You are here

Boss SY-300

Polyphonic Guitar Synthesizer By Paul White
Published October 2015

Boss SY-300 Guitar Synthesizer.

Finally, a truly polyphonic guitar synth that you can use with any standard electric guitar — with no need for a hex pickup!

Until recently, polyphonic pitch–tracking guitar synths required a separate pickup for each string and that meant using a special guitar or having a ‘hex pickup’ installed on a regular guitar. While the hex–pickup approach can work pretty well it also poses a few problems, which I’ve discussed in the ‘Guitar Synths: A Brief History’ box. Boss’s new SY‑300, reviewed here, takes a very different approach that means it requires no special pickup. It’s not the first polyphonic guitar synth to work with a conventional guitar — Electro–Harmonix’s HOG2 and organ–emulation pedals, and Jam Origin’s MIDI Guitar 2 Mac/PC/iOS software all do this too — but it is the first that I’d consider to be the guitar equivalent of a full–blown analogue polysynth, complete with effects. Having played with it for a while now, I’m convinced that the SY‑300 points the way for future developments in this area.

Right On Track

Clearly, this device’s blue paintwork and name tip a nod in the direction of the Roland’s old GR–300 but, with the assistance of DSP and four on–board effects engines, the range of sounds it makes available is far wider. The engineers at Roland/Boss are understandably a little secretive about what’s going on inside the SY‑300 but, given the way other devices work and some knowledge of recent advances in polyphonic real–time pitch extraction, I have a good idea of the essentials.

As you’d expect, some form of polyphonic pitch–extraction is used to control the sound processing but, unlike with most such systems, there’s no latency between plucking/strumming the strings and hearing the sound. This is because the sound you hear actually starts life not as a sample, but as the waveform that comes directly from your guitar’s pickup, just as with any conventional effect. You might not recognise it as such because its harmonic makeup is augmented and re–arranged to produce the familiar square, pulse, triangle, sine, sawtooth, and noise waves used in basic analogue synthesis, but that’s what it is — the processed sound from your guitar. This approach overcomes the problem of latency, of course, but it also means what you hear is directly affected by the way you play or the guitar’s pickup; the SY‑300 restores that organic connection between player and instrument that previous guitar synths sacrificed.

Some form of digital pitch–shifting is then used to detune or retune the individual oscillators by up to 24 semitones (in either direction), and synth–style envelopes, filters and modulations can be applied. So you have plenty of control over the sound before the signal even enters the effects section.

The effects include all you’d expect in the way of overdrives and distortions: there are half a dozen or so models from mild overdrive to full–on fuzz, along the lines of those you’d find in other modern Boss multi–effects units. The same can be said for modulation, delay, rotary speakers, reverb, EQ, T–Wah and so on, but there are some more unusual effects too. The Slow Gear effect, which has been available for a while now, allows you to create slow attacks, and Isolator lets you rhythmically chop out a selected part of the audio spectrum. Boss’s Slicer effect is there too, and there are many more, including hybrid ones such as Chorus/Delay and Delay/Reverb. Each of the four effects engines can access the complete list of effects.

Despite the analogue feel of the unit, all the processing is digital: the 24–bit, 44.1kHz converters use Roland’s Adaptive Focus (AF) technology to improve the signal–to–noise ratio. (Why the existing 120dB or more of a standard 24–bit converter isn’t enough eludes me!)

Ins & Outs

All the audio connections (other than the USB interface) are analogue and presented as quarter–inch jacks. These include the guitar input, a thru socket (to pass the guitar signal on to your amp), stereo main and sub outputs for the synth sound, and a return jack. The last can be used in conjunction with the sub output to place other effects boxes in the signal path. The left main output jack doubles as a headphone socket. There’s also an external control socket (TRS jack), which can accommodate a double footswitch or an expression pedal. MIDI In and Out/Thru connections allow for the sending and receiving of MIDI program changes, clock and controller data, SysEx dumps and so on. (Note that, as this is not a conventional pitch–tracking synth, the MIDI Out doesn’t transmit MIDI Note data.) Power comes from the inevitable external power adaptor.

