source file: mills2.txt Date: Sun, 22 Oct 1995 07:42:36 -0700 From: "John H. Chalmers" From: mclaren Subject: custom MIDI controller --- One of the biggest stumbling blocks in the path of the microtonal revolution is the lack of a generalized MIDI keyboard. If MIDI users could buy a keyboard like the one on the Secor generalized Scalatron, microtonality would take an enormous step forward. Suddenly, it would become simple and easy to perform keyboard music in 31, 19, Partch 43, Wilson 41, Secor 17, or Helmholtz 24-note tunings. Well, guess what? Now you can build your own generalized MIDI keyboard--and for less than $275! PAVO, 10. S. Front St., Philadelphia PA 19106, makes a black box to which you can hook 64 momentary normally-open switches and get MIDI notes out. What kind of switches can you use? The sky's the limit: light switches, doorbell switches, reed switches, infrared or cadmium selenide photocells, contact switches, touch switches, proximity switches, ultrasound- activated switches, moisture-activated switches, odor-activated switches...you name it. Among the ideas PAVO suggests for novel MIDI controllers: [1] sewing reed switches into your clothing and generating a MIDI composition by your movements; [2] attaching multiple photoelectric switches to various parts of a room and generating MIDI notes by shining a laser; [3] building your own custom MIDI percussion controller or keyboard. Of particular interest for folks on this forum is [3]. The PAVO MIDI computer (a black box with a 64-lead ribbon cable coming out of it and MIDI IN and MIDI OUT connectors) comes in kit form. The cost is $265 U.S. and with that you get the PROM of your choice. (PAVO black boxes can do a *lot* of things; the 64-note MIDI controller PROM is only *one* of many PROMS they offer. You can, for example, turn the black box into a "translating randomizer" merely by substituting another PROM into the ZIF socket inside the black box. In this mode the PAVO black box selectively translates one type of MIDI message into any other type of MIDI message, randomizing them within user-selected parameters entered into the front panel. However this post concerns only the 64-note custom MIDI controller EPROM, so if you want more info on the many *other* exotic applications of their MIDI computer black box, write PAVO directly. That address again: PAVO, 10. S. Front St., Philadelphia PA 19106) The limitations of the PAVO box, are to be fair, numerous: first, you're limited to 64 input switches. (If you need a 128-key controller, buy two black boxes and hook their outputs through a MIDI merge box; ditto 192-key controller, etc. At $250 per black box, this isn't all that expensive--especially compared to the *outrageous* highway-robbery cost of $2000 for a 36-pad MIDI marimba bought commerically!) Second, the switches can't be more than 25 feet from the PAVO black box (and should probably be a lot closer for reliable operation). Most limiting of all, the black box does not accept velocity information from the switches. Thus you must set the velocity of the MIDI notes either via a pot on the front panel of the black box, or by means of a MIDI controller foot pedal hooked into the data stream with a MIDI merge box. (It's possible that you might be able to wire an 8-bit A/D converter to the frame of the MIDI controller and feed it into the front pot of the PAVO black box, but since it's not part of the original design...you'd have to do it at your own risk.) All in all, these limitations are minor compared to the advantages offered by this widget. For the first time, you can build your own custom MIDI percussion setup. One of the first and most obvious applications that comes to mind would be to set up a set of plywood or pine squares in the form of a 64-note Bosanquet keyboard and attach the squares to reed or touch switches, then solder the switches to the ribbon cable leads. Plus in the black box, turn it on, and presto! You've got your own Bosqnquet-style percussion controller. This would be ideal especially for those of us you yearn to work in large JI arrays (say, Wilson 31 or 41 or 43, not to mention D'Alessandro or the hebdomekontany) with a percussion-type controller. By fitting the switch array with a DB-25 connector, one could easily disconnect one percussion controller and reconnect another one, thus allowing a performer to move within a less than minute from, say, Partch 43 to 53-tone equal temperament. Since switches are cheap (check the latest JDR MICRODEVICES catalog) and plywood or pine even cheaper, it should be a breeze to build half a dozen different percussion arrays, each suited to a given tuning. (Remember that since we're dealing with MIDI, one need only saw the pieces of wood and glue switches to 'em-- all tuning's done in the MIDI synth.) Neoprene coverings on the plywood or wooden percussion pads would help give the percussion pads a more lifelike "feel," and again it's cheap and easy. Building the PAVO black box sounds pretty simple. They offer a videotape showing the complete process (for those of you who haven't dealt with a soldering iron and a volftmeter before), as well as a diagnostic EPROM. Plug in the EPROM and it'll automatically check your solder connections, chips, glue logic, and run a test on the MIDI ins and outs as well as the 64-lead ribbon connector (via loop-through). PAVO claims that assembly of one of their black boxes takes 5-7 hours, and given the apparent simplicity of the circuitry inside their box, that sounds reasonable. It's basically nothing but an antique 6809 8-bit microprocessor with an EPROM, a kilobyte or so of static RAM and some glue logic and hex buffers to keep the inputs and outputs from fricasseeing if you accidentally hook a MIDI out to the black box's MIDI OUT. All told, this is spectacular development for those of us who burn with the bestial desire to build Bosanquet MIDI controllers! --mclaren Received: from eartha.mills.edu [144.91.3.20] by vbv40.ezh.nl with SMTP-OpenVMS via TCP/IP; Sun, 22 Oct 1995 23:59 +0100 Received: from by eartha.mills.edu via SMTP (940816.SGI.8.6.9/930416.SGI) for id OAA00139; Sun, 22 Oct 1995 14:58:49 -0700 Date: Sun, 22 Oct 1995 14:58:49 -0700 Message-Id: <951022215607_71670.2576_HHB46-1@CompuServe.COM> Errors-To: madole@ella.mills.edu Reply-To: tuning@eartha.mills.edu Originator: tuning@eartha.mills.edu Sender: tuning@eartha.mills.edu