kitrinx wrote on 2020-12-15, 23:01:
yawetaG wrote on 2020-12-15, 22:52:
Get yourself the SC55 manual and look in the back in the section about sysex control. There should be a section listing the patch part parameters (most settings are set per part, not per individual instrument). Wait, I looked it up, page 80 and onwards, the bit that starts with "MOD PITCH CONTROL" and onwards: https://www.manualslib.com/manual/695759/Rola … ?page=80#manual
If a rompler synth manual has a section about sysex, I tend to look into it first because usually it's the fastest way to see what a rompler can do...
LFO rates are -10Hz to +10 Hz. Not sure how that is controlled, IIRC there's a clock crystal on the circuit board so it could actually use that. On the SC88 there even is a 20Hz one (would match -10 to +10 Hz)...
Yes, I've scrutinized this, but the sysex don't really line up with the data present in the control rom. One of the bytes somewhere in the partial data is likely responsible for controlling the default LFO frequency for the instruments. It's possible it's only a nibble of data or somehow else obscured. There is somewhat similar data one byte after each LFO depth byte, but I don't know its meanings yet.
Some instrument samples have vibrato/tremolo/LFO-like effects by default, but it's internal to the sample (i.e. it was present in the sample when the sample was recorded).
For vibrato, it appears the default setting is zero (or lowest value, Roland is inconsistent in their parameter ranges, sometimes they go from 0-127, and other times they go -63 - +63), because the unedited instrument sounds equal to that and you can only add vibrato, not diminish it, from the default value.
I wouldn't be surprised if it's similar for the other LFOs. If we look at the ancestor of the Sound Canvas line-up, which IMHO are not LA synths like the MT32 etc., but the Roland MV30 (U220-derivative, working name U30, little brother to D70, has proto-GM sound set* with same instrument selection as Sound Canvas - see this thread, filter/complex LFO like D70, only 8 parts instead of 16 like on the SC55), the LFO has to be explicitly enabled to start doing something... U220 has no LFO except for vibrato.
* MV30 ROM is actually partially located on a floppy disk, and there's a disk image available on the web...the rest of the ROM should be equal to that of U220.
However, for those parameters that have a master value, on Roland romplers the part/instrument values usually are either an offset value (+/-) from the master value, or relative to the master value. What's making it more complex is that if there are similar parameters at different hierarchical levels in the synth structure, they stack - so you can get something like "offset value x of value y, where value y is relative to value z".
So in "somewhat similar data one byte after each LFO depth byte" maybe the similar data matches the LFO depth byte offset or relative to the master LFO rate.