turn on and off three different effects. The official Line6 footswitch is no longer available but the features can be controlled via MIDI, so we need a box with footswitches that send the appropriate MIDI Control Change messages. I started with a 3D model to help with visualising where the switches should be. Having them in-line across the front of the box increases the risk of hitting switches 1 or 3 when aiming for 2, hence the offset approach.

In previous projects I used some kind of Arduino, but I fancied trying CircuitPython for this project. This has the advantage of the code being stored on the module, allowing anyone to modify it without the faff of toolchains and the relative complexity of C++.

Some requirements to start with:

• It needs to be powered from Andy's existing 9V daisy chain.
• The MIDI cable should be captive so the cable can't become separated from the footswitch, and to simplify setup.
• Each footswitch has a corresponding LED.
• It must be mechanically robust.

I happened to have a Seeed Studio XIAO RP2040, so the design is based on that. I considered hacking it together on Veroboard, but the ridiculously low cost of PCBs from JLC PCB made a custom PCB too tempting. It also makes it easy to allow for five switches and LEDs in case that's needed in a future project.

The schematic:

The XIAO can only handle 5V. The current requirement is only tens of milliamps so an old-fashioned voltage regulator is fine. Here's the final layout:

And KiCad's 3D view:

The box needs some holes:

The PCBs took about about three weeks to arrive:

Assembly:

Putting it all together:

Fully assembled:

The code is available on github.

Fuzz Pedal Remote Footswitch

At least one Zaardvark tune requires Andy to operate his fuzz pedal at more or less the same time as playing the bass pedals. The positioning of the two - about a metre apart - makes this difficult to pull off. What is needed is a remote footswitch for the fuzz pedal that can be placed very close to the bass pedals, making it much easier.

The pedal is a Boss FZ-5 and, like most Boss pedals, uses a momentary footswitch. This makes it simple to bring out the switch's contacts to a socket, allowing a remote footswitch to be connected in parallel. But it also seems useful to have an LED on the remote that confirms the pedal's on/off state. This is more difficult to achieve as you can't just connect an external LED in parallel with the internal one. A buffer circuit is needed:

LED_IN connects to the FZ-5's LED anode. When it is off, no current flows into the base of Q1, so R4 pulls the base of the U$1 to 9V, turning it off, so no current is supplied to the external led via LED_OUT. When the internal LED is on, Q1 and U$1 are turned on, supplying current to the external LED via R3.

This circuit could have been fitted on Veroboard quite easily, but I wanted to get more experience with assembling surface mounted components, and fancied the challenge of making the board as small as possible. The final layout is 17.5mm x 3.5mm:

It's double-sided and will fit inside the pedal easily, enclosed in heatshrink.

Assembly:

Connecting to the 9V supply at the power socket:

Connecting it up inside:

The remote footswitch is connected through a stereo mini-jack socket:

Done:

The remote footswitch:

Demo:

Album

We’ve made an album. It's called "Zaardvark", and if you want to hear it, it's on Bandcamp, iTunes, Amazon, Spotify, Google Play, CD Baby and all the others.

We recorded it with Matt Musial at The Burrow studio in Bournemouth. It was mastered by our long-time friend and hero, Gary Hudspith.

Here are some facts about the tracks:

Avalon Broke My Back (And I Wept)

Time signature: 9/8

Adorned with horns arranged by Dave and Andy, and played by ridiculously excellent jazzcats Ed Johnston (ts), Louisa Revolta (as) and James Lush (t), this tune made us seriously consider writing horn parts for the other tracks on the record. The outro features The Burrow's thumb piano and some eye-rollingly atonal frozen guitar chords courtesy of this. The rhythm section is augmented by overdubs of the Zaardware ZB6 and a keyboard we know as "The Brown", which is a Siel Cruise synth manufactured in Italy the early '80s. This instrument is an odd combination of a very limited monosynth and a very limited stringmachine-type polysynth. It's neither very good or desirable, but it does have its own distinctive set of sounds that we made extensive use of. I think it must have the highest switches-to-usable-sounds ratio in the history of synthesizers, but we do love it.

