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Korg ESX1

Music Production Sampler
Published March 2004
By Derek Johnson

Korg ESX1Photo: Mike Cameron

Rack studio samplers may be pretty much a relic of the past, at least in terms of manufacturers producing new examples, but it's not quite all software and computer RAM yet — not if instruments such as this new one from Korg are anything to go by.

Even before software sounded the death knell for the serious hardware sampler, desktop devices aimed at providing complementary sampling to synth and rhythm-producing grooveboxes have been available, even going back to Yamaha's 1996 SU10 and Zoom's 1999-vintage SampleTrak ST224. Korg's Electribe range has included sampling devices from the start, going hand in hand with their rhythmic or synthy cousins. This practice looks set to continue with the next generation of Electribes, introduced by the valve-equipped EMX1 (reviewed SOS December 2003) and now augmented by the sampling Electribe SX (or ESX1, if you like... there seems to be a conflict between front-panel, rear-panel and manual labelling!).

On The Outside

The Electribe SX comes wrapped in a solid metal package, finished in a head-turning metallic red that complements the blue of the EMX1. In fact, though SOS isn't the type of mag to suggest that a product's colour might be a reason for making it a part of your studio or stage rig, I challenge anyone not to be impressed by the finish of the ESX's front panel. Pictures do not do it justice.

In terms of knobs and buttons, the ESX1 is lavishly specified, offering 69 buttons and 17 knobs, a slider and a ribbon controller. The latter two controls are for the brilliant and intuitive hands-on arpeggiator, which I raved about in the EMX1 review. The new Electribe also features a pair of highly visible, backlit, Russian-made Electro Harmonix 12AX7 valves, which are able to add no small amount of real analogue fuzziness and warmth to its sound.

The layout appears superficially the same as the EMX1's, but is in many ways rather different — as befits a device that is 100 percent sampler. Samples can, however, be manipulated with a similarly abbreviated set of subtractive synthesis tools as those offered by the EMX1. Without any samples loaded, the ESX1 is mute. Out of the box, though, you don't have to start sampling right away, since the machine is stuffed full of samples (and patterns) to get you started. Many of these will continue to be useful even after you've built up a library of custom samples.

Ins and outs are rather similar to the EMX1's, comprising MIDI In, Out and Thru, power in (fed by a carpet carbuncle external PSU), two sets of stereo outs, headphone out, and an audio input. One difference is that the audio input is mono or stereo (on a single jack), rather than simple mono, as is the case with the EMX1's audio in. A SmartMedia socket is provided for external sample storage to cards of up to 128Mb in size. I can finally mention this fact in a review without commenting negatively on their cost: having sourced some since my review of the EMX1, I'd say that SM cards are now pretty cheap. I paid less than 35 quid for a pair of 64Mb cards, and I think I could have done it even cheaper if I'd shopped around.

Audio Input

Korg actually claim the ESX1 has a 16-track sequencer. One of the these 'tracks' is the accent track for the Drum parts, and I find it a little tenuous to include this as a 'track', but I will allow the audio-input track, for here you can record what are essentially mutes and 'unmutes' for any audio that's appearing at the audio input. Perfect for adding, and controlling, the audio from an EMX1 or what?

If what you're connecting to the Audio In isn't an EMX1, and doesn't even have a MIDI connection with which to establish synchronisation, you can instead use the Audio BPM Scan option: this is a pretty accurate way to lock the ESX1 to any music that has a regular beat. You can even arpeggiate the audio input track! And just think of the fun you could have if you added tempo-sync'd delays, filtering and modulation to incoming audio.

On The Inside

Give it a quick glance, and the ESX1 appears to function in a similar manner to the EMX1, certainly as far as sequencing goes. (The effects and arpeggiator are also identical.) Nine drum Parts plus five others, each marrying a sound source with one track of sequencing, are used to record Patterns of up to eight bars in length, in step or real time, with the Patterns chainable into complete Songs. As mentioned above, though, the EMX1 needs to have samples in it before you can start creating those Songs.

The sampler section can record or import mono or stereo samples, at 16-bit resolution and a sample rate of 44.1kHz. Imported samples can be in WAV or AIFF format, and they come into the system via SmartMedia cards. (In view of this fact, it might have been nice if Korg had supplied a card with the machine.) The precise on-board MB memory capacity for samples is unspecified in any of Korg's paperwork, but the memory can hold up to 285.3 seconds (4.75 minutes) of mono samples. That's divided into 384 sample slots: 256 for mono samples and 128 for stereo. If you want more than 384 mono samples, a) Well done! You're being creative; and b) Tough luck. Stereo sampling is always an option, but stand by for some compromises on this front.

