Hydrasynth Keyboard, from ASM Web site
A polyphonic digital synth which constitutes the first (and currently only) product from Ashun Sound Machines. The Hydrasynth is offered in four different models, three with keyboards and one tabletop unit with an array of pressure pads. All use the same synthesis architecture, with some variation in specific features between models.
The voice architecture is basically a conventional VCO-VCF-VCA chain (digital equivalents), with "mutants" being represented as being attached to the oscillator outputs. (Some of the mutants are probably actually part of the oscillators, but the distinction is immaterial to the user.) Each voice has three wavetable oscillators which are capable of wave scanning; two filters, one amplifier, five LFOs, five six-segment envelope generators, a noise source, and a ring modulator. The synth also has a selection of effects, some of which can be inserted into the voice chain. All of the keyboard models have a keyboard with polyphonic aftertouch, and an arpeggiator. 8 voices are provided on every model except the Deluxe.
The oscillators and mutants are one of the outstanding features of the Hydrasynth, and make it possible to synthesize many sounds using modulation and waveshaping techniques, without use of the filters. Each oscillator can select from among 219 waveforms, and up to 8 can be arranged in any order for wave scanning. Two of the three oscillators can have "mutants" applied. Besides the expected pulse width modulation and oscillator sync, there are features that can do things such as emphasize specific harmonics in the waveform, or chop the waveform up into windows and apply different amounts of frequency modulation to each window. An output mixer mixes the results of the three oscillators, the noise source and the ring modulator into a stereo mix.
The two filters (which are stereo) differ in type and capabilities. Filter 1 has 16 different modes, which embrace high-, band- and lowpass response from 1 to 8 poles, or it can function as a formant filter. Filter 2 is a two-pole multimode filter which can sweep continuously between response types. The two filters can be arranged in series or parallel.
The five LFOs have 10 standard waveforms available; however, they also allow for user-defined waveforms with up to 64 points. A mini-envelope on each LFO allows for delayed start and fade-in. Various kinds of sync are available, including BPM sync to an external clock. A one-shot mode is available, and the user-defined mode can also be single-stepped.
The five envelope generators are DAHDSR (Delay, Attack, Hold, Decay, Sustain, Release). The Attack, Decay and Release segments can be synched to tempo, and the envelopes can be looped.
Interfaces include MIDI (both 5-pin DIN jack and USB) and CV/Gate. The latter can support 1 V/octave scaling (nearly all modern equipment), 1.2 V/octave (Buchla and EML), and volts/Hz scaling (mainly older Japanese synths). The MIDI supports MIDI Overflow.
The panel includes discrete controls for some of the most often-used parameters. Others are edited via a set of eight knobs and buttons that flank a pair of OLED displays; one displays functions and operating modes, and a smaller one displays the waveform being output by the component currently being edited. A set of pushbuttons allows specific components to be enabled and disabled, a la the V-Synth. A set of eight "macro" knobs allows for patch morphing, by varying up to eight parameters at once. Patch memory contains 1024 patches arranged into 8 banks. The Hydrasynth Keyboard and Deluxe have pitch and modulation wheels which are in the style of a video switcher T-handle, and are backlit.
The four different models of the Hydrasynth include:
- The original Hydrasynth Keyboard, which is largely as described above, with a 49-key keyboard.
- The Hydrasynth Desktop, which has no keyboard, pitch/mod wheels, or ribbon controller. It can be rack mounted using the included rack ears.
- The Hydrasynth Deluxe, with a 73-key keyboard. The Deluxe has 16 voices and bitimbral capability; the keyboard can be split into zones and patches can be divided between the zones and stacked. In addition to the normal patch memory, the Deluxe has an additional 640 locations for storing split/layer setups.
- The Hydrasynth Explorer, a small unit with a 25-key keyboard. Intended for portable use, this unit can be battery powered. It lacks the ribbon controller, and has touch strips (small ribbons) for the pitch/mod wheel functionality.
Hydrasynth user-maintained site
Hydrasynth Gallery (all photos from ASM Web site)
Hydrasynth Desktop
Hydrasynth Explorer