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Building A Bionic Sax


One of the first things that irked me about synthesizers was the fact that they were originally designed for keyboard players and keyboard players ONLY. Now, I took piano lessons for about a month like everyone else, but my main axe is alto sax. Why couldn't I play synthesizer, too?

Then it started happening. I saw a Lyricon advertised. (A Lyricon is a synthesizer with a controller that can be fingered like a sax or clarinet.) It's about time, I thought. However, when I got down to the bottom line, well, the price was a bit beyond my reach. Similar controllers came out, aiming toward brass and percussion, but again, the price wasn't in my range. Now my question was (and still is): Why can't I play the synthesizer at a reasonable cost? Of course, I bought a keyboard synthesizer eventually, and I can pick out tunes with it and make beeps and bwadn's with the electronics, but my question still nagged me, until one day...

One day I was fooling around, talking to another synthesizer user - this guy had built a percussion controller - and I presented the idea of a cheapo sax controller. He helped me out with the circuit design, and I put the thing together.

Figure 1 is the schematic for the bionic sax.

Figure 1
(Click image for higher resolution version)


I found it difficult to make a controller that could be used with linear VCO's, so I incorporated a top-octave generator chip as the built-in tone source. The two 4051 chips are multiplexer-de-multiplexers, and a description and pinout can be found in Polyphony No. 4. The nine switches change the input codes to the 4051's, and for each code a "gate" opens, letting one tone from the TOG through to the output. Only one 4051 is on at a time to prevent two notes from getting out. Figure 2 contains saxophone fingerings and the equivalent binary input codes to the 4051. The other part of the circuit is the audio portion, which is essentially identical to the TOG circuit in the Oz. It provides continuous tuning and a 5-octave switch.

The circuit can be built on perf-board and stuck in a small box, with ribbon or other cable connecting it to the sax body. Here is where problems crop up. First you need a piece of plastic pipe about 2-1/2 feet long. Carefully saw it right down the middle so it splits into two curved pieces of plastic (a bandsaw would be helpful here). Now, drill and mount the switches and tuning pot where you think they should go, or make a template from a real sax. Use calculator switches if possible. They may be hard to mount, but they're easier to play on in the long run. For the neck, I used a plastic pipe diameter reducer that has a 1-inch hole on the side, and whatever size pipe you use for the body on the other. I bent a 8-inch length of 1-inch diameter plastic pipe in the oven to match the curvature of a real sax neck, and fastened one end in the fixture. If you don't play sax and can't get a real mouthpiece, don't worry - it's mostly for the convenience of the user. Place a small microphone element (from a cassette recorder mike or something similar) in the neck near the end you blow in and drill a few holes in the neck in front of the mike to let air out. Run the mike cable through the horn and out with the rest of the cables, then fasten the two body halves together, using some sort of strong tape.

For a completely self-contained instrument, build an envelope follower-trigger (like the 2720-11) into the electronics box and use the mike as the input. Your breath against the mike will make a trigger. That, plus the audio from the sax circuit can be rim to a three-conductor plug and interfaced with the Gnome the same way the Oz can. An Oz~type battery pack (12 volts DC) can also be used to power the sax. If more versatility is desired, the sax can be interfaced with any PAIA equipment. Granted, it's not fancy, but it's a good start.

"Next time: The Bionic Trumpet"

Figure 2 - Fingering Chart



Three of the "keys" are staggered because they are on a real sax, too. Many alternate fingerings are not provided. Some fingerings produce no output, others give tones. What fingerings give what notes can be discovered by following the circuit diagram and using the appropriate input code. Depressing B, C and G simultaneously inhibits IC1 and enables IC2. NOTE: The A, B, and C inputs on the 4051 chips actually correspond to inputs 2, 1 and 0 on the pinout respectively. You may want to rearrange the codes I give to clarify matters.

Figure 3 - IC1 Coding


Figure 4 - IC2 Coding


NOTE: This chart and the one for IC2 show input coding, but not quite as well as the fingering chart. These may be useful to show alternate and special fingerings, or simply used to double-check. The notes encircled are the proper fingerings for that note. An "X" fingering gives no output.


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Polyphony - Copyright: Polyphony Publishing Company

 

Polyphony - Nov 1977

Donated & scanned by: Vesa Lahteenmaki

Feature by Greg Leslie

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