B-Stock ASM Hydrasynth Keyboard Synthesizer

B-Stock ASM Hydrasynth Keyboard Synthesizer


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B-Stock ASM Hydrasynth Keyboard Synthesizer

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B-Stock Explained

B-Stock is in full working order and is protected by a standard manufacturers warranty as if you are buying the A-Grade equivalent.

B-Stock may be ex-display, opened for demonstration, returned by a customer, refurbished, or have accessories or software missing e.g. gig-bag, manuals etc. There may also be signs of use including minor wear and damage, and it may not come in the original packaging. If you have any questions about the condition of an item, please get in touch with our friendly sales team.


The ASM Hydrasynth Keyboard features a Polytouch 49 note Polyphonic aftertouch keybed and a powerful, versatile sound engine for inspiring performance.

Great Sound, Great Playability and Maximum Flexibility

Ashun Sound Machines have developed a synthesizer that gives you incredible flexiblity and customisation options of your sound.

A smooth workflow combines with an advanced wavetable synthesis engine along with a new keyboard featuring ASM's proprietary Polytouch keybed and much more.

The result is the ASM Hydra synth; an incredibly expressive synth that is a dream come true for sound designers and performing musicians.

ASM Hydrasynth Keyboard Synthesizer Key Features:

  • Metal Chassis with Steel Top and Bottom and Aluminium Side Panels
  • ASM Polytouch Keybed
  • 3 Oscillators
  • Mixer/Filter Routing
  • 5 Low Frequency Oscillators
  • 5 DAHDSR Envelopes
  • Modulation Matrix with 32 User Definable Routings
  • Built-In Arpeggiator
  • MIDI, USB, CV/GATE Interfaces
  • OLED Screen
  • Pre-Effects and Post-Effects

Expressive Polytouch Keybed

The ASM Hydrasynth Keyboard features Ashun Sound Machines' proprietary Polytouch keybed.

Not only does this keybed offer standard velocity and aftertouch, it also supports fully polyphonic aftertouch!

Featuring 49 high quality, standard sized keys, the ASM Hydrasynth keyboard synthesizer's Polytouch keybed has that familiar playing feel but with incredible expression.

Oscillation and Mutation

ASM's Hydrasynth Keyboard is equipped with three oscillators allowing you to choose from 219 single cycle waveforms.

Making wavemorphing easy and customisable, oscillators 1 and 2 have ASM's Wavelist mode.

Using Wavelist mode you're able to select 8 waves from the library of 219, arrange them in any order you want and then morph through them.

Furthermore, oscillators 1 and 2 are routed into Mutators which allow you to seriously shape your sound. Come up with something completely new or recreate classic synth sounds.

You can "mutate" your sound a number of ways using a variety of processes. These 7 processes include Pulse Width, Harmonic Sweep and Wavestack, which creates five copies of your sound and detunes however you wish.

What's more, these mutators can generate their own waveforms in both FM and Sync modes, freeing up your oscillators.

Mix and Filter

The Hydrasynth's three oscillators are sent through a mixer, Noise generator and Ring Modulator for further customisation.

Using the mixer you can set the levels and pan the input source. A dedicated balance control allows you to set the amount of signal from each source that is routed to each filter.

There are two filters on board the Hydrasynth Keyboard. The first features 11 different filter models for a wide rang of sound tailoring.

Similar to the classic SEM filter, the second filter is 12dB per octave and features a continuous sweep from Low Bass to Bandpass and High Pass.

For even more flexibility you can set the filters to be parallel or series.

Gimme 5

Further powering your sonic shape shifting are five LFOs and five DAHDSR envelopes.

Each of the Hydrasynth's LFOs feature a STEP mode for patterns up to 8 steps. With five of these mini step sequencers on the go, you have incredible tone tweaking potential.

You also have 10 standard waveforms to choose from.

Furthermore, all of the Hydrasynth's LFOs feature delay, fade in, 3 triggering modes, smoothing, start phase and one shot modes allowing them to act as envelopes and BPM sync.

The DAHDSR envelopes aboard the Hydrasynth Keyboard all feature Delay, Attack, Hold, Decay, Sustain an Release stages.

You can adjust the time settings for stages in seconds or time divisions. This allows you to set the envelopes to work in sync with your music.

What's more, you can loop the envelopes to create LFOs with shape can be voltage controlled with modulation matrix.

