Dave Smith Instruments Mopho x4 4-Voice Analog Synthesizer

44-key 4-voice Analog Synthesizer with Aftertouch; 2 Oscillators, 2 Sub-octave Generators, 1 Lowpass Filter, 3 Envelope Generators, and 4 LFOs per Voice
Dave Smith Instruments Mopho x4 4-Voice Analog Synthesizer image 1
Dave Smith Instruments Mopho x4 4-Voice Analog Synthesizer image 1
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Dave Smith Instruments Mopho x4 4-Voice Analog Synthesizer
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A Polyphonic Mopho!

If you're an analog synthesis devotee, Dave Smith Instruments' Mopho x4 will float your boat. The Mopho x4 gives you fat 4-voice polyphony, an all-analog signal path, 44 semi-weighted keys with aftertouch, knobby real-time programability, plentiful modulation options, and easy expandability. Each voice sports two analog oscillators, two sub-octave generators, a lowpass filter, three 5-stage envelope generators, four LFOs, a relatchable arpeggiator, and a 16 x 4 step sequencer, making it a blast to conjure super-sized behemoth basses, monstrous leads, insane sequences, and celestial pads. You'll adore Dave Smith Instruments' Mopho x4.

Dave Smith Instruments Mopho x4 44-key 4-voice Analog Synthesizer at a Glance:
  • The Mopho x4 gives you boatloads of fat analog mojo in a compact chassis
  • This synth has the right stuff and a 100% analog signal path
  • Expand Mopho x4's polyphony to fit your needs
  • Designed by an analog synth legend
The Mopho x4 gives you boatloads of fat analog mojo in a compact chassis

Dave Smith, the man who brought us the legendary Prophet 5 and MIDI, is at it again, with a petite polysynth that bridges the gap between his high-end Evolver and Prophet '08 machines and the monophonic Mophos. Dave Smith Instruments' Mopho x4 gives you massive sonics and 4-voice polyphony in an elegantly designed, portable package. Featuring a full-sized, 44-note velocity and pressure-sensitive keyboard and impressive knobularity for its diminutive size, the Mopho x4 is at home in the studio, on the road, or wherever your music takes you. Hmmm, 44 keys - where have we seen that before? This little hottie even has wood end cheeks. A modern classic, right from the get-go.

This synth has the right stuff and a 100% analog signal path

Mopho x4's 100% analog signal path serves up massively powerful sounds with incredible sonic dynamism. When it comes to insanely great analog synth sounds, it's what's inside that counts. Dave Smith Instruments' Mopho x4 is packed with cutting-edge analog technology and has the distinct advantage of being designed by an analog synth design legend. Mopho x4's four voices each sport two analog oscillators, two sub-octave generators, a genuine 2/4-pole-selectable Curtis lowpass filter, three 5-stage envelope generators, four LFOs, a relatchable arpeggiator, and a 16 x 4 step sequencer. Along with all this ear candy, you also get healthy modulation options, with 20 sources and almost 50 destinations. Go ahead, grab a knob and frequency-modulate the filter to create bell-like metallic tones. Dial in some feedback to add tasty harmonic content. With Mopho x4, your creativity just flows.

Expand Mopho x4's polyphony to fit your needs

You can easily expand Mopho x4's polyphony to suit your musical needs. Dave Smith Instruments' Mopho, Tetra, and Prophet '08 can easily be connected to the x4's Poly Chain port to juice its voice count. Poly Chain up to three Tetras with Mopho x4 to create a 16-voice analog monster synth. With the Mopho x4, the sky's the limit!

Designed by an analog synth legend

Dave Smith was the design engineer and driving force behind Sequential Circuits, whose first product was the legendary Prophet 5 in 1977 - the first polyphonic synthesizer capable of storing the value of every parameter within its voicing and control systems. This was a watershed technological breakthrough, and the implications were staggering. Think about this: before the Prophet 5, it simply wasn't possible to enter a patch number into a synth and recall sounds you had stored. The Prophet 5 and its successors were hugely successful, finding their way into every top studio and major act's keyboard rig, and onto countless recordings by artists as diverse as Madonna and Weather Report! Impressive, yes - but Dave also invented a little thing called MIDI. OK, so the man's a legend; one whose current company, Dave Smith Instruments, is responsible (albeit not singlehandedly) for keeping analog synthesis alive and well.

