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. 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. So the Witch isn't just something that you can connect up to a modular Eurorack system, it is, itself, a tiny 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. 

At this point, you might, like I did, be thinking about two Witches...(or more).  A coven of Witches would allow you to program 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, but doesn't want to be tied to using a large monster of a rack. 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. 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... 

Someone is going to do something very interesting with Witches - of this I am pretty certain. It might not be immediately obvious (like Depeche Mode having those big black wedges on stage that hid their synths 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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Sunday, 30 May 2021

The Allegorist - The Third Album: Hybrid Dimension II

I always look forward to releases by The Allegorist, and Anna's third album 'Hybrid Dimension IIcontinues the 'slow building' style of her previous releases, but this time the production value in the sophisticated mix of ambient, classical and electronica has jumped up several notches. This is all the more remarkable because when I first heard her work at an Ableton Loop in Berlin a few years ago, it was already stand-out, drop-dead, slack-jaw perfection. You could kind of tell it was exceptionally good, because Mandy Parnell simply didn't know what to say for several minutes after hearing it. 

The cover of 'Hybrid Dimension II'

There's a huge amount of finesse exhibited in this third album. The opening track has a drone that is gradually replaced by vocals in the invented 'Mondoneoh' language, and it's like an overture to set the scene for the whole album. But the vocals don't just fade in as you might expect - instead the drone's timbre gradually morphs into the vocals, rather like a curtain drawing open and letting higher and higher frequencies out. And this masterful slow building of almost visual soundscapes just continues in the rest of the album - this isn't your standard 'ambient' washes merely produced by using lots of echo and reverb. It is more like one of those 'continuous zoom' videos, where you keep diving deeper and deeper through breath-taking vista after glorious vista. And the blending is seamless, all the way down...

There's a huge variety of vocal, sample and synth timbres, and they aren't static. They wash over each other, like waves crashing on a beach, evolving and slowly changing... It is stories told in music on a grand scale. There's a host of superb pad sounds to die for, and the changes just keep going - just as you start thinking: 'that's a nice pad', then it has already changed into something else equally gorgeous but different, and it just keeps going. There are multiple techniques that are used to transform from one sound to another, and just as you think you have one figured out, along comes another one that does it differently. A sound designer's or synthesist's or producer's cornucopia of riches... Listen and weep.

Amazing. Immersive and confident. I wish I could make electronic music half this good.

I struggle for analogies, but if you go back over 40 years to Jean-Michel Jarre's seminal 'Oxygene', and replace the organ sounds processed by twin EHX 'Small Stone' phasers and VCS3 doodlings with modern sampling, synthesis and vocal processing and production techniques, and you change the genre to 'Ambient crossed with Classical crossed with Electronica', then you start to get a feel for just how much this connects to the very deepest part of me. Or maybe a more modern angle would be The Flashbulb... 

Recommended. Oh wow, is this recommended!


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Saturday, 29 May 2021

Project Proposal seeks Student... (Keyboard Noises)

You know when you have a good idea, but don't have the time or resources to actually do it? Well, here's an example... Cue: picture...

Photo by Kelly Sikkema on Unsplash

You have probably noticed that just about every electronic musical instrument makes a different noise when you press and release the keys on the keyboard. Some are quiet, and you barely notice them. Some are noisy and intrusive in some circumstances. Some make springy sounds. Some make a sort of clacking sound. Some are so jarring that you have to use headphones or turn the amplifier up. Some are an intrinsic part of the instrument (acoustic piano, clavinet, harpsichord...). Some defy description. Everyone has their own preferences for what is an ideal 'noise', or lack of it.

But what is difficult to determine is what an instrument will sound like - in advance. In general, and especially in these 'online purchase' times, it is only when it arrives that you actually get to hear what the keyboard actually sounds like, especially long-term. Even a few minutes in a music shop may not give you a very good idea of how it will sound in your acoustic environment.

