Sunday, 12 September 2021

Repairing a Vintage Expression Pedal

I've had my Casio VP-E Volume Pedal (which also works as an Expression pedal) for what is probably well over 30 years. So I wasn't hugely surprised when it started to get a bit noisy. Now it is very robustly constructed, with lots of aluminium extrusion, and it is a classic mechanical foot pedal, so it seems as if it would be a very good candidate for trying to fix - probably by replacing the potentiometer inside.

There are quite a few designs of foot pedal, ranging from simple passive mechanical designs (with levers or gears) through to sophisticated active electro-optical or magnetic circuits. The Casio VP-E wasn't crazily expensive when I bought it (to go with a Casio CT-1000, if memory serves me...), and you can see a white plastic lever when you move the top plate of the pedal, so it looked like it was a straightforward mechanical design.

Opening the VP-E is easy - there are three self-tapping screws that hold the metal end-cheek in place. 

Self-tapping screws into aluminium extrusions was a standard way of making guitar pedals back in the 70s -  I can remember a Carlsbro Flanger pedal built exactly that way from the late 1970s the was built that way. Not exactly an EHX Electric Mistress, but I'm sure it was cheaper... You can see one of the Carlsbro Flange pedals here...  and (closer up) in this eBay advert (over $600!), although it will probably be gone by the time you read this... and here (from an effects database)... It's interesting to see that the Carlsbro pedal is now worth more than the CT-1000, although the Casio was a very early 'almost a synth' from Casio, but only two and a half years before the CZ-101 et al, which were definitely synthesisers! 

So here's the mechanical arrangement. A bent (probably white (natural) nylon) lever, with a pivot underneath the foot plate on the top of the pedal, a second pivot close to the potentiometer, and result is that the potentiometer rotates a lot more than the foot plate. The 15 or so degrees of rotation of the foot plate is converted to something like 130 degrees of the 200 or more in the potentiometer. There are designs with gears that can do more, but this design is robust and has lasted decades for me so far. 

It all looked very straight-forward, and so would be easy to fix myself. Remember that I've been doing this stuff for decades, so I have lots of experience. If you aren't sure, then go to an authorised, approved, qualified repairer or service centre and get a quote for what you want doing... Keep safe and carry on!

The short black piece of plastic (at the end of the white lever) is wrapped around the potentiometer shaft and tightened with a grub screw. Loosening this screw allows the lever to be moved out of the way. 

Yep, as suspected, it is just an ordinary (for the 1970s or 80s) potentiometer - and easy to replace. 

Now that it is exposed, the potentiometer nut can then be removed and the potentiometer unsoldered. Note how the wires are connected to it - take a photo with your mobile phone!

It is a 47 kOhm Logarithmic pot (short for 'potentiometer' - can't think why anyone would want to shorten that word!), indicated by the 47K and LogB labelling. European pots of this vintage are usually marked A for linear, and B for log, which is different to the rest of the world, where A often means log, B linear, and C anti-log. 

Linear means that the output of the pot changes as you might expect when the shaft is rotated, so it outputs half when half way round. A logarithmic pot doesn't do this - some things just aren't linear. one example might be a frequency control - human beings hear octaves when a frequency is doubled, so if you had a linear pot, then going from 110m to 220 Hertz would be fine, but the next octave up is 440 Hertz (A3 or 4, and that's another story), and the next one is 880 Hertz, and the 1760 Hz. So if we used a linear pot to set frequency, then the low octaves would all be squashed up at one end, and the high octaves would be widely separated at the other end. A log pot would space the octaves out evenly as you rotated it.

Even though the intention is to get a control voltage from our expression pedal, the lever doesn't convert the rotation of the foot plate into rotation of the potentiometer shaft perfectly linearly, and so a log pot is used to give a 'compromise' that feels okay when you use it. Some high-end optical or magnetic expression or volume pedals have a much better relationship between the foot pedal movement and the output, but then they don't have pots inside...

If you feel like becoming a scientist, then you could try plotting the output of the pedal against the foot plate rotation. It ought to be linear-ish. Here's what I found with some of my 'basic' expression pedals:

I should point out here that I don't calibrate my expression pedals, and this is the first time that I've done any comparison process. I'm now wondering if I should do some work on getting them more closely aligned / linearised, although I don't use them interchangeably - they are each usually assigned to a specific role with a particular guitar pedal or synth. I haven't included my Yamaha FC-7 pedals because they are only ever used with my SY99 and Montage. If I was to try and align the pedals detailed here, then that would probably require some custom hardware and software, and that could easily turn into something expensive and time-consuming. I have worked on International Standards (I was one of the Editors of an ISO-MPEG standard...) and I'm not aware of a formal standard for expression pedals - but there are definitely two different ways of using the Tip and Ring connections. As always, my advice would be to use the expression pedal that is recommended by the manufacturer of what you are plugging the expression pedal into. So for my Yamaha synths, then that is the FC-7. 

There are other types of resistance law as well, with various special audio tapers that are found in some amplifiers. If in doubt, then measuring the end-to-end resistance with a multimeter and then plotting the resistance from one end to the wiper, will quickly show if it is linear or logarithmic (or something else!).

