Dave Smith Intros Mopho x4 Polyphonic Analog Synthesizer

Dave Smith Instruments Mopho x4

Dave Smith Instruments today introduced the Mopho x4 keyboard – a new polyphonic analog subtractive synthesizer.

The Mopho x4 is built on the same voice architecture as the Mopho and Mopho Keyboard, but offers 4 voice polyphony.

Here’s a video of Dave Smith introducing the Mopho x4:

The Dave Smith Instruments Mopho X4 Keyboard

Mopho x4 Voice Architecture

Each of Mopho x4’s four voices is composed of two analog oscillators, two sub octave generators, selectable 2- or 4-pole Curtis low-pass filter, three 5-stage envelope generators, four LFOs, a re-latchable arpeggiator, and a 16 x 4 step sequencer. Its voice also comes packed with 20 modulation sources and almost 50 destinations.

Smith notes that the Mopho x4’s 100% analog signal path is ‘powerful, monstrous, and sonically dynamic’.


  • The Mopho x4 is designed to be intuitive to use. Every parameter is fully programmable and editable from the front panel.
  • The x4’s full sized 44-note semi-weighted keyboard has aftertouch and velocity sensitivity.
  • The full sized pitch and mod wheels are freely assignable.
  • You can 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.
  • Dave Smith Instruments says it’s now the only company producing fully programmable polyphonic analog synthesizers.

The DSI Mopho x4 is shipping now for $1299. See the Dave Smith site for details.

51 thoughts on “Dave Smith Intros Mopho x4 Polyphonic Analog Synthesizer

    1. The Tetra is designed to be a multitimbral module.

      The x4 is monotimbral and does not have combo, multi, stack, or split modes.

        1. i’ve often found myself wondering the same thing on multiple occasions with previous, seemingly innocuous posts. kinda funny.

          anyway, synths….

    2. What is the difference between the tetra and EVERY dave smith product? They have repackaged that synth engine into every product that they offer now. They say they are he only polyphonic analog out there but (thankfully) we have or soon will have much more interesting poly synths from Waldorf, Vermona, Tom Oberheim, and MFB, not to mention Mutable Instruments Ambika which may not be fully analog but will arguably sound much better and be more interesting and certainly more original than this thing. I for one and really sick of mr. david smith. He makes these outrageous and misleading claims about his products when he really shouldn’t need to if they could just stand on their own merit. If any one can think of any other analog polys out or soon to be released please add to the list.

        1. That is one I haven’t tried. That is also one that I might still be interested in trying. While I know I didn’t say anything foolish, my point simply was that I dislike that he always makes these false claims when demo’ing his products.
          -When the tempest came out he said that -‘It was the ONLY analog drum machine in production today’- THAT WAS NOT TRUE
          -When he says that his is the ‘ only company producing fully programmable polyphonic analog synthesizers’- THAT IS NOT TRUE.

          1. Can’t say I’ve ever heard Dave Smith make those kind of claims. I’m certain he knows about companies like Vermona and Jomox. The Mopho, Tetra and Prophet 08 all come from the same architecture, with a few modifications to emphasize low frequencies on a Mopho. I thought the Prophet 08 sounded somewhat dull and uninspiring.

            That said, the PolyEvolver is one of the most interesting synthesizers created in the last 20 years. It is nothing like the Mopho/Tetra/Prophet 08. There are 2 analog oscillators and 2 digital wave oscillators per voice. Blending the two into a cohesive patch is like sculpting sonic art. Sounds often take on a life of their own. I read that they use the same oscillators as the Prophet 5 and Prophet VS. There is feedback tuning, grunge, distortion, delay, a 16 step analog sequencer. I was in the market for a Mono Evolver keyboard for ages, but decided I wanted the polyphony. I know I won’t be selling my Poly anytime soon.