So I gathered some keyboard noises from a few instruments: high velocity key-down, and high velocity key release. This is what I got (time waveforms at the top of each set, spectrograms underneath in colour):

SY99, Montage 7, and CLP-930 key noises

These weren't perfect recordings. But what is intriguing are that they key-up is sometimes louder than the key-down (SY99), and that there are wide variations, particularly the Clavinova (echoes from the cabinet, or scrapes from the action?). You will eventually be able to get edited versions of my recordings here.

VI-Control Forum

This topic came up recently on the VI-Control Forum, a place where composers, musicians and technologists with an interest in virtual instruments (Kontakt et al) discuss a variety of topics. In this case it was specific to MIDI Controller keyboards, but the subject of keyboard noise is really a generic one across all electronic musical instruments with keyboards. I proposed that a crowd-sourced approach to gathering the sounds might be a way to get some useful material (by asking VI-Control Forum members to record their keyboards), although I acknowledged that there were some problems to overcome. There wasn't much feedback, and this often happens in forums - they aren't really places for marshalling big campaigns involving lots of people, unless there's a very strong reason that will  motivate people.

The Alternative

Since then, I've been thinking about it a bit more, and I decided that an alternative way of gathering the data could be an interesting experiment. I am sure that it is a good idea, and that the results will be useful, but I don't have the time to do it myself.

So I have written up some more of my thoughts and the background research that I did around the idea, and have produced a rough Project Proposal. That's what follows. My hope is that a university or college student on a music technology course, or maybe an intern at a manufacturer, sees it, and decides to do the research and then publish it. If you know someone who might be interested, then feel free to give them this URL or the project proposal below!

- cut here - - - - - 

Project Proposal

Title: Noises in the Keybed.

Author and Licence: This project proposal is written by Martin Russ aka Synthesizerwriter, and this work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Abstract: The keys on the music keyboards (keybeds) on electronic musical instruments make noises when they are pressed and released. Data on the Sound Pressure Levels (SPL) of these noises, as well as subjective descriptions, and recordings of the sounds that are produced, are not widely available. As a result, it is difficult to make informed decisions when deciding which instrument to use for a particular application. This project aims to provide information on how relevant data can be captured consistently and reliably, and subsequently made available to anyone who would find it useful.

Procedure: There are several stages required to capture relevant data of the noises made when the keys on a music keyboard (on an electronic musical instrument or MIDI Controller keyboard):

1. Preparation of the keyboard, the recording/measuring equipment, and the performer. 

2. Key-down noise (pressing the key on the keybed, from the default 'rest' position, to the full depressed position, where it is stopped by the physical keybed)

3. Key-up noise (releasing the key on the keybed, so that it returns to its default position)

4. Processing of the captured audio files and SPL levels

5. Processing of data from the processed audio files


1. Preparation.

The capture can be carried out by individuals acting as part of a crowd-sourced team, where the results are collated by an individual or a team. Alternatively, the capture can be carried out by a single individual or a team.

The keyboard should be placed on a solid surface, ideally one that is free of rattles, creaks and other noises. The 'performer' should checking for any variation of noises across the range of the keybed, and then choose the noisiest key as the one to use for SPL measurement. If the noise is consistent across the keybed, then a key in the middle of the range of the keyboard should be chosen. Whichever key is chosen, it should be marked with a removable sticker, and this will then be the only key used for the capture. 

If a microphone is used then it should be placed 1 meter vertically above the keybed. This makes positioning easier than close mic'ing. Because the source of the sound is typically inside the keybed, then positioning the mic above the keybed (and with the microphone) aimed at the keybed, should capture the sounds produced by the keyboard, and should not interfere with the pressing and releasing of the keys on the keybed by the 'performer'. This positioning of the microphone should be possible with most mic stands.

If an SPL meter is used then it should be placed in the same way as the microphone: 1 meter vertically above the keybed. 

