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Bradley Labs Iron Horse

March 23, 2012
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Eager to reach your fingertips into the very nerve endings of your amplifier’s circuitry? Then Bradley Labs’ Iron Horse might be an amp for you. This handbuilt, small-shop, point-to-point creation has switches to alter the performance of just about every key stage within the amp—and in fact, off the top of my head, I can’t think of much else that could be made switchable within this compact yet surprisingly powerful little head. As wild as it looks, though, this brainchild of engineer Don Bradley (holder of 41 U.S. and foreign patents in electrical engineering) and Matt Agresta is far more than the moonshot it might first appear.

At its core the Iron Horse is a pretty straightforward all-tube 30-watter with four 6V6s, three preamp tubes, a tube rectifier that’s governed by a Volume control and a three-knob tone stack. But add a whopping 14 mini-switches (see Specs for details), plus extra pots to control Presence and Feedback, and this singlechannel amp’s flexibility soars right over the top. There’s no master volume, but the lone Volume control hides a dualganged pot that governs the signal to the preamp and output tubes simultaneously in a unique circuit that Bradley calls a “Volume Quench.” Beyond the seeming novelty of its myriad switches, the Iron Horse reveals a robust build: heavy duty custom-wound transformers are used for power and output, and quality components grace the inside of the chassis, all hand-wired in a circuit that is inevitably somewhat rats’-nesty, but tidy and impressive nevertheless. It’s styling is groovily retro-modern, too, with a back-angled control panel and a unique “awning” style cabinet that really set it apart from anything else. The 2x12 cabinet, an open-back design with two front-mounted Jensen 12s, is designed to present the full sonic glory of the Iron Horse without too much coloration from the cab itself.

Describing all the sonic permutations of the switches is beyond the scope of this review, but here are a few of my observations: Setting the Bias to fixed, Feedback knob up high, Input Voltage and tone-stack Drive both to high, the Iron Horse yields crispy, clear tones that are in the camp of a blackface Fender Deluxe. The sounds are tactile and lush, and will start to break up at around 11 o’clock on the Volume if you dig in, especially with humbuckers. Changing the Bias to Self (cathode), flipping Input Voltage to low, and dialing back on the Feedback control gets you convincingly into vintage Fender tweed territory, with a browner, grittier tone that is spot on for classic rock ’n’ roll.

Between and beyond these sounds, the shades of gain, tone, and texture are nearly infinite, at least within the vintage realm. The Iron Horse even nails convincing crankedup plexi tones, with all of the thumping lower-mids, chewy playing feel, and singing feedback of a old Marshall 50-watter with EL34s—and at close to the same volume too. The ’Horse is very loud in its four-tube configuration, and being an old-school nonmaster- volume design, the SPL will be blistering by the time you get it to sound even remotely “high gain.” When you do, though, the amp roars and is an absolute pleasure to play. Fortunately, you can flip it down to two tubes for a softer delivery, or to singletube class A mode for scorching lead tones at studio volumes.

Bottom line: The Bradley Iron Horse is an amp that requires you to put some time into exploring its sonic territory, but the reward for your effort will be finding new and enticing tones around every turn.

Specifications

CONTACT Bradley Labs, (408) 778-9330; bradleylabs.com,

Iron Horse

PRICE $2,900

CHANNELS One

CONTROLS Treble, Middle, Bass, Volume, Presence, Feedback. Toggle switches for Pre-EQ shelf, Drive (tone stack), Post-EQ shelf, Post-EQ Coupling, Bright, Pentode, Triode/Ultra -Linear, Self/Fixed Bias

POWER 30 watts (switchable to 15, 7.5, and 5 watts)

TUBES Two 12AX7 and one 12DW7 preamp tubes, four 6V6 output tubes, 5AR5/GZ34 rectifier

EXTRAS Switching for 4- or 2-tube class AB, or 1-tube class A operation. 4/8/16Ω impedance switches. Diode/tube rectification switch

SPEAKERS Tested with Bradley 2x12 cabinet ($520) with Jensen C12K speakers

WEIGHT Head 35 lbs, speaker cabinet 55 lbs

BUILT USA

KUDOS Retro-space-age design with fun “test-lab” style switching options. Excellent build quality. Fierce and dynamic tones,

CONCERNS High cost. May require too much interaction for “set it and forget it” style players.

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