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Month: May 2014

Tony Hardie-Bick: Sun 25th May 2014

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Last meeting on Sun 25th marks one of our most successful meetings yet. It was overwhelming to witness such great attendance, with such a variety of people from different practices, ranging from visual artists and musicians to engineers and product designers. Below is an excerpt of the discussions that took place.

piezo impedance

Piezos are an essential tool to pick up surface vibrations, and here at Acoustic Hacking, we love them for their abundant availability, simplicity and versatility in a wide array of applications. As you can see, this simple circuit [drawn by Tony, a guest practitioner], may be needed to remove the ‘tinny’ sound, an issue commonly associated with piezo discs. The piezo-electric material has very high impedance, and this circuit is designed to match the impedance to mic level input on your mixer or audio interface.

Another tip is to use a shielded cable, to further prevent hum or electromagnetic interference being picked up along the cable.

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Other discussions included how to design a ball for the blind. Some example of such a device/ball are photographed above, sitting on the table. The idea is to design a highly resonant structure embedded at the core of the foam ball. This structure can either be activated by movement of the ball, or possibly the vortexes of air can be harvested through the crevices of the ball to vibrate this ‘strucutre’; much like a whistle — example of whistle footballs commercially available.

watkins_copicat_modified

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Hacked Watkins Copicat Tape Echo by Tony Hardie-Bick

Quoting Tony from an email:

The machine is a Watkins Copicat Tape Echo, made in the 1970s and 80s, there were a number of slightly different designs, some with valves, some with variable tape speed, some using op-amps etc. My modification was to put the four playback heads at non-equal time differences along the tape, and to put two of them on a separate channel, to get an uneven stereo echo, which builds to create complex distorting stereo textures.

The thing that’s perhaps interesting, electro-acoustically, is the piezo mic on the tape arm, which picks up the sound of wheel-scratching and actual physical tape hiss, which can then be mixed in with the main signal, or just use on its own so the thing becomes an instrument in its own right.

The piezo idea was prompted by a performance in Vienna in 2011 by Martin Blazicek and Andras Blazsek. The performance can be viewed here.

Also I wanted to share this link as part of the discussion. This is Michael Vorveld, from Berlin, who I also saw in Vienna. He uses light bulbs in series with bimetallic strips to generate performances like this.

I think the sound also comes from piezos, picking up the vibrations from the bimetallic strips as they switch on and off.

The concept of using bimetallic strips is very interesting and unexplored, possibility to look into this in future workshops!

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Again, huge thanks for the people who attended and contributed to the workshop this time. Please stay tuned here for an updated agenda for next meeting, and possibly another guest practitioner. The meetings are held last Sunday of the month, so ext meeting is going to be on:

June 29th 2014 at 7pm

It is a possibility workshops might be arranged in between those meetings, those will involve more making! this will also depend on people’s desires.

Any enquiries, please email acoustichacking@gmail.com