M15 Tracking saga continued
2007-04-24 by Bryan E Cornell
From Peter Grenader: It is quite possible that the two keyboards are slightly different. ALl of them work on adjustments for settingt their ranges, all of them use trim pots to do that, all trim pots go out of adjustment from time to time. In regard to the linearity bowing you're seeing in the middle octaves with the M15 tracking - is it better than it was last time you reported? I can't address much else here till I know that. How does it track when using your ear instead of a tuner? HOw bad is it dipping out of tune? Again, use y our ear to judge - not the tuner. THey can indicate a drift, but they can't tell you if that drift is unusable or not, doesn't give a damn about 'phat', that sort of thing. The Buzzclick Music Site's Model 15 section has a downlouadable midi file you can use to check your M15. If you have a midi to CV converter. It flies thorugh eight octaves - it's quite an extrnsive test. buzzclick-music dot com As far as the tracking being different with all of your VCOs once put into the case- it sounds like you've got a PSU current limit issue going on. Makre sure the ground wire form the PSU on the case is still bolted to it's side. The MOdel 15 needs a grounded faceplate or everything will be screwey. Bryan's original post: I had a chance to play with the tracking again this weekend and the problem persists, but things have gotten very strange. First, I'll get specific: I patched the pitch CV of my Dotcom QKB15S keyboard into the M15's 1V/O input, sent the triangle through the tuner and out to the mixing board. I followed the directions for adjusting the tracking and I couldn't really get everything to track. I could never get the very top C (i.e. the sixth C) to be in tune when the lowest one was in tune, so I gave up on that and concentrated on getting the fifth octave to be in tune. This I could do. So the bottom C and five octaves higher are in tune, but now some of the C's in the middle are not in tune. Is this possible? When I mounted the module back in it's rack the 5th C was out again. It now appears that there are two problems: 1) it seems the keyboard must be calibrated weirdly, and 2) something becomes gefucked when I put the module back in the rack. I decide to address the first issue and whip out another keyboard controller (AS French Connection), but the tracking was also off on this and different notes were out of tune in comparison to the Dotcom keyboard. Shouldn't two keyboard controllers be outputting the same voltage? I then plugged both keyboards into all my other oscillators and NONE of them were tracking correctly. The oscillators were a Doepfer A110 and a Blacet Oscillator (in a different rack!) These used to be calibrated, but I imagine one has to adjust the tracking from time to time. I would welcome any ideas that could explain all this? Bryan