Low-cost SPL Meters. You 'can' get cheap (about 20 USD) SPL meters from Amazon et al.., but their supplied calibration is difficult to determine, there is anecdotal evidence that indicates that measurements may be several dB different relative to a properly calibrated SPL measuring device, and proper calibration devices cost about 6x that (about 120 USD). This approach seems to be a recipe for making the results worthless because of lack of calibration - but may be the only apporach that is feasible when using crowd-sourcing.

Higher-cost SPL Meters. Properly calibrated and calibratable SPL measuring devices will typically cost over 120 USD, and will require the use of a calibrated sound source (about 120 USD). The same SPL measurement device should ideally be used for the whole of a session, and ideally for as many captures as possible. 

Capture measurements should be of SPL and the sound simultaneously, and so a microphone and SPL meter should both be positioned 1 meter vertically above the keybed. They should not touch. One possible alternative to using separate microphone and SPL measuring device (meter) many be a calibrated USB microphone. One example is: These cost about 120 USD, but can be used to capture both the audio and a calibrated level for the audio (it may be possible to also derive the SPL).

The recording environment should be as quiet as is practical. A 30 second recording of the background noise in the recording environment should be made at the beginning and end of each capture session, so that the recording can have noise reduction applied, if this is required. The ambient temperature in the recording environment should also be noted at the beginning and end of each capture session.

The instrument, of which the keyboard is a part, should be set so that it does not make a sound. For electronic musical instruments this generally means that it should not be connected to an amplifer, or the internal loudspeaker amplifier should be set to minimum volume. For other instruments, then damping may need to be applied to any vibrating part that is not directly a component of the key mechanism. 

The performer, whose role is to press the key on the keybed at five second intervals during the capture session, should wear cotton clothing, a sleeveless tee-shirt, no jewelry, no rings, no bracelets, no ear-rings, etc. Ideally, they should wear no metal or other material that could make any extra noise. The only noise that should be recorded is the sound of the key on the keybed. The performer should breathe quietly and moderately during the capture session.

It may also be possible to find data on the SPL of keybed noises on the InterWeb, although the author has not found any such data. A search for this would be good practice before committing to a full project.

 2. Key-down noise 

The performer's task is to press the defined 'middle' key on the keybed, moving it from from the default 'rest' position, to the full depressed position, where it is stopped by the physical keybed. The start of recording should be indicated to the performer, who then waits 10 (ten) seconds, and then presses the key. Once pressed, the performer then waits for 10 (ten) seconds, and then moves to the next stage ('Key-up')

A range of velocities or strengths, of pressing the key should be used. The minimum set should be High (as fast and hard as possible), Low (as slowly and lightly as possible), and Mid (mid-way between the previous values). If MIDI is available, then MIDI velocity can be used to achieve consistency. Max would have the MIDI velocity value of 127, Mid 64 and Low should be below 30, but this depends on depending on the playing ability of the performer. 

Notes should be taken during the capture session as a subjective record of the 'sound' of the key noises. Words used can include: clicks, snaps, clunks, thumps, spring-buzzes, slides, sizzles, etc.

The three MIDI values:127, 64 and 10-30 should capture most of the variation of 'sound vs velocity', and a single key is not onerous to record: less than 30 seconds of WAV, and probably less than a quarter of an hour to accomplish. If it is discovered that there is a particular velocity or strength of pressing that produces a different opr louder noise, then this should be captured and noted.

Three key-down captures should be recorded.

3. Key-up noise 

The performer's task is to release the key on the keybed, so that it returns to its default position. Based on the techniques used to record acoustic pianos, then there are two extremes that should be captured:

a. Starting from the key being held down (the ending position of Stage 2), then the performer moves their finger backwards so that the key is allowed to rise up to its default position on its own. The performer should strive to avoid making any noise as the key is released.

b. Starting from the key being held down (the ending position of Stage 2), then the performer moves their finger upwards and off the key as quickly as possible, allowing the key to rise up to its default position on its own. The performer should strive to avoid making any noise as the key is released.

