If you’ve heard guitarists talking about amps, perhaps you’ve heard the terms “headâ€, “cabâ€, “comboâ€, and “chassisâ€. 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.
Chassis
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.
combo box or head shell?
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.
Combo
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
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Hello from Northern Ontario, Canada! Great video and article. AWESOME playing. I’ve checked out all your vids on the Tweaker and they’ve been super helpful. I’m going to buy one of these amps and currently trying to decide which one to get. You don’t mention it on your video but is the Tweaker combo an open back or semi open back? I see it has a vent on the top panel that disperses heat. I don’t gig (yet) but I do jam with buddies every now and then, but most often I’d be playing and recording at home. Any suggestion on which version to get?
Again, thanks for the effort you put into the vids and comments. Much appreciated.
Hi Scott,
Thanks for the kind words!. The Tweaker combo is a semi-open back design. There’s an opening that’s about 5″ tall by 13″ wide. As for which version to get, that’s a tough one. If you’re recording at home, it might be nice to get the head and cab so that you’re able to put the head close to you and then run a longer speaker cable to isolate the cab elsewhere so you can turn it up a little. In sessions, players often stack the heads right by their playing station and then run connection to cabs in an iso booth.
Great articles. Really loving the blog. Are those the new Anderson P90s? They sound great. I’m pretty convinced that my next guitar will have P90s but I have to play them. Maybe a good topic for future article?
Thanks, Jim.
Yeah, these are Tom’s new silent P90’s. I’m having a ball with them. I think you’re right about an article on pickups. Singles vs. buckers. vs. P90’s etc.
Cool. I’d also be very interested in your take between the Short T vs Cobra and the PQs vs M pups. I’m getting closer to ordering a new andeson and I think it is going to some combination of the above.
Jim,
The short T is snappier because of the body and neck woods. Mine is swamp ash with a maple neck which is gonna produce a faster attack with more of a scooped midrange. The Cobra is identical in dimensions, but is a mahogany body (with a maple cap) and a mahogany neck. It’s softer and woolier across the board and it has a more polite top end. It’s there, but it doesn’t force itself upon your music. Also, my Short T is hollow so it has more natural compression than a solid (which moves it a little closer to the Cobra) and it’ll scoop that midrange out a little more.
The M’s vs. PQ’s are an interesting debate. I feel like both are essentially voiced like fat single coils, but an M-series bridge pup in my Short T produces some of the greatest classic rock tones out there. Plenty of bite and growl but without the squish that a full-size bucker would give you. The PQ’s are also like fat singles, but it’s less about the output and more about the response. I feel like P90’s are always gonna give a grainier version of singles. Like a raspy single coil. A PQ is like the Joe Cocker of single coils, but it shuts up when you need it to. 🙂
Hello and Thank You so so much for literally the only comparison between Tweaker Head and Combo on the Web. I am still going back and forth a bit with which one to get but, you helped a great deal with my decision to get the combo for now… Still have 20 days or so to swap out… But, thanks again and decisions aside – I do have a pressing question regarding the Tweaker 112. I cannot see the 12Ax7 tubes in V1-V3 glowing at all and can’t seem to get distortion from the amp at low volume levels. Is this normal? Can you see those tubes glowing in your Combo? I am concerned they are not working but, it could just be the covers preventing me from seeing the glow. The 6L6 tubes are definitely glowing and I am getting great Clean sounds from the amp but, I am worried about those 12ax7’s especially since I am having trouble getting distortion from the amp. Thanks again for the super help and the great playing. Demos are best when the playing is good as well. 🙂
Interesting. I think you probably wouldn’t see much glow because of the covers, but the distortion/overdrive thing is what concerns me. If you turn the gain all the way up on the clean mode, you should tsart to get just a little bit of grit, especially if you dig in or have a guitar with hotter pickups (like humbuckers). If flip that switch over tot he Hot mode, you should get loads of distortion, appropriate for guitar leads or chunky rhythm stuff. Does that work?
Good Evening Chef. Thanks for the advice about the tubes not glowing. This is what I figured. Placed a call to Egnater and they were SUPER Helpful. I think what happened is that I had lights off to look for the glow of the tubes and had the master down just enough to kill the volume of the amp as well as distortion. Interesting that Master volume really cuts out at about 8:00 hm… So all is well with the amp and I have happily settled with the combo for more open big sound. Did notice some popping when switching from standby to play and with some of the other switches as well. Is this normal? I am also very curious about your method of plugging your Line 6 M13 in to the front and effects loop on the amp. Can I do this with a BOSS ME70 multi-effect? I see that it has a pre-amp out as well the return and send plug ins.. Would it be correct to hook the Pre-amp out to the input of amp and then run the effects loop to the return and send plug ins on the ME70? Just curious here. Thanks for all the great playing and sharing the blessings of talent and awesome gear. 🙂
What song are you playing at 3:10?
Hi Jason,
At 3:10, that’s just me noodling around in the key of D. I always liked D because you can use the open A, D, G, and B strings toy our benefit and let things ring a little more. I’m sure there are little elements of other pop songs through the years, but that’s all improvisation is- just being able to put on display the ideas we’ve collected over the years.