Dave Smith Instruments Mopho x4 44-key 4-voice Analog Synthesizer Features:
  • Four voices, each with two analog oscillators and two sub-octave generators
  • 44 semi-weighted keys with aftertouch
  • Genuine 2/4-pole-selectable Curtis lowpass filters
  • Each voice sports three 5-stage envelope generators and four LFOs
  • Relatchable arpeggiator and 16 x 4 step sequencer per voice
  • USB 2.0 port enables bidirectional MIDI communication with a computer
  • Expandable via Poly Chain port
  • Designed and manufactured in San Francisco, USA
Analog synthesis is alive and well, with the Dave Smith Instruments Mopho x4!

Additional Media

Dave Smith Instruments Mopho x4

Tech Specs

Sound Engine Type(s) Analog
Number of Keys 44
Type of Keys Semi-weighted, Aftertouch
Other Controllers Pitchbend, Mod Wheel
Polyphony 4 Notes
Number of Presets 512 Factory, 512 User
Expansion Via proprietary Poly Chain port
Arpeggiator Yes (Relatchable)
Sequencer 16 x 4-step
Audio Outputs 2 x TRS
USB 1 x Type B (USB 2.0)
MIDI I/O In/Out/Thru/Poly Chain
Pedal Inputs Sustain, Expression/CV
Power Supply External, 13-15 VDC, 500 mA
Height 3.6"
Width 25.2"
Depth 11.1"
Weight 9.6 lbs.
Manufacturer Part Number DSI-2204

Customer Reviews

Based on 14 reviews
Write your review

Old school sound modern control.

Dave Smith’s MoPho x4 is a great 4 voice synth. All the way from deep bass to 4 note spatial pads and everything in between. I have owned many old school synths from Moog, Yamaha, Roland, Korg even a Realistic MG1. This one sure has the sound. This is a lot of bang for the buck. Five modulators with 20 sources and over 45 destinations. Four LFOs and three 5-stage envelope generators. A re-latchable arpeggiator. Four 16 step sequencers. It is an analog on steroids. I was going to buy the Moog Sub Fatty 37 but opted for this one because it has more features. I might buy a Tetra to Poly Chain later but this will fit the needs for now.
Music background: Musician

Just wow

This was my first Dave Smith product and I got to tell you, I love it. I would not trade it for anything. Once you get the hang of the workflow for editing the sounds, you are on your way to creation some unique sounds you can only get with real analog synthesizers. I can't wait to take advantage of the poly chain by adding a Tetra into the mix.
Music background: Electronic Music Producer