Mark and The Brown

Kot

Time signatures: 12/8, 9/8, 6/4, 6/8

This was developed from a very old demo which featured the sound of a close-miked bicycle wheel being run through all the effects pedals I owned (a sound that didn’t make it to the final version, sadly).
When Zaardvark first started, we had five members (the three of us, plus keyboardist Kerrie and drummer Rich), and we were called Spacecunt. We never did any gigs with that name, but we did start work on several tunes that would survive the great downsizing that saw us become Zaardvark. This video is a run through an embryonic Kot in the echoey old hall we rehearsed in. The arrangement of the recorded version has undergone extensive change, with several new sections, all derived rhythmically somehow from the 3 times table.
The outro fuzz bass (a borrowed Squier Jaguar short-scale) played by Dave standing on an amp, making rock shapes. The track fades out via an automated high-pass filter.

Kramer and pedalboards

Tiny drum kit - 16" Kick, 10" Snare, 8" hats, 10" splash

Volveau

Time signature: 5/4

A radical edit of the original 12" dance mix. Features two drum kits - a normal sized one, with each drum recorded individually to a click (like Heart of Glass), plus a tiny one played conventionally - and three basses (Jazz bass, synth bass and Zaardware ZB6). The melody was written using an audio variation of William S Burroughs’ cut-ups method, and at an early stage there was going to be guttural pseudo-singing. The dub guitar noises were made with the precision multi-fx.

Dave (L) and Matt (R) measuring for overhead mic placement.

Square Leg

Time signature: 4/4 (with the odd bar of 3)

A legacy of our Spacecunt phase, this combines a very old tune of Dave's (jammed here at great length) with a much better tune written by our friend and former keyboardist Kerrie, around which Mark devised the harmony / delay guitar line and Andy came up with the bass solo at the end. The modal noodling was done with Thumbjam, an app we downloaded to amuse the small children in our lives. The guitar 'solo' at 3:00 is mostly Moogerfooger Ring Mod on one of its gnarlier settings. In the first half Andy plays samples of Mark (more frozen guitar chords) with his feet.

Malignant Imperialism

Time signatures: 5/8, 6/8, 10/4

This probably should have had horns, but has skronky guitar, stylophone ensemble and The Brown instead. The initial groove/riff was the result of a challenge Andy set himself to see if he could come up with something that would confuse his band mates but still sound good, and once we'd eventually gotten our heads around it, the tune was developed into our proper first three-way collaboration. The repeated vocal sample is a choir of Andys (played on the organ pedals), the breakdown has a chord sung by a small choir of Daves, and the end section has the three of us singing joined by Catherine and Tiff, who could reach the notes we couldn’t. This is another tune where Andy triggers samples of sounds pre-recorded by Mark. Old footage of early development efforts can be "enjoyed" here.

Andy cheating by using his hands to play the organ pedals.

Psychic Roundabout

Time signature: 3/8

This is electronically varisped so that it very gradually gets higher and faster from start to finish. The ascending guitar line 30s in is a Moogerfooger FreqBox set to track the guitar note, but with a pleasing level of incompetence.

Dave overdubbing with Matt's Jazzuar.

Elfmeter

Time signature: 11/8

Andy plays some lovely Hohner Electra Piano on this. When we perform this live Mark uses a 17-second delay to play the guitar part in canon with himself. The guitar 'birds' at 3:08 were created by driving a Moogerfooger Lowpass Filter pedal's frequency and resonance controls from noise sources built into the Pedalboard Controller.

This Steinberger baritone didn't work out and went back to the shop.

