The ESI Xsynth

It’s been a long while since I last wrote about a piece of music gear (and there are quite a few I got in the intervening years that I have been meaning to write about), but I recently got my hands on the ESI Xsynth and despite only having spent a few weeks with it, I thought I’d write a quick review.

The ESI Xsynth
The ESI Xsynth

Disclaimer: ESI sent me a review sample of the Xsynth free of charge (for which I thank them), and as usual this article follows .

Hardware

The product page has a list of detailed specifications, but there are five things worth highlighting and that I found particularly interesting:

  • Two octave (25 key) keyboard with polyphonic aftertouch
  • 3-oscillator polyphonic (10-voice) synth that has a modulation matrix and several effects that can be applied to both the synth engine and aux input
  • A built-in audio interface that can record the synth engine and aux in directly to a Mac (or iPad) via USB-C
  • MIDI in and out ports interfaces with 3.5mm TRS jacks (so it can also act as a MIDI interface for other devices)
  • Built-in arpeggiator, glide, and hold functions, as well as minimalist pressure-sensitive modulation and pitchbend controls

All of it in a surprisingly compact and portable package that only needs a USB-C connection to work. No battery, but the power draw is low enough that you can use it directly with an iPad without needing anything but a cable.

The device feels solidly built, with a mix of stylized metal and plastic that looks and feels nice–at 387mm x 148mm x 27mm with slightly over half a kilo (634g) in weight, it certainly feels solid enough to take on the road, and given that the encoders are fairly compact and don’t protrude much, I would have no qualms about tossing it into a backpack or laptop bag.

Keyboard

The keyboard was a bit of a surprise for me, since for some reason I was expecting mini keys–instead, what you get is a two-octave set that matches the general dimensions of a normal keyboard (which is great if you have trouble switching between mini keys and regular keyboards), although the mechanism and feel is rather different.

I especially like that unlike my , both the black and white keys are long enough to interleave and allow you to place your fingers in exactly the same way you’d do it on a regular keybed.

A key aspect is that pressing on the keys anywhere results in a nearly uniform response (velocity and aftertouch-wise). You can tap a key at any corner and it will go down uniformly, which is quite a unique feel, and the evenness of that response makes the the Xsynth feel a lot more usable (and expressive) than the NanoKey Studio or an Akai MPK Mini.

On that topic, the polyphonic aftertouch is a bit of a mixed bag depending on whether you’re used to a piano keyboard or a synth keyboard, since given the keyboard has a very short travel distance, the aftertouch response varies a lot depending on how much pressure you’re used to applying.

Despite having a I spend a lot of time on synth keys, so even though I had no trouble with the default velocity curve, aftertouch required some tweaking to work for me to use it effectively–so I recommend using the companion desktop app to tweak things to your liking.

Also, there are no modulation or pitch wheels, just two buttons that are rather short and somewhat unresponsive for my liking. They do work, but I found them somewhat fiddly to use (and, more annoyingly, easy to hit by mistake since, again, I found the orange backlights hard to read).

I spent a while trying out the Xsynth on its own and quickly figured out that I had to use the modulation matrix to send aftertouch values to an oscillator or filter (which not all the built-in presets do), so expect some finagling before you get a result you’re comfortable with.

Both velocity and aftertouch work via MIDI, even though (at least in my case) I have more software with MPE support than “just” aftertouch. In any case, Logic Pro’s Alchemy synth had no trouble with Xsynth input, although, again, a consistent feel was a bit elusive given the limited key travel.

But I can’t think of anything equivalent in this size that has polyphonic aftertouch and all the other features, so I am not complaining too much.

Screen and UI

One of the first things that you’ll notice when you turn on the Xsynth is the built-in OLED screen, which is used to show the current patch, parameters, and other information. It is a fairly small screen, but it is bright and clear enough to be readable in most lighting conditions–much more so, ironically, than the orange backlit buttons, which are a bit dimmer than I would have liked and can be hard to read even in completely dark conditions.