Mopho X4! Wow! It has: Fantastic looks, Excellent build quality, Feature packed, Easy to use and program, Lots of inputs and outputs, Computer compatible, High resale value, High collector's value, Compact size, Retro design, Analog technology combined with digital technology, 4 voice polyphony, 44 full sized semi - weighted piano keys, Arpeggiator AND 16 STEP sequencer, is USA made AND HAS PREMIUM VINTAGE ANALOG SOUND! This is A-LOT OF ANALOG SYNTH for the price and if you like to make electronic music, whether it be techno, 80s new wave, electronic jazz, ethereal, hip-hop or beatmaking you will be HAPPY-AND SATISFIED with this gem! The Mopho X4 is not like a digital Korg, Novation, Roland or Virus synthesizer ( I am not insulting these boards- for the most part , they are all good synths because I own some of them) but rather the X4 is an instrument of pure analog engineering. This beauty will give you moog basses, jupiter 8 brasses, oberheim pads, korg rave sounds, virus hypersaws, perfectly timed arpeggiators, sequenced animated sound effects, and of course Dave Smith's signature 1970s Prophet 5 sounds! But first, a little history on polyphonic analog synthesizers: Can you, perhaps, recall the debut of some of the most famous and well known new wave bands when MTV was first broadcast in the 1980's, such as Thomas Dolby, Human League,The Cars, Gary Numan, Journey, Orchestral Manuevers, Spandau Ballet and A Flock Of Seagulls just to name a few? The 1980s were the first years analog synths with on-board arpeggiators were introduced into amplified music. Polyphonic analog synths such as the roland jupiter 8 and korg polysix, were being used for the first time ever in this newly developed guitar, bass,and keyboard pop type music appropriately called NEW-WAVE. Since the 1960s and thru the early 1970s the first analog synths in use were mostly huge modular moogs that would take up a whole wall, and which used hundreds of patch cords like an old style telephone switchboard in order to manipulate oscillators, filters and envelopes, and at that time those types of synths were mostly used for making science fiction and B movie type sound effects. In the 1960s, for example, every device and equipment sound on captain kirk's starship enterprise ( the transporter, the warp drive, the phaser banks, and the electronic sounds on the bridge) were all made with with a huge monophonic analog synth that used patchcords which were plugged into jacks and although, music had never been made with these monophonic synths, bands like The Who and Pink Floyd had come up with the idea in the 1970s to try them in songs. But they were limited to only one-note-at-a-time lead solos and multitracked stacked sequences, and so that put a barrier on their musical creativity, and pretty much all that was available to musicians at that time anyhow was the minimoog, and because it was small in size , it could be taken into recording studios. But then in the mid 1970's a milestone occurred when Dave Smith invented the Prophet 5. It then became the first five voice polyphonic synth available.to musicians. And so companies like Roland , Korg, and Oberheim began manufacturing their own polyphonic synths. Sequencers then evolved into arpeggiators because arpeggiators were easier to use and to program than sequencers were, control panels were designed with knobs and sliders in order to route oscillators and filters more easily, and keyboard voice polyphony was increased to a maximum of eight voices. So now it was possible to form these awesome analog sounds into chord structures and musical phrases, and now make electric guitar music even more interesting. So this is more or less how it all began. I know this because my age is 48 years and I was around when all of this happened! So, now my little review of the Mopho X4. First and foremost, read the Sweetwater product description, but in expressing my own excitement with this synth, what I would like to elaborate on IS: the synth comes with tons of useable presets ( four banks of 128) to be exact, (but if you change the filter setting from 2 pole to 4 pole you now have double the amount of factory presets because when the button is pressed to change from 2 pole to 4 pole, the sound of the factory patch changes dramatically, thus 8 X 128 factory presets equals !!!!) There are also four banks of 128 user slots to store patches you programmed yourself.. The synth has memory galore. .All the factory presets are programmed by Dave Smith and his team, and they programmed so many fantastic and usable sounds in them, that I have not found the need to make a patch of my own! Now there are two ANALOG oscillators (did I spell osilater correctly ?) BUT they are digitally controlled, this means that you don't have to let the Mopho X4 warm up before you play it, and digitally controlled oscillators also keep the synth in perfect tune! There is also a sub-oscillator (for fat -rich sounding michael jackson, and madonna basses,) and a premium 2-4 pole filter, (Dave Smith's own design) the X4 does not operate with a traditional combination lowpass, bandpass, highpass filter; there is only the pole filter, ( I find this type of filter to sound much richer especially in the higher harmonics register and it also provides better analog drift than a band pass type filter can) and by the way, the pole type filter is one of the most musical and organic sounding filters I have ever heard, (because I have compared it to the many expensive analog and digital synths that I also own. The high and mighty minimoog also uses a pole filter.) The X4 has an old -school clock driven arpeggiator with swing, gate, and tap tempo functions, (you can get perfect Duran Duran Rio or Hungry Like The Wolf sounds with it) but the highlight of the Mopho X4 is an old -school 1970s architecture 16 step sequencer, that operates in a fashion like say , what The Who did on Teenage Wasteland. This sequencer operates in an old-school fashion because in order to assign a note value to one of the 16 steps, you assign it with the oscillator pitch parameter instead of playing one of the piano keys, like on a digital synth. There are four layers of sequences, which play together in parallel and each layer has 16 steps or events, so the four layers simulate 4 tape tracks. Although each layer has 16 steps you only hear 16 steps (or events) because the 16 steps on each of the four "tracks" play together in parallel also. However, every single step on all of the four sequences can be precisely edited and with this type of sequencer, fantastic animated musical or non-musical phrases are achieved. There are also lots of great sounding preset sequences that you can tweak yourself and also use for your music, and to also learn how the sequencer is programmed, and the "Push It" button can start a sequence or arpeggiator