Modifying a Russian EX Big Muff π with a Switching Power Input Socket

I was  recently asked by a friend to modify their old-school Russian Electro-Harmonix Big Muff π, with a standard 2.1mm, switching, DC power input socket (often known as a ”Boss style” power jack), for use with a 9v battery. It was a fairly straight forward job, but I thought I would do a short blog post about it, as knowing how to add a DC input socket is super useful for a whole range of projects. These DC sockets let you switch automatically between battery and adaptor use, while conserving the battery when the adaptor, is plugged in.

Before we go through the mod, let me say something about safety

This project and modification are designed only to be used with the standard 2.1mm ”Boss Style” switching DC input socket that takes a 9v, centre negative DC power adaptor. 

Power from the mains AC power supply (the electricity from the plug in the wall) WILL, AND WANTS, TO KILL YOU.  Never mess with anything that plugs into a wall socket unless you are 100% confident with the power adaptor, that you know what you are doing, and the circuit you are working on.  Absolutely NEVER mess with a device WHEN IT’S PLUGGED INTO the wall.  Please be careful, and always put your and others’ safety first.


Now… let’s take a look at the layout of the 2.1mm DC input socket:

Pinout for the 2.1mm DC power socket showing the lug numbering.
Pinout for the 2.1mm switching DC power (”Boss Style”) input socket, showing the lug numbering.
Top view of the 2.1mm DC power socket showing pinout
Top view photo of the 2.1mm switching DC power (”Boss Style) input socket, showing pinout
Side view of the 2.1mm DC power socket showing pinout
Side view photo of the 2.1mm switching DC power (”Boss Style) input socket, showing pinout


Lug 1 – Ground (All ground connections)

Lug 2 – Power (From battery)

Lug 3 – Power (To board)


BE VERY CAREFUL- Check, double check, and triple check  your soldering and the pinout of the socket before connecting a power adaptor, or you risk frying your board. 

When running on battery, lugs 2 & 3 are connected. When a power adaptor jack is plugged in, the connection between the lugs is broken, saving the battery, and power is only drawn from the adaptor via lug 3.


So here is how the mod went:

1. I opened up the Russian Big Muff:

Russian Pots!
Russian Pots!


2. I drilled a 12mm hole for the DC socket. The metal is steel and quite tough but I managed to get through it:

Fresh hole for the socket
Fresh hole for the socket


3. The old 9v battery snap was broken so I’m gonna use a new one:

Old battery snap not looking very healthy.
Old battery snap not looking very healthy.


4. I inserted the DC Socket:

DC Socket in place.
DC Socket in place.


5. I then soldered the black wire from the new battery snap and the black wire from the old battery snap (that was still connected to the board) to lug 1 on the socket:

N.B. if there wasn’t already a wire soldered to the board (from the old battery snap), I would have had to add one from lug 1 to a ground point on the board).

Using the old wire coming from the board meant I didn't have to touch the board (always a good thing!)
Using the old wire coming from the board meant I didn’t have to touch the board (always a good thing!)


6. Then I soldered the red wire from the new battery snap to lug 2 on the socket:

The red wire from the new battery snap.
The red wire from the new battery snap.


7. The red wire from the old battery snap was still connected to the board so I soldered it directly to lug 3 on the socket (I also added a small piece of insulating mounting tape to prevent the lugs accidentally touching the board):

This red wire in lug 3 will take power from the adaptor to the board
This red wire in lug 3 will take power from the adaptor to the board.


8. Finally I remounted the board, and added a fresh battery:



The enclosure has been screwed back together and a fresh battery added.
The enclosure has been screwed back together and a fresh battery added.


9. And here she is working away:

It's alive!
It’s alive!


– Thom Conaty

Xth Sense – An Interactive Biophysical Instrument Based on Free, Open-Source Tools.

Last year, Italian native and Edinburgh-based sound artist, performer and researcher Marco Donnaruma launched the Xth Sense, an instrument composed of an “original, biophysical interactive system based on free, open source tools.” The public launch generated considerable hype within the DIY/Noise scene, having won first prize in the prestigious Margaret Guthman Musical Instrument Competition as the “world’s most innovative new musical instrument”. Donnarumma subsequently performed, workshopped and showcased his instrument in Edinburgh and also notably at LEAP (Lab for Electronic Arts and Performance) in Berlin.

It was in Berlin that I had an opportunity to have a first-hand experience of the device and its use in performance. Initially I was not blown away, partly due to my overexposure at the time to so many of these quirky biologically-based noise performances, all of which began after a while to produce repetitive and indistinguishable sounds to my tired ears. However the Xth Sense has since set itself apart from all the other instruments I was hearing, and it has steadily crept up again and again in my own reflections on music and sound. I believe that once one takes into full consideration what it is this instrument does and how it manages to do it, it reveals itself as an innovation that is not merely a gimmick. It has such boundless potential, relevant to so many different fields of practice, that I am surprised that the hype around it seems to have subsided. It strikes me as wasteful that I have yet to see it being extensively written about or utilised in performance.

