Although it is a simple matter to walk into the first music shop you see and pick out a guitar amplifier ("amp") at random, you will probably be unsatisfied with the results of this method. If you take a couple of mintues to figure out what you are shopping for, you will be able to make a purchase that you will enjoy for years to come.

Steps

Step 1: Picking the Right Size and Wattage

Determine the size of the amp you will need. Amps are rated by wattage rather than physical size (although high-wattage amps do tend to be physically larger). By wattage, there are essentially three main categories of guitar amplifiers (combos, heads, and rack-mounted amplifiers), with several subcategories:

Combo Amps

Combo (combination) amps combine the amplifier electronics with one or more speakers in a one-piece package. They are the alternative to "heads," which contain only the electronics, and are attached to separate speaker packages (known as "cabinets" or "cabs"). Because it is a one-piece unit, the combo design is generally preferred for smaller, lower-wattage amps. The following are the most common varieties of combo amp:

• Micro amps: 1-10 watts. These are tiny, ultra-portable amps which are useful for practice on the go (or when others are trying to sleep). They don't pack enough volume to be used in most "jam" situations (where you must be heard above other musicians). As a rule, their sound quality tends to be poor (when compared to larger amps). The Marshall MS-2 is an example of a super-portable (1 watt) micro amp which has received good reviews.

• Practice amps: 10-30 watts. Practice amps are also suited for the bedroom/living room environment, although the loudest of them may be used for small gigs (performances), especially if a microphone is used to run them through the venue's PA system. As with micro amps, practice amps tend to compare unfavorably to larger units in terms of sound quality, although as they approach the 30 watt level,a few models offer increasingly competitive sound. The Roland Cube 30 is an example of a practice amp which is generally well-regarded. As a general rule, the best practice amps have at least a 10 inch speaker. This is the smallest speaker size which is generally considered a "real speaker." If you don't have a 10 inch (or larger) speaker, don't try to use the amp outside the bedroom. The embarrassment you save will be your own.

• Full-size 1x12 combos: With 50 or more watts of power and one 12 inch speaker, the 1x12 amp offers the smallest package which is considered suitable as a stand-alone amplifier for small gigs. In better models, sound quality begins to approach levels acceptable to professional musicians. Quality is always important, but perhaps even more so in the case of the 1x12 combo - with a good one, you'll prove the doubters wrong, but with one of the many duds, you won't be taken seriously. The 1x12 is not a big amp, and if you want to bring it to a serious audition or gig without enduring a storm of eye-rolling and chuckling, it had better stand out from the crowd.

• 2x12 combos are similiar to 1x12 combos, but they add a second 12 inch speaker. The 2x12 design is considerably heavier and bulkier than the 1x12, but it is still a favorite choice of working musicians for performances at small to medium-sized venues. The addition of a second speaker allows for certain stereo effects, and two speakers simply move more air than one (allowing more "presence" in your sound). The 2x12 amp is small enough to be used in the living room, light enough to be lugged around by someone without major back problems, and yet formidable enough to be taken seriously at rehearsals, auditions, and even on stage. If you have to buy a single amp for practice, rehearsals, and club gigs, a 2x12 is a good choice. You'll occassionally slip and set the volume knob a bit too high (annihilating your unfortunate neighbors), and you'll be tempted to gripe about lugging 50-80 pounds worth of amp all over the place, but it will all be worthwhile when you avoid being "The Guy Who Showed Up to the Audition or Gig With a Practice Amp." That guy usually becomes an "inside story" for the band to tell other musicians when everybody needs a laugh.

There are other types of combos, but these are the mainstays. Having discussed them, we are ready to move on to heads and stacks.

Heads, Cabinets, and Stacks

A head is an amplifier without speakers. A cabinet ("cab") is a stand-alone speaker enclosure, which can be connected to a head. A stack is a head and a set of cabinets connected together, ready for use. Stacks are generally preferred for gigs rather than practice, although there's no rule against having a enormous stack in your living room - if your family allows it. Fair warning: in most cases, they won't. Stacks are physically bulky, very heavy, and devastatingly LOUD. These are the tools of musicians who either play arenas and stadiums on a regular basis - or at least dream of doing so.

• Heads are all roughly the same size physically, but they come in a variety of wattages. "Small" heads pack 50-100 watts. Full-power heads are generally 100 watts or more. There are also super heads, boasting a tinnitus-inducing 200-400 watts of power. For performances at small to medium-size venues, a small head is more than enough. The smaller heads are often connected to a single 4x12 cabinet (which contains four 12 inch speakers, as the name suggests). This type of setup is known as a "half stack," and it is a favorite of working musicians. The half stack offers plenty of volume, the presence of four speakers, and the "credibility" associated with stacks.