In trying to figure out the numbers, I discovered that saving the memory contents of the ESX1 to SmartMedia card (once I'd maxed out the sample memory) occupied around 27Mb, though I don't know how much of that memory is needed for other data, such as global settings, Patterns and Motion Sequences, which we'll come to shortly. Using the scratch calculation of around 10Mb of storage needed for every minute of 16-bit stereo digital audio at 44.1kHz, this would imply that data reduction, to 'compress' samples into less space, isn't necessarily being used by Korg in the ESX1 (the maximum sample time would need just under 24Mb), though one can't always be certain about these things! Even if data reduction was used, there would not really be any cause for concern: Roland, for example, have developed an entire dynasty of digital multitracks which depend on data-reduction technology.

Effect type is chosen via a chunky knob.Effect type is chosen via a chunky knob.Photo: Mike Cameron

Once created or loaded (and edited if needed — more later), samples can be assigned to one of the Pattern Parts, of which there are 14. Between them, they handle samples in four distinct ways. From the left of the front panel there are nine Drum Parts, labelled 1-5, 6A, 6B, 7A and 7B, with each of the last two pairs not triggerable at the same time, to help simulate hi-hats and other similar rhythmic devices. In most circumstances, you'd assign drum, percussion or sound effect samples to these Parts. Two so-called Keyboard Parts, when selected, can be played from the ESX1's button keyboard — the bottom row of 16 buttons doubles up for this function and is transposable over an eight-octave range, whilst also providing access (in tandem with the Shift key) to a collection of edit functions and menus. The most obvious choice of samples for these two Parts would be those suitable for melodic playback. Samples assigned here can be played with sustaining loops.

Next up are two Part types which allow you to have rhythmic or riff samples play back in time with whatever tempo you've set for a given Pattern: Stretch and Slice. Two Parts can be assigned Stretched samples. In these instances, you simply tell the ESX1 how many 16th notes long a sample is and the machine works out how to play it back such that it'll stretch to fit any tempo. In practice, this DSP-based trick is a little limited — large variations in tempo, in either direction, will not always be terribly faithful, though the effect may well be effective in any case! It's certainly up to the task of moving a few BPM in either direction, though, allowing you to perhaps tempo-match two loops and still be able to play with Pattern or Song tempo later.

There is but one Slice Part, and this is a simple take on the Propellerhead Recycle idea of dividing a sample into discrete segments, each of which is then triggered by a MIDI event. The resulting sample can have its tempo changed to a much greater degree than a Stretched sample, since no DSP is involved: it's exactly the same as creating a drum kit from individual hits and triggering them, except that each 'hit' is a portion of the original sample loop. In fact, it's possible to extract hits from within a Sliced sample for redeployment elsewhere, such as any of the Drum Parts (you'll find instructions for doing this on page 47 of the user manual). In practice, there are issues, since each Slice can't be changed in length. This results in big gaps between hits when a tempo is slowed down a lot, for example, though it's often not a problem as such. However, tempo changes of many BPM in either direction are acceptable.

Now for a few words about stereo samples. They introduce compromises, the main one being that the use of them results in the loss of Parts. For example, if you assign a stereo sample to Drum Part 1 or 3, you lose Part 2 or 4; you can't assign stereo samples to a single Drum Part, or any other Drum Part besides the 1/2 and 3/4 pairings. The same compromise is true for the two Stretch Parts. Choose a stereo sample for Stretch Part 1 and that's all you can choose, with Stretch Part 2 obviously being deployed to hold the other side of the stereo sample.

Other bizarre stereo compromises are the fact that a loop point (more in a moment) can't be applied to a stereo sample, not even a stereo sample assigned to a Keyboard Part, and a stereo sample can't be Sliced (and hence can't be assigned to the Slice Part).

The Factory Set

Though the ESX1 is aimed at people who want to create music with their own samples, it comes filled with a factory set of samples and Patterns. Amongst the giggles, 'whoa's, and soulful wails you'll find a basic but useful collection of drum hits and instrumental samples — the latter being really short! Many are obviously meant to be played down a few octaves, at which point they'll sound for longer (a bit like the old samplist's trick, back in the days when RAM was expensive and hardware samplers didn't have much of it). Setting instrumental samples to loop from start to end also results in a seamless loop, which is helpful.

Patterns are provided by Korg, too, though their number is a bit confusing: the promo blurb at the start of the manual says 192, whereas the Pattern name list at the back of the manual shows just 128. Whatever the case, there are 256 Pattern locations, all of which can be filled with your own work, plus 64 Song memories. The factory examples show off a large number of contemporary styles, with some remarkable programming and ingenious use of the factory samples. Newcomers would do well to have a close look at how Korg's programmers have stretched this fine little instrument.