But what exactly is the Xth Sense? Describing the Xth Sense is quite difficult, in particular for someone with as limited a technological know-how as myself. In an interview with Peter Kirn for, (which I thoroughly suggest reading) Donnarumma describes it as “a biophysical framework for musical performance and responsive milieux.” Peter Kirn adds, “In other words, it is a technology that extends some intrinsic sonic capabilities of the human body through a computer system that senses the physical energy released by muscle tissues.”

The Xth Sense is comprised of small, wearable biosensors (which sounds expensive but surprisingly is not so in the slightest) and a free and open Pure Data based application that captures, analyses, processes and plays back, all in real-time, the actual sound that human muscles make. The sounds that our vibrating muscle tissues make, called MMG (Mechanomyographic signal), are normally not audible to the human ear, yet the Xth Sense picks up these sound waves and amplify them. “By differently contracting muscles one can create and sculpt musical material in real-time. One can design a specific gesture that produces a specific sonic result, what I call a sound-gesture. These can be composed in a score, or improvised, or also improvised on a more or less fixed score.”

The Xth Sense in action.
The Xth Sense in action.

If you have grasped the basic process, and if you have watched the video of Donnarumma performing with the Xth Sense (see above) you will probably, like myself, already have the distinct impression of something intrinsically incredible, almost unbelievable occurring. Part of my initial underwhelmed response when I first heard about it and saw it performed during my time at LEAP had to with my silent assumption that I had misunderstood the process. What I thought I was seeing and what seemed to be creating the sound experience seemed too implausible. This almost sci-fi effect was heightened by how controlled Donnarumma’s execution of the piece was, how little sloppiness and pure chance was involved, and how un-invasive the physical aspects of the instrument were on the performer and the spectators. This allowed Donnarumma to contort and control his muscles like an elegant, futuristic sorcerer.

What has sparked my profound fascination with this instrument is not so much what it does on a technical level, but rather how it contributes to the more conceptual queries of electronic music making. The major importance of the Xth sense is its involvement with the ongoing question of making performable and expressive music with computers. At the heart of endeavours such as the Xth Sense is the drive to retain the expressiveness of physical performance and the tangible presence of the human body during the processes of recoding, in order to produce an amplified, processed sound that is similarly engaging to live performance where the sound and action that produces it are more directly correlated.The problem facing these processes is primarily the way in which the conversion acts like a filtering process through which the unique, material attributes of the bodily functions are caught within the symbolic grid of code. As Donnarumma puts it, “the recoding of the complex patterns and unpredictable textures of human experience into a bundle of organized algorithms, is a rather difficult task, for it puts at stake the true meaning of human expressivity.” The Xth Sense system avoids this pitfall to a great extent by virtue of the provenance of the musical material of this instrument created from organic sound waves within the “fibres of the body”, moulded and structured primarily through the “energy released by the performer”.

It is this last point that personally excites me most of all. Here, expression and the subsequent affects created in the performers and spectators are determined almost entirely by the process of exertion. One can of course argue that this is always the case, that the creation of sound and music always entails a physical application of energy. True, yet by using the Xth Sense, this exertion of expression is literalised, placed as both the source and the outcome of the sound-experience. For this reason in particular I imagine the Xth Sense as a highly potent tool of experimentation, in particular within certain contemporary techno and noise hybrids. Seeing the Xth Sense employed in such a setting would appear to me as the next logical step in a musical field such as techno. The ever-increasing popularity of techno, in its grounding in and celebration of our own physical presence and experience, can be partially attributed to its cathartic relief from our everyday position of alienation from our own bodies. Through techno music, and also through such instruments as the Xth Sense, the body is no longer just an image, a representation, but rather becomes foregrounded as a bundle of fragmentary experiences, and revels in this. In the way we tend to dance to techno and in the way Donnarumma performs with the Xth Sense we can already note this.

I recently came across something that German sociologist and performance theorist Gabriele Klein wrote about dancing to techno music, that I feel can also reveal the latent but crucial potential of such instruments like the XS; “this music [techno] forces the audience to live out its own emotions and affects, its aggressions and fears in the act of dancing collectively. The endless tracks offer not a processing or reprocessing of these anxieties, but an eradication primarily through physical exertion.” Of course, the Xth Sense alone does not allow the performer to make music to dance to, in particular not to such an ecstatic extent as techno music does. Yet as an added component to such productions it seems to make perfect sense to me through its raw immediacy, by placing the primacy of the music on the human body. Already techno-producers such as Regis can be seen employing live-feedback from his own skin within his sets, and surely it must only be a matter of time before these artists delve deeper into using real-time biological sound sources as material to engage viscerally with their audience.

However, this is just my interpretation and how I would like to see the Xth Sense employed. It is the avowed subjection to interpretation and manipulation that is the final fundamental intrigue of the Xth Sense. Unlike other producers of such Hi-Tech devices, the Xth Sense does not force its functionality onto the user. The source code, schematics and tutorials are all online for free, with DIY Kits available, and it is this which allows the user not just to use, but also to familiarise oneself with it so much that one can learn to abuseit, to hack and develop it as much as one feels the need to.

