Date: Tue, 26 Sep 1995 23:17:45 -0700 (PDT) From: MACHINE MEDIA Subject: (303) My Roland TB-303 Modifications WARNING: THE FOLLOWING POST DISCUSSES USES AND MODDIFICATIONS OF THE ROLAND TB-303. IF YOU ARE EASILY NAUSEATED, OFFENDED, OR OTHERWISE DISTURBED BY SUCH A TOPIC, PLEASE DELETE THIS MESSAGE NOW!! DISCLAIMER: I AM NOT AN ELECTRICAL ENGINEER. First off I would like to thank everyone on this list for their knowledge, help and inspiration. I have just gotten done adding 8 jacks and 3 switches to one of my 303's. If I had only one 303 I might not have had the courage to do this!! The hardest part about adding these modifications is the limited amount of space that is there to work with. Stuffing it all back in that little silver plastic box wasn't easy. I had to move several capacitors over onto the foil side of the PCB and fold them over in order to make room for some of the jacks. The first set of modifications that I added was the Kenton five input mod, it adds external control for CV, Gate, Filter Cut Off, Accent and Slide. I like it!! I like it alot :) Oh yeah, before you ask: Kenton Electronics 12 Tolworth Rise South Surbiton Surrey KT5 9NN ENGLAND Voice: 0181-337-0333 Fax: 0181-330-1060 I would not recommend installing this mod yourself without the Roland service documentation at hand. The instructions have very vague graphics. It is not an easy mod to do. It requires some skill at soldering and I used quite a few different tools including several types of wire cutters, tiny pliers, heat sinks, and soldering aids. I can control the 303 with the Kenton mod with the other 303 and have them both play different patches at the same time!! The only information that does not get communicated are the accents, as the unmodified unit does not have accent out. However, the slides are transmitted via CV. You can also run only the CV and not the gate, and have both units run off of the same sync, in this case both units will play the same notes, but play the time and accents of their individual patterns. You can use the Accent in to add accents to a pattern as it is running. However, adding Slide in to running pattern is not that impressive, because the next note is not held from being triggered as the way slides are implemented with the internal sequencer. I am yet to hook up the unit to my Pro-4, but am doubtful as to the use of the Slide in feature. I also added some mods of my own. I did not use Mark Bower's VCA/VCF in mod because using the Mix In on the unit troubled me. I tried to trace the Mix In, but it seems run into a dead end!! I do not see how the signal gets to R156 as shown in the service docs. Can anyone please shed some light on this?? I added: VCO out (with a switched jack that cuts it from the VCF in, you can turn off the internal VCO with a dummy plug), a VCF in (not switched, adding the input of another synth on top of a running 303 pattern sounds really cool!! Tossed in a .1uF capacitor to prevent me from accidently frying it with a CV and it seems fairly quiet), and Accent Out (you can trigger an SH-101 or Dr. Click with it!). I am *very* happy!! I also added three SPST switches off to the left of the Volume knob. I call them Interstellar Overdrive, Accent Spanker and Hydronium Elevator. They all effect the sound of the synth, and even effect the sound of any signal going into the VCF in. In their off position the 303 still retains its original sound. The Interstellar Overdrive makes it sound bassier, louder and adds overdrive distortion. The Accent Spanker makes patterns sound more stacotto and percussive when accents are employed -- it effects the accented as well as unaccented notes. The Hydronium Evelator makes it sound more acid :) It seems very useful during knob performace to keep the Ph low while the resonance knob is turned back. It makes a noticable difference with any knob setting. So far, using it with the internal sawtooth and another synth driven by the CV & Gate out of the 303, back into the VCF in has given me great pleasure :) If anyone has names for these switches that are even more stupid, please let me know :) I am so *very* happy!!!!!! I also adjusted TM3 which is in series with the Freq Cut Off knob to have a wider useful range of application. I have found the first 25% or so of knob rotation is only useful for making bass sounds (the original intention of the engineers who built it) but not very useful for trebly acid lines. I have noticed that several potentiometers are in series with other resistors, pehaps eliminating these resistors and replacing the pots with those of a higher value could be useful. YAAAAAAAAAAAAAAAAYYY!!!! :D PEACE OUT :) MARK