There are several different types of potentiometer that are available: ranging from the expensive Cermet track material that has good thermal characteristics, through more modern 'plastic' materials, and finally to the cheap carbon tracks of ordinary 'basic' potentiometers. There are wire wound pots, but these are coarse and noisy, and would not be my first choice for a pedal. rapidly provided a replacement pot, and this was quickly fitted. Well, I say quickly, but the soldering to the pot was very much 'old school' soldering, maybe from a person used to valve circuitry, because the wires were threaded through the holes in the three terminals tags, then wound around and soldered. This sort of arrangement doesn't fall off, even when all the solder is melted. Pulling at the wire, especially with molten solder present, isn't very good at removing the wire either - and it can spray molten solder everywhere. One effective technique is to cut the wire with cutters, close to the tag, and then to remove the remaining copper wire and use a solder sucker to clean it all up.

(One thing that the InterWeb has revealed to me is that the British pronunciation of 'solder' says the 'L', as in 'sole' 'duh', whereas the US pronunciation drops the 'L', as in 'sodder'.) 

When replacing old pots, then don't forget that pots from the 70s will probably have 1/4 inch shafts (6.35mm), whereas modern pots are more probably going to be 6mm or even smaller in diameter...

Once the old pot was out, the replacement potentiometer shaft was cut to length, was soldered to the cable, was securely fastened in place with the star washer and the nut, and the lever and grub screw were tightened again to grab the pot shaft. Finally the end-cheeks were put back and the pedal tested with the multimeter again. The pot measured 50k as expected (tip to sleeve), and the wiper (ring) to ground (sleeve) varied from 28.9k to 2.2k. Not perfect for a volume pedal, but fine for CV/Expression use... and I could always adjust the angle of the pot shaft if I needed to...

I did contemplate buying a dual-gang pot so that I could have two separate outputs, but decided, based on the astonishing price of the decade-older Carlsbro Flanger pedal, that it would be better to leave it unmodified. 

I now have a slightly smoother and less noisy Volume/Expression pedal!

Theory - Expression Pedals

Expression pedals, and in fact, any foot pedal that provides a Control Voltage that is used to control Expression or Volume in an electronic musical instrument, all tend to have similar designs, particularly at the budget end of the market. Although note that there are at least two different (and incompatible) ways to wire up the stereo jack plug (OK, the balanced jack plug commonly known as a 'stereo' jack), and specifically note that higher-end pedals might well have very different circuits and pin-outs because they use electro-optical or magnetic foot-plate rotation sensing methods. 

Of course, you should always use the Expression pedal recommended by the manufacturer of the guitar pedal or instrument that you will be connecting the expression pedal to... but if there isn't a specific recommendation...

The circuit is very simple. The potentiometer (the fancy word for the electric component that a Roary control or Knob adjusts) has a voltage at one end, and ground at the other. The 'Wiper' then outputs a voltage between the voltage and ground, depending upon how mucho it has been rotated. At one extreme of rotation it will be the voltage, whilst at the other it will be ground. Most volume/expression pedals do not rotate the potentiometer through its full 300-ish degrees of rotation, and so the output never actually reaches the full range from voltage to ground. 

As a side note, this is why many guitar pedals get you to use your Expression pedal when you set up the knobs that are going to be controlled by the expression pedal. By getting you to set the expression pedal to the two extremes (Toe and Heel positions) and then set the knobs where you want them for each extreme, then the guitar pedal knows exactly what the range of control voltages from the expression pedal are...

Some pedals have a switch that swap the ring and tip connections, so that the two main variations are covered. Most of my equipment seems to have the ring as the CV/Wiper connection, the sleeve as the Ground connection, and the Tip as the positive Voltage connection (which can vary from 3.3V (or lower) to 5V, depending on what it is powered from... As always, if you rewire anything, then you do so at your own risk. 

Anyway, the 'swap' circuit uses a DPDT switch (Double Pole, Double Throw) and the circuit looks complex when the two positions are shown (above). The DPDT switch has two 'Either/Or' switches: so One input and Two Output (of which only one can be connected to the Input at any time). But if you think about how you would actually solder the wires to the DPDT switch itself, then the wiring is lots simpler - the input is on one side, the output is in the middle, with a pair of wires crossing over to give the 'swap' function. And that's it. Drawing the circuit out in full kind of makes it look more complex than the actuality.

I didn't add a switch to the Casio VP-E pedal, and I didn't add in the missing series resistor between the potentiometer and the CV point. I decided to keep the pedal 'as supplied'. If I was being technical, then my defence would be that the cable and the plug/socket have some inherent resistance, and so I would must be adding a bit extra.

Modding / Customisation Warning

Of course, you should always use the Expression pedal recommended by the manufacturer of the guitar pedal or instrument that you will be connecting the expression pedal to...  Also, if you modify / change / rewire anything, then you do so at your own risk. If you are not confident of your ability (or your equipment is still covered by a warranty or guarantee) then you should go to an approved, qualified repairer or service centre for any repairs, modifications or customisations. Safe, not sorry, is the correct attitude to have.


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Sunday, 29 August 2021

How do you do a video for people who have just bought a complex piece of technology?

Okay. So you've spent ages reading and watching everything you can about that amazing bit of hi-tech gear that you've wanted for ages. You finally manage to get enough money together to buy it, and you go through the hell of going to the web-site of your favourite supplier, adding it to your basket, filling in all your details, and checking out - very aware this is a lot of your real money. Then there's the awful wait whilst it is travelling to you, and the agonising wait for the courier to deliver it. And then the unboxing...

And here you are. New item on the table. However, unlike those confident reviewers who persuaded you to buy it with all of their amazing knowledge and demos and tips, this is all really and totally new to you. You don't know what to do, how to connect it up, where the web-site is, how you turn it on, what you do first, and it is very SCARY!

What you need is a video that is the exact opposite of the detailed, complex video review that impressed you with how amazing the gear was. What you need now is something that starts simple, and stays simple. Doing the basic things like connections, power up, web-site navigation, and what to do first. Reviewers never show you these things - because to them it is all obvious. But this is your new bit of gear, and you have no idea where to start!

Here is the 'First Time' video that I did for Rebel Technology's Witch polyphonic synthesizer (and more) module:

It is deliberately not a review (although you can see my review here...). it sets out to show you how to make the audio connections, what web-site to visit to use the Witch, how to connect the Witch to a computer, how to use the web-site, how to select a patch, how to change volume, how to control patches, and essentially get you started for that first time.

Hi-tech music gear these days is often very complex, has lots of functionality, requires a computer to get the most out of it, and this can all be overwhelming. What this video aims to do is to be an antidote to all of that mountain of 'stuff', and instead, to provide a simple introduction. Once you've got the hang of the Witch, then you may never watch this video again, but for that first time, when you have no idea where to start at all, then this is the 'first' video. 


Whilst this video is very specific to the Rebel Technology Witch, the principles behind what is inside the video are very universal. Lots of hi-tech music gear comes in a box without a manual (you are expected to print that out), and often without any 'Getting Started' sheet, or even a URL so you know what web-site to go to... I have become very aware of this 'minimalist' trend, and this video is my attempt to provide an example of an alternative - a video that helps new users with those first few tentative steps. The idea is that the box just needs to have a small piece of paper with the URL for the video printed on it. 

And that's it. Expensive, complex and deep are all very daunting things to get in a package - and there's a lot of self-imposed (and external) pressure for you to become proficient very quickly and without any obvious effort. The reality is often not quite as easy. Life isn't a movie where a quick montage of shots of you looking and learning will turn you into an expert in a few seconds. Real life can be messier, slower, and definitely requires effort. This type of video aims to reduce some of the stress of that 'First Time', and to ease you into getting proficient with that amazing piece of hi-tech gadgetry that you have bought!

---    - THE page to visit!   -  The 'First' video (as described here!) - Product stuff - Unboxing

#rebeltechwitch. - the hashtag


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Tuesday, 3 August 2021

What is 'Bathroom Door'?

I have gradually been ascending the learning curve for the amazing Decent Sampler, from the multi-talented composer, musician and programmer: Dave Hilowitz ( @dhilowitz ). My most recent Virtual Instrument published on Christian Henson's is called 'Bathroom Door', and it looks like this:

The 'Bathroom Door' virtual instrument in Decent Sampler

There's quite a lot going on there, so this blog post is effectively going to be the User Manual for it.

Bathroom Door

The name comes from a squeaky handle on the bathroom door, which is probably disappointingly mundane. I captured this (at some stage I really must get a Zoom recorder, but until then I'm using a modified mobile phone to implement a trick that I discovered back in the 1970s...) in stereo and then did some processing in Audacity. Yes, Audacity, and you can see why here - I am rarely impressed by media over-reactions, and the world does seem to now be driven by a huge amount of almost always unwarranted outrage. Also, that computer isn't connected to the InterWeb, and only gets updates of data via USB memory sticks (with some automatic scanning and stuff...).

Processing of audio falls into a small number of types, in my personal categorisation schema. There are the basic tools, like Audacity, then 'Plug-In' hosting tools, like Element (et al) and DAWs, which let you use VSTs and other plug-ins, and then there are the high-end editors, processors, repairers and even mastering tools, like DSP-Quattro, Pro Tools, iZotope RX8 and many more. I have example applications from each of these main categories, and I try to avoid too much duplication of functionality... But Audacity is home to some of my Nyquist plug-ins, and I really must get around to updating them to the latest version of Nyquist...

Anyway, the basic technique that I use for processing samples tends to be noise reduction, followed by Paulstretching or granular processing, looping (usually long cross-fades), and probably too much normalisation.  Actually, a lot of the major 'processing' happens inside Decent Sampler...