Once the key has been released, the performer should wait 10 (ten) seconds before the next Stage 1 key-down, or if this is the third capture, then the performer should wait 10 seconds and the capture will stop.

Three key-up captures should be recorded in total per chosen key on the instrument. If one key has been chosen, then three captures. If two keys have been chosen (noisiest and quietest, where there is a noticeable range of noise levels), then two sets of three captures should be recorded in total.

4. Processing of the captured audio files and SPL levels

The recordings of the key-down and key-up events stages (2 and 3) will be in pairs (down then up), and there will be three contiguous sets of the pairs. Each stage should last for ten seconds, with an extra 10 seconds at the start.

The audio files can be trimmed so that there are 10 seconds of near-silence before the first stage 1 capture, and 10 seconds of near-silence after the third stage 2 capture. The audio files should be stored in a linear, uncompressed format. WAV files, either 24 bit or 32 bit floating point, ideally at 48 kHz sampling rate. 44.1 kHz can be used if it consistent across all captures. Mixtures of 44.1 kHz and 48 kHz sampling rates should be avoided if possible.

If an SPL meter is used, then the peak measurement during the three captures should be noted.

Files should be saved with names that include the date, instrument name, a capture session ID, the sample rate, and the bit depth (24 or 32float).

5. Processing of data from the processed audio files

A spreadsheet should be used to hold the metadata noted during the capture session. Columns should include the date, instrument name, a capture session ID, the sample rate, the bit depth (24 or 32float), the measured peak SPL, the name of the performer, the name of the recording engineer or co-ordinator, any notes (quiet, noisy, clicky, thumpy, etc.) and any other comments. 

A cloud-based spreadsheet is recommended. Airtable is a sharable spreadsheet with advanced capabilities that offers a free service for small numbers of rows in the spreadsheet.

Stages 4 and 5 are just spreadsheets, and file management, and will appeal to a very particular type of person. 

The results should be shared as widely as possible. The VI-Control Forum is one possible place where a post could be placed.

Conclusions: I hope that this project proposal is useful to someone. Please feel free to share the URL or a printout of it to any researcher, student or intern that might find it useful or inspiring. This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License, so that it is available to all under clear usage terms.


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Thursday, 27 May 2021

Black Dust From An Old Keyboard Rack...

So, there I was, working away in the studio, when I noticed some black dust on the keyboard of my Yamaha SY99 on my keyboard rack. I looked at the Synthstrom Audible Deluge above it, and moved it a little, and more black dust appeared. What? 

Black dust
The Black Dust!

The dust is dark black, gritty, and very fine. I have no idea what it has been doing to my synthesizer keybeds or key contacts... I have to say that this isn't a complaint - after over 30 years, then I would expect some deterioration of some components, and everything else about the rack is still perfection! 

After some investigation, it turns out that the rubber pads on the keyboard support brackets on my custom hand-built Ultimate Support Systems rack have perished over the last 30-odd years, and need replacing. (As an illustration of how things have changed over those intervening years: Ultimate now only seem to make those stage-friendly 'Z' and 'X' shaped stands... )

Just removing the support brackets created dust!
Just removing the support brackets created dust!

Fixing the problem requires pulling apart a five-tier custom keyboard rack ( the modern equivalent would be something like ), removing the keyboard support brackets, removing what's left of the pads, then removing the 30-year-old adhesive (nasty and difficult), then putting on new better pads, putting the keyboards/synths, drum machines, sequencers, mixers and stuff back, then cabling it all up again - not quite a five minute job. 

The rubber pads are now very fragile
The rubber pads are now very fragile...