The sampling process itself is separate from the deployment of samples within Patterns but is as straightforward to access as any other aspect of the instrument. Anyone new to sampling may need to take a little time to familiarise themselves with basic concepts, and the issues of setting input levels, managing memory, and deciding what a decent loop point is, but the ESX1 is a good enough tool with which to learn.

As one might expect, mono or stereo samples can be recorded from external audio, either manually or via an automatic level-sensing option. If, when you first try to sample, nothing happens, press the Audio In button — it's on the other side of the front panel from the other sampling controls. The sampling procedure is initiated by pressing Shift + Record (in the transport controls); the Record button has text just above it, to remind you.

The Electribe's mix output can also be resampled quite easily. Thus if you get something going that you'd like to use in another track, or would just like to preserve before changing settings, simply sample the ESX1's mix and move on. Resampling will capture any Motion Sequences (more later) recorded into a Pattern, plus any changes you make live during the sampling process, which adds to the spontaneity of the process. Note that if you record a stereo source (such as the ESX1's own mix output) in mono, it still monitors in stereo, which can be a little disconcerting.

Running SX & MX Together

I mentioned in my conclusion to the EMX1 review that I had such fun creating strange sounds and textures that I found it valuable to sample the output continuously, so as not to lose anything. The computer-less amongst us could now do this entirely within a Korg-branded environment, if they own an ESX1. I did this and it worked perfectly. My one niggle is not a complaint about sampling the EMX1, but one about the way in which stereo samples are handled by the ESX1 — see the main body of the review for more. And as I'd hoped, it's also possible to resample a mix of the ESX1's audio plus whatever appears at the audio input — including audio from a sync'd EMX1!

Helpfully, resampling of the mix starts in sync with the Pattern playback, so there will be no dead space at the start of the resulting sample. You can't define a number of bars to sample, but you'll get the hang of hitting 'stop' at the right point to make a perfect loop, if that's what you ultimately need. It's worth noting, though, that resampled audio is not processed by the valve circuit — shame, since it adds such character to a mix.

Post sampling, the usual tools are available, including sample naming. A finished sample can have start and end points set, and a loop point added if desired, using a slightly unhelpful numeric display — the small LCD means no chance of graphic editing! The data knob increments or decrements values in single-sample steps, though engaging the 'Shift' button allows changes to be made in 10000-sample steps. There seems to be no way to edit to zero crossings (to minimise clicks), but one soon develops the aural tools necessary to sense or hear good start and end points, and, more importantly, a smooth loop. Once a sample is edited, any unwanted material outside the start and end points can be truncated.

Normalisation is available, to optimise the level of any samples that might have been recorded too quietly. There are specific options to do with preparing samples for use in the Stretch and Slice Part slots within ESX1 Patterns, and samples can be tuned +/-64 semitones with cent resolution; this provides loads of leeway for customising any imported samples that don't adhere to the expected 44.1kHz/16-bit format. Such samples will play back at the wrong pitch, so being able to tune over a wide range is welcome.

One thing the ESX1 will not be able to do is multisample — but I wouldn't expect it to. Even so, this is not just a loop playback and drum-hit box, as the two Keyboard Parts reveal.

Sample Modification

All ESX1 Parts have access to a set of synthesis and sound-manipulation tools. They're boiled down to the essentials, but (as with the EMX1), this abbreviation never gets in the way of creativity. A multi-mode filter is at the heart of the synthesis tools, offering Low-pass, High-pass and Band-pass variants, plus a Band-pass option which adds the output of the filter to the sound's original waveform. The filter, as I discovered after the EMX1 review went to press, is a newly-modelled 12dB/octave design, making its first appearance on these two instruments. Apparently, a simulated analogue drive circuit helps the filter produce a more convincing resonance peak, whilst avoiding digital clipping — so it sounds even more like an analogue filter than earlier Korg models — and the maximum cutoff frequency has been increased as a result of algorithm and sampling-frequency improvements. One significant difference on the filter front between the ESX and the EMX is that the ESX's 'Drum' Parts each have a filter: this was not the case with the EMX.

There's a basic modulation section, which can be sync'd to Pattern tempo and routed to pitch, filter cutoff, amplitude or pan. The simple EG, controlled by one button and one knob, again proves its worth. New controls for the ESX1 are sample-specific: a start point offset knob, and a reverse button.


The ESX1's effect implementation is simple but useful, arranged as three processors accessed by a kind of all-in-one insert/send-type system from each Part. Only two parameters per effect can be edited, though the choices are generally the right ones. The three effects can be used independently, or linked in a two- or three-effect chain. Included are the standard — mod delay, sync delay, reverb, chorus/flange, phaser and so on — and the off-the-wall, represented by the grain shifter, decimator and talking mod. You'll also find distortion, compressor, EQ, and low-pass and high-pass filtering in the arsenal.