The USB interface (which requires dedicated driver software) makes some neat tricks possible. For instance, it allows you to record the guitar to the computer, with or without synth processing, and then play it back, either as is or via the synth for reprocessing of the guitar part after you’ve done the basic recording. Or, of course, you can reprocess any existing clean guitar recording.

It’s worth noting that the SY‑300 can also be used with bass guitar (you select this in the setup page), and there’s nothing to stop you trying out other instruments to see what happens — you won’t break anything!The USB connection on the rear takes care of firmware updates and audio–interfacing duties, and allows the SY‑300 to communicate with its Boss Tone Studio control software.The USB connection on the rear takes care of firmware updates and audio–interfacing duties, and allows the SY‑300 to communicate with its Boss Tone Studio control software.


There are three separate oscillator sections and two mixers, with several preset routing options. The oscillator mixer combines the different oscillator signals and there’s also an output mixer that allows you to mix in a USB return from the computer. The basic guitar sound may be selected as an oscillator source as an alternative to the synth waveforms; the filters, amps LFOs and effects can be used to reshape this. Note, however, that pitch shifting and arpeggiation is not possible on oscillators when the guitar is used as the source waveform. The effects routing is very flexible, with each effect capable of being placed directly after an oscillator or used to process the mixer output. If you wanted to put all the effects in series after just one of the oscillators, for instance, you could do that.

For each oscillator there’s a waveform selector, and different modifying controls become available according to which waveform you select. For example, if you choose the pulse waveform, you’re given the option to apply pulse–width modulation, whereas if the noise waveform is chosen there’s a Sharpness control, to move it from pure noise to a pitched, though still very complex, waveform. Speaking of pulse–width modulation, this can be controlled via an LFO or via the envelope of the input signal.

As long as the guitar is not selected as the source waveform, oscillator sync can be applied. Sync, which is controlled by the frequency of Osc 1, resets Osc 2 and/or Osc 3 to the beginning of their cycle. Ring modulation is also available on Osc 2 and 3 using Osc 1 as the second input. No true portamento is possible but you can set each note picked to swoop up or down to pitch at an adjustable rate if required. It’s curious that pitch shifts such as this can’t also be applied to the guitar waveform.

The filter and level envelope settings are much simpler than for a keyboard synth. There’s a single envelope control for each that moves from slow attack, through to an envelope similar to that of the incoming signal, and then on to a fast attack and short decay. Separate controls affect the depth of the sweeps. The Slow Gear effect may also be used to add a slow build–up to sounds or mixes of sounds, including any guitar–sourced oscillators. Normally the synth sound dies away as the guitar sound itself decays but it’s also possible to use a footswitch to activate sustain on your choice of oscillators, for indefinite sustain. Filter sweeps can be set up in either direction, based on high, low and band–pass resonant filter types with 12 or 24 decibel–per–octave slopes. Each oscillator also has its own LFO section, via which it’s possible to modulate the pitch, the amplitude and the filter frequency. There’s a range of LFO waveforms, including a couple of random sample–and–hold variants. (A delay vibrato would have been a useful option here but I was unable to find one.)

The 16–step arpeggiator section I mentioned earlier can be set to produce a pitch shift of up to 24 semitones up or down set in one-semitone steps using sliders, though there’s an overall depth control that can scale this back if all you need is a gentle pitch undulation. For this facility, you can set the tempo manually or sync to a host tempo. When MIDI is being used, MIDI Clock can control the tempo of any tempo–related parameters. A comprehensive MIDI implementation document may be downloaded as a PDF, along with a full parameter manual.

