[sdiy] Roland SH-2000 VCO question

Oakley Sound oakleysound at btinternet.com
Wed May 1 09:42:53 CEST 2019

The actual VCO core is based around the SCR Q103. It's a linear VCO with 
the main timing cap C102. I believe the 555 is being used as a 
'semi-fixed' monostable to produce an error CV, courtesy of IC101 pins 
1, 2 & 3, that partly compensates for high frequency tracking droop and 
also allows some control over the overall pitch of the VCO core.

Regarding the ladder filter - only the early ones had the transistor 
ladder, most have the five stage diode ladder. Years ago I converted my 
old SH2000 to a transistor ladder and although, I thought at the time, 
most of the presets sounded better some of them most certainly didn't. 
The flute and bass guitar sounded better with the diode ladder.



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