pattern in perfect time with your drum machine and can also be used for song introduction. (The sequencer can even make retro analog drum sounds, and can even "slew" notes! And the sequencer is very easy to learn how to program. I have never seen a synth of any kind with this type of sequencer; not even my ridiculously priced 1990s alesis andromeda has this! The designer of the X4, (Dave Smith) is from the old school. He is an electronic technical musical genius like Les Paul and Jim Marshall were and he believes in designing his products old school, because he believes that the old school is the best! If you call for tech support, you might even be lucky enough to talk to him,( I've talked to him before;) Dave is a friendly down -to -earth guy and he likes it when you discuss retro or vintage musical subject matter with him, and he will answer all your synthesizer questions too. Dave Smith is also the genius who invented midi technology, because way back in 1983, a Prophet 5 played a Jupiter 6, by connecting a single communications cable between the two of them. Mr Smith had found a way to make musical keyboard notes communicate with each other through digital channels, and keyboards could now "play each other," and that is why our drum machines can now follow our arpeggiators in perfect time! So, if you buy a Mopho X4, you are getting a piece of his genius, and his timeless reputation of analog synth technology. In other words, Dave Smith is still running his own company and he still designs, and builds his synthesizers the way HE wants to. There may come a day when Dave may not want to design and build analog synths anymore, and that is the reason you should get a Mopho X4 now, because if you do, his magic will be inside of it. (example: I bought some of the best marshall 100 watt heads BEFORE the great Mr. Jim Marshall passed on; because at that time he designed and engineered all of them while he was running and owning his corporation.) A few more words about the Mopho X4; it does not have any digital effects-it sounds so good it does'nt need any, but what I did was I bought myself a little korg kp kaossilator effects processor for about $160.00, and by running the Mopho X4 thru it, I now have all the awesome delays, reverbs, pitch shifts, etc that I need, and an effects processor also adds a whole new personality to the X4. If you need more than four voices, you can connect a Dave smith Tetra module to the X4 and then have eight voice polyphony. There is an empty space on the right hand side of the X4 so you can put your drum machine, another midi module or whatever. You cannot split the keyboard into two sounds, it is limited to one sound only but that is part of the beauty of this synth. The x4 is powered by a small and lightweight traditional AC adaptor, not a huge lump line type with a cord coming out of each end ( like the one on my korg radias YUCK!) and included with it are two foreign country outlet adaptor plugs. The synth cannot be powered with batteries,but only with AC power. The controls are a combination of both start and stop- smooth turning potentiometers, and also a few click type detented endless encoders, and are all very responsive when tweaked. But there are more potentiometers than there are encoders, so on the functions that you would use in performance, such as frequency and resonance, (we all like to tweak those while we're playing) they are potentiometers and not detented encoders. The function buttons on the panel are tactile type switches, (the ones that are hard to press down and then snap when you release them) but these ones actually press down very easily and do not snap too loud when they are released. The pitch and mod wheels are tight and move smoothly with just the right amount of resistance, the keyboard is very responsive, with a good action and feel to it. (they are full sized keys, not tiny microkorg piano keys.) The synth has aluminum housing (not plastic) and real wood sides. And the blue lit LCD display looks nice and is easy on the eyes . The synth has some weight to it and it feels solid,so it will remain stable on your keyboard stand or computer table. The only thing I don't like about the X4 (and it is minor) is the flimsy little tiny slide type on/off power switch, they should of put a rocker type switch instead, (but if you move it gently it should last forever.) The Mopho X4 also includes a software librarian / editor so you can program and store patches in your computer, one might also be able to use the X4 as a usb midi controller to run other keyboard software as well, but I am not sure about that. There are no patch buttons on the panel though, to call up your favorite presets in stage performance, so one might have to switch the increment / decrement buttons very fast, or use the encoder to rapidly find favorite sounds, Perhaps if a song performance requires more than one sound, this could be achieved by storing the needed sounds in the user slots in their own numerical grouping and then accessing them with the up / down buttons or the encoder; this could be the easiest way to perform with the X4. But with all the great features and capabilities of this synth, user favorites patch buttons might be overlooked! The X4 also comes with an easy to understand (less than 100 pages) user manual, and the factory shipping carton will make a suitable carrying case (thanks to the two thick foam blocks that will protect the synth from shock) until you can get the custom case for it. Now I'd like to point out that with the Mopho X4, an alesis sr 16 drum machine, a korg kp effects kaossilator, an allen & heath zed 10 compact analog mixer, an art 1990s sgx nitro guitar processor, (I'll never sell that art nitro!) a 1990s alesis nano compressor, and most importantly a 1990s tape based alesis adat 8 track multitracker, I have managed to complete an 8 song album (album is old school for cd) of my own composed music that is based on my own style of heavy metal guitar solos played to techno and hip hop beats. It is all instrumental and, I will call my album Metal Synthness. The Mopho X4 provided me with all of the fantastic analog synthesizer sounds I was seeking for my record. I did not even use a bass guitar, I used the synth for all of the bass tracks. (I wanted those Peter Gabriel type basses.) The X4 is a professional quality analog instrument that will give you great satisfaction in playing and in owning. So, in closing my review, (which took me two hours to write) I am hoping it provided some necessary information about the synth that the site could not provide. I am very pleased with my Mopho X4 as it was my Christmas present to myself, (figuratively speaking, it was my red ryder bb gun!) and (if you buy this) I am sure that you will like it too.
Music background: Semi pro musician and musical hobbyist