            1. I think the Prophet ’08 is underrated – it can produce amazing and huge sounds, clean or crunchy, warm or glossy, dark or bright, and can be beautifully expressive. Lots of routings, sequencing, layers, splits, 4 LFOs, dual stereo outputs, CV in… I just wish it had poly aftertouch like the T8, and maybe a numeric keypad like the Prophet 5 for fast patch selection. 😉

              1. Agreed – the ’08 is wonderfully expressive, and count me among those who found it immediately inspiring. Mine is the PE version (potentiometers where they count, instead of encoders) and is a real joy to play. I also happen to find the feel of the keybed to be superlative, with an especially inviting aftertouch.

                Also agreed: a faster way to jump to a fave patch would be quite helpful! I suppose one could just map the ones used live to a cluster at one end of Bank A or B’s range, but still. . .

          2. Duke – you coming across as angry and uninformed. I don’t understand the hate!

            If you’re going to criticize one of the most important synth pioneers, on a site dedicated to synths, make sure you know what you are talking about and come up with some intelligent criticism.

            You criticize Smith for saying his company is the only one making programmable analog poly synths, and then you spew out a long list of examples of companies that aren’t making programmable analog poly synths.

            Waldorf makes synths, but not programmable analog polysynths. Maybe you’re thinking of their virtual analog synth, the Blofeld? Or their monosynth, the Pulse?

            Vermona makes a poly synth, the Perfourmer, but it’s a very different beast. It’s designed as four simple monosynths in one box. Very cool, but not programmable and it has a much simpler voice architecture. Also, it’s close to two grand.

            Oberheim has announced a duophonic synth – aka the Two Voice – and it costs three times as much as the Mopho x4. They’ve announced a four-voice, but it will have limited programability. Oberheim hasn’t announced pricing, but it seems likely that it will cost more than their Two Voice, which is $3500.

            The other synths you bring up are vaporware at this stage, but also won’t really be comparable to the Mopho x4 when they get released.

            If Smith’s synths aren’t your cup of tea, fine. But don’t call him out with nonsense, when he’s actually making kick ass synths that carry on the tradition of some of the most revered keyboards in synth history.

            1. I didn’t intend to express anger. I am not angry at all. I just thought that I had a valid point to make. I do appreciate Dave Smith and his work. I own a few of his products. I just find his last few to be short of the standard that I have come to expect. I also wanted to make a point about his claims when promoting his new products lately, while I stand corrected on a technical detail, there is no harm in expressing my thoughts for the sake of discussion. It’s only my opinion and I have no anger regarding the issue. Let’s just chill out here people.

      1. Well Vermona make the Perfourmer that’s an polyphonic analogue synth, but Waldorf, only make VA’s at the moment, oberheim only make mono/duo, MFB only make monos and the mutable has digital oscillators, Dave’s is polyphonic,programmable and has analogue oscillators, that does make him reasonably unique and most truely analogue gear is monophonic.

        1. In all honesty, I’m a bit underwhelmed. I, personally, would have preferred the MEK to stay in production, which, I assume was replaced by Mopho X4. I understand a company the size of DSI can only maintain so many products at once, but I find the evolver infinitely more interesting.

          So, I, personally, don’t really see it as more analogs on the market. Just a replacement. Don’t get me wrong. The size is great. The price is really great. It’s outstanding for first time buyers. I just find it uninspiring, like the afterthought of a name.

          Razmo made a good point, but I don’t believe it’s the Pulse 2 that DSI is reacting to. I believe it is the Minibrute. I’m sure DSI saw it eating into the sales of the more expensive mopho keyboard and MEKs. Cheapest way to one up Arturia is to offer a polyphonic version of existing architecture. Less capital spent getting a new product to market. That is why I find it uninspiring.

          Up side is that the current chip has now run it’s course. I can’t wait to see what DSI unveils at Winter Namm. I also can’t wait to see what other analog units come to market. Yes, Korg, I am staring uncomfortably at you. Something with keys. Please?

          ps~ DSI, please, please keep your poly evolver on market. I still dream of owning that blue bastard.