As you can probably sense, it's all a bit fraught here at the moment, and I have no idea how much damage that black dust (gritty, abrasive, horrible stuff) has done to my keyboard contacts and keybeds. Vintage gear, eh? You think that all you have to contend with are LCD backlights failing, or electrolytic capacitors drying out - and then you get awful black dust everywhere. I'm just glad that I have spotted it, that I don't move stuff around on the rack very often, and that I don't have any of those amazingly expensive synths that you see on eBay and Reverb. I'm also guessing that there may be more than a few other synthesiser owners who haven't checked the rubber pads on their more-or-less permanently-installed keyboard racks for quite a while... Now could be a good time to check. It did seem that, as with 19 inch racks, heat may be a major contributor to problems - the worst deterioration did seem to be where the synth/sequencer/drum machine/etc., got warm...

The support bracket, the gripper bracket, the bolt and an Allen key...
The support bracket, the gripper bracket, the bolt and an Allen key...

Some mechanical details are probably a good idea here - because the modern racks from people like Jaspers are different (Yep, in more than 30 years, designs have changed!). The basic tubing of the rack is black anodised aluminium: 38 mm in diameter.  the gripper clamps/brackets use an Allen key to tighten them in place by gripping the tube, and a pozidrive bolt holds the support bracket onto the gripper clamp/bracket. As you can see, there's a design problem with the gripper clamp/bracket - it is in one piece, and so can only be removed by pulling almost the whole keyboard rack apart (in most cases!). That is a lot of dismantling! A two-piece gripper clamp/bracket would be a much better design...

The black dust removed from a support...
The black dust removed from a support...

After two days pulling my keyboard rack gradually apart, and then attempting to get the rubber pads off, I now have a much better idea of what is involved, and I also have a lot of black dust... 

Chemical failure...
Chemical failure...

The adhesive is the worst part - after more than 30 years it is almost part of the metal. I've tried scraping at it, Fairy liquid, various degreasers, orange oil (my secret weapon) and a scary adhesive remover that is covered in warnings and is apparently toxic, flammable, harmful and more. None of them shifted it. As usual, take care with chemicals: read the warnings, do it in a well ventilated place (or outside) if recommended, etc. 

So I stopped the arms race of ever-more-scary chemicals, and went old school. Time. 

After soaking overnight...
After soaking overnight...

Yep, there are very few things that a little time won't degrade - as shown by the rubber pads! So I soaked them overnight in a hot dilute fairy liquid solution. Fairy liquid, or your alternative favourite washing-up liquid, is designed to do degreasing and a few other useful dish-washing tasks, but the important ingredients here are time, and water. Water is a strange liquid. It has all sorts of properties that are unusual, and it turns out that the more you investigate it, the more interesting it becomes. Anyway, the recipe, again, is water, time, and heat to help reactions along a little. Let's pause here overnight, and maybe another overnight...

Scraped off and allowed to dry...
Scraped off and allowed to dry...

So, when the adhesive remnants have changed colour (paler, less saturated colours, and a milky appearance), then things have probably got a lot easier. After two overnights, then the remnants of the adhesive can be scraped off very easily using a screwdriver or an old credit card (another secret weapon). This leaves just a few bits, which I soaked again overnight. 

Finally! Clean to my satisfaction!
Finally! Clean to my satisfaction!

I was now starting to see some progress, and after drying them, then one of the 'not quite as alarming warnings' spot cleaner got me very close to a clean metal surface. And a final wash and dry got me to a final look that I was happy with, and one that was suitable for the new clear rubber stick-on pads that should apparently last for 50 years. 

Just before reassembly and sticking on the new pads...
Just before reassembly and sticking on the new pads...

If anyone had told me that the 25mm square rubber pads on my keyboard stand were going to be such a major problem, I would never have believed them. Amazing. I'm dreading opening up the keyboards to see what I find inside.

Brackets with new rubber pads...
Brackets with new rubber pads...

And that was that. Several days of work to remove the gear, remove the brackets, figure out how to remove the remains of the rubber, then how to remove the adhesive, and finally clean the bracket ready for the new self-adhesive pads. Oh, and then put all the gear back, rewire it, etc. In the process, you can't help but reappraise the gear and start thinking about modernising, modding...

