The Suhr SL68 MkII provides Marshall Plexi fanatics with the dynamic, bone-crushing tones of their dreams and then some for an investment that, while costly, is much less than the price of a vintage Plexi.
Pros
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Classic and Variac Marshall Plexi tones at any volume.
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Variac reduces voltage and switches to optimal bias setting. Fat, Mid Boost and Bright switches expand tonal spectrum.
Cons
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Expensive.
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Single-channel operation.
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One could spend a lifetime searching in vain for the ultimate late-’60s Marshall Super Lead Model 1959 100-watt Plexi head.
While these tube amps do appear on the market sporadically, the best ones seem to be stashed away in the hands of rock stars and deep-pocketed collectors, and the readily available examples usually have either undergone savage modifications or are anemic-sounding survivors that have been swapped more frequently than a bogus two-dollar bill at a Florida flea market.
Fortunately, Suhr offers the SL68 MkII, which offers guitarists everything they would ever want from a blazing Marshall 100-watt Plexi and much more at a cost that is a small fraction of inflated vintage prices.
The SL68 MkII features the same familiar tone and volume controls and four inputs as a classic Super Lead, but it also adds one of the best designed master volume circuits available today, Fat, Boost and Bright switches and a Variac low-power mode. The tubes are a quartet of EL84s for the power and three 12AX7s for the preamp and phase inverter.
Granted, there are numerous Plexi clones on the market these days, but the difference between the Suhr SL68 MkII and most other clones is like the difference between a Domaine de la Romanée-Conti Grand Cru Burgundy and a mass-produced USA Pinot Noir.
(Image credit: Suhr)
Every element, from the carefully selected components to the attention to the finest detail, is on another level. A key feature is its custom output transformer, which is meticulously designed to provide clarity, dynamic responsiveness and elusive expressive feel of the real deal.
The SL68 MkII’s EQ section is the classic Marshall tone stack with Presence, Bass, Middle and Treble controls that deliver the amp’s most aggressive and open tones with everything rolled up to 10.
There are also separate volume controls for channel I (bright) and II (normal), and each channel has its own pair of high- and low-sensitivity ¼-inch input jacks. Like a classic Plexi, this is really a single-channel guitar amp with no channel switching, although you can jumper the bright and normal channels together via the bright/low and normal/high inputs to blend them together.
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(Image credit: Suhr)
(Image credit: Suhr)
Three mini toggle switches located above the control expand the amp’s tonal and textural range. The Fat-Cap switch is inspired by a secret mod that John Suhr saw on a legendary artist’s Plexi amp that came through his shop in the mid-’90s that adds body to the bottom-end without making the overall tone more muddy or dense.
The difference between the Suhr SL68 MkII and most other clones is like the difference between a Domaine de la Romanée-Conti Grand Cru Burgundy and a mass-produced USA Pinot Noir
The Mid Boost switch pumps up the gain to midrange frequencies to make the tone more notably aggressive but also more focused and prominent. The Bright switch provides three different settings that go from off (original Suhr SL slightly rolled back brightness), in-between (a subtle brightness boost) and vintage (the full brightness of a vintage Plexi).
The Master Volume control is the sole feature on the amp’s back panel other than the two speaker output jacks and 4/8/16-ohm impedance selector. The master volume circuit is removed when its control is turned all the way, and at lower settings it maintains the genuine character and feel of an amp with its power tubes pushed hard, allowing guitarists to enjoy that elusive Marshall amp grind and dynamic crunch at apartment – and recording studio – friendly levels.
Unlike typical full/half and triode/pentode modes found on many modern amps, the SL68 features Hi (full 100-watt) and Lo (Variac mode) settings accessible via the power switch.
Suhr Classic S Vintage Limited Edition guitar and SL68 MkII amplifier - demo - YouTube
The secret to effectively using a Variac is to drop the voltage with the Variac and readjust the bias for the lower voltage level, and this is exactly what the Variac setting does instantly at the flip of a switch. This changes the amp’s dynamic character, making the attack less overtly percussive while also enabling artificial harmonics and palm muting to pop more prominently.
The most impressive feature of the SL68 MkII is the sensation of déjà vu experienced while playing it. Using the guitar’s volume knob as a “channel switcher,” all the sounds you could ever want from a Plexi, from Eddie and Angus thru Jimi and Jimmy to Yngwie and Uli, are there in spades.
The crushed glass harmonic crunch is world class, as are its viciously aggressive overdrive punch and sweetly singing solo tones. The Bright channel’s clarity and definition are pristine, delivering treble with brilliant zing and bass with muscular brawn.
Specs
PRICE: $3,449
TYPE: Tube amp head
OUTPUT: 100 watts
TUBES: 4x EL43, 3x 12AX7
CONTROLS: Presence, Bass, Middle, Treble, Volume I, Volume II, Master Volume (on rear panel)
Chris is the co-author of Eruption - Conversations with Eddie Van Halen. He is a 40-year music industry veteran who started at Boardwalk Entertainment (Joan Jett, Night Ranger) and Roland US before becoming a guitar journalist in 1991. He has interviewed more than 600 artists, written more than 1,400 product reviews and contributed to Jeff Beck’s Beck 01: Hot Rods and Rock & Roll and Eric Clapton’s Six String Stories.
