Bolt BTC-100/212 and BTC-50/410 Combos

March 26, 2012

Advances in digital signal processing and its use in guitar amps have made it possible to offer breathtaking feature sets. Purists will argue, however, that for optimum tone and feel, tubes still rule the roost. Working from this premise, Bolt Amplification of Salt Lake City, Utah, combines tube and digital platforms in a range of amps that seeks to achieve the best of both worlds.

Like other heads and combos in the range, the BTC-100/212 and BTC- 50/410 combo use tubes in places where the amp interacts with the outside analog world—a 12AX7 at the input, and four or two 6L6s (respectively) at the output, with a 12AX7 driver/phase inverter and a comprehensive DSP engine in between for gain and overdrive tones, EQ, and reverb. While doing so, however, Bolt amps avoid the computerized look of many modeling amps, and there isn’t a preset menu, LED screen, or data wheel in sight. “We wanted to stay true to tube technology, by providing a traditional interface,” says Jeremy Geisler, head engineer at Bolt.

As such, all amps have traditional control sections, with independent Gain, Level, Bass, Mid, Treble, and Reverb controls, plus a 3-way Voicing switch and Active Tone switch on each channel (Rhythm and Lead in the 50-watters, plus Crunch on the 100-watters). The Voicing choices are EL84 Class-A British, American 6V6 and 6L6, or British EL34 crunch, while the Active Tone function switches the tone controls from a passive tone stack (à la Fender blackface, Vox, and Marshall) to active, which utilizes a British console-style EQ with +/- 12dB of boost or cut. In Active mode you can also get a true midrange boost on each channel.

The master section has controls for Level, Presence, and Solo Boost with engage button, with further pushbuttons for channel selection and effects loop. All pushbutton functions illuminate when engaged, providing an instant reference to which selections are active, plus the 100-watter has a cool Tube Saturation meter that indicates how hard you’re pushing those bottles.

The back panel of the 100-watt BTC-100/212 has send and return for two switchable effects loops, with independent level control, +4/–10dB switch, and a series/parallel switch for each, as well as switches to automatically assign them to the selected channels. There’s also a line out with a switch for SM57-miked cab simulation, and—another benefit of the DSP—a switch to assign each channel independently with plate, spring, or hall reverb. The 100-watter has a half-power switch, while the 50-watt BTC-50/410 lacks the second effects loop, but retains the other features. Both have connections for multiple footswitch options, too. A standard stomp switch to select channels is included with the 50-watt models. A BFC-7 multi-function footcontroller included with the 100-watt models additionally selects loop, reverb, boost and voice. An optional BFC-5 footcontroller for selection of channels, loop, reverb, boost, and voice on the 50-watters is also available for $199 (street).

The construction of both amps appears to be rugged all around, and both Bolts feel like they should be able to handle plenty of journeys in and out of the van. The combos come in open-back cabs, the BTC-100/212 with a pair of Celestion Vintage 30s, and the BTC-50/410 with four Eminence Legends.

Tested with both a Les Paul Standard and a Telecaster, the BTC-100/212’s rhythm channel does impressive tricks right out of the gate, dispelling my memories of the lackluster clean tones I’ve experienced with some hybrid and modeling combos of yore. It’s big, bold and clear, and can be tweaked to approximate anything from a pumping Twin Reverb to a Hiwatt short of clipping, or crank its Gain with Level down a little to induce juicy, bluesy overdrive. The reverb options are a real bonus in this territory, and range from convincing spring emulations to lusher, more studio-quality effects. The crunch channel on the big combo is meaty and bold, with just a little fizziness at its core when you push the gain past noon. As a result, the crunch sounds don’t entirely slay me, but it works for achieving clean-ish tones verging on breakup, or fuzzy retro leads with Gain maxed.

The lead channel takes the firepower up another few notches, and proves a lot of fun as a result, yielding singing, liquid solo tones with great sustain and easy feedback. Articulation is still a little muted here, and I don’t quite hear or feel that bitey, edgy pick attack that you get from many a high-gain tube amp. Still, it roars, and does it well at reduced volumes, too, which is one of Bolt’s bragging points. The Voice switches provide useful alterations in basic response, and the Active Tone switch is extremely handy, perking up the response on all channels when it’s engaged and shifting your EQ range options to boot. The effects loops provide excellent flexibility with rack and pedal units alike, and all bonus features function just as they should. The 100-watter is loud when you roll it up, and you can drive some chunky old-school crunch from the Rhythm channel when you do, provided you have a gig that tolerates that much volume. The BTC- 50/410 performs many of the same tricks, with a similar cornerstone tone, but obviously less overall volume (though it’s still plenty loud). It also delivers a slightly faster, more detailed, and somewhat scooped foundation thanks to the four tens.

Both Bolt combos combine an impressive feature set and useful switching options with a traditional amp interface. While the different speaker configurations may cause you to choose one over the other, the BTC- 100’s added channel and dual loops make it a better value in my opinion. Still, if you want a little more of that Super Reverb mojo on the clean side and a tighter overall response, consider the BTC-50/410.


CONTACT Bolt Amps, (801) 265-0917;

BTC-100/212 Combo

PRICE $1,999 street
CONTROLS Gain, Level, Bass, Mid, Treble, Reverb, Voice switch and Active Tone switch on each channel (Clean, Crunch, Lead); Level (master), Presence, Boost volume, and assorted selection pushbuttons in master section
POWER 100 watts
TUBES Two 12AX7 preamp tubes (one for phase inverter), four 6L6 output tubes.
EXTRAS Dual switchable and assignable effects loops, three-voice reverb, speaker-emulated DI, dual speaker outs with 4/8/16Ω switch, multiple footswitch outs, frontpanel Tube Saturation meter, BFC-7 multi-function footcontroller included.
SPEAKERS Two Celestion Vintage 30s
WEIGHT 82 lbs
KUDOS A stunning range of features. Great flexibility. Quality construction. Impressive range of tones in the Clean channel alone.
CONCERNS High-gain tones could stand more presence and definition.

BTC-50/410 Combo

PRICE $1,649 street
CONTROLS (Rhythm and Lead channels) Gain, Level, Bass, Mid, Treble, Reverb, Voice switch and Active Tone switch. Level (master), Presence, Boost volume, and assorted selection pushbuttons in master section
POWER 50 watts
TUBES Two 12AX7 preamp tubes (one for phase inverter), two 6L6 output tubes.
EXTRAS Switchable effects loop, assignable three-voice reverb, speaker-emulated DI, dual speaker outs with 4/8/16Ω switch, multiple footswitch outs, single-button channel-switching footswitch included.
SPEAKERS Four Eminence Legend 10s
WEIGHT 65 lbs
KUDOS Great flexibility. Quality construction. Versatile Clean channel.
CONCERNS High-gain tones could stand more presence and definition.

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