Guitar/Buying an Amplifier

Amplifiers come in a wide variety of designs and your choice of amp should be based on the type of music you wish to play. Your local guitar dealer will let you test the different amps they stock though they may only offer a small range due to space restrictions. Its always a good idea to visit many dealers including pro-audio outlets to test amps across the entire price range before committing yourself. This chapter will explain the difference between a tube amp and a solid state amp as well as exploring the variations on these two basic designs.

Tube, Solid State and Hybrid Amps

Ashdown Peacemaker 20 Tube amp

Tube

Tube amps are associated with the classic guitar sounds of the 50s, 60s, and 70s. Artists such as Jimi Hendrix, David Gilmour and Brian May have all created personally identifiable sounds with tube technology. Tube amps produce a "warm" and "fat" tone that is popular with guitarists. New models of tube amps are available from different manufacturers including Marshall, Fender and Vox as well as other manufacturers many of whom have an equal reputation for quality. Vintage tube amps are available to buy though maintaining them can be more expensive especially with regards to the cost of replacement parts. The continuing popularity of models from the 50s, 60s and 70s, like The Fender Bassman, Epiphone Valve Junior and the Marshall JMP100, has resulted in a market for reissues.

Tubes amps are sensitive to their input signal. The harder you play with your pick, the more they tend to break up and distort. The softer you strum, the warmer and breathier they appear to sound. This is known as touch sensitivity. Multiple preamp gain stages can sometimes push an amp to the point where you do not hear the pick attack on the string. Finding a balance where pick attack and sustain are clearly articulated is the sign of a superior matched preamp and power section. With a good quality tube amp, the subtle changes you make with your pick and finger pressure has a dramatic impact on the sound and is part of the process of creating your own identifiable style.

Mesa Boogie Mark IV Combo Tube amp

Within tube amplifiers, there are also three different types of operation: Class A, Class AB and Class B. However, Class B is virtually never used in guitar amplifiers and so will not be discussed.

• True Class A works by having the power tubes running at full power, regardless of actual sound output. Class A is characterized by a smoother, sweeter distortion. Most class A amplifiers use a single output tube. Thus, the wattage is generally low, as class A by itself is inefficient. Furthermore, the fact that current constantly flow into the tube will make the tube have a shorter lifespan. Due to the low efficiency, mostly only low wattage amplifier, such as Epiphone valve junior or Fender champion 600 use true class A; the typically wattage, is no higher than 5-7watt RMS per power tube.
• Class A can also use a pair or a quad of tubes for more power. A good example of this is the Orange Tiny Terror. These amps, while still Class A, have the tubes operating in opposing pairs, called Push-Pull. Typically, when the power tubes are cathode biased, they are labeled as class A.
• Class AB work by using a pair of tubes, with one always working for the "positive" voltage and another always for "negative" voltage. A good example of this is the Vox AC-30. Due to the nature, class AB is thus more efficient, and has slightly longer tube life. It also have more headroom if needed. Class AB has a different sound than Class A. Class AB, by being push-pull, has less distortion and has a cleaner tone at lower volumes. When pushed into overdrive, it will have a more abrupt transition into distortion than class A. Marshall, as well as many other high power amplifiers, use class AB. In fact, most of the famous Fender amplifiers are class AB.

Both are respectable to even the most hardcore tube enthusiast. However, most will agree that tonally, class AB is less dynamic, and thus is less suited for blues and jazz, but good for high-gain guitar styles, such as hard rock or metal.

Tube amps:

• A tube is based on vacuum technology and requires more energy than a solid state amp with the same wattage.
• Vacuum tubes are expensive and require replacement every one to four years, depending on use.
• Due to the need for a transformer on the power amp, amplifiers with tubes are generally heavier than solid state amps.
• Tube amps are usually more expensive than a solid state amplifier.
• Tubes require a warm-up period before they reach optimum performance.

Solid State

While it is debatable when solid state amps became most popular, typically it is associated with a hard rock sound. Some attribute this to the popularity of modified Marshalls in the eighties, which frequently incorporated a solid-state preamp feeding into the Marshall's tube preamp - allowing guitarists to have more gain, and deliver a more in-your-face tone and volume when overdriven. Solid-state amps also have a fast attack time, where the note is immediately present when strumming. They also have the benefit of not needing to warm up, unlike tube amps, which requires 15-30 seconds minimum to play and 30 minutes to an hour to sound their best. This means you can just plug and play.

