Duophonic pickup

duophnic pickup diagram.jpgThe standard electric guitar is polyphonic, but the pickup ultimately sums all the notes down to a single output – which can be limiting as strings can’t be processed individually.

One solution was to create a 2 voice pickup that could split the outputs of the top and bottom 3 strings. Here’s a potential use case : a portable one-man band setup with a 2 voice instrument around the guitar which would allow a guitarist to process their strings individually to play bass register notes and normal guitar notes at the same time. When combined with hybrid picking styles (a la Martin Carthy and Chet Atkins), an octave pedal and some careful chord fingerings, it would be possible to play the simultaneous lead and bass lines.

This could be achieved with a fairly simple setup – two pickups, each amplifying only 3 strings of the guitar. Check out more about it on our post at Banana Apparatus

DIY Guitar Effects – 2

After a few months of work (and plenty of distractions), I have finally got a few working pedal prototypes going.

They are:

  • The Trishul Dirt box: a switchable boost/OD followed by an option of 3 fuzz circuits
  • Craig Anderton’s Dual Voice Filter – built from a musikding kit, this contains two bandpass filters at a low and high frequency range. My plan was to mod it to act as a wah pedal, but the sweep doesn’t reseemble an actual wah.
  • The Clari(not) – an awesomely fun envelope controlled delay/modulation box
  • The Envelope Filter from outer Space: Based off an MFOS design, I modded it to add sidechain input, a resonance knob and a band pass option (nicer for guitar). It’s more fully featured now, but could still use controls for attack as well as an overall gain knob (it’s really loud right now).

Here is a video showing as much of the pedals as I could in 40 seconds:

Banana apparati

A post shared by Saurabh Levin (@saurabhlevin) on


And another demonstrating the sidechain input of the Envelope filter. I’m using a volca beats to control the sweep of the bandpass filter:



DIY Guitar effects

For a while now, I’ve been obsessing over a (mostly) DIY music setup. The first step was to build a set of effects and studio tools for my guitar. Here are the circuits I’ve got up and running so far:

  • Fuzz factory.
  • One knob dirt boxes – Ritual Black Fuzz  + EQD Speaker Cranker + EQD acapulco Gold
  • Envelope following low pass filter
  • Clari(not) noise delay
  • Dual Voice Filter – two band pass filters + distortion for a cocked wah effect
  • A Phase 90 clone
  • BA328 based equalizer
  • Engineer’s thumb Compressor (still needs some troubleshooting)
  • A patchbay + signal splitter/mixer

It isn’t easy to find hammond enclosures cheaply in India, so I’m trying to think of an alternative ….maybe a eurorack-ish format with aluminium plates sitting between railings. That way I could add and remove modules as needed.

For now they sit in plastic electrical boxes that can be found in most hardware stores.

Here is a video of a few of the effects:


Katari Punk Console

This here’s the Katari, or the kit version of the Atari Punk console that I helped put together while at ISRO. It’s based on the Atari Punk Console and aimed at being used for workshops for electronics and noise making. (http://www.jameco.com/Jameco/PressRoom/punk.html?CID=punk). It’s more or less the same design, just housed in little electrical boxes you can find for 20rs or so. We added 2 light detecting resistors to make it a little more interactive and fun, as well as switches to select between the different controls. It’s a gloriously noisy little thing.

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kit version

Modded Voice Looping toy

A friend got this fun voice looping toy from the souvenir shop at MoMA that lets you record 3 second long clips and play them back. It has a pitch/speed shifting dial, which is fun, but it does lack one or two features that could make it pretty usable. To remedy that, I added an option for line out, and a toggle switch instead of the pushbutton, so that it could play back a given loop infinitely. Here’s a quick test of the same:

Gear: Hacked MoMA voice box-> MXR Blue Box-> Digitech hardwire looper

Career Fair workshop

Last week, Arun and I did a workshop at a career fair for ITI graduates, which took place at Freedom Park (Bangalore). It was organized by Quest Alliance, an NGO that works with Design in Education mainly with students from ITI’s (Industrial Training Institutes). ITI’s are government-run colleges that provide students with the basic skills to do the job of, say, an operator or craftsman.

As with any other engineering institutes, ITI’s (or any institute, for that matter) are plagued by the usual issues of teaching being imparted soullessly, as a means to a lievelihood, and without any idea of individuality of the student. After initial ideas flitting around doing an arduino workshop with them where they’d learn the necessary skills of using the arduino environment and basic prototyping techniques, we decided we weren’t quite experts in the field ourselves, and tried a new track.

We decided to focus on introducing them to open-source projects and doing innovative and fun things with low-cost alternatives. It seemed more valuable to show them the available possibilities of DIY tech, for us as well as them….seeing that this was our first time taking a workshop like this, it didn’t make sense to go in acting like we knew what was going to come out of it. Anyway, here’s a summary of what happened:

We began with a simple demonstration of the DIY webcam microscope, as a sort of icebreaker. It got their attention, but the number of times I practised that routine beforehand made the sensor get all foggy, which did dampen its impact somewhat. After seeing a couple of fuzzy pixels on my laptop screen, we progressed to showing them some stuff we’ve worked on as Ternup, from our low-cost water testing kit (Caddisfly), and the simple colour sensor hack we based it on, to our DIY rain gauge using piezo discs as contact microphones, just to give an idea of some basic technology that could make a difference if just used a little differently. They seemed pretty intrigued by the contact mics, as they associated the parts with the buzzers that are usually found in toys and greeting cards .

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Since we had finally segued into the topic of making a potential racket, it was time to get down to making synths.

We had a bunch of students who had no idea about electronics, so we skipped most of the techy bits of the presentation, and had them try to make the arduino synth – the Auduino. The circuitry required to set it up is extremely basic, just a few pots and wires (the fun stuff happens in the code) so they managed to connect it up fairly quickly and listen to their instruments as well (they seemed to be in a  hurry to be elsewhere).


We gave the to-be-engineers (who had done soldering, and were used to working with breadboards and building basic circuits) an analogue synth called the Atari Punk Console. It’s pretty easy to make, although not simple enough for the two hour long session we had. I forgot that, as with any other circuit, it required approximately the same amount of time to troubleshoot it as to make it.

Atari Punk Console

They did get a few wheezy squeaks out of the badly grounded circuit, though. At the end of it a couple of them came up and asked me to give them the circuit diagrams so they could try making it at home.

Anyhow, they left mostly without the expression that we had irreplacably stolen 2 hours of their life, so I guess that went well. For a first workshop along these lines for either of us, perhaps more so.