Enter The Matrix

The ASM Hydrasynth Keyboard's modulation matrix is what really opens up a world of possibilities with the Hydrasynth.

You have 32 user definable modulation routings to set up paths for the 29 modulation sources and 155 modulation destinations.

Almost any feature on the Hydrasynth Keyboard can be set up as a modulation destination, including the effects and arpeggiator. Even the modulation matrix points can be set up as destinations.

What's more, you can also use the CV Mod, In & Out Jacks and MIDI CCs as both modulation sources and destinations.

A World of Wonder

There's just so much you can do with the Hydrasynth Keyboard and so many ways to do it.

The musical, creative potential that the ASM Hydrasynth offers is just astounding.

Buy the ASM Hydrasynth Keyboard synth from PMT Online now and enter a wonderful world of synthesis with the Hydrasynth as your vehicle.

Hydrasynth Firmware Update

Ashun Sound Machines has released firmware update 1.4 for their Hydrasynth Keyboard and Desktop.

As well as several bug fixes, Firmware 1.4 adds some fantastic new features such as a new Mutator and some new types of Noise.

The new Mutator, called PhazDiff, creates a new waveform which is derived from the difference between the incoming waveform and its inverted and phase-shifted counterpart.

The Noise feature has 7 different options. These now include red, blue, violet and grey noise which pushes the Hydrasynth to new sound design capabilities!

You can download the Firmware 1.4 update from the Ashun Sound Machines website here.

ASM Hydrasynth Keyboard Synthesizer Specifications:

Physical Specifications

Metal Chassis

  • Steel top and bottom
  • Aluminum side panels

PolyTouch Keybed

  • Polyphonic aftertouch
  • Velocity

4 octave (67 cm, 26.4") Ribbon controller

  • Pitch bend mode
  • CC control mode – modulation source
  • Theremin mode - triggers envelopes and plays pitch
  • -Continuous pitch or choose from multiple scales

5 banks of 128 patch memories

CV gate input and outputs

  • Support multiple CV/GATE standards
  • -CV
  • --1v per octave +/-5V
  • --1V per octave 0-10V
  • --Hz to Volts +/-5V
  • --Hz to Volts 0-10V
  • -Gates
  • --V-trig, S-trig
  • --3V, 5V, 10V
  • -Mod In/Out range
  • --+/5V, 0-10V, 0-5V, 0-1V
  • Clock in and out
  • -1PPS, 2PPQ, 24PPQ, 48 PPQ
  • -Clock Voltage - 3v, 5V, 10V


  • Voice overflow mode for expanding voices with another Hydrasynth

Expression pedal input

Sustain pedal input

  • Polarity sensing input

DC input jack

USB port

  • Supports USB MIDI In/Out


  • 80 x 35 x 10.3 cm
  • (31.5 x 13.78 x 4.05 inches)


  • 10kg (22.05 lbs)

Sound Path Specifications:

8 Voice Advanced Wavetable synthesis

2 Wavemorphing Oscillators

  • 219 single cycle waveforms
  • User wavetables - 8 user selectable ‘wavelist’ per osc to build user wavetables
  • Every osc and patch can have its own user wavetable
  • WaveScan parameter for modulating through wavetables.
  • Keytracking – 0-200%
  • +/- 3 octave tuning range

1 fixed Wave OSC

  • 219 single cycle waveforms
  • +/- 3 octave tuning range
  • Keytracking – 0-200%

Dual Mutators per oscillator

  • FM – Linear FM
  • -Selectable Modulator source
  • --Built in Sine & Triangle, OSC1, OSC2, OSC3, Mutators A, B, C, D, Noise gen, Ring Mod, External Mod 1&2 input.
  • WaveStack – Generates 5 detuned waves from input source. Detune amount.
  • Pulse Width Mod – Adjust pulse width of ALL waveforms.
  • PWSqueeze – Compresses the center section of the waveform. Differnnt type of PWM
  • PW-ASM – 8 User adjustable wave squeeze/stretch points.
  • Hard Sync – gives that classic sync sweep sound.
  • -Selectable Sync input source.
  • Harmonic Sweep – will scan through the harmonics of the incoming sound.
  • Dry/Wet mix to blend the original OSC source.