What is interesting is that I realised that I also have a 'vintage' keyboard rack' for my 'vintage' gear!


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Tuesday, 20 April 2021

This tool sucks! (which is good!)

One of the downsides of having vintage gear is that time takes a toll on old electronics. Quality counts, but the ravages of time can affect even the highest quality of components. I have covered fitting replacement displays (LCDs) with backlights previously (TX7, RM-1x), but I've recently been replacing electrolytic capacitors and switches, which are also sometimes the unfortunate casualties of time. Capacitors can dry out because of heat, from CPUs and power supplies, mostly. Switches just have finite numbers of cycles, and the front panel of a synthesizer can require a lot of button-pressing depending on how it is designed - 'Enter' buttons, or cursor buttons, or increment/decrement buttons, or 'Play/Stop' buttons are all candidates for repeated presses over the lifetime of a piece of gear. Some switches fail because of metal fatigue, some because of dust, and some because conductive plastic loses its flexibility over time. The switches that you get on older, vintage equipment from the 1970s and 80s tend to be 'proper' metal contact switches, and so the failure mechanism tends to be just plain old 'wear and tear' - but at least they are individually replaceable. (More modern gear can use conductive rubber switches which are made as sheets, and have to be changed all at once, trying not to get any dust underneath them. And no soldering required, usually!)

Removing thru-hole components from printed circuit boards (PCBs, but not Poly-Chlorinated Biphenols) can be tricky. You want to avoid damaging the pad or tracks, and yet you need to heat up the joint sufficiently to be able to remove as much of the solder as possible - which are a difficult pair of requirements to juggle. The key words here are:

'Removing the solder...' 

Ideally, I would have invested in two soldering stations: one for surface mount components (with a tiny soldering iron bit, a heat gun, and strong magnifiers - something like this or this or this), and maybe one for thru-hole (with built-in suction). But this isn't an ideal world: I used to have an Antex soldering iron back in the 1970s, and I have had a very basic (and a bit industrial) Weller soldering iron for many years, that really needs replacing with a more modern TS100 model. 

But at the moment, I've been struggling with an antiquated classic; the almost-all-metal RS components 544-516 model solder sucker. The sucker itself works perfectly fine, but I have been totally unable to find any replacement plastic nozzles for it - and the RS website, and Farnell, and others. all laboriously lead you down a series of labyrinthine pages that never actually lead to a replacement nozzle. 

So I have the classic problem where the end of the metal rod, sticks out of the nozzle, and reduces the suction enormously - but no obvious way of fixing it... 

I did try one of the 'affordable', part plastic, part metal alternatives from Amazon, but that has a wide nozzle, a small metal rod, and doesn't suck very well. It also has the unobtainium problem with replacement nozzles as well. 

I even reminded myself that I don't like solder wick, although I know some people who like it, and I also know some people who mis-use it to create solid ground links on digital audio boards. 

Finally, I decided to stop messing around and do what I should have done in the first place: buy a decent solder sucker (and defer the surface-mount soldering/heat gun workstation to another time). 

The Engineer package - without the solder sucker!

After some research, I found the Engineer SS-02 from Japan: an all-metal, guard-less solder sucker with a bright red plunger button, and a replaceable silicone plastic nozzle (and a spare length of tubing included) and where additional tubing sections can actually be found and bought on Amazon! 

The included tube (top), plus an extra pack of two tubes

I have to say that the combination of a flexible plastic nozzle and huge amounts of suction, is just wonderful! For removing thru-hole components, then you heat up the joint until the solder goes shiny as it melts. Then you let the molten solder spread to all of the joint (you can see it go reflective and start to move), then position the nozzle as close to the soldering iron tip as possible and press the button on the side. The plunger is pushed out by the internal spring and the red button jumps upwards as air (and solder) is sucked through the nozzle inside the sucker.  

