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On the DPO both VCOs are capable of generating complex and harmonically rich waveforms. This is accomplished through the use
of FM and Hard Sync on VCO A, and FM and Timbre Shaping on VCO B.
FM Bus
The internal FM bus is hardwired for Sine wave in both directions and makes use of the Normalization Switch found on the
mini-jacks, so with nothing patched to the Linear and/ or Expo FM inputs the associated attenuator sets the nal index of FM
applied to each destination. As you increase the Index Level, the Amplitude of VCO A Sine Bused to VCO B Linear FM and Expo FM
attenuators is increased. At the same time the Amplitude of VCO B Sine Bused to VCO A Linear FM and Expo FM attenuators is
increased. Therefore you could have dierent amounts of Linear and Expo FM in Both directions, all at once. At greater than 5:00
Index, all of the FM bus lines (Linear, Expo for both VCOs) go into overdrive when the associated attenua-tors are set to beyond
about 80%. The FM overdrive combined with the Bi-Directional Dynamic FM results in some extreme Cross Modulation
capabilities. These sounds get out of hand quickly. The key to controlled FM within the DPO is attenuation since setting the Index
to 100% really does push the circuit to its limits.
VCO A core behavior
With none of the LEDs lighted VCO A operates as a Standard Triangle Core oscillator. When performing FM and Audio Rate
modulations of Timbre parameters, there is a greater chance for error in the frequency ratios. This is not always a bad thing. These
errors manifest themselves in a looser interpretation of the ratio programmed, making each note have subtle dierences.
The Blue LED indicates Lock, an extremely-weak synchronization of VCO A to VCO B, where as VCO A’s frequency approaches an
integer of VCO B frequency, VCO A resets to match VCO B and thus small tuning errors will be corrected. Lock is useful for cleaning
up FM patches where VCO A is acting as the modulator and VCO B is the carrier (the signal that is heard), as well as audio rate
modulation of the VCO B Timbre parameters (via the Mod Bus). Lock will not impart much change in the timbre of VCO A. It does
not introduce strong harmonics. It is mostly used when VCO A is the modulating signal in an FM patch.
The Pink LED indicates Hard Sync of VCO A to VCO B where VCO B will restart the period of VCO A at each cycle so they have the
same base frequency. Sync introduces strong harmonics to VCO A. Sync is achieved when VCO A Frequency is higher than that of
VCO B. The timbre of VCO A may be altered by varying it’s frequency against that of the Master Frequency set by VCO B. Slow
modulation of VCO A Frequency, such as an envelope or LFO patched to VCO A Expo CV Input, results in sweeping of harmonics.
The best results are achieved by setting VCO B to at least 100hz (around A2) and sweeping VCO A Frequency from 100hz up!
The Amber LED indicates that VCO A is being operated as a Low Frequency Oscillator. This is very useful with the Mod Bus.
Especially the Shape and Angle parameters respond well to LFO modulation.
VCO B is not directly aected by the VCO A Lock, Sync, and LFO modes. However, if VCO A is used to modulate VCO B through the
FM or MOD Buses, the resulting modulations are aected by these settings.
Complex Waveforms through Frequency Modulation and SYNC:
