Photo by Jon Roncolato / Carter Vintage Guitars
In our mad pursuit of boutique gear, it’s easy to overlook the humble speaker cabinet. While we drill down on the merits and specs of various speakers, the box that houses them typically takes a backseat to everything else in our signal chain. Which ain’t right, if you think about it. No guitarist is going to wow the crowd dangling a raw 12" speaker from a pole, right? The truth is, your cab plays as important a role as any other device in your rig, so it’s worth taking the time to explore it in its various forms. We’ll cover key points that will better acquaint you with what you already own and help you make an informed decision the next time you purchase a combo amp or extension cab. And while we’re at it, perhaps we’ll dispel a few myths.
Cabinet material. If you ask guitarists what their cabs are made of, most will say “wood.” That’s the short answer, but it’s also very broad and incomplete. There are many different types of wood, and what a builder chooses will affect how the cabinet performs. Each type of wood has its pros and cons, and whether a cab has an open or closed back has a huge bearing on what a builder chooses to construct it with.
Many combo enclosures are made from solid wood—particularly vintage Fenders, which were built with solid pine. And since vintage gear is the gauge by which most new gear is measured, replica pine cabinets have grown in popularity over the years. Solid pine cabs typically have an open back, meaning the speaker is exposed to the air and thus delivers a more diffused and less directional sound. Solid pine is lighter than other cabinet woods and, as anyone who has lifted a combo amp knows, weight savings can be crucial—especially if you haul your gear to lots of rehearsals and gigs. But pine flexes, and this can emphasize certain frequencies. Because open-back combos don’t trap soundwaves, but rather allow them to escape, you don’t end up with resonant frequencies being accentuated by the cabinet walls. This explains why solid pine is ideal for open-back combos. Closed-back cabinets are more focused and directional, so it’s rare to find one made of solid pine, due to the aforementioned flexing and the sonic chaos it can bring.
Most closed-back, or sealed, cabinets are constructed from plywood, as are some combos. The industry standard is 18 mm Baltic birch plywood, which differs from the sheets of plywood sold at the hardware store. To be a useful cabinet material, plywood needs to be voidless—meaning there is no trapped air between the plies. Unlike plywood used for less demanding tasks, Baltic birch plywood is made to be voidless, and this prevents the cabinet walls from rattling when you play. In Baltic birch plywood, each ply is a uniform thickness, laid with the grain alternating between north-south and east-west, and the boards are laminated with exterior-grade adhesives. The rigidity of Baltic birch plywood makes it an excellent material for closed-back cabinets, such as 4x12s and bigger 2x12s. Because of how it’s made, Baltic birch is nearly indestructible. However, this also makes it very heavy, which is why you see wheels on a lot of these larger cabinets.
You’d think the strength of Baltic birch would make it a good material for bass cabinets. Well, bass cabinets tend to need more rigidity than even Baltic birch offers, so they’re often made with chipboard or medium-density fiberboard (MDF). Both of these materials are extremely strong and have little-to-no flex because of the way they are made. Chipboard, sometimes called particleboard, is made by gluing together many different chips of otherwise useless wood scraps—and sometimes even sawdust. The chips are bound together with a resin and then drawn out into boards. MDF is made in much the same way, but, as its name suggests, uses much more finely broken-down wood fibers. This material is then pressed together with wax and resin at high temperatures. While the strength of these engineered materials is very high, so is the weight.
As a general rule, to do justice to the low frequencies of bass, mass wins. You need all that physical weight to help produce a burly low end. But there’s a downside to these man-made materials: They can deteriorate over time with heavy use, such as banging the cabinet against every stair as you hoist it up three flights to play for those 10 people.
Many combos have medium-density fiberboard cabs, which are sturdy but heavy. Some players opt to re-house their combos in aftermarket enclosures made of solid pine—the wood Leo Fender originally used. Available for popular models like this Fender Blues Junior, pine cabs look cool, shave pounds off the combo’s total weight, and arguably enhance the amp’s tone. Photo by Andy Ellis
Cabinet joinery. I’m sure you’ve heard a lot about different types of corner joints and how the joinery method impacts the cabinet. There are three main types of joints: the rabbet joint, the box or finger joint, and the dovetail joint.