It is an interesting balancing act. You want to heat up all of the solder in the joint so that it can be sucked out, but you do not want to over-heat the pads and the tracks they are connected to. You want to get the solder sucker nozzle as close to the soldering iron tip as you can, and yet you don't want to stress or damage the silicone rubber nozzle by over-heating it - although it does seem to withstand a lot of heat!

Then there's the longer term question of what happens to the solder? It ends up inside the solder sucker, either as tiny round spheres, or as thin streams. When you push the red button to reset the plunger, then the metal rod pushes down through the nozzle and sometimes pushes some parts of those thin streams of solder out. Some solder stays inside the sucker, and so you have to unscrew the end every so often and shake/tap out the bits of solder. The inside of the sucker also tends to get coated with remnants of flux from the joint, and this goes sticky and dark over time. 

You can't see what is happening inside the solder sucker, and so emptying it tends to happen when you can't push the plunger back down until it clicks. The internal entrance to the nozzle tends to get clogged with solder that the rod can't push through, and so then you have to empty the sucker. The more solder you remove, the more often you need to empty it, and so a good solder sucker tends to need emptying more often - which is a sure sign that it is working well!

Ideally, enough of the solder has been removed from the joint, so that the component (capacitor, switch...) is now loose. To help this process, with that third hand that you probably don't have (soldering iron in one hand, solder sucker in the other) you should be applying pressure to the component so that it comes free as soon as there isn't enough solder there to hold it in place. In practice, as soon as the solder sucker has done its suction thing, you drop it, move the iron away, and nudge the component so it comes free (the component is on the other side of the PCB, of course, which just makes it all the more challenging!). 

It's a complex ballet of movements to try and remove the solder and loosen the component, and you really need an extra hand. Trying to co-ordinate two people's hands and associated tools in the tiny space near a solder joint is very difficult, but can work with larger PCBs. Another technique is to use the soldering iron tip to jiggle the component lead as the solder is sucked away, which works better with capacitors than switches, because switches tend to have more solid connections rather than flexible leads. Flat-bladed screwdrivers or tweezers can be used to lever the component as the solder is sucked away, so that any remaining solder can't freeze and lock the component in place again. 

Some people advocate twisting the cans of electrolytic capacitors axially so that the leads break, which makes the remnants easy to remove - sometimes the lead just drops out when you heat the joint and suck the solder away. But this can damage solder resist and pads, and is difficult to do if the capacitors are tightly packed together, which is often the case. 

So the solder sucker is only a temporary home for the solder. Unfortunately, it doesn't magically disappear - the sucker moves it from the joint to inside the sucker, and you then have to empty the sucker. The next step up are solder suckers which have heated tips like a soldering iron, but they also have suction through a hole in the middle of the tip, and the solder ends up in a glass tube. Again, over time, the tube fills with tiny spheres and streams of solder, and needs to be emptied - the glass tube just makes it easier to see when you need to empty it.

In conclusion, the Engineer SS-02 is especially perfect for removing switches and capacitors from PCBs... I may have put off buying a proper suction station for another day...

Name choice

I just have to comment on the choice of brand name by the Japanese manufacturer of this solder sucker. 'Engineer' is a totally brilliant, deceptively descriptive (and tautological), choice for a brand name: these are obviously tools for serious engineers, hence the name. But there's no doubt about what the purpose of the tool is: 'Hobbyist' or 'Bodger' wouldn't be very good choices, whilst 'Professional' and 'Expert' have been so over-used that they have become mostly worthless. 'Serious'? - it just sounds like irony. So 'Engineer' is a near perfect name.

And as a final thought. It turns out that my favourite, 'go to', special purpose pliers, that I use to adjust/tweak/remove awkward small bolts/objects in tight locations, are also made by Engineer. and it is only just now that I noticed... They are PZ-57s if you are interested. 


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