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Use your ears. Evaluate your needs. Understand what defines an amp's overall tone. Learn the categories.

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Yes, it seems remarkably uncomplicated and highly un-technical, and there are really no acronyms to cover it. However, it's important to realize that from the outset, you have to like the sound the amp makes relative to the style of music you play.   A Marshall amp sounds absolutely amazing—if the style of music you're playing falls in to the Van Halen, Cream, or AC/DC camp. A Fender amp also sounds amazing—if you're going for more of a Stevie Ray Vaughan, Jerry Garcia or Dick Dale sound. The best way to determine what an amp sounds like is to play your guitar through it. If you are more of a beginner, not confident about your chops, but want an amp you can "grow into," have somebody at the store play it for you. The critical issue here is how amp "a" sounds when compared to amp "b," so do whatever it takes to get a good comparison. Amps are rated by wattage rather than physical size (although high-wattage amps do tend to be physically larger).    Lower wattage tube amplifiers will tend to create harmonic distortion at lower volumes, which is preferable in practice, studio, and miked stage performance.  Higher wattage tube amplifiers will distort at higher volumes—which will require more creative mixing for live situations. The wattage has an effect on both the actual and perceived sound volume. In general, it takes 10 times the wattage of an amp to double the perceived volume. For example a 10-watt amp will sound half as loud as a 100-watt amp The wattage and cost of an amp are rarely related, as 10 watt amps can be two, three, or even ten times the cost of a 100 watt amp—depending on the quality of the components and the design. A knock-off 100-watt solid-state amp is inexpensive to produce compared to a boutique 5-watt tube amp. The sound quality experienced from an amplifier can be determined by many things, including (but not limited to):   the preamp tubes used power amp tubes used the wood material used for the speaker cabinet the type of speaker cones the resistance of the speakers the guitar used the cables used the effects used the pickups in the guitar and even the fingers of the player. There are two main categories of guitar amplifiers configurations: combo and head/cabinet.   Combo (combination) amps combine the amplifier electronics with one or more speakers in a one-piece package. These are generally smaller, as combining a powerful head and a couple large speakers can quickly push an amp into the "weightlifter" category.     {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/7\/7f\/3343-4b1.jpg\/v4-460px-3343-4b1.jpg","bigUrl":"\/images\/thumb\/7\/7f\/3343-4b1.jpg\/aid3343-v4-728px-3343-4b1.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"<div class=\"mw-parser-output\"><p>License: <a rel=\"nofollow\" class=\"external text\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">Creative Commons<\/a><br>\n<\/p><p><br \/>\n<\/p><\/div>"}  Head/cabinet arrangements solve the weight problem by separating the speaker cabinet (cabs) from the head—or amplifier—cabinet . Heads can be free-standing units that generally sit atop the cabs, or they can be rack-mounted units which are great for touring and more complex guitar signal chains.     {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/8\/81\/3343-4b2.jpg\/v4-460px-3343-4b2.jpg","bigUrl":"\/images\/thumb\/8\/81\/3343-4b2.jpg\/aid3343-v4-728px-3343-4b2.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"<div class=\"mw-parser-output\"><p>License: <a rel=\"nofollow\" class=\"external text\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">Creative Commons<\/a><br>\n<\/p><p><br \/>\n<\/p><\/div>"}