The User Interface

I am happy to admit that before I started using Native Instruments' Kontakt, and in particular, the Spitfire Audio sample libraries, I wasn't very familiar with the idea of 'Mic' sliders or mixers. I learned synthesis on real analogue, dual VCO, 'Moog' ladder-type VCF monosynths, where the source mixing was limited to the two VCOs and the noise source. So all of the top row of 'Bathroom Door', and the left hand side of the second row, wouldn't have made much sense to me. I was never a fan of the ARP Pro-Soloist type of UI whert you had a row of switches to select a sound, and I know that it was popular back in the late 70s. 

Now that I have spent more time programming virtual instruments, I'm beginning to see some of the appeal of having direct control over the sounds from many sources. Compared to the usual 'subtractive synth' technique of 'fix it with processing', this is the exact opposite (and more akin to mixing) - 'start with the right sources'. 

The Top Row Mic Sliders 

This is where you mix the main sources of tone and timbre. From left to right, you have Tones, then Clicks in the middle, then Noise on the right. 

[ Tone ]

On the left, the 'Tone' set of mic sliders are the pitched 'melodic' part of the final sound, and the main part of the pitched timbre - Feel free to mix the four sounds - these are not ON/Off buttons for a reason! 

[ Noise ]

On the right, the 'Noise' set of mic sliders are there to provide background 'fill', and this can affect the perceived timbre quite a lot. There's a fascinating psycho-acoustic phenomenon where your ears will assume that noise in a sound must be associated with the pitched portions of it, and will associate the two together. If you add noise to sawtooth 'string' sounds, then the strings sound brighter - and kind of less synthetic / more realistic! So don't be afraid to try mixing in a little bit of grit, dort, grundge...noise.

[ Clicks ]

In the middle, the 'Clicks' set of mic sliders are quasi-rhythmic loops of background textures that give a sort of 'evolving or moving' pad feel to the overall sound. As is often the case with this type of 'extra' element to a sound, you do not need very much volume to get the right balance of pitched sound and supporting movement. These definitely are not intended to be the loudest and most obvious part of the final sound! Subtlety is your friend here. 

The Extra Mic Sliders

On the second row, are five extra mic sliders. These are just little bits of extra tonality to add a bit of spice to the main 'top row' mic sliders. 

[ Detune ]

The 'Detune' set of mic sliders are just deliberately detuned versions of the 4 'Tone' sliders that are directly above them vertically. One obvious thing to do is to just raise the same Detune mic slider as the main Tone mic slider that you have above it. But there are no rules! - There's nothing to stop you using different Detunes to your Tones!

[ Fab ] 

Just a little bit of fun, this is the exact opposite of putting effects after a synth or sampler - it puts a phasing effect into the source mix! The phaser is deliberately 1970s in feel, and can either add a little bit of subtle movement to the final timbre, or can be over-used to swamp the sound in washiness. Or places in between - you choose.

The Processors

There's always a temptation to add too many processors. More rotary controls is better, yes?

But sometimes, less is more. This isn't meant to be a full synthesizer - note the name: Decent Sampler. (Not 'Decent Synthesizer'!) And samplers have different UI design rules - lots of controls are definitely too many. So I've deliberately kept to a minimalistic set: 

Attack and Release to control the start and end of notes (and slow versus fast 'Attack' settings can change the feel of a sound quite remarkably, which is often overlooked in a world full of patches with appealing names...).  

Tone (Low-pass filter cutoff frequency) and Q (Resonance) for setting the brightness of the sound, or rolling the top end off. The cutoff frequency is mapped to the Mod Wheel and MIDI CC 1 as well. I'm still trying to get my head around the <midi> section of Decent Sampler's .dspreset XML file, and so Expression (CC 11) and other MIDI controllers are still in the pipeline for a future version. 

Size and Reverb complete the processing section. Room size is an interesting control - just about everyone starts out with it on biggest, and gradually learns that smaller can be better, depending on the timbre. The Reverb rotary control is the Wet/Dry mix (Do not put a string reverb into water!) and again suffers from the 'more must be better' syndrome. This is only true in Demos and (maybe) in Christian Henson YouTube videos! 

Using It

'Bathroom Door' isn't a 'single sound' type of virtual instrument. It can provide unusual leads for melodies or counterpoints, as well as background pads, plus there's a lot of scope for atmospheric fills and effects. It got a 5 Star review on where the reviewer seemed to like it, and said that it was well suited to Pierre Henri material and ambient music.

Getting It

'Bathroom Door' can be downloaded, for free, from


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Thursday, 29 July 2021

Rebel Technology's Witch

I'm going to start by talking about an older product, but so that I get a picture of the new product on the Interweb, then I have to include it here, first. So here is: The Rebel Technology Witch:

The Rebel Technology Witch

I've mentioned Rebel Technology before... I like their open hardware, open source, 'open' approach to making synthesis and audio processing devices, and so I bought an OWL effects pedal from them, added a footswitch (one of the advantages of making technology open is that you can easily get the circuit diagrams, and other technical design details!), wrote some Gen patches for it, and generally loved it. OWL1  OWL2 I still do!

