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Midi Issues

 

Calibrating VCO's

 

Calibrating VCF's

 

Adjusting VCA's

 

Adjusting the Ringmodulator

 

Calibrating CV1 input of the mixermodules

 

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Calibrating VCF

 

 

At this page you find some info concerning the Fénix. If you are not sure please contact me by mail.


Why needs to calibrate the VCF.
The VCF has (like the VCO) a 1v/oct input to control the frequency of the filter. This input is less accurate as the VCO.

How difficult is adjusting the VCF
It is simular with calibration the VCO, but since it is less critical it will be easier

You need a voltage source. Fi a keyboard CV or you can use the CV-mixer 2. Like calibrating the VCO's you can do this by ear and a reference oscillator or with a frequency counter.

VCF 1/VCF 2

Calibrating the 1v/oct
VCF2 and VCF3 having each 3 trimpots, One is for the 1v/oct settings the second is for the initial frequency setting and the last is for adjusting the resonance.
Before calibration switch the Fénix on for warming up. Turn the frequency knop at 12 o'clock and the resonance frontpanel potmeter at max. The Led must light up. Listen or measure (with a oscilloscoop) at the LP output while you sweep the filter with the (frontpanel) frequency knop from low to high. The output level must be stable. There could be a slight dip. If the output level significant change at the high frequency you can adjust this with the resonance trimpot.

Set the frequency knob so that the VCF oscillate at about 100Hz. If you use as reference voltage source a keyboard, play first the lowest key. If you use CVmixer 2 switch this at -1 volt.
Play 3 octave higher (or switch to +2 volt). Adjust the VCF with the 1v/oct trimpot at 800 Hz. Go back to the original note (lowest key or -1volt) and check or the frequency is 100 Hz. If not start again.
If you not have a frequency counter it is easier to use a interval of 1 instead of the above used 3.


4e PCB board with VCF1 and VCF2
.


VCF 3

Calibrating the 1v/oct
VCF3 has 4 trimpots, There is one for the 1v/oct settings, one for the initial frequency setting, one for the resonance settings and the last is for temperature setting of the log converter. This last one needs only be adjust if parts are replaced.
Before calibration let the Fénix warming up for about 15 min
Turn the frequency knop at 12 o'clock and the resonance frontpanel potmeter at max. The VCF should be oscillating. (Note this filter doesn't have a stable output level when sweeping the filter from low to high like VCF1 / 2). Set the resonance trimpot so that the filter is still oscillate if the frequency knob is set at 8 o'clock.
Set the frequency knob so that the VCF oscillate at about 100Hz. If you use as reference voltage source a keyboard, play first the lowest key. If you use CVmixer 2 switch this first at -1 volt.
Play 3 octave higher (or switch to +2 volt). Adjust the VCF with the 1v/oct trimpot at 800 Hz. Go back to the original note (lowest key or -1volt) and check or the frequency is 100 Hz. If not start again.
If you not have a frequency counter it is easier to use a interval of 1 instead of the above used 3.
When finished, remove the voltage source from CV1 and set the frequency frontpanel knob at 10 o'clock. Set the resonance trimpot so that the VCF just start to oscillate.

Temperatue setting
If you replaced IC2 at this board you need to adjust the temperature settings. Also you need the 1 v/oct calibration as discribe above after you have finished this calibration.
Measure at pin 7 of IC2 the voltage. Adjust slowly with the temp trimpot this voltage at - 0.55 volt. Wait a while and check this voltage and repeat this adjustment.
If you not have a frequency counter it is easier to use a interval of 1 instead of the above used 3.


5e PCB board with VCF3

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