Occasionally you stumble across a problem that's absurdly simple, and seemingly easily solved, but turns out to be really difficult to solve. Point in case: For our live setup, one of the keyboard players in my band plays my MIDI'd Prophet-5 along with an Alesis Ion. One really annoying detail of the Ion is that it's really a bitch to change patches quickly on it (before you write and tell us how incompetent we are, try doing it in the roughly one second time period between a verse and a chorus, while continuing to play something with your other hand). You can either hit one of the tiny, poorly located, poorly labled up/down buttons, or you can take your chances with the inc/dec knob and hope you don't overshoot it by turning it too far. Now, the humble Prophet-5 has eight BIG, LED-lit program select buttons right by the keyboard that you CAN'T miss- much better.

Since the Ion has no shortage of program memory slots, I thought it would be a much better plan to use the Prophet as a sort of "master" program selector, and duplicate programs where necessary. This seemed like a genius idea until I plugged a MIDI cable from the Prophet's MIDI out to the Ion's MIDI input. The program change messages certainly worked, albeit not on a one-to-one basis, but that didn't matter since the Ion has 512 program locations. The real problem, can I get a DUH!, is that setting them both on the same MIDI channel not only duplicates program changes, but it also causes notes played on the Prophet to play on the Ion as well. Which is six flavors of no good, because layered synth patches ain't what we're after. After a fairly large amount of experimentation and Ion manual perusal, I concluded that the only way to make the Ion ignore MIDI note on/off messages was to change MIDI channels, and then it'll ignore programs changes too, thereby defeating the purpose. I figured there had to be some sort of external filter device that would let me filter note on/off messages, but still allow program change data through. Here's what I discovered: • Digital Music Corp MX-8 This is a deep MIDI-routing/patchbay device in a 1U rack. Would work, but way too complicated and an extra 19" rack just for this one function was way too much hassle. • Yamaha MEP4 Same problem as above- 19" rack unit. • MIDI Solutions Event Processor All purpose MIDI processor/filter. Little. Just what the doctor ordered! $149! Too much money, forget it! • Anatek Pocket Filter Simple wee MIDI filter with DIP-switch selectable filtering, MIDI-bus powered. Really really what the doctor ordered. Trouble is, Anatek folded years ago, and I couldn't find one. Damn. So... more research pointed me at various DIY Arduino-based solutions (that's a sort of DIY community software/hardware standard). That would be ok, but the only programming skillz I have to have to with drum machines and VCR's, not BASIC and C+. Finally, I happened upon the web page of one Tom Scarff. Tom sells cool little Miduino kits with ATmega168 processors pre-programmed to do various MIDI functions (they have pins for USB interfaces to allow adventerous types to re-program them, and I believe it's all open source code). Tom had kits allowing all manner of MIDI functions, but he didn't have one that would filter note on/off data as I needed. I took a wild stab and emailed Tom to see if he could help me, and sure enough he got right back to me and said he could help. Just paypal 45€... so I did. About a week later, an envelope arrived with a PCB, and a small pile of components, including two MIDI jacks. All the construction information was on the website. Since this is raw kit, i.e. a bunch of resistors, caps, diodes, etc., I don't know that I'd recommend it if you have no experience soldering things, but that said, construction was pretty easy. I happened to have an old Midiman MacMan serial MIDI interface laying around, and since I don't see serial-port Macs coming back any time soon, I sacrificed it for its case. I had to do some extra drilling for the standoffs used to mount the PCB as well as the screws for the MIDI jacks, but the size of the case was just about perfect for the PCB. I rattle-canned the top cover white just to get rid of the original graphics. The kit needs external power either in the form of a battery or DC-adaptor, but like most music nerds, I have a pile of orphaned power adaptors, and I was able to find one that worked (the Miduino kit accepts anything between 7-17 volts- you just need to insure that the polarity is correct). Once I had it all soldered together, nothing worked at all. After some headbanging I realized I had soldered one of the LED's backwards, and this was enough to prevent power from properly flowing. Once that was corrected, I had power, but still no MIDI, until I realized I had installed one of the IC's backwards. Big duh, especially since I pride myself on NEVER installing parts backwards. Lucky for me, the opto-isolator IC wasn't damaged, and once I flipped that sucker, everything worked gloriously; I could play the Prophet without triggering notes on the Ion, but program changes from the Prophet simultaneously changed programs on the Ion. Yay! Here's the funny part- as I was checking Tom's site today, I noticed he added my "note filter" as a standard product. I should get some kind of signature/product endorsement deal, right?