Hi Folks
Still working through the testing phase and uncovered something that I wondered if anyone could help with:
I’m checking the Voice Modulation behaviour in cyclic mode, so listening to each VC separately for how the above modulation is affecting the sound.
Listening just to OSC 1; applying the FILTER CONTOUR pot setting to OSC1 FREQ - so in other words, the filter envelope generator is impressing its shape onto OSC1 FREQ; using a long ATTACK setting and no D,S or R. The result is a ramp up in pitch as you hold the keyboard note down. After the attack phase has done its job in modulating the pitch, the pitch drops back to the note pitch - all ok.
The issue is that the attack time for each VC is not the same. The worst offender is about 2 seconds different. Holding two notes down results in the time taken for the two pitches to drop back down to the root note pitch to be noticeably spaced apart in time.
The issue appears to be with the 3310 itself, as moving the worst offender to control a different VC takes the extra long attack time with it.
Looking at this reference, it looks as though the current into pin 10 could be used to trim this for better matching between multiple 3310s used in a polyphonic scenario; however on the MM this appears to be fixed and set with R123 (33.6 kohm), R156, R185 etc for each VC.
https://www.muzines.co.uk/articles/electro-music-engineer-cem-3310/3647
Does anyone have any experience of this phenomenon they could share, and/or whether adding a trimmer to the 33.6 kohm resistor might help here?
Also - kind of related - I can’t find calibration info on the VCF CONTOUR OFFSET trimmers in the service manual (it does detail it for the VOICE MOD OFFSET ADJUSTMENTS on page 46 however) - have I missed this somewhere…or is there a recommended procedure to dial this in? So this is for trimmers R131, R164 etc
Many thanks for reading again,
Tim