The default setting is to render the current waveform, which for me isn’t overly useful–so I disabled that as soon as I could to be able to always see patch names and parameters:

The screen while editing a patch
The screen while editing a patch

In general, the UI is really straightforward–each of the four left encoders corresponds to a parameter, and you can switch between pages of parameters by hitting the left and right buttons. The far right encoder is used to navigate through patches, and the enter button is used to confirm changes, except in a particular case that gave me a bit of trouble:

You can hit the “Global” to init a patch, and it is far too easy to hit Enter by mistake and completely wipe out the current patch, simply because the “Cancel” button is immediately on top of the “Enter” button and (again) the buttons are a bit dimmer than I would have liked:

My nemesis - the init patch dialog
My nemesis - the init patch dialog

So I ended up wiping out a few factory patches before I got used to this quirk. Strangely enough, saving edits to a patch required me to hit the “Enter” button in some circumstances, which is a bit counterintuitive (I kept hitting it once and then wondering why it didn’t save).

I would have preferred a “hold down X for 2 seconds to confirm” type of confirmation for both resetting or saving patches, or at least a “hold down X + Y to confirm” approach for more destructive actions.

But going back to the Global menu, that’s where you can set up MIDI channels and other parameters, including having local audio on or off, which is useful if you want to use the Xsynth as a MIDI controller only:

Global menu interface showing MIDI and audio settings
Global menu interface showing MIDI and audio settings

Synth Engine and Patches

You get four banks (A-D) of 128 patches, the first two of which have factory presets of various types (bass, lead, pad, etc.). I typically skip over effects and bass patches (it’s just a personal preference), but a few of the leads and pads were quite nice, and I ended up using those as starting points for my own parameter tweaking.

A nice touch is that you can browse through patches using a category mode, which lets you quickly skim through all pads or leads, etc. This is a lot more useful than the usual “scroll through all patches” approach, and it makes it easier to find something that fits your needs.

But there is a surprising amount of flexibility in the synth engine itself:

Block diagram showing the internal signal flow of the Xsynth
Block diagram showing the internal signal flow of the Xsynth

If you look at the block diagram above, you’ll see that the Xsynth does a few interesting things:

  • The three oscillators are set up in a Y cascade (with the first one cascading into the second and third), but with feedback from the third oscillator to the first one, and with a separate ring modulator.
  • The envelopes and modulation matrix extend from the oscillators through to the filter and amplifier, which I’ve only seen in the Arturia Minifreak (which I’ve never actually written about here either, but which I also have and use).
  • The aux input actually goes through the mixer, filter, amplifier and effects chain, so you can use the Xsynth as a simple effects unit for external audio sources, which is a nice touch especially considering that it has a built-in audio interface.

This doesn’t mean that it’s easy to create patches (as with any modern synth, you need to spend a fair amount of time learning the implications of some controls), but it does mean that you can do a lot more with the Xsynth than you might expect.

For me at least, it was much more productive to use the desktop editor to create and edit patches, since it has a much larger screen and a more intuitive interface for editing parameters:

The Xsynth desktop editor

The editor is available for both macOS and Windows, and as a bonus it can also be used to do firmware upgrades and restore factory settings.

Effects

In a nice departure from the usual “effects are a separate box” approach, the Xsynth supports a small set of built-in effects that (as you can glean from the diagram above) can also be applied to incoming audio, and fall into roughly four categories (which are mapped to the four right encoders):

  • Distortion (several kinds), Compressor, Auto-Wah, Lo-Fi
  • Reverb (Room, Stage, Plate, Spring)
  • Chorus and Delay
  • EQ (various types, with selectable frequencies)

The reverb is serviceable and the delay works well enough, and I spent a little while trying to get the Auto-Wah (of all things) to work with the aftertouch. So yes, you can have some fun with the effects, but they are not the main selling point of the Xsynth.

Like I mentioned above, the aux input can also be used to process external audio, and they worked fine with , which I hooked up to the Xsynth via both MIDI and audio.

Portability and iOS Compatibility

Despite being bigger than I initially expected, the Xsynth feels rugged enough to just drop into a backpack and laptop bag without a lot of concerns, and like I mentioned above, I was able to use it with my iPad Pro 11” with a single USB-C cable and use AUM with it:

Using the Xsynth with AUM on iOS

I also had no issues using it with GarageBand, and went for AUM mostly because I completely suck at looping and having a keyboard that I can use as an audio interface was a great way to hook up a few of my standalone synths and use them as audio sources for practicing that.

The Xsynth as a Master Keyboard

I also had no trouble using the Xsynth as a master keyboard for my Mac and with on a Linux laptop1 and it worked well enough with both Logic Pro and .

If you want to use the Xsynth as a master keyboard, you can do so by connecting it via USB to your computer and using Midi CC to control your DAW or other software.

What I found most useful is the ability to have multiple pages of CC assignments for the encoders, which you can switch between by hitting the left and right buttons.