Planet Of The Plastic Miners

Time signature: 4/4

One day our descendants will be employed to dig through our rubbish to recover plastic we threw away when it seemed the oil would never run out. Again, this really should have had horns on the big unison riff. All three of us are playing guitar on this one. The guitar sound at 2:54 is a combination of the LPF and RingMod 'foogers, with the LPF's envelope output driving the ring mod's frequency control input. Then from 3:01 an expression pedal is used to ramp up the wet/dry blend of the ring mod to increase the unpleasantness. Dave recorded some rhythmic mining noises for this, but they sounded a bit too Seven Dwarvesy, so they weren’t used.
This tune was the only one we recorded twice - our first attempt wasn't up to scratch, so we started again. The new version fixed the issues we had with the first one, but the original had noises in the introduction that we really liked, so producer Matt got out the digital razorblade and splicing tape and made the old intro fit.

By the final drum session, we had a much bigger kit.

Hammo

Time signatures: 9/4, 4/4, 5/4

Having evolved from a jam between Dave and Andy when Mark was ill and unable to make rehearsal, this came out as a sort of Turkish reggaeton. Features flourishes from a Yamaha FS1R synth, along with synth guitar, synth bass and synth snare drum. And a mellotron brass sample played on the organ pedals. Our tunes have no singing, so we don’t call the sections things like “verse” or “chorus”. Instead, they have names like "The Scrunges", “Slidy fantasia”, "WWJMD?", and in this case “Gary Numan”,“Barry Puman” and "Slack Puman". The melody at 0:50 is a Pigtronix Mothership guitar synth sounding much cleaner and more controlled than it is in real life. It's a twitchy beast.

Mark prepares to double a guitar part with The Burrow's P-bass.

Transmission de Valerie

Time signatures: 7/4, 4/4

Comme la musique d'un Neo-noir drama. Banjo et mandoline, FS1-R et multi-fx de haute precision. En anglais:
the sustained guitar chords were produced by a combination of EHX Freeze pedal and EHX Pitch Fork, with the pitch control being modulated by a slow LFO from the Pedalboard Controller. The aim was to induce an uneasy, slightly queasy feeling in the listener. This is the one track where the ZB6 is used as a conventional bass - elsewhere (e.g. Avalon and Volveau) it's played in its higher registers, palm-muted, with a plectrum and with the pickups out-of-phase.

Learning the banjitar part for "Valerie"

We can't remember what this represents. It might be a guide to comp together takes of something.

Andy's Bass VI

Dave tracking vocals.

Some drums.

Can't remember which track we tried this on - it didn't make it to the final mix.

An Alden Quadrastar and various lesser instruments.

Bass 6 Conversion #2: Longscale.

A few years ago (just before Fender released the Squier VM Bass VI) I converted a cheap copy of a Gibson EB-3 into a short-scale (30" / 762mm) 6-string bass. I wrote this about the process.

I've been really pleased with the instrument, and have used it for various overdubs on the recently completed Zaardvark album alongside Andy's Squier VI, but since putting it together I've had a nagging curiosity about how a longer-scale (34") version of this instrument would work. The few commercially available Bass VI-type instruments (Fender, Eastwood, Burns, Schecter, Revelation etc) are all short-scale, but I don't know whether that's due to ergonomic considerations, or because of the underlying physics. I did wonder if perhaps strings that long would start colliding with one another when vibrating if six were squeezed together onto a neck designed for four.

With this in mind I thought initially that it a 5-string bass would make a better candidate for conversion, but I had a chat with Andy about it, and he reckoned that the tight string spacing was part of the unique appeal of the Bass VI, so I decided that I would at least try to convert a 4-string neck. It would have to be at least as wide at the nut as the Fender VI (42mm), so if I was going to stick with Fender-derived models I'd be looking for a Precision bass rather than a Jazz as my test subject, and given that I wasn't sure I'd end up with a usable instrument it would have to be very inexpensive. I started watching eBay and Gumtree for something suitable.

