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Accessory File: Rivera RockCrusher

June 19, 2012
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We’ve all heard the joke, and to be fair it often does take sheet music to get us guitarists to turn down. Sure, we have ways to turn down—master volumes, power scaling, digital modeling—yet there remains something irresistible about the primitive, teeth-rattling roar of a cranked tube amp, so our rude and unschooled reputation lives on.

Enter the Rock Crusher, a reactive power attenuator from legendary amp designer Paul Rivera. The concept of an attenuator is simple: patch it between a hard-working amp and speaker to bleed off unwanted volume as heat. Similar devices have been around for decades, but the Rock Crusher sets a new standard for build quality, transparency, and touch-sensitive dynamics.

Everything about the Rock Crusher is over-engineered, from the thick welded steel case, to the hulking attenuator switch, to the giant Ohmite load resistors. Attenuation happens in five fixed steps with master bypass. A “Studio” mode adds an additional Level control for continuous volume adjustment down to whisper quiet. Input impedance is switchable between 8Ω and 16Ω, two toggles engage “Edge” and “Warm” (treble and bass boosts), and a second front panel Level control adjusts the 1/4" and XLR line outputs. The Rock Crusher has more features than most attenuators, but it’s not as complicated as it appears—in most cases you’ll adjust only the single Attenuation knob and maybe the two EQ toggles.

I tested the Rock Crusher with vintage 50- and 100-watt Marshalls, as well as a Suhr Badger 30, into an 8Ω 2x12 THD and a 16Ω 1x12" Hermit Cab. In all combinations, the Crusher served up a spongy and dynamic squish reminiscent of playing at high volume. That’s a high compliment for a power attenuator—it not only sounded nearly transparent, it retained some of the feel of a loud amp. Rivera uses an inductive network to mimic direct amp/speaker interaction, and the result is more buttery sustain and compression than I expected, even at low volume levels—especially when beefed-up by the pillowy fatness of the “Warm” boost.

For a more scientific comparison, I recorded a mic’d speaker at various attenuation levels so I could quickly listen to it with and without the Rock Crusher. And since this was developing into a shootout, I threw two time-tested attenuators into the ring: a THD Hotplate, and Dr. Z Airbrake.

The verdict? I have yet to hear a “perfect” attenuator—all impart subtle coloration to tone and dynamics—but the Rock Crusher was easily the most transparent of this trio. It slightly muted the 50-watt Marshall’s brightness, and imparted a bit of treble lift with “Edge” engaged, but minor tweaks to the amp’s controls easily compensated for this. The Crusher was also impressively consistent throughout its volume range. By comparison, the Airbrake sounded great for minor attenuation, but became unnaturally bright at lower volumes, and the Hotplate delivered good range, but rounded and darkened the Marshall’s tone more than the Crusher.

The Rock Crusher isn’t perfect, either. At its minimum “3dB” setting, I measured actual volume reduction more like -8dB at 8Ω and -12dB at 16Ω. From there, the attenuation increases in much smaller steps, but if your rig is just barely too loud, the Rock Crusher might be overkill. And the manual warns against connecting an amp with less than 8Ω output impedance, which rules out otherwise ideal candidates like the Fender Super or Twin. The Crusher works great as a dummy load, with a natural-sounding line output (you’ll need a speaker simulator for DI recording), and the balanced XLR is a nice touch, but would be even better with a ground lift.

The Rock Crusher is conservatively rated at 120 watts RMS, but can comfortably handle bigger amps. It stayed cool to the touch wrangling a dimed 100-watt Marshall, and given the component ratings inside, I’d be surprised if any guitar amp in existence could make it sweat. And while many attenuators present a load that varies or is unnaturally high, the Rock Crusher hangs within 1Ω to 2Ω of its rated impedance at all settings, which can only be a good thing for sonics and safety.

The $500 price may seem a lot for a power attenuator, but the Rock Crusher is an impressive beast, and given the top-ofclass sound and build quality, it’s a good value. If your amp sounds great loud, the Rock Crusher will help maintain your state of sonic nirvana even when you’re forced to turn down. Unfortunately, when the sheet music comes out, you’re on your own.

Specifications

CONTACT Rivera Amplification, (818) 767-4600; rivera.com

MODEL Rock Crusher

PRICE $499 street

CONTROLS Bypass, Impedance (8Ω or 16Ω), Equalization (Edge and Warm on/off toggles), Attenuation (5 fixed steps, 6th position “Studio” with variable Level)

EXTRAS Line out (unbalanced 1/4" and balanced XLR) with Level control. Two speaker jacks

MAX POWER 120 watts RMS

DIMENSIONS 15" (w) x 9.5" (d) x 3.25" (h)

WEIGHT 8 lbs

BUILT USA

KUDOS Easily tames the loudest amps. Musical and organic throughout volume range.

CONCERNS None.

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