Hackoustic . London

The Frame has somewhat always been a core project we've been developing for sometime. The objective was very simple; to be able to hear and listen to any ( or at least most ) physical objects. In the photographed contraption, any object hung in the frame can be heard via headphones. An enthusiastic listener can hang any object she/he likes to listen to.

It is indeed simply built, and uses Piezo discs picked up from Maplins to transduce the sounds of the objects. As in the spirit of DIY and Hackspaces, we hung an old used circular Saw blade, and a rafter's square - both of which sound absolutely sublime. It was great to witness people from all ages appreciate what otherwise could be dangerous, or just extremely boring ordinary objects.

It is unfortunate our sound recordings of the event were corrupted, below is the only recording that survived. Admirably, it is the sound of the relays and solenoids used in the glockenspiel photographed below, plus the ambient sounds of the Maker Faire!

Introducing the Automatic Glockenspiel; a generous number of relays and solenoids; meticulously controlled instrument by the computer. A precise glockenspiel, which can achieve lightning fast play speeds, otherwise unachievable by the mere average human being. We're no longer needed to play anything, let the machines rule! We've filmed this in previous posts if you want to have a look. More info. and possibly tutorials on how this works soon. We're very excited to try this on other instruments as well :).

It was amazing to participate in such an energetic event. The feedback we received was incredibly reinvigorating, and an essential source of energy for all of us to take into an exciting new year. This will help us take our projects and objectives to new heights.

We're very thrilled to end this year on such a high note. Our next meetup will be on Sunday 25th January 2015 7pm at the London Hackspace. We're looking forward to the new year, and the adventures that await us.

Best Wishes this Christmas.

Any queries, please email [email protected]

Unpredictability has always been a thrilling aspect of our meetups, as the tone of the meeting widely varies between one to another. In this one, we've have somehow managed to create an ideal environment for experimentation and true self-expression.

This meetup, we had the pleasure of meeting Gervais Currie; an instrument repair expert at Portobello Music. Gervais has been repairing amplifiers, fixing instruments and installing pickups for over 20 years [ link ].

To summarise, here are some tips and the most discussed points of the evening:

When designing a pickup system for a stringed and bridged instrument, use two Piezo discs instead of one. One is placed under the bridge and another is placed over the bridge. The two Piezo Discs must be wired in the same polarity (to avoid phase cancellation). This would provide an extra 6dB of gain, and among other benefits this can be used as a ‘differential’ setup as described here [ Wikipedia ]

The famous Panasonic WM-61A capsules have been very well known all over the internet, and you don’t have to dig deep to find out why. These beautiful little omnidirectional electret condensers have brilliant flat frequency response [ as claimed in the datasheet ], cheap as chips [ eBay ], and their tiny size factor means you can make them fit virtually anywhere.

The main idea is to use one of these capsules to mount directly onto the top plate of an instrument, in this case Gervais’s Banjo, and here this tiny creature really comes alive.

These capsules obviously have to be phantom powered or plugin powered ( Here is an example of such setup on Wildlife Sound ) – if you don’t have a mixer with phantom power. Although among us, we have yet to test these out.

Note, most handheld recorders provide Plugin Power.

The Art of Electronics is highly recommended [ Buy ]

Class D Amplifiers crept up in our discussions, and the reason is because they don’t require much power, and are very musical sounding. Therefore they would make for a great portable general purpose amplifier for use on the go.

If interested in reading, here are Class D Amplifiers explained in Detail [ Link ]

Vaguely touched on what’s called ‘Acoustic Transformers’ which deals almost exclusively with matching ‘Acoustical Impedance’ rather than Electronic Impedance. This can take the form of for example, a horn [ Horn Loudspeakers and Acoustic Impedance ].

If interested, have a read this Audio Express Horn Theory Paper from our resources folder [ link ].

Gervais recommended to trace Harvey Gerst’s tips around the internet for thorough understanding of the technology and history of microphones. [ his profile ] Harvey Gerst has 50+ years of experience as a gold record songwriter, studio musician, recording engineer, producer, musical instrument designer, and manufacturer.

Make sure to browse the stickies by Harvey Gerst on the Home Recording Forum [ link here ].

These photographs mark the end of this megapost. Warm thanks to everyone who attended, and our special guest for making this meetup truly fun memorable. This one has definitely been the most 'musical' meetup we've had!

We’re encouraging people to participate in our friendly discussions on our own forums [ link ]. Hop over there, and you can click join to enter the Acoustic Hacking circle, and you’d also receive latest updates of our discussions. We’re also constantly adding resources such as papers and links to the Goodies Folder, so have a browse if you fancy doing some general research or even solve some mathematic equations [ link ].

Join us next time on Sunday 28th September 2014 7 pm at the London Hackspace. Agenda will be uploaded soon! See you.

Any queries, please email [email protected]

Follow us on Twitter, and Soundcloud

Browse through our Youtube Playlist for a summary of all the instruments presented.

At the core of this visually-stunning instrument is the pickup coil. This beautiful structure is essentially a transformer, being used here to pickup the changing magnetic field of the stretched steel springs.

There is definitely a certain aesthetic to how these instruments are made. It is just pure eye candy! And regarding craftsmanship, there is a meticulous level of attention to some details, and some rather simple and unique solutions to making instruments such as using brackets and bolts to mount strings.

Here demonstrated is the ceremony of christening and welcoming a new member to the group. Inspired by the old string telephone trick, the same principle can be applied to listening to things such as our favorite of all blades - the circular saw blade. You can hear what they're hearing if you listen through our soundcloud playlist.

Messiness is great...

Because you've reached near the end of the post, you'll get a little news treat. We're currently working on a collaborative project, and part of a new plan, there are ideas for a make day. It won't be a day, more like few hours, where we present big ideas in small packages. The design of the ideas will be from combination of other artists, instrument makers and ours. We'll hopefully arrange these soon.

And we continue discussing bowls and saw blades, which do seem to becoming a major fascination among us. In fact, we're dedicating 13th July to a saw blade frenzy, anyone is welcome to join. If you happen to have any saw blades lying around, please don't hesitate to bring them along.

Dates of next meetups

Sun 13th July 12 pm - Saw blade Frenzy Make Day (Still to be confirmed)

Sun 27th July 7 pm - Usual meetup time

Note: I've uploaded some books and papers in the Goodies Folder. These may look incredibly technical and daunting at a glance, but they are great sources and amazing ideas, so check them out.

Any enquiries, please email [email protected]

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.

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.

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!

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.

In line with his project, there was a sparking interest around various coil designs, such as the ones used as transducers i.e. in speakers. Below you can see what’s called a Tesla Coil (which I wound myself) being used to resonate the bowl, physically changing its shape as a result.

Along with this, as you can see below, we continued from previous meeting messing with motors. Below you can Arduino to PWM control motor to produce tones, and also an amplifier driving a gentle sine wave into a motor. Steel blades sound amazing.

Announcements

We now have our little temporary blog, which will probably at some point turn to a proper website. Everything from updates, announcements, information about future meetings as well as contact info, etc… will be posted here as well as the LHS Thread. Name of the blog is also still undecided, if you've got an idea, send it through.

Another thing, Acoustic Hacking will be permanently on the last Sunday of each month at 7pm. This means next meeting will be:

Sun 25th May 7pm

If this is not the greatest time for you or have other ideas, please do contact me or Tim. Agenda for next meeting will be up soon. Again, huge thanks for Kevin and everyone who attended this time.

Join us in next meeting,