• The full stack is the dream of many a guitarist. This is usually a 100 watt head connected to two 4x12 cabinets, although other wattages are sometimes employed. The cabinets are stacked vertically (one on top of the other), giving the setup its distinctive name. A full stack is as tall as a grown man, making for quite an impressive sight. The sound is equally impressive. If you set one of these up in your living room and play it to its full capabilities, you will be evicted from the neighborhood (unless you are an isolated hermit). A full stack can handle all but the very largest of venues. Guitarists who are truly sadistic (in a sonic sense), such as some heavy metal players, may run one of the 200-400 watt super heads through a full stack. With any full stack (and especially the "hot rod" setups), you will require ear protection to play at higher volumes without sustaining potentially serious ear damage.

Stacks are great for playing big venues (and for impressing your friends), but if you aren't a working or touring musician, they can be "overkill" for most situations. Lugging around full-size 4x12 speaker cabinets is hard work, fit only for "roadies" who are getting paid to do it. Showing up to an audition with a full stack and a hand truck to set it up can be almost as bad as showing up with a practice amp. If you lug in a stack, you'd better have the skills to justify it, or (once again), you'll become another "inside story" for the band to chuckle about after rehearsal - "The Newbie Guy Who Brought a Full Stack to the Audition."

Rack-Mounted Products

Many musicians use "racks," usually a reinforced metal box with removable panels on the front and back. The front side of the rack, when open, has two verticale rows of threaded screw holes on the sides. Rack sizes have been standardized for years -- they are made to fit ALL rack-moutable units, including recording gear, PA amplifiers, vocal processors, chromatic tuners, DJ gear, etc. in addition to guitar amps. Rack-mounted products have a sturdy metal face plate strong enough to support the entire product; they are a standard width, a standard maximum depth, and are usually much shorter than they are tall or deep. The face plate is wider than the rest of the unit and has screw holes on each corner, spaced to line up with the screw holes on the front of any rack. To attach gear to the rack, lay your rack on its backside, place the unit in the rack so that the unit dangles down into the rack, its entire weight supported by the face plate, line it up with the screw holes, and fasten it at each corner with properly-sized screws. The smallest rack products are the shortest, covering only two screw holes -- these are said to take up "one rack space." A larger product that covers up four screw holes on your rack takes up "two rack spaces," and so on. To figure out how many spaces a rack has, count the screw holes on one side and divide it by two.

A rack-mounted guitar amplifier rig is similar to heads in that they have separate amplifier components that are plugged into external speaker cabinets. But nearly all rack-mounted amplifiers are broken down into two further categories -- the pre-amp and the power amp. Both heads and combos have these separate components as well -- racks merely separate them out into two units. Most major amplifier manufacturers, including Marshall, Carvin, Mesa-Boogie, and Peavey make rack-mountable amp rigs.

• The Pre-Amp shapes the signal entering your amplifier into a tone. In its basic form, a pre-amp defines the levels of treble, bass, and middle in your tone. However, functions such as gain, presence, and contour have become standard features of modern guitar amplifiers, and rack-mountable pre-amps usually have many more functions indeed -- they are essentially effects processors. Footpedal multi-effects processors are also pre-amps. Plug your guitar into the pre-amp. Most rack pre-amps only take up one rack space.

• The Power Amp is connected to the pre-amp by a speaker cable. It takes the signal the pre-amp shaped and gives it volume. Like heads, power amps are available in different sizes, from a minimum of 50 watts to monster 200-400W power amps. 100W or larger power amps will take up two rack spaces. The power amp plugs into the speaker cab like on a head. However, as many power amps as you want can be connected in a daisy chain or to different pre-amp outputs to boost the power of the signal, as well as possibly blend the tonal influences of two different power amps.

Disadvantages of Rack Rigs. As you can probably tell, racks are frequently very complicated rigs. A novice guitarrist may find them perplexing. They are also heavier and bulkier than heads -- and add onto that the bulk and heft of the rack itself. Since you need to buy multiple products and accessories, the price for a new rack rig can be (but isn't always) higher than that of a head.

Advantages of Rack Rigs. On the other hand, using a rack allows you to mix and match products by different manufacturers and find a tone that is distinctly "yours," not the boutique design concept of some engineer at Marshall or Fender. And if you have a reasonably good mind for engineering or basic spatial sequencing (i.e. lining things up in order), even complicated digital pre-amps can be surprisingly user-friendly, providing a more easy-to-understand interface than a row of inscrutable knobs on the front of a head or combo. If you are already a DJ, vocalist, or recording artist, or want to become any one of these, many valuable products are availble that can be mounted right on the same rack with your amplifier.

