The Boss CS-3 Compression Sustainer

Bob Leggitt | Thursday, 20 September 2012 |

That the Boss CS-3 Compression Sustainer has been in production for over a quarter of a century attests to the excellence of its design. In fact, whilst the CS-3 went on sale in latter 1986, it was only a relatively minor update on the CS-2 of the early ‘80s, which means there’s a good three decades of history attached to this pedal. In the course of its run, the CS-3 has been modified, but the basic design has remained constant. The CS Compression Sustainers have always done what Boss does best: take an effect, make it sound good, and package it into an idiot-proof format. As long as a Boss pedal is regarded as both good, and idiot-proof, there’s no need to re-design it.

There are four knobs on the Boss CS-3. They can prove slightly confusing for someone who hasn’t previously used a compressor – particularly since the device doesn’t distort or modulate the sound in any way, and therefore hearing what’s happening can be a lot more difficult than with, say, an overdrive pedal. But as compressors go, it really doesn’t get much more simple than the CS-3. First, you have a Level control (the effect volume), which balances the output volume of the effect-treated sound with that of the dry signal. Then you have a Tone control: fairly self-explanatory – it adds or subtracts brightness to/from the effect-treated sound. So, volume and tone, idiot proof so far…

Boss CS-3 Compression Sustainer Pedal


The third and fourth knobs take a little more explaining, and in order to answer the very important question above, I’m going to look at the fourth knob – the Sustain – next. The compressor doesn’t really increase the sustain of your guitar, of course, but it does create an impression of greater sustain by tinkering with the output volume through the course of the envelope of a note or chord.

In the simplest terms, all the compressor does, is makes louder volumes quieter, and quieter volumes louder. This ‘dynamic squeezing’ is what creates the impression of greater sustain. As your note dies away and the volume naturally reduces, the compressor progressively compensates for the loss in volume with its circuitry. The quieter your note gets, the more the compressor boosts its volume, so it sounds like the note is sustaining for longer. The fact that the compressor also reduces the volume when the note is louder (near the beginning of its envelope), adds even more to the impression of one long, even, sustaining note. In reality, a compressed note lasts for the same amount of time as an untreated note, but the compression tricks the ear into thinking the guitar has greater sustain. It changes the whole feel of playing too. Adding the right amount of compression seems to make playing the guitar feel easier and more comfortable.

The Sustain knob on the CS-3 merely controls the amount of ‘dynamic squeezing’. At or near the minimum setting, there’s little or no effect on the tail of the note, and the unit performs as a limiter – just reducing the volume of any loud ‘spikes’. The sound in general remains natural, and it’s very difficult to tell the effect is being used. But at or near the maxium setting, the higher volumes are heavily reduced, whilst the lower volumes are heavily boosted. This really squeezes the dynamics and you get a very strong impression of long, sustaining notes. The CS-3 has plenty of squeezing capability, and since the effect is greater on high output guitars, you need to be careful not to use too high a setting. The idea, in most guitarists’ eyes, is to set the effect high enough for a strong impression of sustain, but not so high that the envelope sounds synthetic, and unwanted feedback is produced.

Going back to the third knob, we find the Attack parameter. This adds a clear percussive edge to the initial pluck of the compressed notes you play. With the Attack set near the minimum, you get a smooth and more ‘legato’-compatible pluck. With the Attack set near the maximum, you get much more definition in the pluck, and individual notes/chords sound more choppy and percussive.


Anyone who wants to increase the impression of sustain in their clean guitar sound would find the CS-3 an ideal solution. But for me, compressors are more about evening out the volume of both rhythm and lead playing so a mix sounds more professional. The tonal dynamics remain intact when you use a compressor, so you still get the sound of loud and soft playing. What you don’t get, is the wide array of different volumes. The result is consequently easier for recording equipment to handle. And because the way a compressor squeezes the dynamics has parallels with the way valves and a guitar speaker squeeze the dynamics of an electric guitar at high volume, the result can also add the excitement of playing loud, without the need to actually do so.

One of my favourite uses for the CS-3 is to chain it with a fairly mild overdrive – compressor first in the chain. This is a great way to simulate the characteristics of a loud valve amp cracking under the strain, but without exceeding practice volumes. Many guitarists overlook the power of combining compression with overdrive. Neither effect simulates a hard-driven valve amp on its own, but using the two pedals in combination, it is possible to get a very close approximation.


The CS-3 Compression Sustainer was introduced amid a progressive but fairly intensive period of redevelopment for the Boss range. The CS-3’s immediate predecessor (the CS-2) had not been one of the company’s biggest selling pedals in summer 1986. Not in the UK, anyway. In the run up to the CS-3’s release, four of the top five best-selling effects in the UK (based on dealer feedback to Making Music) were Boss pedals. Incidentally, this wasn’t the top five effects pedals, or the top five guitar effects – this was the top five effects, full stop. The outright top seller was in fact the DD-2 Digital Delay, with the CE-2 Chorus and HM-2 Heavy Metal in second and third place respectively. The OD-2 Turbo Overdrive also crept into the chart at number five, but the Compression Sustainer, perhaps surprisingly given the breadth of its genre-compatibility, showed no sign whatsoever of troubling the top five. The introduction of the CS-3 did nothing to change that.

But dominating the effects market as they were, Boss were clearly on a mission to make their range in general unchallengeable – striking whilst the iron was hot to keep the competition at bay. Whilst the CS-3 had no immediate impact on the upper reaches of the sales chart back in the mid 1980s, it has now out-survived some of its comtemporaries by more than two decades. The MZ-2 Digital Metalizer, for example, introduced just over a year after the CS-3, did have an almost immediate impact on the top five best selling effects, and in fact got as high as number 3 in 1988. But its popularity quickly waned, and by the end of 1992 it was no more than a memory. With the CS-3, Boss took a different approach, ignoring the fads and trends of the mid '80s, and perfecting a classic, timeless effect pedal which would be as much at home 25 years in the future as it was in the present. In the ruthlessly competitive, come-and-go world of musical instrument effects, the Boss CS-3 Compression Sustainer is a notable survivor, and it's as valid a presence on stages across the world today, as it ever was. An easy-to-use, great quality effect which, once you have it, kind of becomes indispensable.

You can find lots more retrospectives on Boss pedals (incorporating lesser known info) on this site. The Boss articles are grouped together under PICKUPS, GUITAR AMPS, FX AND GADGETS on the Guitar Reviews and Retrospectives page.

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