If you’ve heard guitarists talking about amps, perhaps you’ve heard the terms “head”, “cab”, “combo”, and “chassis”. Often, manufacturers will offer the same amp in multiple configurations to better suit the playing customers. For those of you who are new to the land of guitar gear, those terms refer to different formats for a single amplifier.
For starters, the chassis is the pressed steel or aluminum metal box that all of the knobs and wiring go into. This is the brain and the power of the amplifier and consists of all of the controls, the wiring, the transformers, and the tubes (if it’s a tube/valve amp). Please keep in mind that removing the chassis from a combo box or head shell could expose you to lethal levels of electricity. If you don’t know what you’re doing, take your amp to a competent technician for any under-the-hood work. I know it sounds sexy to be able to say you’re working on your own amp. But it’s so much less sexy for your mom/wife/girlfriend/friends to have to tell people you’re no longer with us because you shocked the crap out of yourself and died. As a general rule, let’s just say the safest thing for you to stick into your amp chassis is a 1/4” guitar cable, deal? Anyway, the chassis is a the metal box that actually IS an amplifier. The wooden box that it gets stuck into defines the configuration.
Head and Cab
The first configuration is a head and speaker cabinet. This is two separate wooden boxes: one for the amp chassis and another for the speaker(s). Many players prefer this configuration and it’s because there are a number of benefits. For starters, it cuts down on the weight of the amp when lugging it in and out of gigs- not mathematically speaking, but when you can carry one part in each hand, it just distributes the weight and makes it seem easier. The second benefit is that it allows you to mix and match heads and cabs to see which speakers and cabs work for which gigs or recording sessions. I have a number of speaker cabs and I end up bringing different ones depending on the show and the amount of space I have on stage. Also, just a word of caution, some speaker cabs LOOK loud because of their size and it’s easy for sound men/women to ask you to turn down while you’re still unloading your gearwagon. haha In those cases, I bring a second, very small cab that LOOKS quiet so that I can maintain peace and harmony (and keep working so that my children have food to eat and shoes on da feet). In a head and cab format, you have the ability to mix and match components to better suit your gigs. Another benefit that I have heard from others is that a head/cab format is better for the amp itself. Namely, because you’re separating the chassis (filled with intricately soldered components) from the vibrating speaker box that could do some damage. Since a speaker cab is a resonant wooden box, it will vibrate when you put music through it (duh) and that vibration could wear away at the strength of soldered connections over time. I have not owned an amp long enough to actually see this happen and the old amps that I have owned have had plenty of work done to keep them updated and running in tip-top shape.
The second configuration is a combo (short for “combination” of both head and speaker cabinet). The combo amp is a favorite in metropolitan cities like New York where a player might potentially carry his or her entire rig on a subway or might have to carry the whole rig up three flights of stairs to the gig. Having the whole amp movable by one handle is a luxury. Also, lots of players talk about having a “grab-n-go” amp, which would be something easy to grab quickly and head out to a rehearsal or small club gig. Other benefits to a combo are that it’s normally less expensive than the matching head/cab version and it requires one less cable to carry since the speaker cable is often contained in the chassis itself and a head/cab version would need you to plug in a speaker cable between the head and cab every time you played. I’ll probably talk specifically about open back cabs vs. closed back cabs in a future post, but I should also note that just about every combo I’ve ever seen uses and open-back cab design because if it was closed back then the tubes would create too much heat in the closed container. Essentially, the open back creates ventilation for the chassis. If you prefer the sound of closed-back cabs, it almost forces you to choose the head/cab version.
Since each version has its own benefits (remember, everything in this world has a feature set), I’ll leave it up to you to decide which one you most prefer. If you’d like to see a comparison of the same amp in both formats, I recorded a video today of the Egnater Tweaker in both configurations and posted it on YouTube.
Love from the kitchen,
-The Tone Chef