        2. I’d have the flexibility of Shruthi-1’s digital oscillators over the notion of authenticity VCOs have acquired. Just sayin’, like.

        3. to be fair, Waldorf have been making the Q+ for a while which has digital oscillators but analog filters – arguably bringing it fairly close in concept to the PolyEvolver, they also make the Wave which I believe also has analog filters. I think if you’d class something like the PE or even an old PPG as analog then Waldorf’s products must surely be similarly acknowledged.

      2. You clearly have no idea what you are talking about. The Polyevolver, MonoEvolver and Tempest have zero to do with Mopho “synth engine”. Outrageous claims? What is wrong with you ? What claims are you talking about ? Let me know when Mutable, Waldorf, MFB, Oberheim or Vermona does something more original than the Polyevolver. The man offers great sounding, powerful, analog synths at very reasonable prices.

  1. There are a load of people that will say it needs more knobs, but it’s a Mopho, not a Prophet, and it’ll be priced accordingly. As far as i can see, it’s got the same number of knobs as the Mopho keyboard, which with the shift key, whilst not ideal is fine for most needs. You want more knobs, buy the Prophet. I think it’s a brave move in the current economic climate, and it looks lovely – very portable. I hope it integrates well with the Tetra. Good luck Dave! (i think i want him to be my dad).

  2. too bad this wasnt at summer naam 🙁 DSI has really worn this synth model out by now, an awesome synth mind you but for $1299 you could save money and buy a tetra with a midi controller. does this stop me from wishing i had one… nope!

      1. Nice? What there is nice? Original idea of a sub oscillator was to create more bass presence I think. Poly bass would sound like shit, so I can’t see multiple sub oscs being any useful therefore…

    1. SrOok – I have a Mopho Keyboard and a Tetra, and it’s a powerful combination, but not nearly as simple to use as a polysynth as it first seems, and certainly not as simple as this Mopho X4 – you have two outputs that you have to match exactly, otherwise you get a quiet or loud notes when you don’t want them, you have to copy patches backwards and forwards (which in my case means swapping MIDI leads round). It depends on what you need them for (if it’s just in the studio it’s probably better) but for me – I don’t use them together now – the Tetra plays chords, the Mopho leads and basses. They both do a great job at those things.

  3. I’m trying to figure out how it differs from using a Mopho Keyboard and a Tetra. I’ve got a Mopho Key and want to get some more voices, seems like just getting a Tetra would be better for me, and that makes one extra voice too!

    Cool synth, but I’m just seeing how it’s really setting itself apart. It seems like they just took the Mopho Key and extended it to the side for more keys and did it in black. I wish they had taken a more unique approach and gave it something to make it stand apart from the rest of their products, especially after discontinuing the Mono Evolver.

  4. Most of the comments are negative!
    You ask for analog synths and then you criticize!!!!!!!!!!!!!!!

    I say:

  5. I don’t QUITE understand the whining about “why theres no analog synths”


    People are salivating at simple MONO synths € 500. This is versatile polysynth with 4 oscillators @ $1k+ range. What else is there for grand?

  6. I love DSI. Very nice instruments at a reasonable cost who treat their customers well. The more analogue poly’s the better.

  7. Some people probably want a bigger keyboard, and more voices than the Mopho Keyboard has to offer, so I believe this machine is made more for the performance oriented byers, cause the Tetra has more to offer in the studio in my opinion (Yes I’ve got one).

    With this said… I think it’s time for Dave to start looking into some different filter chips, cause he’s been using this same chip brand for every synth he’s done for quite a while now, and they are beginning to be on the short side with features, not the least sound a bit alike filterwise … we are seing more and more new machines with multimode analog filters, and I think Dave will have to start looking a bit into the future regarding this if he want to continue to make something “special”.