All I can say is wow. For $1299 you are getting a beast of a synth that can hold its own against many synths 2-3 times its price. The analog filters, oscillators, and LFO sounds so fat and warm yet very aggressive. One thing to note; a lot of people compare this to the Moog LP when in reality its a completely different animal. The LP is a more buttery sounding whereas this one has a much more "pushed" sound. Each one is great in its own way, but the Mopho x4 is a winner in my book, won't be letting this one go anytime soon.
Music background: Pro Musician

Analog Synth Heaven!

I've been going back and forth between picking up a Moog Little Phatty or the original Mopho Keyboard. With the release of the X4, the choice was obvious. It's essentially a 4 voice polyphonic Mopho with a great 44 note 3 1/2 octave keyboard in a nice, compact little package - perfection! I also like the more subdued color scheme vs the day glo yellow, which was a negative on the Mopho for me. The killer feature of the Mopho as well as all of the Dave Smith synths Os the insane modulation capabilities, with 3 EGs, 4 LFO and an insane number of modulation routings. To top it off, add in the 4 track 16 step sequencer that takes the sonic landscape possibilities to another world, with the ability to add complex rhythmic, sonic and melodic textures to your sounds. The arpegiator is the most capable I've ever seen in a hardware synth...a welcome addition for performance. The oscillators are very rich and the DSI Slop parameter fattens things up nicely. The Curtis filter is awesome and evocative of both the original Prophets in 4 pole mode and capable of producing classic Roland and Oberheim sounds when switched into 2 pole. The filter self oscillates easily abd you can actually 'play the filter' - check out the last patch of bank 4, which is a filter test patch with the oscillators turned off - it totally wails! I wish DSI would include high pass or band pass filters on these, which would make the synth even more versatile, but maybe some other day. The only negative aspect is the fact that it is not multi timberal like the Tetra, and is purely a one sound at a time instrument. Note to Dave...this would be a great add-on via software update!
Music background: Bass Player, Analog Synth Enthusiast
See also: Dave Smith Instruments, Dave Smith Instruments Synthesizers