Rebel Technology's OWL Pedal

(In a world where guitar pedals continually try to out-do each other with eye-catching designs, the OWL still managed to be spectacularly bold! IMHO)  

So, here we are, a few years later, and Rebel Technology asked me to help them with beta testing of a forthcoming new device! I was overjoyed, of course, because it was like several generic mid-December festivals/holidays all at once! In those years, of course, things have changed a lot, except, in this case, the size of the device, and the Gen programmability (plus lots of other programming languages!). So, here's the device for which I have been one of the beta testers... The Rebel Technology Witch... (and that picture again!)

Rebel Technology's Witch

As you can see, the influences for the Witch are very different to the OWL. There are bits of Eurorack (the 3.5mm patching jacks), bits of desktop synths (the knobs and the four buttons), and modern MIDI design (USB host socket, USB socket for WebMIDI).

What you can't see are polyphony, versatility, MPE, a Class Compliant Audio Interface and lots more. Although some of the OWL patches will run on a Witch, there's more processing power and broader capabilities in the Witch. There's also lots more detail about the Witch on the Rebel Technology web-page:  Pre-built and kits...


In a world where programmability is rapidly becoming the norm, how do you design something new and different? The Witch is a perfect example of one way to go in a very different direction, by combining programmability with patching, and mixing up bits of modular synth flexibility with desktop accessibility. The first break from tradition is those patch sockets. You are probably expecting them to be for just hooking the Witch to a Eurorack modular system, and you would be half correct. But those sockets are also outputs for the internal LFOs (or envelope followers, or whatever else you program them to do), and those sockets next to the buttons control the buttons - with the buttons controlling functions inside the software running on the Witch. So a button might trigger a note, or sustain a note, or change the audio routing so that the sound goes through a filter, or through an audio effect, or change the algorithm used for an audio processing algorithm, or tap-tempo for an LFO, or a gate, or... (whatever can be programmed...)

And whatever the button does, you can activate it using the associated socket. The four main rotary controls also have jack sockets inputs as well, and so you can control them via patching as well. Actually, you can use them as Offsets, or as CV Attenuators, because there's a tiny black 'Mode' button right in the centre that provides extra control over what does what. 

So you can patch the Witch itself, using its own sockets - an LFO might be connected to control the time of a delay, or the frequency of an oscillator, or the cutoff frequency or a filter. Or an envelope might be used to control the delay time of an echo, or anything else. But here's the really interesting bit - the CV output and gate sockets are programmable as well, so whilst the factory synthesis patches have LFOs assigned to those four red sockets, there's nothing that stops a programmer assigning them to other purposes. One of my (coming soon) patches outputs an envelope follower, for example. So this isn't patching replacing a modulation matrix, it is open and reconfigurable modulation sources (and destinations) as well. Another of my 'coming soon' patches outputs LFOs that run at different rates to the ones that are used inside the patch running inside the Witch. I'll say that again in marketing speak: if you've wanted to have a different LFO rate for the filter mod, the phaser and the stereo panning, then the Witch can provide those LFOs, and if you derive them from the same master LFO, they will track each other... You just need to hook the Witch to a phaser and a stereo panning module...

A quick reminder before you get too focussed on hooking it up to modular again -  the Witch isn't just something that you can connect up to a modular Eurorack system (or, actually any synth!), it is, itself, a tiny reprogrammable, modular synth that you can patch to control itself. This kind of goes against one of the paradigms that you often see in many modular synth modules - they are designed to be patched to other modules, and it is quite rare for a module to patch itself. And that patching is between sources and destinations that are also programmable! (Your jaw is allowed to be slack here...)

At this point, you might, like I did, be thinking about two Witches...(or more).  A coven of Witches would allow you to program just about any functions you want (or can find a patch for, or can write, or can persuade someone to write for you) into the Witches, and then to patch them: locally on one Witch, or across/between the Witches. There's really only one word to describe the possibilities that this opens up:


Having something this flexible, versatile, patchable and totally programmable in a form factor this size is very probably a game changer for anyone who wants to explore modular synthesis (or add a little bit of extra synthesis power to an existing keyboard or desktop synth), but doesn't want to be tied to using a large monster of a rack. Actually, it is an interesting add-on for someone who has an array of keyboards, because that USB socket provides access to USB-MIDI, and so the Witch is an expander as well - except that this is an expander that kind of also eases you into modular. Desktop synths are another potential companion for the Witch, so just about anything synthy that has MIDI, USB  or CV sockets is potentially suitable - so a Novation Circuit (OG or new), there's a YouTube video of a Witch and an Ensoniq SD-1, or a Deluge, or... One way of looking at it is to consider the programmable modules that you can already get for modular synths, but turned into a stand-alone little box - that's what the Witch is. And if you like the sound of a totally programmable module, then Rebel Technology made one of these programmable modules in collaboration with Befaco - it is called the Lich:  
So whilst most people think of a programmable module as a way of getting a custom module that does exactly what they want in their modular system, a Witch is not constrained to working as part of a modular system. it can be stand-alone, or work with other Witches, or work with a modular system. A Witch provides freedom to do whatever you want - want a wavetable synth (or a Speech Synthesis algorithm like Vosim, or...) to go with a Virtual Analogue synth: Done!. What did I do? I programmed a drone generator into a Witch and realised that it would be just a small part of my personal cabin baggage allowance for a flight... (whenever that mode of transport returns to whatever new normal eventually arrives...)