Also, big racks frequently have caster wheels, making them very easy to roll around, and having a rack can also simplify pre-gig or -practise setup. Instead of having to plug in all your components from scratch, your components can already be plugged in and ready to go as soon as you wheel your rack onto the stage or into the studio and remove the front and back panels. A rack-mountable power conditioner (essentially a rack-mounted power strip with surge protection) can be invaluable to this end as most rack units are independently powered -- simply plug all your products into the conditioner, then whenever you arrive at a gig or practice, plug in the one master power cable from the conditioner, plug in your speaker cab and guitar, switch everything on, and you're ready to rock. If you have pedals, microphones, etc, you can usually fit them into the rack as well, making it your all-purpose, highly-portable gig box (provided that it's on wheels).

Finally, racks are uncommon, and will attract attention. People will be impressed if you wheel a rack rig into rehearsal or performance, but beware -- they will expect you to be a seasoned guitarrist, or at least be able to effectively USE your rack. Don't bring your rack anywhere unless you know how to get those pre-amps and processors to do exactly what you want them to do. Such professionals asU2's The Edge and Nirvana's Kurt Cobain have favored rack rigs.

MIDI. Many rack-mounted pre-amps are digital and use MIDI (Musical Instrument Digital Interface) technology. This allows pre-amp settings to be saved in the pre-amp's digital memory to be recalled again later at the push of a button. These buttons can be on the faceplate of the unit, but MIDI pedalboards can be utilized to access those pre-set channels by stepping on footpedal buttons, to prevent a guitarrist from having to go to his rack and search out the right setting in the dark between each song.

Step 2: Selecting the Right Sound

In order to get the most from a guitar amplifier, you need to understand how different types of amps suit different styles of music. For the most part, amps are not "one size fits all." Although there are all sorts of amps, they can be classified in two broad categories - "vintage" and "high gain."

Tone Wars

Vintage amps produce (or reproduce) the classic sounds of early amplifiers. For the jazz, blues, or blues-rock guitarist, the vintage sound is still widely considered the best tone available. Vintage amps can be actual antiques, or they can be modern amps that replicate the sound of antique amps. The sound of Fender, Vox, Marshall, and similar amplifiers from the 50's, 60's and early 70's is the foundation of the vintage tone. When you think "vintage," you think Hendrix, Led Zeppelin, Eric Clapton, Deep Purple, etc. These are the sounds that started it all.

High-gain amps produce a sound with greater distortion than that of vintage amps. Although there is some debate about the evolution of high-gain amps, many believe that a large part of their history is owed to Eddie Van Halen, who took apart his vintage-style Marshall head and played around with the electronics, allowing him to get far more gain (the source of the classic rock/metal distortion sound). With his landmark "Eruption" solo in 1977, Van Halen introduced the roaring, face-melting sound of super high gain to the guitar community. At around the same time, the emergence of heavy metal bands added another dimension to the high-gain phenomena. For hard rock and heavy metal music from the early 80's and beyond, vintage amps are overshadowed by their modern high-gain counterparts.

If you want to play jazz, blues, blues-rock (in the style of Led Zeppelin) or very early heavy metal (in the style of Black Sabbath), a vintage amp may be your best choice. If you want to play hard rock, 80's metal, and "shred" guitar (in the style of the countless 80's "guitar heroes"), you will probably want to go with a high-gain model. Note that many newer amps can provide both high-gain and vintage sounds, although some purists feel that the only vintage amps worth playing are the actual antique amplifiers themselves. "Amp modeling" technnology (which allows one amp to simulate the sound of many different amps) is a relatively recent development which has both fans and critics. If you don't plan to specialize exclusively in vintage-style music, a modeling amp can be very useful, although if you're a purist, nothing beats walking in with a real Fender Twin Reverb, an ancient Marshall "Plexi" head, or something similar.

Tube vs Solid State

In the vintage days, all amplifiers used vacuum tubes to accomplish the actual amplification. Nowdays, many amps use transistors instead, sparking a long-standing debate about which is better. The concensus is that for almost all types of music, the sound of tubes is noticeably superior. However, tubes have several drawbacks:

• Tubes can be expensive, depending the tubes used. Expect to replace them after 4 or more years of use, depending on their quality and how loud/often they are used.

• Tubes are somewhat unreliable. They can and do go out at random times, crippling the amp. This can be aleviated by using good quality tubes.

• Tubes (and the associated design factors) add considerable weight to the amplifier. Back problems caused by skinny guitar players lugging around big 2x12 tube combos are an insurance company's nightmare.