In the meantime, I started thinking about the work that would be required. I remembered this thread from the Offset Guitars forum, where user rainbowdoom showed how he'd re-shaped the headstock of a Fender Bronco bass as part of a VI conversion. The re-shaping was necessary in order to get the six guitar-sized tuners into positions where the strings wouldn't be pulled through the nut at a crazy angle - Shortscale.org user Matthew K gives a good explaination of the problem in this thread, and also links to this handy graphic:

With this in mind, I found pdf scale drawings of various Fender guitar headstocks, and started overlaying them on a Precision Bass head to see which shape would be easiest to achieve. The closest fit was a pre-CBS Strat headstock, shown below in blue.

As you can see, whilst there is a surplus of wood available in the P-Bass headstock, not all of it is where I would like it to be. I figured that if I cut off a section of the head (shown in green) and re-attached it closer to the bridge there should be enough timber in the right places. 

According to Photoshop, it should just about work. There would still be a small area on the treble side of the head where there wouldn't be enough wood to follow the Strat shape faithfully (indicated below), but this section would be contoured at the rear, so attaching additional wood wouldn't be an option. 

What I eventually ended up with was this:

I printed it out onto card, double-checked the scale by measuring the nut width, trimmed it down...

...and glued it to a sheet of 6mm MDF, using the existing straight edge of the material to make my work cutting it out a little easier.

To assist with the template cut-out I made a sanding drum, and a work table with a corresponding cut-out. It even has dust-extraction, courtesy of an old Dyson.

At this point a suitable donor bass appeared on Gumtree - a Precision copy by Westfield. It looked okay and it was very cheap.

I dismantled the bass, to discover that not only was the body made of plywood, but the neck pocket looked like this:

Not good. But the neck itself felt pretty good. I took off the tuners, and drilled the holes slightly larger to fit some dowel I had left over from another project. I cut the plugs much longer than required so I could manipulate them with mole grips without damaging the wood that would be going into the holes.

I offered up a replacement nut I'd bought - the spacing and width were good, but it was a couple of mm too shallow. Another approach would be required.

Whilst waiting for the glue to cure, I cut and sanded the MDF headstock template to shape.

I also made a prototype bridge combining the P-Bass plate with Strat saddles. I could have used a hard-tail Strat bridge here, but the overall string spacing would have been too narrow, which would have resulted in the strings being pulled across the radius of the fretboard, making a decent setup difficult - the action would have to be pretty high to stop the strings choking.

With the glue cured, I trimmed the plugs flush.

And then sanded front and back.

Here's a paper headstock template showing how the knob at the top of the head will have to be moved bridgewards.

Not having a table saw, and it being critical to get this cut dead straight and square I clamped a straight edge in place to use as a guide for my oscillating saw.

With the cut made successfully, I used the paper template to position the off-cut section.

Using some more pieces of dowel and a workmate I made a jig to clamp the headstock for re-attachment.

With the glue cured, it looked like this:

At this point, Gumtree provided again. I wasn't keen on re-using the plywood P-Bass body, and a Jazz body / pickup configuration would have been my first choice, so when a sunburst Jazz copy came up locally for very little money I pounced on it. 

On examination, it turned out that this bass actually had a 42mm width nut, as opposed to the 39mm that a Jazz would normally have. This gave me cause for pause, as it might have been better at this point to abandon the P-neck and instead re-shape the new neck. I decided to stick with the first neck for the following reasons;

• I'd already done several days work.
• I preferred the feel of the first neck - the one on the 'burst was chunkier than I like.
• If I messed up the first neck, I'd still have the other one for a second attempt.

So, back to the P Bass neck! I taped a paper template to the front of the headstock, and drilled two pilot holes for the low E and B tuners.

I drilled corresponding holes in the MDF template, and screwed it to the back of the headstock. 

I trimmed the headstock roughly to shape with a saw so the router wouldn't have too much work to do.

