StewMac Valve Factory 18 Review

Most amp kits are Fender flavored, typically recreating historic 5F1 Champ, 5F2-A Princeton, or 5E3 Deluxe tweed-style circuits. And since an actual late-’50s Princeton, for example, costs about $3,000, at well less than a third of that price a DIY kit is an affordable alternative for any guitarist with soldering skills and the patience to follow instructions. But what if Fender isn’t exclusively the taste you’re looking for? What if Valco, Ampeg, Marshall, or modern takes on classic tones also float your rubber raft?Enter StewMac’s mighty little Valve Factory 18 head kit, a 12-pound beast that punches above its weight class, offers a variety of classic-inspired sounds, and hints at modern boutique amp voices. Flexible FryerPart of the Valve Factory 18’s versatility is due to the two preamp tube options provided in the kit: a 12AX7 or a 12AY7. But it’s mostly the result of a concise-but-flexible set of controls. On the front panel, there are volume, gain, and tone dials, but the way they shape sound depends on whether your guitar is plugged into the low- or high-input jack. The low input is the clearer of the two and hews close to Fender tweed world. But the high input offers gentle breakup that, to my ears, gets into gnarlier old amp voices. Both channels offer plenty of headroom and work well with pedals, but if your primary sources of tone color are stompboxes, the low input may be best for you. Both also benefit from a clean boost footswitch that pumps up the volume without altering the tones in play too much. On the back, there’s an impedance switch with 4-, 8-, and 16-ohm settings, so the Valve Factory 18 can be used with most cabinets. There’s a single speaker-out jack, and on/off and standby toggles. And as its name implies, the amp delivers 18 watts, and it’s a loud 18 watts at that—fitting for today’s small-amp sweepstakes.Brick By BrickConfession: StewMac sent me an immaculate, pre-assembled review model rather than a kit. But I still settled into a meticulous reading of the highly detailed and lavishly illustrated instruction book. It begins with a menu of the included parts, which are metal film and metal oxide resistors, plus a single wire-wound resistor, two 1N5408 diodes, nine various capacitors, a pair of custom-built Pacific Trans transformers (power and output, naturally), wire, heat-shrink tubing, sockets and tubes (more on the tubes later), the fuse and fuse holder, the pilot lamp, screws and locknuts, input jacks, control pots, front and rear faceplates, the fully assembled footswitch for the boost, and a very solid anodized metal chassis.Point-to-point assembly begins with the filter cap and works through the sockets on up to populating the circuit board, and so on. It’s advisable to have a digital multimeter handy to check each resistor before installation. Our test Valve Factory 18 arrived ready to go save for installing the tubes, which was easy, since this amp does not have a cabinet, so, it's merely a matter of plugging the tubes into the slots on the top of the chassis. Two JJ 6V6s live atop the amp’s crown next to the filter cap, which is also adjacent to the 18-watt power amp. I inserted the provided 12AT7 phase inverter tube and then decided whether to plug the 12AX7 or 12AY7 into the preamp slot.Totally TubularThose aren't the only tubes that can be swapped in the preamp slot. The amp will function happily with 7025, 5751, 12AT7, and 12AU7 valves. But I stuck to the provided 12AX7 and 12AY7. Both performed true to their tendencies. I used the Valve Factory 18 to power a Sam Hill Custom 1x12 cab with a 50-watt Eminence Private Jack and plugged in a two-humbucker Les Paul, a PRS SE Silver Sky, a Dean electric resonator with a lipstick pickup and a piezo, and a Steinberger Spirit. In all these combinations the 12AY7 yielded a little more headroom than the 12AX7, little breakup when pushed, and a cleaner sound profile overall. That is not to say the 12AX7, my favorite of the two, lacks headroom—especially when I plugged into the low-input jack. But playing through the high-input side, the 12AX7 gave me exactly what I want from an amp: enough clean tone to stay articulate along with a gritty patina that speaks the language of rock and blues.For me, that sound sings best with the tone between 10 and 2 o’clock and the gain between 10 and 12 o’clock which generates genuine old-school breakup. The tone control has great range. Turned hard to the left, it creates a booming, bass dominated voice; hard right, it’s bright and cutting, but never piercing. I did not find an unsatisfying sound within its scope. Dialing the gain to the top and the tone to about 8 o’clock, visions of doom rock danced in my head. With the tone at noon and higher, and the gain all the way up, I could hear the hard rock and metal applications, though the Valve Factory 18 isn’t a 5150 by any means. The volume dial simply makes things louder without significantly impacting the tone, which is ideal. The VerdictShort story: I dig this amp in all its sonic variations. Although the Valve Factory 18 is simple to use—and seems relatively easy to build—it is cleverly designed too. Playing it is a joy. So much so that I am disappointed that it’s not gig-ready. Without a cabinet or some cover to protect the tubes, transformers, and filter cap, it’s easily damaged. That said, the power, versatility, tonal range, and sense of accomplishment in building a point-to-point packed with character seems well worth $599.