In my case, I set it up to control Arturia’s Analog Lab on my Mac (which really demands eight controls, but it’s workable).

Conclusion

I’ve barely scratched the surface of what the Xsynth can do in a couple of weekends, but one of the reasons I wanted to write this review is to share my initial impressions before Summer vacation starts and I have a bit more time to play with it.

The size and comparative ruggedness makes it quite suitable to use on the go, and I can see myself taking it along with me on Summer break instead of the , which can’t do much more than act as a MIDI controller and has no built-in synth engine.

It does have a few quirks, but like Floyd Steinberg, who did a video on it recently, I would rate it an 8/10 (or 4/5 stars, if you prefer that rating system) for its price point and features, especially considering the built-in audio interface and range of effects.

For me, other than the software quirks, the only physical changes I’d make would be switching the orange backlights to white and adding more conventional modulation and pitch controls (perhaps control strips).

Given that I prefer to travel with an iPad, I would love a mini-keys version of the Xsynth that I could pack in roughly the same space as the iPad Pro 11”–I will probably update this review after I have done a couple of trips with it and can figure out whether the full-sized keys make up for their size.

But I am quite happy with the Xsynth overall and look forward to diving deeper into its capabilities in the coming months.


  1. I forgot to mention that the Xsynth ships with a few goodies including Cubasis LE and a 8-track license, which is a nice touch. ↩︎

Checking In

It’s been a crazy few weeks, and in keeping with the geopolitical situation, it doesn’t seem like it’s going to get any better soon, so keeping positive things in mind is a bit of a challenge.

Additionally, the weather has been warming up so that office crawls past 27oC most days, which means I am spending as little time in there as possible.

Reviews

As such, I’ve been trying out a few things I don’t need a desk for. Writeups will appear ASAP, but one has been an intriguing complement to AudioKit’s completely amazing (and totally free) Synth One J6 app for the iPad – however, the lack of musical inspiration due to workload has been too much for me to write about either….

3D Printing

But I finished my tiny SE/30 and compiled an SDL-only version of BasiliskII for it, which is currently running System 7 and (of course) the After Dark screensaver:

Cozying up on my desk
Cozying up on my desk

The steps to get the core software going (and minimize boot time) are mostly documented in this YAML file (I have no time to do a full write-up, but this is meant to be reproducible).

Like I mentioned I also got a roll of “platinum grey” filament from Polymaker. but since I want to do a version with proper audio, better internals and a slightly different look and there are no STEP files available, I’ve been recreating a usable model from the STLs I have:

Cleaning up the STL into something editable
Cleaning up the STL into something editable

…and, since I want to have a period-accurate mouse, I am indeed modeling one – starting with the fittings for a modern three-button one (with wheel). The tiny mice I’m using are cheap enough that I am planning to do a couple of these (a period-accurate one and an ADB version), and I’m definitely not rushing things:

Tiny Mouse platform, with wheel support
Tiny Mouse platform, with wheel support

The mechanism I’m using seems to be pretty common in AliExpress US$2 mice, and looks like this (SD card for scale, since I was out of tiny bananas):

The mechanism, to scale
The mechanism, to scale

Other Stuff

There’s a lot more going on, including the fact I’m shifting the static site builder to an ARM VM on Azure that is 30% cheaper (and has twice the cores) than the Intel one that’s been publishing my updates but I’ve also been changing the way I deploy the builder service, so it’s not all there yet.

But I am very happy with the approach I was taking at , and a few smaller things are already running that way. I just got distracted by work and the somewhat crazy notion that I should rewrite my RSS feed summarizer in just because I wanted to get off the usual “ is the AI runtime” beaten track–I get enough of that at work.

But I am going all “agentic” on the idea of converting the older 4000-odd entries on this site to pristine Markdown with some sort of AI workflow. That might arguably be an even bigger time sink than anything else since like any other massive AI-driven content or code conversions, validating the results is a nightmare…

Six Months with the Supernote Nomad

It’s been (and around six months since I started using it), so I thought some kind of update would be in order and gathered my notes into a sort of mid-term review.

In short, pretty much all the pluses and minuses in my original conclusion have panned out: it’s become a part of my writing workflow and a device I reach for several times a week to do a substantial part of my reading, but not taken over either completely, largely for the reasons I pointed out at the time–and a few more.

