The Cracklephone

The ‘Cracklephone’, nicknamed ‘The Blue Parrot’, is my second project recreating a classic design.  The first, The Hedgehog, was a version of the famous Atari Punk Console; this one was my take on the ‘Cracklebox’ (or ‘Kraakdoos’ in the original Dutch).

The original Dutch Cracklebox was created by Michel Waisvisz at STEIM (the Studio for Electro-Instrumental Music) in Amsterdam in the 1970′s.  Waisvisz died in 2008, but his description of the Cracklebox can be found here: http://www.crackle.org/CrackleBox.htm.

This is what it looks like:

Photograph by Sascha Pohflepp.

You can buy one like this from STEIM at http://www.steim.org/steim/cracklebox.php.

Waisvisz’s early experiments with electronic sound were of the type now known as ’circuit-bending’, and the Cracklebox was developed as a natural extension of this: STEIM’s philosophy is very much in favour of low-tech electronic music-making and the ‘creative misuse’ of technology.  In particular they emphasise the importance of human touch in musical performance.  Accordingly, the Cracklebox is based on an early op-amp chip numbered 709 (LM709, MC709, uA709 or MC1709CG), provided with 6 pads or touch points which cause it to oscillate in a not entirely predictable way.

The 709, as a matter of fact, was the first widely-used op-amp on a single chip.  It was invented by legendary designer Bob Widlar – an ‘irrational, eccentric, and outspoken personality’, ‘alcoholic loner’ and ‘celebrated dropout’ according to his Wikipedia entry at http://en.wikipedia.org/wiki/Bob_Widlar.  Whether or not STEIM knew of it, I don’t know, but I feel sure they would have approved of the physicality of his practice of ‘widlarising’ – ‘methodically destroying a faulty component or a flawed prototype with a sledgehammer’ . . .

Be that as it may, the 709, as a very early design in the field, required more external circuitry for ‘frequency compensation’ than later and more familiar op-amps like the ubiquitous 741, so lends itself to greater possibilities of interference by touch.  As people are different, so the Cracklebox sounds different when played by different people – the player and the electronics combine to make a unique instrument between them.  (Indeed, it is possible for two or more people to play the Cracklebox at once, by touching separate pads, or each other.  There are videos on YouTube demonstrating this).

I had been using the computer a lot in recent projects, but the low-tech approach is another strand I’ve been following.  Fortunately, circuit diagrams and advice on the Cracklebox were available at this website: http://www.eam.se/kraakdoos, and there was much discussion of it on the electro-music forum, for example: http://electro-music.com/forum/viewtopic.php?t=11052.

In some places I read that the 709 could be difficult to get hold of, but I had no trouble in getting them from one of my regular sources, Cricklewood Electronics, at a perfectly reasonable cost.  I have also read that the NTE909 works as well, but have not had cause to check this out.

The circuit I used looked like this:

The reason why there are 13 touch points, rather than 6, is to do with the case I built it in.  I mentioned in an earlier post that I had acquired a number of broken Stylophone Beatboxes.  I had used one for the ‘Big Boy’ Stylophone mod, and had been looking for a project in which I could use another.  As the Beatbox has a large and attractive circular ‘keyboard’, divided into sections, I thought this would be ideal for a series of touch pads, as used in the Cracklebox.

The Beatbox keyboard – or as it is now, ‘playing surface’ – has 13  segments, hence the duplication and addition of extra touch points.  The original 6 are marked  *  on my circuit diagram.

As many as possible of the Beatbox’s original switches were retained – mostly with different purposes, of course – and the volume control, in particular, proved useful to keep, as it could be manipulated with the right index finger while playing.  The odd arrangement in the middle of the circuit diagram is designed to make use of this – the first variable resistor sets an average, maximum or minimum volume, and is not much used when playing.

Other additions to the basic circuit are:

- voltage starve.  I added a switch to this arrangement, the idea being that the voltage starve could be applied or not, as required, and there is a choice of direction of turn of the control pot.  After practising with it for a while, I prefer position 3, with voltage starve on, turning clockwise to increase voltage.

- resistor bypass.  There’s only one resistor in the circuit, so I added a 1M potentiometer in series with it, to increase or decrease the resistance between pins 2 and 6.  I know that knob-twiddling isn’t entirely within the philosophy of the original Cracklebox, but I found it a useful addition, affecting the pitch of the sounds produced.