• Tube amps are, generally speaking, more pricey than solid-state amps. You will almost certainly pay more for this ancient technology than you will pay for modern solid-state (transistor) electronics. There are tube amps, however, like the Fender Blues Jr., that go for roughly $300; the Fender Hot Rod Deluxe (which is an extremely loud, 40 Watt, 1x12 amp), goes for about $550-$600. A Vox AC-30 2x12" reissue, on the other hand, will set you back no less than $1200; and a Marshall head + half stack can be well over $2000.

If you can afford a tube amp, you should strongly consider buying one. In almost all cases, the sound is noticeably better. One possible exception to this is for heavy metal players. Many metal guitarists find that the harsher sound of transistors suits their style of music. Given the reliability, weight, and price advantages of solid-state amps, even the professional-level heavy metal guitarist may not require a tube amp. Pantera's Darrell Abbott used solid-state amps, as do many other notable heavy metal musicians.

Your amp will have two different kinds of tubes -- pre-amp tubes and power-amp tubes (a few combos and heads mix and match between tube and solid-state pre-amps and power amps). Many modern guitarrists have forgotten that the original rock 'n' roll "crunch" or distortion was created when guitarrists like Pete Townsend turned their amps' volume up to 7 or 8, causing the power tubes to overdrive. A pre-amp perameter called "Gain" has been added to most amps to simulate that overdriven distortion. But unless you're into the tinny thrash-metal sound, no artificial gain setting can compare to the sweet, distorted tone of overdriven power tubes turned up to 7. The problem is, most guitarrists, especially new ones, go whole hog for a 100W amp, which cannot be turned up to 7 or 8 in a small club without blowing the doors off. They turn their amps down to four or five, turn the gain up to ten, and never know what they are missing that they could get froma 50W amp turned to 7 with the gain down to 5. Angus Young of AC/DC plays live with both a 100W tube head turned up to 6 for his rhythm parts, and a 50W tube head cranked up to 10 for comparable volume but extra overdrive that he switched to for his solos.

Tips

• When shopping for an amp, price should not be your only consideration. Some lower-priced amps offer admirable sound, while you may find some costly amps unsuitable for your needs. To judge quality, read user reviews on various guitar websites. However, be aware that many equipment vendors publish only good reviews (to ensure product sales). Do your research and make an informed decision.

• If you purchase a tube amp, try not to abuse it physically. In general, transistor (solid-state) units are designed to take loads of punishment, but tube amps are much more delicate. If your brand new (very expensive) Soldano tube head falls down a flight of stairs, you are probably in deep trouble - while the same thing happening to a solid-state combo will probably result in nothing more than a momentary panic and some laughs (after the fact). In short, do not kick, hurl, slam, pummel, or viciously bludgeon a tube amp - and try to discourage others from doing so. If you're wondering why such a warning is necessary, you probably haven't spent much time with rock musicians.

• If you need one amp that can do "everything," consider purchasing one of the new modeling amps with onboard effects. The best of these amps can reproduce the sound of many other units with passable accuracy, and you have instant access to those cool effects that make even crappy guitarists (like me) sound good - delay, chorus, flanger, reverb, etc. With enough effects, your little old grandmother can sound like a rock star. Okay, that's an exaggeration, but if guys like me can sound good, you can too. Crate and Roland (among other companies) make some good effects combos.

• Unless you are playing heavy metal, it is generally better to buy a smaller amp with good tone than it is to buy a big loud amp that sounds cheesy. You will never regret having a nice tone, but you will always regret bad tone. If you play with a band, you will likely find that you never need that much volume anyway unless you are playing an arena, and if you are reading this I don't see any arenas in your near future. Buy a small tube amp with a nice sound. Some music stores will try to sell loud amps with loads of effects to beginners. Don't fall for that. Don't fall for all of the "cool" effects; effects get old after a while. Use your ears and pick an amp whose tone you absolutely love, and don't part with your money until you find that amp.

• For most beginners, a 15 watt amp will be more than enough for your bedroom and small gigs.

Warnings

• Buying a large combo or (especially) a stack for the purpose of wailing in your living room at all hours can lead to divorce. So can spending $2000 on an amplifier without telling the wife (because you know she's going to say no). As a general rule, guitar equipment is to be treated as if family members had a restraining order against it. It doesn't matter if people pay good money to have you assault their eardrums with your frenzied solos every weekend, nobody at home is going to want to hear it. Whatever type of amp you buy, headphones are a must for home practice. Similarly, if you plan to install an enormous Marshall stack in your garage for rehearsals, make sure it's a detached garage. The Mrs. doesn't want to have Black Sabbath's "War Pigs" rattling windows and knocking pictures off the walls while she is entertaining her Saturday bridge club.