When played cleanly, solid-state circuitry provides a powerful sound, making it very suitable for jazz or acoustic music. Solid state provides a wide-frequency reproduction, especially with large speakers that provide a full bottom and smooth high end. Examples would be Fender's Jazz-King and Steel-king and the most famous jazz amplifier, the Polytone Mini-Brute. A good quality solid-state amplifier can still provide richness, depth, warmth, color, and dynamics. Those that use FET transistors on the preamp stage are considered to reproduce all these desirable characteristics. Solid-state lends itself to guitar styles that use effects combined with the cleanness of the signal.

Solid state amps are effective because they can take very high gain, and this is used most effectively in heavy genres, especially metal; this is because that at a certain distortion level, solid state amplifier allow a lot of tight Bottom end.. Breaking from the traditional Marshall tube stacks, more and more metal musicians discover the benefits of pure solid-state amplifier, especially those with no build in modeling. Examples of such amps are the Randall Warhead and Fender MetalHead, which at high voltage provide much more gain than its tube equivalent. Basically, they emphasized upon the philosophy of "going to 11", with extreme distortion and extreme loudness. Playing this kind of ultra-high gain amps require a pair of earplug, especially at high volumes.

The most important benefit of Solid State is simple: it's smaller, lighter, and cheaper. Examples of these include Crate's CPB150, Fender's Ultralight Series, and ZT Lunchbox. All these are less than 10lb but output more than 150 clean RMS sound, and with proper pedals will sound well as a backup amp.

Solid State amps:

• The solid state amp requires less energy to power than an equivalent tube amp.
• Solid state circuitry needs minimum maintenance and there are no tubes to replace.
• The solid state amp is more robust.
• Solid state amps are available in an affordable price range.
• Solid state amps require no warm-up.

Modeling

A deviation of solid state that attempts to mimic the gain-compression on a Valve-based amp, it is basically a combination of a very clean power amplifier and a tone modeling unit producing most of the tone. Some may consider this as the Swiss-army knife of amplifier. The best of these amps can recreate the sound of many other units with acceptable accuracy and also have effects such as delay, chorus, flanger, reverb. The effects and modeled amp are patched into the correct configuration to recreate classic rigs such as a Gibson L5 being played through a Fender Twin Reverb or a Fender Stratocaster coupled with a Marshall stack. The power of modeling allows preset patches to be created that can emulate an acoustic guitar or synth. The guitarist Pat Metheney has composed and recorded with digital modeling and signal processing to produce unusual sounds and tones. For beginners cheaper modeled amps or a small emulation box like the Line 6 POD may initially be useful though if you find yourself returning to the same patch then it may be time to buy that particular combination.

There are basically three kinds: Analog circuitry, Dedicate DSP, and modeling processor (typically also have many digital effects onboard). Analog circuitry and dedicated DSP are typically the best kind, while modeling processors seems to have a bit of a lag between your pick attack and the sound produced, and you should test one carefully before buying it.

Hybrid

Another attempt to provide a valve sound with a solid-state speed is to use a Hybrid approach, which have the following configurations:

• Tube preamp coupled with a solid state power amp
• Solid state preamp coupled with a tube power amp

"Solid state" here also include modeling, be it analog or DSP.

Typically, metal players prefer the tube preamp with solid state power amp, believing that it would provide the tube tone with a fast attack. However, in numerous blind test, one cannot differentiate between a tube preamp and a solid state preamp, but it is easy to spot whether it is tube or solid state in the power amp. Thus, it was said that one that use tube preamp is no different from a normal solid state power amp, while a well made tube power amp is as good as a true tube amplifier. This is another reason why more and more metal player prefer complete a solid state amplifier with very high wattage.

When using a solid state preamp, particularly of modeling preamp, it provides the versatility of high gain sound while allowing power tube distortion that actually makes it warm and fat with compression of the sound. However, some believe without any tube preamp gain, it will be less warm compare to a true tube preamp.

In order to counteract the aforementioned deficiency, a recent trend is to include both a tube preamp and a tube power amp, and couple this with solid-state circuitry. There are two approaches to this:

• all-in-one single-tube circuitry containing both tube preamp and tube power amp, between solid-state preamp and solid state power amp. this is employed in the Vox Valvetronix system. As it typically use a dual-triode tubes, usually designed only as a preamp and not power amp purpose, it is often questionable whether this provide the necessary tube gain.
• Provide some tube preamp gain before feeding into the tube power section, with at least one triode gain stage. Example includes Line 6's Spider Valve, and Fender's Champ XD series; as both are coupled with a modeler, such scheme provide traditional tube sound while having versatility of a modeler.

Physical size

The guitarist must consider some practical considerations when buying a large guitar rig. A Marshall head and full-size cabinet when bought as separates are bulky and heavy items to transport. A full-sized Marshall cabinet has two handles, one on either side, and requires two people to lift and move it safely. Professional bands with a suitable budget will normally employ roadies for moving equipment though in the early stages most bands transport and setup their own equipment. Be aware of the added factors to do with storage and transporting when buying a large guitar rig.

