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August Issue
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The Mean 18: British-Style 18-Watt Amp Kits from Mojotone and Tube Depot

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Mojotone British 18 Watt Style 1x12 Combo Amplifier kit

The parts. Mojotone stocks their kit with premium, retro-style parts. The all-important power and output transformers are high-quality custom-spec Heyboers. Most other parts bear the Mojotone brand, and the company prefers not to disclose the individual manufacturers. But the large-format capacitors and chubby carbon-composite resistors appear period-authentic and gratifyingly “mojo,” as is the vintage-style cloth-insulated push-back wire. The Mojotone-branded speaker is a Celestion Vintage 30 sound-alike. The kit includes a two-button footswitch in a high-quality metal enclosure for activating the trem circuit and toggling between low and fast speed ranges.

The build. Most amp kits are light on documentation, and the Mojotone kit is no exception—all you get is a schematic, a wiring diagram, and a parts list. (You can download them for free from the Mojotone site.) Like other kit vendors, Mojotone does not provide unlimited, on-call support. (According to Mojotone’s Andrew Simmons, “Mojotone is available for technical support via phone or e-mail, although e-mail is preferred. We do expect potential kit builders to able to read and understand the wiring diagrams and schematics before attempting to build an amp kit.”)

This kit definitely demands some tech expertise. Example: The wiring diagram doesn’t depict all the tube-socket connections, but includes a note reading “Heater wiring omitted from drawing for clarity.” My hunch is, if you don’t know what that means or have access to someone who does, this project may be a bit advanced for you. (The heaters, by the way, are the elements in tubes that supply the current.) On the plus side, all the small parts are organized in a pair of compartmented boxes, perfect for workbench assembly. All parts are identified on the inside of the box lid, and labels include such helpful details as color codes to verify resistor values. It’s a thoughtful, builder-friendly detail.


Mojotone stocks their 18-watt kit with vintage-style parts, including carbon-composite resistors, large-format capacitors, and cloth-insulated wire.

Most of the caps and resistor reside on a turret board, though a dozen or so passive components attach directly to pots or tube-socket terminals. Mojotone includes a premade turret board. Components are logically laid out, though some solder points are tricky, with as many as five connections meeting on a single turret. Possible trouble spots for DIY novices include the finicky tube sockets. Those tiny metal terminals have a tendency to pop out of their sockets, and the plastic bases melt all too easily. These probably won’t be problems if you work quickly and confidently, but if wiring errors force you to rework the connections repeatedly, you may find yourself ordering a few extra sockets. The jack connections can also be challenging. There’s no documentation on mounting the chassis in the cab or installing the speaker, though it’s pretty easy to figure out. Minor drilling is required.

It took me about a day to assemble the kit. (For perspective, I’ve built more stompboxes than I can count, but I’ve only made half a dozen amps, all from kits.) The normal channel sounded great from the get-go, but I encountered wiring problems with the trem circuit. I tried to pinpoint the errors on my own, but failed—I needed help from an amp tech. (Nothing wrong with the kit—the errors were mine alone.) In the end, it took almost as long to troubleshoot the amp as to build it—not a rare DIY occurrence. An expert builder could probably tackle the project in five hours or so—and get everything right the first time.

Ratings

Pros:
Superb mid-’60s Marshall tones in a small package. Top-shelf retro-style parts.

Cons:
Minimal documentation.

Tones:

Ease of Use:

Build/Design:

Value:

Street:
$952

Mojotone British 18 Watt Style 1x12 Combo Amplifier kit
mojotone.com

The result. Building an amp is an intense experience. By the time you’ve completed a successful build, the project is your baby. Who doesn’t love their own baby?

But even allowing for such subjectivity, the completed amp is a knockout. The hardware feels substantial. (How substantial things are inside depends on you.) The tone and feel are comparable to what you’d encounter in a boutique 18-watt selling for over two grand.

The tones are faithful to original ’60s sound. You get strong power amp distortion at relatively low levels, creating the impression of a larger, louder amp. The highs sizzle with excitement, but never get nasty. As on the original, lows are modest—this amp type probably won’t suit metal players, or anyone else seeking substantial bass wallop. (Out of curiosity, I tried the amp through a closed-back cabinet. Naturally, there was a bit more bass impact, but the sound lost some of its unique character.)

The way distortion accumulates as you raise the volume feels a bit Vox-like (no surprise, since most Voxes use the same EL84 power tubes). But despite the EL84s and open cab, you probably won’t mistake the sound for that of a Vox. Even with the volume maxed, notes and chords retain impact, definition, and high-end animation. (In fact, one of the most fun ways to use the amp is to floor the controls and regulate the output via your guitar’s volume and tone knobs.)

The clean tones are wonderful too. They’re far from Fender-like, but they have an airy shimmer you don’t always associate with big British amps. The single-band tone control is a delight, with usable sounds throughout its range. This amp sounds good no matter how you set the controls.

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