Someone, nay, several someones, is/are going to do something very interesting with Witches - of this I am pretty certain. It might not be immediately obvious (like Depeche Mode (and others) hiding their synths in those big black wedges on stage for some tours (which ages me a bit!)), but it seems like a very real possibility. 

The Problem

When you have something that can be a VCO, a VCF, a complete wavetable synth, a VOSIM voice synthesis system, a sample replay box, a flanger/resonator, a couple of complex LFOs, and much more, then it gets difficult to make decisions. They say that the biggest spur to creativity is limitation, and whilst the Witch has limitations, it also has lots of flexibility. Possibly the most interesting thing about the 'Someone' that I mentioned is who they are - I'm expecting someone with aspirations and limitations, who has never had or used a large modular. These are interesting times. The mix of hardware and software seems to be reaching a critical mass, and that usually results in an explosion!


Yes, I am, indeed, biased. Having done some of the beta testing of Witch then I am way too close to be independent. This is why I'm not doing a full review of the Witch. For that I would point you towards Loopop, or Benn Jordan, or Andrew Huang, or CDM, or your favourite source of insightful comment and review. 

But, I still know something interesting, different, and exciting when I see it! Full marks to Rebel Technology for stepping well off the 'path well trodden'. 

In an astonishing break from normality, I have made some videos! They are, of course, slightly quirky, but you expected that, didn't you? Here you go:

#rebeltechwitch.     - Hashtag for the Witch  An unboxing video!  A very quick intro...  Another viral video?


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Saturday, 17 July 2021

A Doubly Virtual Talk...

I recently gave a talk to my local tech network. You.know, those things that used to be get-togethers and networking events for tech people, entrepreneurs, start-up people, innovators, inventors, etc., and that people discovered you could do using Zoom during the pandemic. And they obviously work, because we are still doing them.

Anyways, a casual comment I made at one of these tech chats turned into a talk about one of the things that I do, inspired by by soundtrack entry in the famous Westworld competition organised by Spitfire Audio a couple of years ago. It seems that there's a lot of interest in how current technology can make working with audio and music a lot easier than it was in the previous century, and so I just basically did a bit of show and tell...

Remember 'big presentations? Photo by Sigmund on Unsplash

Now when I say 'show and tell', I do mean exactly that. I never wanted to do yet another boring slide presentation full of slides with bullet points. But just watching someone share their screen for an hour is also not so great - I've been in quite a few zoom calls where person after person shared their screen and worked on software, and after watching someone else tweaking MaxForLive for a while, you kind of want to do some programming yourself. Probably my least favourite calls have been the ones where a series of musicians talk for about 30 seconds on some of their techniques, and then spend 20 minutes doing DAWless improvisation. It's the inevitability of it - you get 30 seconds of interesting information, and just when you start to learn about a technique that might be useful, they say: '...and here's a track I put together using a different approach...'. Cue 20 minutes of doodling...

So, no slides, no bullet points, and not too much boring screen sharing. It's a challenging recipe. So I used online videos (mostly YouTube, although I subscribe to Nebula and love it, but YouTube has the advantage of being accessible (and I'm struggling to think of any other advantage...)), web-pages instead of photos 'from the internet', and yes, some screen sharing where I avoided any code and concentrated on showing interactive arranging stuff. 

At the end of it, I thought that I should capture it, so that others could have a similar experience, and so the rest of this blog is just the resources that I used, minus the potentially boring screen sharing where I probably droned on about doing music for pictures. So you get just the good stuff to browse through as you wish, and that's all upside, as far as I can tell... 

(When I type: 'Just the good stuff', there's a caveat, but you probably know that already - you have to wade through me adding all of these explanatory words. Unless you just ignore my words and click on the videos, of course...)

"And now, over to Martin..." <screen goes black>


To set the scene, I used an opening music clip - 'Journey across the Red Planet', an excellent piece of music from Paul Thomson, which demonstrates some of the sounds from the Spitfire Audio 'Abbey One library. (Paul is one of the two founders of Spitfire Audio, a cutting-edge UK ‘sample library’ company: ) I explained that 'everything you are hearing is produced by a computer, using recordings of real instruments'.

I suggested that they should close their eyes for a minute or so, listen(!), then open them and look for the connections between what was happening on the screen and what they could hear. The video shows a DAW (Logic) playing the music, and so you can get some sense of how a DAW uses lots of individual tracks of virtual instruments to reproduce music, and there were piano rolls and MIDI Controller editing shots that illustrate that there's a lot of fine detailed control. Overall, the linkage between the music and the video is pretty effectively shown, but then Spitfire Audio do make vey good videos. So, yes, I started with virtually an advert for Spitfire Audio, but then I do have quite a few of their libraries, LABS instruments and a lot of the associated instruments, so I'm slightly biased. If you've read this blog for any time, then you will have seen that I've been to various events at their HQ (back before Pan Demic and her band put the world on pause for a while...) and I've met Christian Henson and Paul Thomson... (But do they remember me?)