- LDR.  When I had finished, there was an unattractive hole remaining where the Beatbox tuning control used to be.  I decided I needed to fill this in and calculated that an ORP12 LDR was the perfect size to do this.  I put this in series with the 1M resistor, and added a switch so it could be selected in place of the 1M potentiometer.  The effect it has varies considerably according to the ambient light level and the type of sounds being produced: sometimes it acts almost like an on/off switch, allowing for ‘gating’ effects.

The  op-amp section and the transistor section were built on two very small scraps of veroboard to make sure they could be fitted inside the case – there was very little room above the large keyboard PCB.

There is an LED shown in some versions of the Cracklebox circuit diagram.  I intended to incorporate this as shown, but I wired it as an on/off indicator at some point when I needed to know whether power was getting to some parts of the circuit and in the end I left it that way.

Here’s what it looked like when I finished:

As soon I started to use it, however, I realised straight away that the best way to play it was to turn it upside-down, with the keyboard and speaker facing away from me.  This made it easier to touch the playing surface with my finger tips: seeing where they were wasn’t important, as playing was all done by feel.  This meant the underside of the instrument  – now the upper side – had to be decorated, too.  It now looks like this:

In fact, the Beatbox keyboard turned out to be a very good playing surface, allowing for a certain amount of variation in the strength of touch and the possibility of sliding gradually from one touch point to another.

There is much discussion at the links mentioned above about whether a direct output could – or indeed should – be included, and if so, how this could most effectively be done.  As the principle behind the original Cracklebox was that it should be a ‘stand-alone’ device, I decided to deal with this issue by purchasing – for under £2 – a small goose-neck mic.  This plugs into a 3.5mm socket on the rear of the Cracklephone, and is bent to point at the speaker; adjacent to this is an out socket going to the amp.  These sockets aren’t connected to the rest of the electrics in the case, so this is just a simple way to mic the instrument up, enabling it to be amplified or recorded however or wherever it’s being held or moved.

At the moment, I can only get this to work when plugged into my laptop, not through my general effects and amplification system – but I’m working on it.

I also added two 4mm banana sockets so the instrument could be connected directly to a (better) external speaker.  The external speaker arrangement is described in another post.

The working title for the project was the ‘Cracklephone’, since it’s a combination of the Cracklebox and a Stylophone Beatbox.  I liked the look of the blue parrot stickers, and it sounds very reminiscent of a parrot, so it acquired its nickname – also a reference to Sydney Greenstreet’s bar in Casablanca.

Sound files to follow

The Big Boy – Mod 4

[Edit: the BigBoy, alas, is no more!  I irreparably damaged the  circuit . . . but now it lives on in the BigBoy Beatbox, which is described here].

The creation of the Big Boy came about as the result of the blindingly simple, though ultimately pointless idea of transplanting the workings of a Stylophone into the body of a Stylophone Beatbox.

I had a number of broken donor Beatboxes, and proceeded to dismantle one of these.  There are 12 ‘keys’ on the circular board, laid out in a similar way to piano keys, or the keys of a Stylophone, so one octave was available.  I decided there should be three octaves, so had two challenges: one, to connect the Beatbox keyboard to the Stylophone keyboard; two, to add switches to change octaves.

Connecting the two boards together proved fairly simple.  FirstIy I had to saw off the end of the Stylophone board to make it fit into the Beatbox case, and although this made it impossible to use the higher notes, there were still at least 12 left.  So I used the lowest 12 keys, soldering one end of a wire to the middle of each key on the Stylophone board, and the other end of the wire to the connection on the edge of the Beatbox board for the appropriate key.  It was easy to see which key on the Beatbox board led to which connection on the edge.

There are also two built-in switches on the main Beatbox board, operated by depressing either side of a plastic ring around the keys.  I also made connections to these, for later use.

The existing on/off switch was used, with its associated LED, and the space taken by the 3 way slide switch used for selecting the drum, bass or vocal beatbox modes was used for the Stylophone 3 way tone switch.  The Beatbox stylus was attached to the place on the Stylophone output board where the Stylophone stylus had been attached.

I carefully removed the Stylophone tuning pot and used it to replace the Beatbox tuning pot on the small board which is attached to the inside of the base of the Beatbox.  One end terminal of the pot was attached by a wire to the place it was originally attached to on the Stylophone board; the centre terminal was connected to +V at the same place on the Stylophone output board as the stylus, via a series of preset potentiometers, as described below.