Control & Operation

Basic hardware control and patch editing/selection is via a backlit LCD screen and a number of knobs and buttons. Four footswitches with status LEDs are arranged across the front of the top panel. You can bypass the synth sound using the leftmost switch, scroll through patches, and access three user–definable parameters per patch. (The way bypass operates can be changed in the global setup page.) By default, the two right–most pedals act as patch up/down switches leaving only switch two to control the effects, but you can change this designation to allow switches two, three and four all to control effects. Depending on what you set up, the switches may be used as latching or non–latching types. They provide a great way to, for example, change the speed of the rotary speaker effect from fast to slow (the ramp up and down times can be set in the effect editing section). You can also set them to bring in vibrato, pitch sweeps, filter sweeps, turn on oscillators and so on.

Boss SY‑300By default, pressing down the right two footswitches at the same time brings up a tuner and mutes the output, but this can be locked out for live performance if needed. You can also restrict the number of accessible patches to the ones you wish to use in your set.

Four knobs below the screen control the currently displayed parameters. A knob on the left sets the output level and another on the right, which incorporates a push–switch, selects patches or is used, with the aid of the two page–selection buttons below, to navigate the edit menus. Two more buttons access the menu and exit the edit pages. Over to the left are three further buttons that access the Synth FX, Blender (I’ll come to that shortly) and Write options, which include patch naming. The unit comes with 70 fixed factory presets plus 99 user memories, and you also get access to an online tone library, which is worth exploring.


The front–panel menu system is pretty logical and surprisingly easy to navigate, but the freely downloadable Boss Tone Studio editor software (Mac or Windows), which communicates with the SY‑300 via USB, offers more comprehensive control. In addition to editing, this allows you to download patches from the Boss Tone Central web site and to archive patches. Other niceties include a step sequencer (up to 16 steps) that can play arpeggios from a single note played on your guitar. The Blender function is really useful: it allows you to take any of the three oscillator settings from any existing patches to drop into the one you are currently working on. A Layers page allows you to set a pitch range for each oscillator to create the guitar equivalent of a keyboard split.

The software is divided intuitively into pages that address the various synth functions, and you’ll find clearly–labelled controls on each. To move the effects, you simply drag them to their new location in the block diagram. Click on an oscillator and you get to the oscillator edit page. The software also makes it easy to do your initial setup: you can tweak the sensitivity of the unit to match your guitar and you can also apply some compression. Furthermore, there are low– and high–pass filter controls that help balance the pitch extraction part of the device, and a display shows which pitches are being detected. Once optimised, the sound will be smoother, as this pitch information seems to be used to control filters and other processing elements.

I mentioned earlier that you can hook up two external footswitches or an expression pedal. While the user can assign the functions of these via the front–panel controls — the designers made this as simple as possible, with a logical menu structure and block diagrams representing the signal flow — it’s best done using the software, as having everything visible on a larger screen makes it so much easier; you simply choose the required functions from a drop–down list. Any parameters that aren’t available are greyed out, but their controls and previous values remain visible.

Sound Judgement

While the SY‑300 probably wouldn’t wow many keyboard players with its repertoire of sounds, it provides the guitar player with the means to call up some convincing analogue–style synths sounds with stompbox convenience: if you can use a fuzz box, you can use the SY‑300.

The Boss Tone Studio software includes some interesting additional facilities, such as a  16–step sequencer for the creation of arpeggios.The Boss Tone Studio software includes some interesting additional facilities, such as a 16–step sequencer for the creation of arpeggios.The basic waveforms sound very convincing and can sustain for an impressive time. On their own they sound rather dry, of course, but it’s clear that there’s no perceptible latency and that the pitch always follows exactly what you play. If you chuck in a pinched harmonic, for example, the structure of the synth waveform changes accordingly, without anything becoming confused.

You can get you close to the old analogue GR–300 sound here, but the effects engine makes so much more possible. Big, gritty analogue sounds are easy to achieve and monophonic lines sound very convincing, so if you want to fake a Moog solo or play a fat bass–line you won’t have any problem. There are some surprisingly delicate ambient treatments in there too and, while some of the brighter chordal patches can sound a tad ‘dirty’, they sound great with filter sweeps, and creating warm analogue pads with string–like or brass–like qualities is no real challenge.

