“I’m 18, and I like it.” —Alice Cooper

In 1965 Marshall unleashed the first 100-watt head, the biggest, loudest guitar amp to date. At the same time, the company went small, unveiling three 18-watt combos that looked like scaled-down editions of the JTM-45, Marshall’s earlier flagship model. The 100-watt amps were instant hits, forever changing—if not defining—the sound of classic rock guitar. Meanwhile, many of those mini-Marshalls languished in music shops, collecting dust. Guitarists barely noticed when the 18-watt line expired two years later.

Nearly half a century later, things are different. In that era of primitive PAs and monitors, you needed a monster amp to fill the auditorium. You could never rock the Fillmore with a dinky 18-watter! Today, of course, you can rock the Fillmore with an iPhone and an amp simulator app. So while a market for Magnum-sized amps remains, we’re likelier to choose our ideal wattage for tonal reasons than for sheer volume.

Meanwhile, guitarists gradually realized that those old 18-watters delivered exquisite rock tones. When the boutique amp scene blossomed in the ’90s, builders often drew inspiration from these feisty little combos. Interest snowballed thanks to the 18watt.com site, whose members reverse-engineered the originals and pooled resources to source parts. And now, thanks to the current DIY craze, the 18-watt clone has become one of the most popular amp projects, with multiple manufacturers offering complete kits. Today’s 18-watt fan can choose between boutique spinoffs, DIY kits inspired by the originals, and handwired Marshall reissues starting at $2,499.

The 18-watt doesn’t provide Fender’s focused shimmer or Vox’s electrifying crackle, but its big, bold distortion tones are guaranteed to flutter the hearts of classic rock fans.

For this article, I tackled two projects: Mojotone’s British 18 Watt Style 1x12 Combo Amplifier Kit ($952), and Tube Depot’s Classic British 18W Tube Guitar Amp Kit 1x12 ($849). We’ll look at the parts, discuss the build experience, and evaluate the final results. But first, a few words about the magic of these mini-monsters.

Eighteen watts of fury. Fans of the 18-watt celebrate its simplicity, portability, and surprisingly virile volume. But the amp’s most oft-cited attribute is its ability to deliver big British tones at relatively modest levels. The frequently heard claim that the 18-watt provides plexi-like tones at bedroom volumes isn’t quite true—its dual EL84 tubes yield a sound quite distinct from their larger cousins with their KT66s and EL34s. The 18-watt’s tone stack is simpler—each channel has only a single simple tone control. Also, much of that classic plexi color has to do with the distinctive phase cancellation produced by closed-back 4x12 cabinets. You don’t get that effect from a single speaker in an open-backed cab.

Still, you’d never mistake the tones of the 18-watt for those of the comparably sized Vox AC15 or Fender Deluxe. The 18-watt doesn’t provide Fender’s focused shimmer or Vox’s electrifying crackle, but its big, bold distortion tones are guaranteed to flutter the hearts of classic rock fans. Its less overdriven tones are great too, though they’re seldom completely clean—this is an amp that wants to shift into overdrive, and even its low-gain tones have a fair amount of “hair.” Cascading the amp’s dual channels with a jumper cable—sort of a proto-Mesa/Boogie effect—unlocks additional cool colors. The amp even boasts a distinctive tremolo circuit with a thick, deep throb.

Tube Depot’s kit includes the parts, templates, and tools to build a turret board from scratch.

There are some 18-watt naysayers, who rightly point out that model lacks the bass impact of a larger amp. Others bemoan a lack of brilliance, though I certainly don’t find the model lacking in highs. But at the risk of oversimplifying, those who a) love the British big-amp sound of the ’60s and b) seek it in a sensibly sized package are likely to adore the 18-watt. Mind you, it’s on the loud side for a home amp, at least if you crank it (and cranking it is sort of the whole point). In fact, it’s got enough volume for many gigs, or at least ones without super-loud drummers.

About the kits. Both kits here are inspired by the 1x12 version of the 18-watt. Like many kit vendors, Mojotone and Tube Depot offer multiple versions of the product, priced according to which parts are included, since some DIYers prefer to provide their own cabs, tubes, speakers, and/or transformers. I built the complete kits, which come with everything you need except a workbench and tools.

Both kits stick closely to the ’60s schematic (though their board components are laid out differently). They boast stout, solid-wood cabinets and rugged external hardware. (Actually, the two kits are nearly identical in those regards.) Both kits include a full complement of JJ tubes (two EL84 power tubes, three 12AX7/ECC83 preamp tubes, and a EZ81 rectifier). Both use high-quality pots and switches, but employ modern plastic tube sockets and closed plastic jacks. But beyond that, the parts, build experiences, and sonic results differ.