Combo amps are favored by many professional guitarists due to their smaller size and matched amp and speakers. Brian May uses a Vox AC30 and many Blues guitarists like the tonal qualities of a Fender Twin; both amps are easier to transport and store than a full-sized Marshall rig. Small practice amps like the Vox DA5 or Epiphone Valve Junior are suitable for home use and recording and their size means they are easily transported and stored.

As a rule of thumb when buying it is always essential to like the sound of your rig and in this respect size is a secondary though important consideration.

Typical features of an amp

Essential

• Input - where you guitar cable goes in
• Power - turn it off and on
• Volume - adjusts the volume, and at higher levels, how much distortion
• Speaker or Speaker out - where the sound comes out. For speaker out, never plug in a speaker out port with a speaker that has different ohms than what's labeled on the jack (e.g., 4 ohm or 16ohm into 8 ohm)

An amplifier that only has these is Epiphone's Valve Junior and Fender Champion 600, both are popular budget tube amps.

Almost standard

• Gain — determines the amount of distortions. The higher it goes, the more overdrive it has.
• EQ / Tone - Used to control the tone of the sound. May have only 1 knob (simply general tone) or two (treble and bass), but some even have a 7 band EQ that not only control treble, midrange, and bass, but also other including prescene.
• Phone output — used to plug in headphones so you can practice in the middle of the night.
• Channel selection — most modern solid-state practice amp have two channels; one for a clean signal and one for overdriven output. Many of the more expensive tube amps have multiple channels as well.

Other stuff

• Additional inputs: On high-end amplifiers, there could be more than one input. Some are merely doubling the inputs, while some may have a high and low input; low is for low impedance inputs (e.g. guitars with active pick-up). One way to get a cleaner signal from tube amps is thus to plug into the "low" input; conversely, to get distortion earlier on, plug into the high input.
• Modeling - One way to solve the clipping problem in a solid state amp is the use of DSP modeling, which allows one to play tube-like overdriven sound.
• Extra effects — some units have build in effects, such as reverb and chorus, which can be easily controlled right on the panel by one or more knobs
• Effect loop — can be a single plug (and need to be split), or separate plug as "effect send" and "effect return". Used for time-based effects (delay, chorus, looping, phase shift, and flanging), as using the effect loop will preserve the sound and effect of the amp.
• Line in, 1 or 2 — used to plug in external audio sources. they come out without passing through the preamp, and thus just louder.
• Line out - used to connect to another power amplifier or PA system.
• Speaker out - connect to another guitar speaker. Typically only found in head units, but some combo units have them too to provide flexibility in speaker choice.
• Footswitch plug — allow the use of foot-switch to control internal effects, or may even select channel.
• Impedance switch (on tube amps only) - allows you to change the impedance of the speaker out jack so you can plug in speakers of different impedances.
• Standby switch (on tube amps only) - allows the tubes to warm up before turning on the high voltage required for operation. This greatly extends tube life. Also functions as a mute switch if needed.

What makes a good amp?

When you buy your amplifier, the shop owners (most who play guitar themselves) may say something along these lines:

• A tube amplifier is always better than solid state amplifier.
• Digital amp/effects are the poor man's substitute.
• A good amplifier makes all the difference in terms of artistic skill.

These are more or less true, depending on the style of music you wish to play.

A solid state amplifier can provide a good tone. In fact, many pedals that are designed to create a metallic tone are designed to use the hard-clipping functions that the solid state amps provide, one thing that tube amps cannot do well. Solid state also makes for a great budget amp, as they are often many times less expensive than an otherwise equivalent tube amplifier. Also, for styles, such as heavy metal, a solid state amplifier is better suited for the edge that these players are looking for.

However, a solid state amplifier has not yet been able to recreate the dynamic feel of a tube amp. While a solid state amp can get fairly close in tone, it's many times harder to influence the tone simply by how the guitar is played. A good tube amp will distort on command when digging into the strings, while a lighter touch cleans everything up with seemingly infinite levels in between. Where as, a solid state amp usually requires adjustments to the controls in addition to playing style to have any effect on the tone. It is also important to note that while their distortion can be suitable for metal playing, many guitarists find solid-state amps sterile and harsh sounding for comparatively lighter rock overdrive tones.