Pitch shifts of four or five semitones work well for those big Emerson Lake & Palmer synth–brass sounds but you have to be careful when pitch shifting by an octave or more, as the pitch–shifting and filter–tracking technology seems to be optimised for single–note playing; pick one note and there’s no audible glitching at all but play a chord and the shifted sound can get a touch ‘lumpy’. If this device has an Achilles heel, this is it: polyphonic sounds aren’t always as pristine as single-line melodies. Whether this is purely down to the pitch–shifting algorithms or also related to the effectiveness of the polyphonic pitch–extraction that controls some of the processing, I can’t say. It’s not always noticeable, as it depends on how the patches are constructed, how much shifted sound is mixed in and what effects are used, but I did on occasion find it frustrating. To be fair, part of the reason for this frustration was that everything else worked so well!

I was particularly pleased to discover the pseudo–organ sounds. These don’t stand up to scrutiny nearly as well as the dedicated Electro–Harmonix B9 and C9 organ–emulation pedals, but that’s an unfair comparison because the EHX devices generate more virtual drawbar pitches than is possible via three oscillators. Once I added some rotary–speaker effect, the SY‑300’s organ sounds sat rather well behind a guitar part. Another pleasant surprise was the noise waveform: with the Sharpness control fully clockwise, this essentially tracks the noise with a resonant filter to produce a pitched, yet very textural result, that works fine as an alternative to the usual waveforms.

As you’d expect of a Boss device, the effects are both easy to use and extremely capable. I was glad to see the Uni–Vibe effect putting in an appearance and, as always, the variety of Boss distortion, overdrive and fuzz effects was welcome. I was especially impressed, though, by the rotary speaker emulation: being able to ‘ramp’ from slow to fast using a footswitch is really handy. It’s an effect that works as well for guitar sounds as for organs, and it’s worth noting that a decent dedicated rotary speaker simulation pedal costs around half what you might pay for the SY‑300. This impressive and extensive palette of effects plays a very important part in sculpting the synth sounds, and is an area where the SY‑300 most definitely scores very highly against the old GR–300.

If you plan on doing more than a touch of casual editing, I highly recommend using the software editor, which required very little assistance from the manual. I found I had to think a little harder when confronted with the controls routing page than the others, simply because this is rather like a keyboard synth’s modulation matrix, which means there are many possibilities. But when in doubt, you can pick a factory patch that’s doing nearly what you want and see how it’s done. I did feel that some aspects of the editor could be enhanced by adding graphical envelope displays, as it’s not always clear in which direction you should turn a knob to get the desired result, but on the whole Boss have done a good job here.

At the time of writing, there were three sets of patches provided online by the manufacturer’s demonstrators so, out of curiosity, I loaded some of these into my user bank. There were some very good patches and if you wanted to learn more about editing it would be well worth examining their settings in more detail.

The software also makes it easy to tweak the SY‑300’s sensitivity to the guitar signal, and to filter and compress that signal to produce more reliable results. The software also makes it easy to tweak the SY‑300’s sensitivity to the guitar signal, and to filter and compress that signal to produce more reliable results. One area that Boss don’t seem to make a big deal out of is that, as you can choose the guitar as the sound source for any or all of the oscillators, you can use those four effects engines to process your guitar sounds just as you’d use a conventional multi–effects unit — and there are some great guitar sounds to be had by doing exactly that. There’s even a basic amp emulator in the effects section to process the overall sound.

When working in a live situation, I’d recommend sending the output from the SY‑300 in stereo to a mixing console, as the editor allows you to pan the three oscillators wherever you like, and this allows you to create some interesting, wide soundscapes. Many of the effects are stereo too. At a pinch, you could feed the SY‑300 into a guitar amp but remember that although a guitar is the input source, it’s not the sound you’re trying to create, so you’ll find that some of the more ‘glittery’ patches will lose a little detail. If you turn down the volume on the guitar, the synth sound follows, but be careful if you’ve used any of the noise–gate settings when working in this way, as they will mute the sound when the input signal falls below a certain level.


