From analogue-request@magnus.acs.ohio-state.edu Tue Mar 23 14:08:35 1993 Received: by quark.magnus.acs.ohio-state.edu (5.65/3.910213) id AA14566; Tue, 23 Mar 93 14:08:26 -0500 Errors-To: analogue-request@magnus.acs.ohio-state.edu Sender: analogue-request@magnus.acs.ohio-state.edu Received: from nkosi.well.sf.ca.us by quark.magnus.acs.ohio-state.edu (5.65/3.910213) id AA14561; Tue, 23 Mar 93 14:08:22 -0500 Received: from well.sf.ca.us by nkosi.well.sf.ca.us (5.65c/SMI-4.1/nkosi-930322-1) id AA25544; Tue, 23 Mar 1993 11:08:19 -0800 Received: by well.sf.ca.us (5.65c/SMI-4.1/well-930216-1) id AA20568; Tue, 23 Mar 1993 11:08:07 -0800 Date: Tue, 23 Mar 1993 11:08:07 -0800 From: Chris Meyer Message-Id: <199303231908.AA20568@well.sf.ca.us> To: analogue@magnus.acs.ohio-state.edu Subject: Adventures in Synthland pt.1 Status: OR After an interesting experience tuning up my EML101, I thought I'd pass along some hard-learned wisdom (of sorts)... I wasted well over an hour on a simple operator error. In the first part of the tuning procedure, you are supposed to use the oscillator's fine tune knob to adjust the low frequencies, and the keyboard's tracking knob to adjust the highs. I had a direct out from the oscillator plugged into a strobe tuner. No matter how I fiddled with the keyboard tracking knob, however, the tuning would not change. Was something broken? After a lot of wire tracing and schematic studying (schematic ended up being wrong in some places, of course), I figured out that the tracking control directly affected the voltage applied across the keyboard; then, when I struck a note, that voltage was sampled by a S/H and held until I struck the next key. Changing the tracking while the key was up didn't affect the S/H, which in the end meant my range adjustments would not be heard until I struck the key a second time. A wedge to hold the key down ended up letting me heard my adjustments "in real time." Two tangents: One is that I saw S/H "droop" first-hand, where releasing a key resulted in a slight dropping in the osc's frequency. If I tuned when the key was up, I was slightly off from the freq of when the key was down. With the exception of perhaps drones, the key down tuning is more often heard, so I used key wedges and made sure I tuned to that. Another is I tried to save time changing the strobe tuner back and forth between F and C (low and high keys on the EML) and instead leave it at F to take advantage of their close harmonic relationship (by looking for the "ghost" of a C while the tuner was set to F). However, since the tuner assumes equal temperment, the relationship is not exact, and again I almost induced an error by trying to take a short cut. The EML manual suggests you use an X/Y 'scope to tune the oscillators to each other. I did, but when I tried to patch a sound, I found the synth was still out of tune. It seems that the EML more than others has a strong tendency for the oscillators to lock together in sympathy, even though they may still be out of tune (ever have what seemed to be an unstable synth where the oscillators would fitfully be in tune, then beat, then lock back in tune, etc.?). Also, staring at a 'scope it's easy to convince yourself it's "good enough" when in fact it isn't. I went back and re-tweaked using my ears. In my investigations, I learned to my surprise that the EML actually uses a linear system for the keyboard control voltage (i.e. C3's voltage is twice that of C2, not 1.0 volts higher), and then internally changes them to log to control the oscillators. This means the jacks on the front panel are for interfacing to linear equipment, not log(!), which means direct pitch CV connections with Moog and Arp gear will not work. (Again!: anyone have a Korg MS02 log/lin convertor they're willing to sell me?) I also confirmed today that my wife's Yamaha CS30 is linear, giving my Korg MS20 and (blush) 4 cabinets of PAiA gear extra company. Finally, on a completely different note, I read in Music Technology (UK) that Cheetah has ceased to make synths. That might bum out those who were thinking about buying a MS6 as a stand-in for a Matrix 1000. Myself, I was interested in the raw digital filth the MS800 was rumored to be able to belch forth (being into Industrial etc.) - did anyone ever get a chance to hear one of these? Are they still available somehow in the UK or elsewhere? Everyone have a good weekend, now... - CM P.S. This ended up being sent Tuesday instead of Friday, so excuse the last line... P.P.S. Remember those odd detachable power cords that were used on early American synths, like the Oberheim 2-voice and Arp Soloist? An oval with three round holes inside? I need one - someone lost the cord to a Soloist I was borrowing to sample, and I can't return it without the cord... Anyone have a spare, or know of a source? Thanks!