The Good Bits

The Nomad has been a great reading device. I really like going through The Economist on it every week, and with the longer afternoons leading up to Summer I’ve also been using it to catch up on my book queue as the larger screen size makes it more comfortable than my aging Kindle.

Ratta has been updating Chauvet (the Android underpinnings of the Nomad) as well as the bundled apps (including passing through some updates to the Kindle app) and adding a few entirely new features, like drawing straight lines (great for diagrams), a sticker feature (that I also tried to hack for drawing architecture diagrams with relative success), and even an entirely new app that lets you use your Nomad as a drawing tablet for your Mac.

That’s not bad at all considering the above also includes quite a few minor bug fixes and improvements (and is already a better track record than most device manufacturers), so that has been a definite plus–as has the fact that none of those enhancements included AI features, which remains a plus for me.

And I have no doubt that the periods of time I spend using only the Nomad to organize my thoughts have been more focused and of (arguably) better quality output, but I can’t just look at it in isolation, and some shortcomings have come to the fore.

The Gaps

For instance, I’m still using my Kindle every evening, simply because I can’t keep my bedside lamp on into the wee hours–a back light is still much less intrusive and, let’s face it, a killer feature for night time reading.

Then there’s the actual note taking. As it happens, inspiration for a lot of the notes I take comes from some kind of reference material–papers, web pages, RSS feeds, etc., and all of it is effectively digital in nature. This means two things:

  • Trying to use a paper metaphor for most of it doesn’t quite fit.
  • Getting my notes across to other devices is really important, and not necessarily in ways where the Nomad excels.

For instance, I find myself constantly wanting to annotate stuff inside the Kindle app (which doesn’t really work), and trying to find workarounds like syncing EPUBs or PDFs back and forth ended up breaking whenever I tried to get my notes outside the companion app (which I went back to for a bit).

There is another constraint where it comes to annotating PDFs–as I originally mentioned, the Nomad’s size doesn’t help a lot there, and zooming and panning is so slow that it makes it hard to quickly skim and clip off things from a document–something I can do much faster on an iPad, with the added benefit that I can round-trip annotations to my Mac. We don’t have Preview on the iPad–yet–but I can still do it better and faster than with the Nomad’s features.

This is not to say that using the Nomad is hard or unnatural, but paper is still a separate medium, and there are all sorts of corner cases when you try to make it digital. Moreover my review was done during a period of time when I was actively trying to minimize both my screen time and the number of things I was doing at once, and after the Christmas break I had to go back to actively multitasking, which in my case makes it hard to set aside even half an hour of uninterrupted time for quiet writing.

And when I am on a roll, waiting a few seconds for the Nomad to catch up on anything (switching apps, searching for info, syncing with my other machines, etc.) significantly increases friction and actually causes me to lose track of what I am doing.

The Hacks

One of the things that really drove home the point that my note-taking is primarily digital was that once I got to run on the Nomad, I pretty much stopped using the built-in Notes app except when I wanted to do a simple diagram or needed a distraction-free environment.

completely replaced the Nomad’s (very limited) task list for me as well as a good chunk of the (largely missing) calendar functionality, since I do a bit of journaling and planning, and I think this says a lot about what I need in a note taking device–I could do the exact same thing using Apple’s Notes, Calendar and Reminders apps (especially now that Reminders can do kanban very well), but having the lot integrated in a single cross-platform experience is hard to replicate.

That doesn’t mean I can’t use the Nomad to capture notes on the go (and I’ve settled on a mix of and the unofficial Supernote plugin for Obsidian to have my handwritten notes synchronized to my other devices), but the initial note is such a small part of the process that I sometimes question whether having a more focused, distraction-free device for capturing the initial idea is really important.

After all, I spent many years using Palm devices and early smartphones to capture To-Dos, and a surprising amount of text on this site was painstakingly edited on an iPod Touch (and then an iPhone, iPad, etc.), so looking back, I think that the key challenge for me with the Nomad over the past few month has been exclusively a matter of focus.

Flow Matters

I do so much context-switching (and need to carry so much across contexts) that the Nomad tends to fall behind–things like the iOS share sheet, AirDrop, cutting and pasting snippets of text via Continuity or just plain Apple Notes have less friction and are faster than switching to or waiting for the Nomad’s cloud services to sync.

Of course, Summer is upon us now and I fully intend to take the Nomad with me on vacation, so maybe I’ll again be able to hit that sweet spot of thoughtfulness and patience that made it feel so good–and it would be nice to at least be able to read my handwriting again.

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