In most respects, Boss have achieved exactly what they set out do: the SY‑300 puts a wide range of synth sounds into a stompbox format that can be treated just like any other effects pedal, and it does this very well indeed. Importantly, there’s neither any perceptible latency nor any need to modify your playing technique in any way. You can even strum chords if you really must! It can not only produce a wide range of analogue–style sounds but can process more conventional guitar sounds courtesy of the built-in range of familiar Boss effects. There are plenty of useful presets, and the online library is likely to grow over time, too, but in the meantime, if you’re happy to tinker you can come up with some great new sounds yourself, something the Blender facility makes particularly easy. And if even that’s too hard and you have plenty of patience, you can always invoke the random–choice option.

The effects can be easily dragged and dropped into place using the software — though almost everything is also achievable via the hardware unit’s top–panel controls too.The effects can be easily dragged and dropped into place using the software — though almost everything is also achievable via the hardware unit’s top–panel controls too.To my ears, the end results are not dissimilar from what’s already achievable using the HRM section of an existing VG guitar processor. However, all VG units require a hex pickup, and the SY‑300 offers some extra bells and whistles in the modulation and arpeggiating departments. The smoothness of the SY‑300’s polyphonic performance when pitch shifting could certainly be improved, and for chordal sounds the VG processor works more precisely (not a surprise, given the hex pickup). As the USB port can accommodate firmware updates this is hopefully an area in which we’ll see improvements in the future. In the meantime, by taking time to make use of the input sensitivity setup page, you can greatly improve the sound quality (I found that switching on the compressor on this page made a positive difference).

That aside, it’s very hard to criticise what must surely be the dawn of a new era for guitar synthesis: the SY‑300 is an impressive piece of kit that requires no special pickups and shouldn’t daunt even the most technophobic guitar player.


Roland’s VG processors can produce a range of similar sounds using their HRM processing, but they require a guitar with a hex pickup, as does the Boss GP–10. Electro–Harmonix build some very effective guitar–synth–style products that use a standard guitar signal, in the form of their HOG, POG and B9/C9 organ pedal ranges. Jam Origin’s MIDI Guitar software app also provides conventional polyphonic pitch–to–MIDI conversion, in a surprisingly reliable and straightforward way, and you could always try using Celemony Melodyne Editor if you’re content with extracting MIDI from already recorded guitar parts.

Guitar Synths: A Brief History

Let’s be honest, the guitar synthesizer got off to a very shaky start in the mid 1970s and it’s continued shaking ever since, with just a brief period of ‘lesser wobbliness’ when Roland’s GR–300 was launched as the successor to their monstrous GR–500. I bought both of those machines, along with several of their successors, and wobbled along with them! The all–analogue GR–300 worked by processing the sound coming from the guitar strings, which gave it a limited palette of sounds but great playability. Even the pitch shifting was analogue, relying on phase–locked loops to reset ramp generators, so everything always sounded smooth. All subsequent Roland models, and those of pretty much all their competitors, other than the most outlandish, use pitch tracking, the success of which depends very much on a clean playing style, an avoidance of fast strumming and a tolerance of tracking delay or latency. To be fair, though, the last of these has improved considerably in recent years. Perhaps the greatest problem with later generations, though, was that the extracted pitch was used simply to trigger samples — and that meant that the important interaction between how you played and what you heard was lost. Thankfully, the SY‑300 looks set to change that!


  • Easy to use.
  • No hex pickup required.
  • Compact and affordable.
  • Free editing software.


  • Doesn’t always sound as smooth when used polyphonically as it does on single-line melodies, though in most cases you won’t notice if there are other instruments playing at the same time.


This impressive faux–analogue synth offers an impressive amount of control and a good range of effects. Importantly, there’s no latency and no special hardware required — it can be used with the simplicity of a conventional stompbox.


£549 including VAT.

Roland UK +44 (0)1792 702701