From jhusted@halcyon.comTue May 23 10:56:14 1995 Date: Tue, 23 May 1995 07:28:06 -0700 (PDT) From: James Husted To: Dudeness Cc: analogue@hyperreal.com, nwilson@morgan.com Subject: Re: OB 4-Voice On Fri, 20 May 2005, Dudeness wrote: > > First, and most importantly, the keyboard CV only works for the first > octave. After that, everything's the same. Interestingly, switching the > Programmer from 1-8 to 9-16 extends this to 1 1/2 octaves. I suspect the > problem lies within the Programmer. BTW, the battery's dead in the > Programmer. All the programmer does is supply bias voltages to the control ins of the SEMs. It doesnt do any real switching of audio sources or mess with the keyboard. Thats why you can rip the thing out and not change much. > > The other prob is that the Voice Assignments don't make any sense. Unison > works fine, but otherwise it can be quite bizarre. The lower 1/2 will play > just voice 1, w/ voice 2 playing on one keys - B in the 1st octave. > Bizarre. > If you have ever worked with the roland midi-cv converter you are familiar with the way the keyboard should work. the modes (if i can remember them from when I owned a 4vox) were unison of the whole keyboard, unison of each keyboard half (2 sem/half), and 1-3 3-1 splits. The scanning modes were rotating through voices with each key hit (great with different voicing for a choral effect) and last note priority (but still remembering what voice was used for that last note and trying to use the same voice!) I would bet the cableing or keyboard module is wacked. > Someone kludged on a Rotary switch which apparently switches the CV IN/OHUT > jacks to select one of the SEMs. I don't think this is causing a problem. > > Does anyone have a Service Manual for the Programmer, Keyboard, and/or SEM? > I have schemos (very bad copies) of the keyboard, programmer (some pages may be missing) and the SEM's. I also have the operation manual for the SEM's which has the call-outs for all the molex connectors on the back. My suggestion it to yank all the sem's and rewire the whole thing. That way you'll know not to blame the wiring. The common thing to go on the old obies is the power regulation on each module (the main power supply is un-regulated +/-18v and each module has a 723 regulator). > Can someone explain what the #1-Ext-#2 knob in the VCF section of the SEM does? They pan between the external audio 1 and 2 inputs (line level in molex L1and L3 and M1and M3 pin 1 is ground) > > Has anyone rigged up a modular SEM using the jacks on the back (yes, we > have the pinout desciption)? We're seriously looking at getting rid of the > Keyboard & Programmer...they just don't seem THAT useful. Your best bet is to not use the jacks they hace ans use your own. They used to normalize out the keyboard when the jacks were used, so you can't transpose external cv. I had a quad sequencer that i made (stealing designs from the Oberhiem 2vox SEQ) and plugged into the second cv ins (B3 and D3 which are probbably used by the programmer which I didnt have) ad was great to transpose 4 sequences at the same time with one chord. My 4vox didnt have a programmer so I turned the blank panel they had in it's place to a 30 some point patch bay. Perfect location. oscillator-- james ************************** ** James E. Husted ** ** jhusted@halcyon.com ** **************************