I wasn't 100% confident that the glue joint in the headstock would withstand the stresses of routing, so I drilled a couple of 6mm holes through the grafted section into the main part of the head and glued in dowels to strengthen the joint. I forgot to take any pictures of this step, but the dowels can be seen in later images.

I ran the router around with a flush-cut bit, and ended up with this:

As you can see below, the router bit dug in a bit too much at the boundary of the hard maple and the softer dowels plugging the old tuner holes, resulting in a pretty rough edge. Filler and veneer would be required to make this good. New tuner holes have been drilled.

Some maple veneer was obtained, and front and back pieces were cut roughly to shape using the MDF template as a guide. A cut-off strip would also be used to cover the top edge of the headstock.

The old screw holes and sundry imperfections were filled and sanded flush. In the picture below you may be able to make out the 6mm dowels I put in to re-enforce the graft before routing.

The strip along the top edge was fitted first.

Next, the piece on the reverse of the head was glued on.

When the glue set, it was trimmed and sanded to shape, and the tuner holes gently opened up with a small grinder bit in a Dremmel-ish rotary tool.

Finally the front piece was attached. This was the trickiest veneer to affix, as it required heating with steam in order to bend it to the contours of the head around the truss-rod adjuster, and I had to make a clamping block which matched those contours in order to apply even pressure when gluing it up. Unfortunately you can't really make it out in this picture due to the many clamps.

When all was set, I trimmed it and opened up the tuner holes as I had on the back. I also had to open up the hole for the truss-rod adjuster.

I test-fitted the tuners...

...and began to get an idea of what the finished article would look like.

I decided to use the existing nut rather than wait for a blank to be delivered, so I masked off both sides with tape and filled the existing slots with two-part epoxy. 

Whilst I was waiting for this to harden I turned my attention back to the bridge.  I made a new plate for the saddles to anchor to, and bolted it to the existing bridge plate using the holes which had previously been the anchor points for the A and D strings. Next I made a template with the computer which showed me where to drill holes in the bridge for through-body stringing.

These are at an angle (estimated by measuring other basses) to compensate for decreasing string gauge and hopefully allow for correct intonation.

And here is the new bridge assembled and installed.

A six-string bridge and a six-string head:

I was at the stage now where the neck could be attached. The neck pocket on the J body was slightly wider than that on the P, so a couple of brass shims were added to make it snug. You can probably make out the one on the bass side of the pocket in the photo below.

The now-filled nut, marked up ready to cut the new slots. You can see here that the veneer around the end of the fingerboard is looking a bit ragged. If the bass functions as I hope I'll sort this out when I come to refinish the neck.

The first string goes on...

And here it is fully assembled. The strings are a real mixed bag: The E, A & D were on the sunburst bass when I got it, but the E was clearly a replacement as it didn't match the other two. The D, G and high E are taken from a 30 " Kalium Bass VI set. Unfortunately the lower three strings from this set wouldn't fit because they started to taper down before they passed through the nut. As luck would have it I'd kept the old strings, and they seemed to be in almost new condition so they were a good match tonally for the Kaliums. Overall the gauges are approximately .023-.100.

I had planned to fit at least one string tree for the B and E, but with the strings on there was more than ample tension to keep them all in place without one, so I didn't bother.

You might be able to tell in the picture below that the string spacing is slightly off on the bottom three strings. This is because the epoxy in the nut wasn't quite as hard as I'd thought, and the E and D strings had been slowly pushing it aside and following instead the underlying E and A slots. When the concept has been proved I'll get a bone or Tusq blank and make a proper nut. I'm going to space it for equal gaps between the strings, rather than equal centres, which will hopefully make things a bit less crowded at the bottom end.

Pickups and wiring are stock for the time being, but this will probably change at a later date as the pole-piece spacing is now off, to the point where the A and B strings are slightly quieter than the others. I might get some rail-type pickups, or I might try introducing additional pole-pieces to the existing pups - if they're ceramic types I might be able to squeeze some more in.