So I hope that this article has whetted your appetite for this astounding system, and if my wishes come true I’ll be seeing it performed in Dublin sometime soon; maybe in a club, by a band, in a theatre-production, by a street performer, or anywhere the new generation of DIY musicians wants to take it. 

More on the Xth Sense can be found at Marco Donnaruma’s site:

– Aran Kleebaur

Essential Reading: Handmade Electronic Music by Nicolas Collins

So you’ve seen the monome, x0xb0x, atari punk console, people making their own pedals/synths and the vast amount of interesting things to be done with the Arduino. This abundance of DIY activity has awakened a primitive beast deep down in the reptilian core of your brain. This awakening infiltrates the rest of your consciousness and suddenly you find yourself looking at videos of smug jerks with their own DIY instruments thinking, “I hate you so much. I want to make things too. F__ off with your home made modular synth. I hope you choke on it!”

If the above describes you perfectly then you may very well have some rage issues which I cannot help you with. What I can help you with is your potential hacking skills by advising you to buy a copy of “Handmade Electronic Music” by Nicolas Collins.

This book should be the foundation for anyone attempting to get into hardware hacking, electronic instrument building or any form of DIY music making. First published in 2006 (second edition 2009),  this book takes the reader from the very beginning and teaches you the fundamental rules and techniques of hacking as well as what tools and materials you will need to get started.

Collins introduces us to the fact that there is music all around us in our everyday lives. (I’m sure he would have gotten on swimmingly with John Cage if they ever met.)  In one chapter, any electrical appliance can become a source of interesting sound using just a small amplifier and a pick up coil (see video below). In another, he unlocks the hidden audio potential of credit cards and other objects that make use of electromagnetism. It is essential to be aware of unusual sources of sound when hacking and Collins lays this foundation before moving on to more advanced topics.

While on the one hand opening our eyes and minds to the untapped musical potential of our surrounding environment, Collins importantly takes time out to explain essential hacking skills such as soldering (without which you won’t get very far), finding the clock circuit in hackable toys (and subsequently how to mess with said clock to produce cool sounds), how to understand different types of switches, how to power and package a hacked toy, how to take an idea from breadboard to circuit board and how to put the finishing touches to a completed project. You will also learn some very useful theory such as Ohm’s Law which is explained very simply and clearly.

One of the best aspects of the book is that it was written with the musician/composer in mind rather than the electronic engineer. This means that any possibly confusing principles or technical jargon are explained thoroughly and are related directly to the projects that comprise much of this book. (Speaking of the projects, there is also a DVD that accompanies the text with 13 video tutorials (also on YouTube), 87 video clips and 20 audio tracks from an international array of hackers, musicians and artists.) These projects include making your own condenser mic, pseudo-theremin, analog to digital converter, animated dagguerreotype, digital to analog converter and even a small power amplifier.

Another thing I really like about this book is that Collins relates each topic and chapter to artists and musicians that make use of DIY principles and techniques in their work. He also places everything into context with historical anecdotes detailing the progression of the technology he is talking about.

I can’t recommend this book enough for anyone interested in DIY music making. The only difficulty I can see people having with this book is the sourcing of the components for each project. Appendix A goes through some resources but because Collins is resident in the USA they are mainly based across the pond. The only source he lists that would be applicable to Irish or UK hackers is Maplins (which would probably be my last choice of supplier due to ridiculously high prices). A good source for components in small consumer quantities is Bits Box which is based in the UK.

Without a doubt, this book will give you the know-how and skills necessary to confidently attempt to make any demented contraption you can think of and is the perfect introduction to the art of hardware hacking.

Bryan Dunphy

Introducing: Jeri Ellsworth

Today I would like to introduce you to the queen of DIY electronics. Her name is Jeri Ellsworth. She has done many amazing things in her career as an entrepreneur, self-taught computer chip designer and all round DIY hacking legend.

Her interest in electronics began when she taught herself how to program using manuals from the Commodore 64. By the time she was in high school, she was designing, making and selling dirt-track race cars. From the age of 21 she ran her own computer repair shop before selling up in the early 2000’s.

In 2004 she went on to develope the extremely popular C64 Direct to TV .This ingenious device is a Commodore 64 within a single joystick that contains 30 games from the 80’s. As documented in the Lifehacker article where she was named MacGyver of the Day, she impressively reverse engineered the Commodore 64 using an FPGA (field-programmable gate array). If this wasn’t impressive enough, she did it all from this photo.
Other interesting projects and hacks include a 52-inch Etch-A-Sketch, Nintendo Purse, DIY Pinball Machine and a C64 Bass Guitar.

I will leave you now with some sage advice straight from Ms. Ellsworth that will keep you in good stead when traversing the often intimidating world of DIY electronics.

by Bryan Dunphy