    I’d say that one thing that Dave is doing with his machines that no other company does like him, is the MIDI implementation… it’s deep, it has SysEx to full specs… this many other companies could learn A LOT from!!! I’m sick and tired of all these “CC controlled analog synths”… there are still people out there that use Emagic SoundDiver, or want to make fullfeatured editors, and in these cases it’s a pain in the neck with this new “trend” of skimping out on the SysEx specs.

    With the coming Waldorf Pulse2, I believe Dave has to begin thinking that he is no longer above the competition… I think that would be wise of him.

    If he’d make a one to four-voice simplified (read; CHEAPER!) module of the Tempest I’d consider bying that… a bit like what the Tetra is to the P8.

    Just my opinion… yours may differ…

  8. Well done Dave Smith for keeping the analogue synth flame burning. Stop complaining folks cause if he pulled the plug, we’d be down one analogue synth maker and that would only be a bad thing.

    As for repackaging the same product – just how many versions of the Moog Voyager are there?

    Thank you for producing great synths Dave 🙂

  9. I personally own a Mopho, Evolver desktop, and MEK. DSI is a great company (small company) with excellent customer service and unique-sounding products. Most of the times I have contacted them, Dave Smith was the one answering my calls. He even let me interview him for a history paper I did in grad school.

    That said, This synth will be super cool for those looking for classic analog type sounds. I’m a little sad that he stopped making the MEK, which IMHO was the most “out there” mono on the market.

    If you don’t like this or the Mopho, check out the evolver. It is overwhelmingly strange and powerful.

  10. Dave’s work is impeccable. He’s one of the godfathers of MIDI, so how about a little respect, sheesh. I’ve owned 2 Prophets and they roared. Anyone who is into this realm “should” have at least one DSI synth, along with just a few from other makers. Its part of the gig of varied synth colors. I am more of a DAW user now, but if a Tetra would also save 4-voiced combis the way it saves single programs, I’d be much keener on it and its plenty potent as is.

  11. I’ve got to check it out in the store, but 4 voices at that price point is going to give the little phatty a run for the money.

    1. Choices in analog synths! How awesome is that?

      It wasn’t that long ago that everything was knobless and virtual analog. Does that make me an old-timer?

  12. affordable analog synths are ok by me. i’m sad that i can’t polychain my MEK with my MophoKey. I have had a heck of a time as far as customer service goes with DSI with regards to the crap encoders they put on it.
    I understand why they used them, but i have bit the bullet and gone for the Pot edition encoders (same as the MophoKey) and moved on.
    The tempest is very much a work in progress and has it’s shortcomings too.
    I have been playing for a long time and every great synth i have played or owned has it’s weaknesses. we play through those and draw on their character and unique blah blah blah

    these are good times for synth players and i have seen DSI’s reasonable price-points have a trickle-down effect on both new and old companies.
    that alone deserves a lot of respect.

  13. I love Dave Smith Instruments.

    I own an Evolver Desktop and just recently bought the Tempest and both are absolutely incredible machines.
    Wish I had another €2500 to get the Poly Evolver keyboard. This must be absolutely massive and for sure a synth you never want to get rid off..
    The Mopho x4 looks pretty cool as well, almost like the Tempest but with a keyboard instead of pads. Don’t care about the “same” synth engine either because the Dave Smith sound is fantastic.. There is absolutely nothing to say against it.

    Although I have to mentioni: I wish they would have put more time and effort (and maybe a second programmer) into the Tempest’ OS development instead of releasing a new synth.
    The Tempest OS is still so buggy and crashes a lot of times and this is very annoying and time consuming…
    Nevertheless I think once they fix all the bugs and add some new features, I would also never want to get rid of Tempest 🙂

  14. Taken from the official DSI Mopho X4 manual:
    Tetra is the best candidate for poly chaining with the Mopho x4; the voice architecture and programmable parameters are identical. ….. Both the Prophet and Tetra have two layers for stacked and split programs; Mopho x4 does not. When Prophet or Tetra programs are loaded into Mopho x4, layer B is ignored.

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