Anyways, the music and the video serve as that all-important bridge, where you leave the real world, and enter the artificial world of 'the talk'. I've never liked the idea that putting up a slide that shows the title of your talk, followed by another slide that tells your life achievements in bullet points, is the perfect way to move people out of their default mind-set and into one where they are ready for fully engaging in a presentation. Closing your eyes and listening helps too, and it often puts any older members of the audience to sleep, so they can't ask tricky questions about DIN sync in the 1970s.

Anyways, I introduced virtual instruments, and how they replayed recordings of real instruments. Or unreal instruments, and so I showed them my BankOSC MaxForLive device that makes 32-oscillator drones and sweep sounds, and basically makes it sound like you have a humungous hardware modular synth, when actually you must have Ableton Live and a free bit of software that I published on

I explained that quite a lot of the non-orchestral sounds that I used in my Westworld competition entry were produced using BankOSC, and I then talked very briefly about MaxForLive, and then Ableton Live.

I've already mentioned adverts, so you won't be surprised that I told them they could read more about the sound generator in my blog:


I found some good links that explain MaxForLive and Ableton Live, curiously made by Ableton themselves:


Ableton Live 

I explained that there are many types of software applications for working with audio, but the terminology that they will probably often hear in music technology circles is ‘DAW’ which stands for Digital Audio Workstation. I said that a DAW is a general purpose music composition and arranging tool that works a bit like a multi-track tape recorder – which is what used to be used in recording studios in the 80s…  I'm quite sure that some of the audience had no idea what a multi-track tape recorder was, whilst some others were probably reminiscing about the 80s and remembering 'Duran Duran' music videos...

For comparison with how you might generate that sort of 'big oscillator' sound in hardware, I should have introduced one of the leading lights of the YouTube ‘Synthesizer’ community, giving an introduction to the vast world of hardware modular synthesis:

But I have the advantage of being able to incorporate it seamlessly here, and no-one will know the difference.

I quickly introduced more relevant terminology in a bot more depth:

Sample Libraries 

(Collections of pre-recorded sounds, where each note that a musical instrument can produce has been captured by a computer, whilst playing it in various ways: soft to loud, different intonations and playing techniques, etc.)

Virtual Instrument 

(The software that plays the sounds of a musical instrument in a sound library.)

And finally, I got to the Westworld competition – where the task was to score a short excerpt from Season 3 of the TV series.

I mentioned my entry:

And I mentioned the winner:

I then revealed that if they were intrigued by just how accessible making music on a computer can be, then a good starting point is an orchestral library (Because the results are probably going to impress parents, friends, colleagues, maybe even ordinary people!) – and some of them are free:

Okay, so I mentioned another free (or low cost) Spitfire Audio product. But I bought Discover, and I like it. There are other free (and non-free) orchestral libraries, of course. 

I closed by reminding them that, whilst laptops (and other computers) may be busy making a lot of music, orchestras are also very occupied doing live tours (often of music produced by computers), making sample libraries - and just making music. And let's hope that as the world learns to live with Covid, 'music' and 'live' and 'performance' can happen in the same sentence once again. 

And that's it. A virtual presentation, made from other virtual presentations. This may be the future...


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Saturday, 26 June 2021

A 3D Printed Project Case

Prevarication. Yep, for quite some time, I've been putting off getting into 3D-printing, but a recent thread on the VI-Control Forum got me thinking (which is always dangerous), and that led to me trying out a 'pathfinder' project. So here's what happened...

Never The Right Size

Boxes or cases are one of the hardest parts of building custom electronics. Commercial boxes or cases are never quite the right size, or they never have quite the look that you want... I have spent way too many hours looking for perfectly sized, good-looking 'professional' cases, then buying them and finding that dimensions are not always correct, plus appearance is very subjective, and as a result I have quite a lot of cases that turned out to be not quite the size or look that I wanted - plus mostly-finished projects that are still waiting for a decent case... You know the sort of thing...

Photo by Nicolas Thomas on Unsplash

I know that I'm not the only one, and when I saw a thread on the VI-Control Forum asking about how to mount 100mm sliders for a long-throw MIDI Controller (why are sliders always so short on MIDI Controllers?), then I read it with great interest. First, I found out that metal panels were not as difficult to fabricate as I had imagined, and then.I kind of volunteered to make some 3D designs and do some testing of commercial 3D printing companies. Well, it definitely got me doing something

As you might expect, there are a number of places that will do 3D printing for you (which is a good way to 'try before you buy', especially if you already have one hobby that is prone to Gear Acquisition Syndrome (GAS: synths!). I did a Google search in the UK for '3d printing on-demand one-off UK', and found several companies (you should localise the search terms for your location, of course!). 