Noise Generator

  • White, Pink, Brown noise sources

Ring modulator

  • Selectable input sources
  • -OSC1, OSC2, OSC3, Noise, All Mutator outputs, External Mod ½ in.
  • Depth control

Sound source mixer

  • Mix the following sources - OSC1, OSC2, OSC3, Noise, and Ring Mod.
  • Panning for each source
  • Filter routing mix
  • Solos for each source (solo status is saved in the patch)

Two Filters

  • Series or parallel routing
  • Filter 1
  • -12 & 24db modern ladder (compensated)
  • -12 & 24db vintage ladder (uncompensated)
  • -Threeler HP, LP
  • -MS20 HP, LP
  • -Low Pass Gate
  • -Vocal filter
  • --Multiple vowel order parameter
  • --Formant parameter
  • Filter 2
  • -Continuously Variable Lowpass-Band pass-High pass (Oberheim SEM style)

Modulation Specifications:

5x Low Frequency Oscillators

  • 10 static waves
  • -Sine, triangle, Square, Saw up, Saw down, S&H, Low random, Noise, Pulse width 25%, Pulse Width 12.5%.
  • Step Wave – 8 steps that the user can set (like a step sequencer).
  • -Step smoothing
  • -Step glide
  • Clock sync
  • Starting phase
  • Start delay
  • Fade in
  • Master output gain
  • Trigger modes – mono, poly, free
  • One shot mode

5x Envelope Generators

  • 6 stage DAHDSR envelopes
  • -Delay, Attack, Hold, Decay, Sustain, Release
  • Slope curves for ADR stages
  • -Variable from full exponential to full logarithmic
  • Tempo or Time option for setting length of each stage.
  • Looping of AHD stages for creating LFO types of modulations.
  • Trigger modes – Legato, Reset, Retrigger

Matrix modulation

  • 32 slots for source-destination mod routings with amount
  • Modulation matrix slots can be mod destinations

8x Macro knobs and buttons

  • Each macro knobs allows positive and negative of up to 8 destination controls


  • Arp parameters can be modulation destinations.
  • Modes
  • -Up, down, up/down, Up&down, random, note order, chord, pattern
  • Octave
  • -Range, 1,2,3,4
  • Play order
  • -Up, down, up/down
  • Swing
  • Gate time
  • Ratchet – repeats notes
  • Chance – sets how often the ratchet takes place.

Effects Specifications:

Pre-effects – before Delay and Reverb

  • Chorus
  • Flanger
  • Rotary
  • Phaser
  • Lo-Fi
  • Tremolo
  • EQ
  • Compressor (with side chain)


  • Tape
  • Ping-pong
  • Analog
  • PitchShift
  • Reverse
  • Filter delay


  • Room
  • Hall
  • Shimmer
  • Cloud
  • DarkSpace

Post-effects – after Delay and Reverb

  • Chorus
  • Flanger
  • Rotary
  • Phaser
  • Lo-Fi
  • Tremolo
  • EQ
  • Compressor (with side chain)
More Information
Manufacturer ASM
SKU 307071-B
Shipping Weight (kg) 11.000000
Number of Keys 49 keys
Key Action Non-Weighted
Synthesis Type Digital / Modelling


We have a wide range of Delivery Options available, depending on the value of your parcel and budget. Select from our 2-3 Day Saver Service or our Next Working Day options at the Checkout.
This will include a text or email on the day of delivery giving you an exact hour window of when your gear will be with you, and the drivers name - just so you know when to turn the volume down!

  • Free Delivery Available on Selected Products
  • Weekend UK Mainland Delivery (Saturday-Sunday): £19.99
  • Small Items (Under 750g) Small items will be delivered by Royal Mail starting from 99p
  • Heavy Items (Over 30kg): Pallet Service Doorstep Delivery £65

For heavy items, courier details, out of stock products, out of area postcodes or international deliveries see our full Delivery info here.


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If you and your item aren’t getting along, you have 14 days from when you receive the goods to contact our PMT experts either by phone or email to return your item.

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If you've changed your mind about something you bought in-store, bring it back within 14 days of purchase and we'll be happy to exchange it for another product, a gift card or store credit.


B-Stock is in full working order and is protected by a standard Manufacturer's Warranty as if you are buying the A-Grade equivalent!

B-Stock may have been opened for Demonstration, returned by a customer, refurbished, or have non-essential accessories or software missing.

There may also be signs of use including minor wear and damage, and it may not come in the original packaging.