1 General Note
Fully schematic is not supported by this manual. If you think you really need to receive it, please write to
spectralaudio@swissonline.ch .
2 Manual Changes
2.1 Having pulse-width modulation (P M) for the rectangular wave on
OSC1..OSC3
2.1.1 OSC1
remove U01 pin 13 from round (it's connected on both side of pcb, so you have to heat up the pin with the
solder gun and pull the pin out)
2.1.2 OSC2
remove U11 pin 9 from round (it's connected on both side of pcb, so you have to heat up the pin with the solder
gun and pull the pin out)
2.1.3 OSC3
remove U12 pin 9 from ound (here it's more easy, just on bottom side you have to cut the connection to the
Via)
The free pin is now the input of a DC voltage in the range to have pwm 0..50%.
2.2 OSC3/LFO sync with OSC1 or OSC2
For this, connect a 470pF to Base (middle pin) of T03 (OSC2) or T01 (OSC1).
2.3 Even faster envelopes
To increase even more speed of E 1 (Volume), you may solder a resistor in the value of 100 Ohm down to 10
Ohm parallel to R118. For the VCF Envelope use R100. Both may be result in some click noise because of the
low rise and decrease time of the Envelope.
2.4 Increase the tuning range for OSC1..OSC3
It is possible to reduce the value of R001 for OSC1, R022 for OSC2 and R128 for OSC3. Its standard value is
1M5. Decreasing its value may also mean to decrease of R002, R021 and R129 to have the reference note in
the middle of the Tune Pot. To learn another Reference Note over MIDI is another solution but this decreases the
note range.
2.5 General in/outputs
2.5.1 Oscillators
The easiest way to get the signals of the Oscillators are the switches SW02, SW03 and SW11. Amplitude is 0 to
+12V. Same for the noise generator.
2.5.2 Envelopes
These signals can be taken on ENV MOD potentiometer for the filter envelope and on the Volume potentiometer
for the VCA envelope.
2.5.3 Filter
The Filter input is at C18 and its output is U07 pin 8. Control voltage is applied to the Base of T05 and R073.
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