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Tone King Sky King Review

A shape-shifting evolution of Mark Bartel’s original design dishes scads of tone and performance possibilities.

  Clean Channel
0:00 – Stratocaster, bridge pickup, amp set to “Pentode mode”
0:22 – Same guitar and settings, amp set to “Ultralinear mode”
0:45 – Stratocaster, neck pickup, Pentode mode, reverb and tremolo on.
Lead Channel
1:24 – Les Paul, bridge pickup; Lead Channel Vol 2 o’clock, Tone 1 o’clock, Mid-Bite 8 o’clock (Pentode mode).
1:45 – Mid-Bite turned up to 4 o’clock (all else the same).


A versatile and cleverly designed combo, offering a number of excellent tones at a broad range of output levels to suit different venues.

The onboard attenuator is handy, but the tone can become a bit over-compressed and indistinct at higher volume-reduction settings.


Tone King Sky King


Ease of Use:



Tone King has built stylishly retro and tonefully infectious amps for two-and-a-half decades. And when introduced in 2013, the original Sky King was both a repository for all that founder and designer Mark Bartel had learned up to that point, and a signpost to a new way forward. It featured dual onboard output attenuators, a switchable output transformer configuration, and a totally handwired circuit, while previous Tone King models had carried quality hand-soldered printed circuit boards.

A lot has changed in five years. In 2013, Tone King was part of the Premier Builders Guild (alongside Two-Rock amps and Fano, Koll, and Baker guitars), although Bartel was still at the helm design-wise. With the dissolution of PBG and Bartel’s departure, Boutique Amp Distribution of California is now home to Tone King. They’ve released a revamped Sky King that aims to retain all the plusses of the original design while improving a handful of details in the process.

The new 1x12 Sky King combo generates 35 watts from two cathode-biased 6L6GC output tubes, with foot-switchable rhythm and lead channels, onboard reverb and tremolo (tremolo is also foot switchable, reverb is not), and an attenuator for each channel. The format may not be revolutionary, but the Sky King is unique in many respects.

Crowning Glories
The first-generation Sky King won fans for its impressive combination of performance-enhancing features, deceptive versatility, and, well, kingly tone. Known first and foremost for capturing alternative takes on Fender-inspired sounds, Tone King branched out with this model without sacrificing blackface-like voicings.

Wide-open is where the Sky King sounds best.

Situated just after the combo’s single input, the lead channel has controls for volume, tone, and mid-bite. The latter control adds gritty tweed-like drive to the amp’s sometimes Marshall-y roar. The rhythm channel sports volume, treble, and bass controls. The two channels share knobs for reverb and the tremolo’s rate and depth. You’ll note an absence of a master-volume control. Instead, the Sky King dials down output level via a pair of built-in, reactive-load Ironman II attenuators. With an independent 6-position knob for each channel, it’s a superbly handy feature. And it allows you to tailor independent lead- and rhythm-channel output levels, meaning you can crank the former for maximum grind and still dial it down at the output and leave the latter more wide-open for optimal headroom. The mode switch, found on the amp’s back panel, toggles the output transformer between pentode and ultra-linear modes. Pentode feels faster, more responsive, more articulate, and bolder (think Fender blackface), while ultra-linear is rounder, richer, and a bit reduced in overall output.

Probing deeper into the Sky King’s workings reveals both a heavier redesigned chassis and a printed circuit board in place of the former handwired circuit, which Tone King says has been adopted to minimize noise issues. It’s worth noting that the amp’s 5AR4 tube is also a change from the original version’s 5U4G, and denotes a somewhat stiffer rectifier.

The new combos also use a different speaker—a Celestion-made Tone King 1660, purportedly for a wider overall frequency response. That and the other changes bring the 2018 model in eight pounds heavier than the circa-2013 combo, at 56 lbs. The TV-front cabinet is of the same 24"x18.75"x12" dimensions as its predecessor, and still reflects Bartel’s meticulous design sense and his goals of maximizing resonance, projection, and clarity. It also looks great in the retro-kitsch turquoise vinyl that covers this one.

King Me
Given all that the Sky King can do—from mid-gain and midrangey JTM45-inflected crunch to scooped and crystalline Pro Reverb cleans, to grinding ’50s tweed and fat, plummy ’60s Valco-inspired tones—it’s surprisingly easy to dial in. Tested with a Collings City Limits with PAF-style OX4 humbuckers, a ’57 Telecaster, and a Novo Serus J with Amalfitano P-90s, the Sky King revealed the character of each guitar, and added many sonic textures that are utterly its own.

The pentode setting on the back panel’s mode switch was optimal for extracting maximum bark and aggression from the lead channel, or more spanky and sparkling clean tones from the rhythm channel. With the Telecaster in hand I got superb late-’60s, Buck Owens-inspired twang tones from the rhythm channel. The Les Paul-like Collings and the lead channel, meanwhile, veered easily into classic-rock territory. (I found it important to avoid maximum tone and/or mid-bite settings to avoid fizziness here).

Flip to ultra-linear, and the rhythm channel exudes a rounder, creamier clean that compresses when pushed—essentially taking us back a decade to thick ’50s moods. The lead channel, meanwhile, reveals a juicier, browner output. (Because ultra-linear is a little softer output-wise, you need to dial up your channel volumes, or dial up the attenuators a notch, to compensate, if desired.) The tube-driven reverb and bias-modulating tremolo both sound excellent, and selected together they’re pure atmospheric heaven.

With the attenuators set to 0 (bypass) on both channels, the Sky King produces a loud 35 watts. But as handy as the built-in Ironman II is, I’d also say that wide-open is where the Sky King sounds best. You can’t expect any amp to sound exactly the same quieter as it does loud, and the lowest couple of notches on the attenuator can sound a little compressed and diffuse. But the Ironman IIs are very practical tools, and a great means of suiting the amp’s volume to your performance space.

The Verdict
Stylish, versatile, and cleverly configured, the Sky King is an appealing amp from all angles. How does it compare to the original? From memory, the new Sky King might lack just a little of the original’s depth and sweetness. Although, to be fair, I don’t have them side by side to A/B, and haven’t played its predecessor for about three years. That said, it’s a great amp however you slice it. For an added eight pounds, I might want my benefits a little more clear and present in the results, but the Sky King still soars by any measure.

Watch the First Look: