CARE & FEEDING OF THE PLAN B MODEL 15 VCO
The following procedure outlines the steps required to calibrate your Plan B Model 15 Complex VCO. It is recommended that this be
done on a monthly basis to assure your oscillators are in proper adjustment.
Periodic calibration of Voltage Controlled Oscillators (VCOs) used in the generation of music is essential to assure they are operating
to their fullest potential. This is true of any analog VCO, regardless of manufacturer. The trimpots required to adjust these precision
instruments into spec do, over time, go out of adjstment. There are many reasons for this - change of seasons, change of PSU driving
the VCOs - and especially true if your instrument is frequently used for live performance.
I mention a monthly check - this is being conservative. If you find that after the first few months your VCOs are still in cal, then back off
the calibration to every two months and so on. Its impossible to forcast the interval that works for each of you because all of each and
every user’s operating conditions vary.
Step One - The Right Tools for the Job
.
Most important rule in doing any job - make sure you’ve got the correct tools to do it correctly. The following may require a small
investment on your part, but the rewards will pay off immediately. The tools you’ll need for this cal are in two groups:
1)
1V/OCT ADJUSTMENT
A) Adapter power cable
B) Small straight-blade screwdriver -or- (preferred) a plastic trimpot adjuster - commonly referred to as a ‘tweeker’
C) A reference electronic keyboard (such as a digital device or virtual analog instrument)
D) Good set of ears!
2)
WAVESHAPE ADJUSTMENZTS
A) Adapter power cable
B) Small Philips-head screwdriver -or- (preferred) a plastic trimpot adjuster - commonly referred to as a ‘tweeker’
C) Oscilloscope
D) Good set of eyes!
Notes:
Make yourself a Doepfer-type flat power cable long enough so that you can easily sit your VCO upright, out of the cabinet and
you can do this while the VCO is powered by the same PSU used in the cabinet it came from. If you have more than 1 M15, it’s
best that you make one that will allow two or them to be powered at once....there’s a reason for this (next page)!