Circuit-wise I originally envisaged having three pickups, with on-off-on DPDT switches for in- and out-of-phase sounds, but having played it through a couple of amps I'm pretty happy with the range of available tones. What I may do at some point is replace one of the volume controls with a push-pull pot to invert the phase of one of the pickups, and maybe another controlling a Jaguar-style strangle circuit. That will give a broad range of sounds without having any extra toggle switches cluttering the layout.

Next to Andy Zaardvark's Squier VI, for comparison.

I was surprised to find that they're pretty much exactly the same size - the Jazz VI feels much larger when you're playing it due to the wider fret-spacing.

Andy trying it out in rehearsal. It hadn't been set up at this point - I just wanted to hear it through a bass amp and get some feedback from Andy. Initial impressions were that it sounded awesome (growly, but tight in the bottom end and clear and defined up high), but was very hard work to play in comparison to the Squier.

UPDATE AUG 2017:

 

Having lived with the big VI for a few months, I overhauled it, making the following changes:

 Neck - I made a bone nut to replace the plastic/epoxy stopgap. The only blank my local music shop had in stock was a huge one for a classical guitar bridge, so this took a lot of work and smelled absolutely terrible. It's a huge improvement, so worth the time and effort.

I also sanded the remainder of the original finish off the neck and left it as bare wood, just because I prefer the feel.

 

Bridge - I  came to realise that I'd miscalculated the ideal position for the string-through holes in the bridge and body, meaning that I didn't have quite enough travel in the saddles to get all the strings correctly intonated. To fix this I made a new bridge plate from steel angle with the string-through holes further from the neck. The original holes through the body had been enlarged at the back to accomodate washers which served as ferrules to anchor the string ends. These were plugged with hickory cut from broken drumsticks, and new holes drilled to match the new bridge. The back of the guitar looked pretty horrible after this remedial surgery, so I covered it over with the tremolo cavity plate from a strat.

I also attempted to make some brass saddles of the correct width for the wider-than-a-Strat string spacing, but the tools I have weren't of a high enough tolerance to produce a satisfactory result.

Pickups - the original Jazz pickups didn't sound bad, but the poor alignment of strings and pole-pieces meant the output level was very inconsistent. I also had a hankering to install a third pickup in the neck position, so I started experimenting with some cheapo ceramic strat pickups I had floating around. After a while I'd assembled a mixed bag of pickups with the correct impedances and pole spacings to do what I needed. I routed a new cavity and cable channel for the neck pickup, and made a new pickguard with holes of the right size and shape. The neck and middle pickups have flat black covers, partly as a nod to the Fender Mustang, and partly because they didn't match that closely. The bridge pickup is a hot rails knock-off, mounted in a piece of 3-ply plastic that I shaped to vaguely resemble a Jaguar / Bass VI switch plate.

Electronics - the circuit is very similar to the standard Jazz wiring, just with another pickup i.e. 3 volume controls and a master tone. The neck and middle pickups have push-pull volume pots that invert the phase when pulled out, meaning that any phase combination of the three pickups is possible. I was thinking about also having push-pulls on the bridge volume and tone controls for coil tap and low-cut respectively, but I didn't have the parts on hand when I assembled the circuit and I don't think I'd really gain much by adding them retrospectively. The phase options available offer a variety of thinned-out, twangy sounds already.

The output jack was relocated to the edge of the body, and in order to accommodate the push-pull pots the control plate had to be raised up slightly on a gasket made of recycled scratchplate plastic.

Everything got shielded with aluminium tape, and I discovered that it also makes a great material for shimming necks if layered up - much more precise than the brass I used previously.

I think it's just about finished now, there are some further refinements to make (saddles and pickups custom made to suit the non-standard string spacing) but this instrument is fully functional in its current form.

And I've started work on the next one!