The costs were not as high as I expected, some of the companies had quite sophisticated ways to estimate the costs of 3D printing a part, and overall, the capabilities varied enormously - you will need to acquire some knowledge in order to understand the materials used, the file formats used, how to prepare 3D files, and various other bits of jargon - but more Google searching will quickly fix that.. Four example notable companies that I found were: (Seem to be 'hobbyist' oriented...) (This is very 'Pro' in feel...) (£50 minimum order)

The learning curve is not that steep, really, and there are some free 3D drafting applications available to produce the STL, OBJ, AMF, or 3MF files that describe then3D object you want. I used TinkerCAD, a free web-based application, from AutoCAD, to produce the 2 STL files for printing a box and lid. Because I was expecting to get things wrong at least twice, I chose a very simple case - just something to house a switch and some jack sockets for a monitor switching box.. The STL files were for the box and the lid:

My first two STL files :for a box and a lid

I used to do the prototype. Their online quote generator took the STL files and showed me what the box and lid would look like (useful confirmation!) and how much they would cost, and generally made it very easy to place an order... The cost was about twice what a similar sized plastic or die-cast metal 'hobbyist' box would cost, except that this box was exactly the size I wanted, and could have any holes, legends or decoration on it that I wanted. I chose the 7-10 days economy service, ordered two sets of box and lid so that I was over the £40 minimum order value, and waited for the parcel to arrive.

The TinkerCAD web-app was pretty easy to use, with lots of tutorials available on the web-site. I would almost suggest that some music software has a bigger learning curve...So whilst I was waiting, I designed an angled box which is more like I would want for something to hold some sliders or a MIDI Controller...

There seemed to be some interest on the VI-Control Forum for a few designs as starting points for people wanting to make their own cases, so I will make all of my designs freely available on the TinkerCAD site. Here's a more develop version of the previous box...

This case reflects my own personal design preferences, but it wasn't that difficult to make, and there's a huge advantage to getting a case that is the right size, instead of a compromise. 

Here's the boxes and lids that arrived:

The texture is interesting: it is matt, and quite smooth, really, but those highlights make it look much rougher. - it certainly didn't have the obvious lines that you see on some home-printed 3D parts. One thing to note is that whilst this looks like it is full of carbon and conductive, it is just black nylon, and so it is an insulator. You would need to sort out screening if you had any high gain electronics inside - but if you make wooden cases then you face the same problem... 

So here are all the bits, plus a plan for the holes. I did a bit of guestimating based around the jack sockets and the switch, and didn't give myself very much room beyond that, so this is a much smaller case than I would normally get for this type of project. 

 Here's the drilled case, using one of those stepped pyramid drills that are perfect for making holes in thin metal. The black nylon is easy to drill, although because it has been 3D printed, it does tend to melt if you try too hard with the drill. The walls of the case are about 2nn thick, and it seemed very strong. 

I always buy stereo switched jack sockets, because you never know when you might want some clever functionality, and the cost difference in bulk is very low. In this case, I didn't need any switching or resistors around the jacks and I wasn't going to PCB-mount them, so bending the legs over was a good way to save space.

And here are the jack sockets, with all the legs bent to save space.

I've probably mentioned this before, but doing a test assembly as early as possible can be very useful. Here's me trying to figure out the optimal placement of the sockets...

Doing a test assembly also gets you a better feel for  how all the bits fit together in 3D!

In this case, I figured that arranging the sockets in two rows of three was best, and so I used double-sided tape to fasten them together. Using the case as a jig when soldering wires can be useful, but sometimes solid is better.

Here's the common 'Sleeve' grounding of the jacks. I'm ignoring the Ring connection , so these are all going to be mono jacks - my monitor speakers are all mono wired. 

And all the wiring completed. There's no gain in this box, and low impedances, so I have used screened cable for these very short wire runs.

And here is the assembly check using the box as a jig. Everything seems fine, so I turned the box over and moved the sockets and switch inside...

What I discovered is that I could probably have made the case even smaller...

The interesting thing about 3D printing is that the parts you get are exactly the size you specify in the 3D file. Unlike moulded plastic parts, there are no slopes so that the parts will fall out of the mould, and so I specified that lid to be slightly larger inside than the inside of the box, and so the two parts snapped together with a reassuringly tight fit. A little bit of glue would make it very strong indeed. A little bit more time in the 3D drafting package and I'm sure I cold have added a hole and receptacle for a bolt or two...

One thing that I did get wrong was the height of the jack sockets - I took the overall height, not the bit that would be inside the box, and so when you subtract the parts of the sockets that are outside the box, then you get a case that is too deep! I may try to cut it down as en exercise in making neat cuts. And don't forget that the sides of the box are parallel - you can cut it down and the lid will still fit perfectly. There are no hidden slopes or tapers here!

Completed! Yes, I should have put some text or symbols onto the outside of the box, but I'm still learning the 3D drafting software. But overall, for a first attempt, it isn't bad. Most importantly, I know that it isn't that hard to make a custom 3D printed case, and I've staved off the GAS need to buy a 3D printer for the moment. (Although there's a very well-equipped local MakerSpace that has 3D printers and laser cutters...)


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