The preset potentiometers were designed to produce the three octaves.  If there had been room for a 3 way rotary switch in the body of the Beatbox, this would have been simple.  But there wasn’t.  There was room for a three way miniature toggle switch of the ON-OFF-ON type, so I decided to use one of these.

With a simple 3 way switch, it would just have required three presets, each adjusted to produce the same note in different octaves; but with the 3 way toggle it required the middle terminal to be permanently connected, and the other two pins – representing the switch in the ‘up’ or ‘down’ position – to be in parallel with the middle terminal resistor.  This proved quite complicated, and many adjustments were required before the 3 octaves became available.  The Stylophone functions in such a way that the lower the resistance, the higher the pitch.  As the rule about two resistors in parallel means that their combined resistance is always lower then the resistance of the lowest of the two, the middle position had to be the lowest octave, and the ‘up’ and ‘down’ positions had to be two octaves higher and one octave higher, respectively.

The integral switches on the board, operated by the plastic ring, duplicated the function of the toggle switch, allowing for momentary octave changes when either the left or right switch was depressed – this only really worked when the toggle switch was in the middle, ‘off’, position, but that was the most practical setting for most uses, I found.

An extra 10k resistor had to be placed in series with the stylus connection, to ensure that the correct pitch could be achieved with the tuning pot roughly in the centre of its travel.

How I started

I’m writing this Blog to document some work I’ve been doing in the field of electronic music-making.

I wasn’t an expert in any of these things before I started – and I’m probably not an expert in any of them now, but I’ve learned a lot as I’ve gone on, and I hope if I can pass it on it’ll be a source of interest and in some small way an inspiration to others who are getting involved in this field

When I began thinking about this project I decided to do it in the following way:

a).  To avoid working with computers (until the very end).

I’d used computers extensively in my music before, from Logic for straightforward composed pieces to a variety of other programs for electronic composition or sound treatment.  I expected to return to using the computer in the end, but with the benefit – hopefully – of new knowledge and new sound devices.

b).  To incorporate where relevant some projects I’d started, and mostly not finished, many years ago.

I’d made some guitar effects with a degree of success that could be described as ‘mixed’ – some of them I use to this day, which work very well and can’t or don’t need to be replaced by anything new; some are still around, not quite working the way they were intended to; some never worked at all!

So I decided not to go back to guitar effects, but to concentrate on sound producing devices.

c).  To explore certain specific ‘movements’ in electronic sound-producing, such as ‘circuit bending’ and ‘Lunetta’ devices, and construct some of the ‘classic’ designs along the way.

d).  To explore alternative methods of music input – isomorphic keyboards, game controllers, and other home made devices.

One of the intentions behind this was to create music in more of an informal and  ‘live’ way than I had done using the computer; another was to explore the variety of music- and noise-producing devices now available – usually cheaply in sales, second-hand shops and on eBay.

I also wanted to pursue my obsession with the Stylophone, an early electronic synthesiser of the late 60’s and early 70’s, but recently reintroduced.

I’ve divided the different parts of the project into the following categories:

1.  Modification

In this first phase I would take existing devices and add new features, or expand existing ones.

My principle in doing this was understanding the circuits (to a certain degree) and making appropriate changes to produce specific effects.

2.  Construction

Phase 2 was to build a number of sound-producing devices from scratch, using circuit diagrams and descriptions from books and magazines (I had a number of these collected over the years, and hand-drawn circuits copied from publications in libraries) and from the internet.

Again, a certain amount of understanding of the principles of the circuits would be necessary.

3.  Circuit Bending

In this phase the idea was to take existing electronic instruments – children’s toys mostly – and make them produce sounds they were never intended to produce, mostly without worrying too much about the circuits that produced these sounds and how they were working, which I felt was more within the spirit of the enterprise.

4.  Freeform designs

The intention then was to extend the knowledge gained in previous phases to create new designs, partly modified, partly constructed, incorporating past ideas I had had, but never put into practice and new ideas discovered through experimentation.

5.  Software/MIDI

This phase was to be mainly computer-based, involving programming, which I had not done before.

As it turned out, I was overtaken by events, and parallel with the Modification and Construction, have got involved in some slightly different areas.  However, I’ll write about each of my projects in order, and put them in the appropriate category.