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Combined frequency and amplitude modulation
The ZPO’s modulation section features both frequency and amplitude modulation. By pairing both modulation types, the performance and tonal shaping possibilities available with the ZPO are significantly increased. The pairing also results in a balanced response across the ZPO’s bandwidth. Both the frequency and amplitude modulation can be used in unison or independently.
Through-zero FM (TZFM)
TZFM works differently to how traditional VCO frequency modulation works. TZFM works by flipping the negative polarity portion of the input signal into the positive region. By doing this, the modulation source voltage remains 100 percent positive and effectively doubles the rate of modulation.
To fully appreciate the effect, the carrier VCO must also reverse the direction of oscillation. The ZPO utilises a tuned TZ amplifier to accomplish this effect. When applying modulation to the signal, the ZPO operates as a standard TZFM. Thanks to the ZPO’s amplifier design, added benefits include more increased modulation stability, wider range of usable modulation rates and a much broader range of tonal possibilities using the Zero Point Control.
The TZ-MOD switch allows the user to place the oscillator in LIN, EXP or ALL position. Alternatively, the TZ-MOD can be bypassed entirely. When active, the applied modulation is routed to both the signal rectifier into the VCO and the Zero Point TZ Amplifier. The Zero Point control will then offset the balance of polarity reversal, producing an auditory change in the balance of the modulated waveform. The effect will vary dependant on modulation waveform, output waveform and depth of modulation.
Dynamic depth of TZFM
To create the most natural FM effect, the modulation source amount should vary over time, resulting in more expressive modulation. The ZPO’s TZFM technique is particularly suited to creating this effect. This is different to traditional TZ VCO's that would include a CV Input VCA for the FM input. In the ZPO, the varying modulation source amount is already built into the zero-point control and can be modulated with an Envelope or VCO/LFO. This can be inserted via the ZERO-P (Zero Point CV) input.
Multiple wave-shaping outputs
The ZPO features eight different waveform outputs. In addition to this, two more variable wave-shape outputs are provided on either side of the module. These outputs (Wave A and Wave B) are independent from one another but identical feature wise. Each output has associated control and cv inputs. By using these outputs, the user is capable of creating various hybrid wave shapes using the waveform control. The two WAVE outputs can be used separately or in stereo operation.
Morph wave shaping
The Morph function is a key feature of the ZPO and works in conjunction with the Wave A/B controls. Morph offers ultimate, wide control over waveform mixing and allows any of the wave shapes selected by wave A/B to be morphed together. This can create unique harmonic content as a wide variety of waveshapes can be created.
Morph and Wave A/B modulation
The ZPO is packed with a range of features that allow it to create a huge variety of tones. CV inputs for wave A/B and morph allow dynamic automated control over the wave-shaping parameters. With slow modulation applied, subtle effects can be created. By introducing audio rate modulation, even more, non-standard wave shaping can be achieved.
- Tunable pitch control lockout for easy interfacing with sequencers and hardware
- Unique sync circuit, works with any waveform
- 3 voltage controlled waves shaping outputs
- Linear, exponential or simultaneous Lin/Exp through Zero FM
- TZFM can be switched off for typical FM effects
- Ring modulation & LFO mode
- Integrated MOSFET soft start to protect your modules and PSU
- Ultra high quality design Incorporating discrete components and Burr-Brown op amps throughout