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Dave Smith Instruments Mopho x4 Synthesizer Keyboard

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Building upon the same award winning voice architecture of the Mopho and Mopho Keyboard, the Mopho x4 boasts huge sound and 4 voice polyphony in an ideally sized, portable, and elegantly designed pack... Click To Read More About This Product

Available 02-15-2018 You will not be charged until order ships. Email me when this is in stock.

Gear returned in mint condition. If you're looking for a virtually new instrument in possibly less-than-perfect packaging, this is a great value.
  • Includes 45-Day, No-Hassle Returns
  • Includes full manufacturer's warranty
Gear returned in great condition, with only minor signs of use, such as slight scuffs or pick marks. It looks and plays like new and may be considered an equivalent to display units found in retail stores.
  • Includes 45-Day, No-Hassle Returns
  • Includes full manufacturer's warranty
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Building upon the same award winning voice architecture of the Mopho and Mopho Keyboard, the Mopho x4 boasts huge sound and 4 voice polyphony in an ideally sized, portable, and elegantly designed package. Use it to create huge unison basses, creamy leads, maniacal sequences, and ethereal pads.

Each of Mopho x4's four voices is composed of two analog oscillators, two sub octave generators, selectable 2- or 4-pole famed Curtis low-pass filter, three 5-stage envelope generators, four LFOs, a relatchable arpeggiator, and a 16 x 4 step sequencer. Its voice also comes packed with 20 modulation sources and almost 50 destinations. You can FM the filter to create metallic bell-like sounds and use the feedback path to add subtle or destructive harmonic content to your sound. Mopho x4's 100% analog signal path is powerful, monstrous, and sonically dynamic.

Work less, play more
Mopho x4 is intuitive and inviting. Every parameter is fully programmable and editable from the front panel. The controls are logically laid out, lending themselves to quick access so you can tweak knobs without missing a beat. The x4's full-sized, 44-note semi-weighted keyboard has aftertouch and velocity sensitivity. The sturdy full-sized pitch and mod wheels are freely assignable and sport smooth reliable action.

Expand your sonic horizon
Expand Mopho x4's polyphony using it's Poly Chain port. Mopho, Tetra, and Prophet '08 can all be connected to the x4 to increase its voice count. You can Poly Chain up to three Tetras with Mopho x4 to create a 16 voice analog super synth.


  • 100% analog signal path
  • Two oscillators per voice capable of producing sawtooth, triangle, saw/triangle, and variable pulse width square waves, with hard sync
  • Two sub-octave generators per voice (one octave below oscillator 1 and two octaves below oscillator 2)
  • One classic Curtis low-pass filter per voice (switchable 2- or 4-pole) with audio rate modulation, self-oscillating in 4-pole mode
  • Analog VCAs
  • Three envelope generators per voice (ADSR plus delay)
  • Feedback loop per voice with programmable level and gain
  • White noise generator
  • 4 LFOs per voice
  • Gated 16 x 4 step sequencer per voice (one sequence per program)
  • Arpeggiator
  • Glide (portamento): separate rates per oscillator
  • Full-sized, 44-note (F to C), semi-weighted keyboard action with velocity and aftertouch
  • Full-sized modulation wheel and spring-loaded pitch wheel
  • Fully programmable with four banks of 128 read-only factory programs and four banks of 128 user programs (1,024 total)
  • I/O
    • USB type B receptacle
    • MIDI In, Out/Thru, and Poly Chain
    • Left and Right audio outputs: 1/4" phone jack (unbalanced)
    • Sustain pedal input (accepts normally on or off momentary footswitch with 1/4" phone plug)
    • Expression pedal/control voltage (3.3 VDC max.) input (1/4" TRS phone jack)
    • Headphone output: 1/4" TRS stereo phone jack
    • Power supply for 100V - 240V AC operation
    • Operation manual
    • Free downloadable software editor for Mac OS and Windows
    • Dimensions (LxWxH): approximately 25.2" x 11.1" x 3.6" (64cm x 28.2cm x 9.1cm)
    • Weight: 9.4lb. (4.35kg)
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    • Repair costs covered for up to five years from date of purchase
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    • Customer Reviews

    Review Snapshot

    by PowerReviews
    Dave Smith InstrumentsMopho x4 Synthesizer Keyboard

    (based on 2 reviews)

    Ratings Distribution

    • 5 Stars



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    • 2 Stars



    • 1 Stars



    Reviewed by 2 customers

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    (3 of 3 customers found this review helpful)


    Great Synth

    By REN

    from San Jose, CA

    About Me Novice


    • Easy to Use
    • Realistic Sound
    • Responsive / Good Action
    • Touch Sensitive Keys


      Best Uses

      • Electronic Music

      Comments about Dave Smith Instruments Mopho x4 Synthesizer Keyboard:

      I tried the Minilogue and Gaia. Both are good for their price, especially a used Gaia. Monologue has analog VCO's, the Gaia is a ROMPER. I prefer full size keys, and instead of getting 2 synths, I picked up a used X4 at GC. Although there are limitations (every synth has limitations), the X4 is intuitive to program and essentially has a patch bay of modulation options which are user selectable and can be routed just about everywhere (4x LFO, 4x Mod sources, 3rd envelope, etc). All are easily accessible from the top panel. The nice feature if that when you are editing a parameter, the original value is displayed on the top line. Neither the Minilogue nor Gaia has this feature (you can get this in there Gaia with s $90 editor). Although a lot of people knock the Gaia, is it actually a great sounding synth, easy to program and play. But if you are going to use the editor to see the actual programmed values, you may as well just get a iPad Synth app or Mac app.... Im still 50/50 on a tetra or a minilogue in the future.

      The presets on the X4 do not seem to be built for the sonic quality, but instead to showcase the vast modulation options. Most of the DSI and YT videos are tweaking the parameters, vs playing the keyboard. You have to trust DSI, they have been building synths for 30 years. You really need to dive into all there options to create excellent sounds from this synth, but this is easy to do. The 44 key keyboard is perfect, 61 is too big at times, 37 comes up just a little short. 4 note poly is OK, it actually fits my style so this is not an issue. I believe you can program around all the "limitations" once you figure out the options.

      This is a quality instrument, I was surprised there are no other reviews for this.

      (0 of 1 customers found this review helpful)


      Nice Synth for the price

      By Armand

      from Hemet, CA

      About Me Experienced

      Verified Buyer


      • Easy to Use
      • Portable
      • Pre-programmed music
      • Realistic Sound
      • Responsive / Good Action
      • Touch Sensitive Keys


        Best Uses

        • Electronic Music

        Comments about Dave Smith Instruments Mopho x4 Synthesizer Keyboard:

        The arp setting still can't figure how to change them on the owners manual. Customer support was no help, told to refer to owners manual.

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