Considering how profoundly a compressor can affect guitar tone—indeed a guitarist’s very approach to playing—it’s a wonder these devices so often fall into disuse. Then again, ask most guitarists to describe how a compressor works and you’re likely to get a litany of abstractions about squish, squeeze, and missing tone. On top of that, the benefit to your sound can be elusive. A fuzz? You can describe that sound with any number of song citations or signature tones. A compressor? Not so much.

Even when the effects of a compressor are clearly audible they can do more harm than good if you haven’t done your tinkering and homework. And the truth is that the best sounding compression you hear on record is probably courtesy of some legendary vintage rack module worth more than your entire freaking rig.

This convergence of forces says a lot about why the compressor is a pedalboard tool of untapped potential. It also explains much about why the Rivera Sustain Shaman, with its 2-channel compressor power, tone shaping tools, and Super Sustain function is so remarkable: It’s dynamic, highly tailorable, offers colors from subtle to strong, and has more than a few tricks up its sleeve.

Burly Build, Secret Sauce
Rivera’s Sustain Shaman is a sturdy stompbox built with the realities of frequent gigging in mind. The knobs are arranged in recessed area to prevent accidental activation, and the potentiometers have a taut resistance that keeps you from shifting settings with an errant boot. That latter aspect of the Sustain Shaman’s design is especially important, given the interactivity between the controls and how critical small adjustments can be.

The heart of the Sustain Shaman is a 2-channel compressor, and each channel has its own familiar-enough controls for attack and sustain. The two channels also share an effect level control. Unlike a lot of compressors, however, the Sustain Shaman has tone and effect blend controls that work for both channels, and they’re some of the real keys to the Sustain Shaman working as effectively as it does in so many situations.

The real secret weapon on the Sustain Shaman is the Super Sustain switch. It’s activated with a small toggle, rather than a footswitch, and it works only for channel B. But with its ability to significantly change the voice, function, and nature of channel B when activated, this switch essentially places a second effect onboard.

About the only aspect of the Sustain Shaman’s design and construction that’s less than brilliant are the decals that label the knob functions. Granted, we’ll take this unit’s top-notch assembly, design, and parts quality over cosmetics, if the alternative significantly boosts manufacturing costs. The good news is that these labels are made of polycarbonate material, which can handle a beating better than screen printing, and they are also replaceable.

Sustain Supreme
While it’s a fairly complex stompbox, it’s easy to get down to business with the Sustain Shaman. Where a lot of budget compressors will seem to add little more than noise and blunted attack and high end, it’s almost impossible to get a lousy sound from the Sustain Shaman.

The attack and sustain controls for each channel are responsive and have a perceptible range. The attack control—this adjusts the speed at which the compressor turns down signals hotter than the threshold—is the subtlest. At slow speeds, pick attack and high end tones will sound blunted, but you can also get a cool backwards-tape-like suction, depending on how aggressively you set the sustain and effect levels. At lower effect levels, the range of the attack control becomes a lot less perceptible.

The sustain control has the most obvious influence on your tone and playing, and is more perceptible at lower effect levels. But with the effect level at a 50-percent split between dry and wet, it’s easy to hear how much range and tone-shaping power it has. Super-low sustain levels will actually have a major impact on gain, picking dynamics, and the range of your guitar’s volume control, though the lower ranges are useful for dialing up a sweet spot for percussive rhythm. Up around noon and 3 o’clock, the sustain starts making your guitar sing a little more, but keeps the best parts of your guitar’s voice intact and beautifully emphasizes high-mid harmonics.

These levels are particularly effective for use with fuzz and overdrive, provided you use the level knob with care—the Sustain Shaman isn’t entirely beyond inducing feedback. Cranking the sustain creates a delightfully sizzling layer of high and highmid harmonic content that adds a swirling, psychedelic wash to 12-string arpeggios and a lingering vocal bite to leads.

The Sustain Shaman’s rabbit in the hat is the Super Sustain function, and it’s no wallflower of an enhancement. Cranking the sustain and turning on the Super Sustain toggle gives individual notes the droning, sonorous sustain of a church bell. This is a glorious effect for arpeggios on a Telecaster, the bridge pickup of an SG, or a Rickenbacker 12-string—guitars that cut, but become interstellar with a little sustain. Combine this effect with a long or backwards delay, and it’s as if you’re watching time itself melt and stretch.

Setting up the A and B channels with identically aggressive attack and sustain settings, and then engaging the Super Sustain function demonstrates the considerable boost in gain and high-midrange content you get with the Super Sustain control on. This is killer at quiet club levels, but something to be mindful of at loud performance levels. You’ll also notice a slight volume swell when you really hold onto a note, and this is most obvious in spare arrangements.

The Verdict
The Sustain Shaman is one of the most thoroughly designed compressors you’ll see outside a studio, and it’s not constrained to a single voice, thanks to the two independent channels. The Shaman is also noticeably less noisy than typical stompbox units.

A lot of the Sustain Shaman’s versatility comes from the tone and effect blend controls— functions that can add another range of color to a given set of attack and sustain settings, and let you accommodate just about any guitar or musical context. The Super Sustain function, however, makes the Sustain Shaman a potent stage weapon and an impressive tool for altering how your guitar, amplifier, and fingers interact.