Kurzweil K2661 Musician’s Reference Manual page 391

Here's a different way to look at it:
Parameter Value
(Decimal)
Unsigned, 128 to 255
Unsigned, 0 to 127
Signed, 0 to 127
Signed, -128 to -1
For example, if you wanted to send a value of 216, the MSB would be 01 hex, and the LSB would
be (216 - 128), or 88 decimal (58 hex). To send a value of -32, the MSB would be 7F, and the LSB
would be (-32 + 128), or 96 decimal (60 hex).
If you're using a dedicated MIDI source to generate SysEx, you might not need to calculate the
parameter values, since the MIDI source might do it for you. For example, with one well-known
MIDI fader box, the following values configure a fader for control over the Wet/Dry mix of the
effect on the Aux bus:
Function String
String F0 07 00 78 1B 2A 00 pr pr F7
Min 0
Max 100
Param Format 2Byte, 7Bits, hi -> lo
Moving the fader changes the values represented by pr.
MSB (Hexadecimal)
01
00
00
7F
SysEx Control of KDFX
LSB
(Parameter Value - 128 decimal)
Parameter Value (decimal)
Parameter Value (decimal)
(Parameter Value + 128 decimal)
MSB and LSB
B-5