As with the EMX1, there's an unfortunate link between a sequencer Part's level and its effect send: if the effect send button is enabled, the level knob controls both overall level and the send level to the selected effect. The problem can be overridden via MIDI, but not on the machine alone, as it stands. Cost was obviously a consideration, as were, apparently, space and DSP, but the effects complement is still a significant improvement on the single on/off effect that appeared on the original Electribe range.


We're mainly in pattern-sequencing territory here, though real- or step-time recording is not only possible but practically available simultaneously. Each Pattern (of up to 256 on board) has a length of up to eight bars, and a choice of resolutions means that a bar can offer 16 16th-note steps, 16 32nd notes, 12 8th-note triplets or 12 16th-note triplets. A wide range of potential time signatures, in addition to the 4/4 and 3/4 options implied by the basic resolutions, can be bodged by changing the ESX1's Last Step parameter.

Drum Parts can be triggered by their respective buttons — as if they were pads on a drum machine — and the 16-strong strip of buttons at the bottom of the front panel shows the result by their lit or unlit state. As mentioned earlier, these 16 buttons also double up as a chromatic keyboard for playing the Keyboard Parts (though there's no transposition as such). The buttons come into play again for triggering Stretched samples, or the individual Slices of a sample assigned to the Slice Track. If a Pattern is longer than one bar, a pair of buttons scrolls back and forth between bars, with you keeping track of where you are via a handy line of red LEDs.

None of the buttons generates velocity information, though an Accent track allows Drum Parts (only) to have a little variety; unfortunately, the Accent is global for all drum hits: accent one beat, and all drum samples sounding on that beat will be accented. The other cheat is that the Accent track defaults to all steps being active, so the user is actually taking away accents after the fact, rather than adding them to something that's just been created but would benefit from a bit of 'oomph'. There is no Accent track for the other Parts, as there is on the EMX1. (Note that Drum and Keyboard Parts respond to velocity over MIDI, and Keyboard Parts respond to pitch-bend data, though this incoming data cannot be recorded by the ESX1.)

A 'Motion Sequencer' offers a simple way of creating Pattern diversity, allowing you to overdub (and edit) the tweaks of up to 24 knobs or buttons in a Pattern. The EMX1's Motion Sequencing options of Smooth and Trigger Hold are replicated here: the latter records changes in discrete steps, while the former extrapolates the changes between those steps for smooth parameter changes. A separate Motion Sequencer is provided for the effects section, though only the two edit knobs for the three effects can be sequenced — that's six controls in total — and data is only recorded 'Smooth'-ly. As we'll discover elsewhere in this review, the audio input can be affected by a wide range of editable parameters, which can themselves be Motion Sequenced, and the Accent level parameter of the Accent Track can be changed dynamically with its own Motion Sequencer.

Patterns are chained into a Song (of which there may be up to 64 on board) to create a finished piece. There are 256 steps per Song, and each step could be a completely different Pattern (though beware of the machine's 20,000 event limit). Equally, a single Pattern could be repeated for the length of the Song, since a certain amount of remixing and data overdubbing can be achieved in this mode. Mutes and solos can be recorded, as can transpositions, Motion Sequences and, even more helpfully, an extra Song-length 'keyboard' performance/solo, either triggered from the arpeggiator or played live by you. However, this performance can't, unfortunately, be edited.

The Arpeggiator

Korg ESX1Photo: Mike CameronThe interface of the interactive, hands-on arpeggiator was unique when introduced on the EMX1, but is now less so since two instruments feature it! Basically, the user can initiate synchronised arpeggiations of whatever Part they happen to be playing from the keyboard, at any time, by touching the ribbon controller on the left. Moving up and down the strip changes note length, whilst wiggling the adjacent slider at the same time transposes the effect through one of 31 preset scale types, over two octaves.

It works with just one key held down, or will arpeggiate whatever chord shape you create on the button keyboard, in the order you pressed the keys.


Criticisms about the Electribe SX are very few. However, I had an issue or two with the manual, and found that combing the table of contents is usually more helpful than the index. Also, in some cases it would have been nice to have an easy way to move backwards through the OS, since occasionally the only way to stop something you might have done by accident is to start the operation again. This can be a bit annoying, since some processes take many button-pushes to achieve. Loading individual samples from SmartMedia card would also have been made more streamlined had the OS remained in the load screen between each sample.

But the bottom line is that Korg have done it again: as easy as the EMX1 made synthesis, sequencing and rhythm programming, the Electribe SX makes acquiring samples, editing them (to a certain extent) and creating music with the result. This is a fabulous tool in its own right, and it almost goes without saying that as a partner to the Electribe MX, it's perfect.

Published March 2004