The most important thing to remember is that many of the famous artist just make do with whatever equipment they have, which often is seen as "poor quality". Nirvana used PA amplifiers as this was all they could afford at first. Many artist started out and keep on using cheap Danelectro guitars, which use plywood for body. Hendrix is said to start out with a severely battered acoustic. Thus, in the end, the players makes the tone, and the player decide whether the tone is good or not.

Digital effects are used prominently by many big name artist running solid-state amplifiers, which provide clean tones. Some say that effects are best suited for solid state amplifiers. Ultimately, what sounds right depends on the player; after all, no matter how good a equipment, a poor player will still show his poor skill, while a good skillful player can turn even the "worst" stuff into something decent.

Keep in mind that a the bigger the amp, the more the commission the salesman makes. Remember that bigger is not always better.

Size and Wattage

How big? How many watts? How many speakers? If you are just starting out, you should think carefully about where you want to go in the future with your music, and buy appropriately. As a general rule, doubling the wattage will only increase the volume by about 3db. 3db is not a large difference, however, don't forget that these 3db may make all the difference in a loud band. Multiplying the wattage by 10 (i.e., 10 watts --> 100 watts) increases the volume by 10db and is perceived as doubling the volume. Many other factors effect final volume including type and amount of speakers, as well as overall tone of the amplifier. For example, doubling the amount of speakers will result in a 3db increase. As well, a really bright sounding amplifier will cut through noise better than a dark sounding amplifier so not as much power will be needed if your amp is bright. 25 watts into a 4x12 cab will be as loud at 100 watts into a 1x12 cab. This is one reason full stacks are so loud, because 100 watts into 8 12in speakers is like 800 watts into 1 12in speaker.

Speaker configuration

Your two main options are single speaker units, and multispeaker (often 2 speaker) units. Most 2 speaker amplifiers, ranging from the smallest 50 watt combo amps to the MG15MSII "Microstack" offered by Marshall, have basically have the same amplification circuit of its single-speaker siblings. Sometimes, such 2 speakers configuration may use smaller diameter speakers than their single speaker cousin (e.g.: 2 x 10 inch instead of 1 x 12 inch).

The main benefit of having multiple speaker is that it increases volume as well as bass response without sacrificing the higher frequencies. By having more speaker cones, the speakers will move more air. For example, a 2x10 have the surface area of 157sqin, while a 1x12 only have 113sqin. A 4x10 cab is often used for large combo amplifiers as it provides most of the bass response you'd get from a 1x15, but retains the high frequency that the 1x15 can't produce. Also, it will have increase power-handling capability, or more precisely, they split the amp output. Thus, given same amplification head, a 2 speaker configuration will have louder volume, but only half the power to each speaker. This has yet another advantage.

All else being equal, generally a low power speaker is louder at the same power as a high power speaker. This is known as efficiency or sensitivity. A 25 watt speaker with a 10 watt amplifier will generally be louder than a 100 watt speaker on the same 10 watt amplifier. Thus, a multi speaker cab will allow the use of low power speakers with a high power amplifier. The original Marshall full stack used a 100 watt amplifier with 8 25 watt speakers.

Lastly, in some styles of music, such as rock and blues, the speakers sound their best when being pushed close to their max power ratings. When buying cabs for your amp, the best power rating is about 150% of your amp's rated output. 150 watt for 100 watt amp, 75 for 50, etc. Any higher and you'll actually loose volume. For harder music, pushing the speakers that hard may cause an unwanted smoothness. If money permits, buy cabs rated for 2-4 times as much as the amp.

Wattage amount

Shure SM57 and Beta57 mics

While on the surface, higher wattage means better amplifiers, in reality this isn't true. For example, many 100 watt amplifiers can be too loud when turned up high, and thus the user automatically lowers the volume and try to compensate with more gain. However, it may sound better by having a 50 watt or even 20 watt amplifier, which allows less gain but higher volume, producing the same amount of final volume. Guitar amps are a lot louder than their wattage lets on to. Some guitarists have used 5-10 watt amplifiers successfully on stage. The norm is closer to 20-50 watts. However, each amplifier has a unique tone. If volume is the only issue, consider placing a Sure SM57 mic in front of the speaker and running that through the PA. Many artists use surprisingly small amplifiers (1-5 watt) in the studio because of their more manageable sound levels.

Also, due to the way tube amplifiers and solid state amplifiers distort, there is a perceived difference in loudness, with tube sounding louder given the same wattage. The truth is that both are equally loud, but the sustain on solid state amps is not as good, which results in a perceived lose of volume. If you are gong to be in high overdrive all the time, solid state amps will actually sound louder, but often more piercing.

Another question is whether you need the louder wattage. On one hand, doubling wattage only increase 3db, which is not a lot in that case. On the other hand, in order to push the lower frequencies of the sound, wattage is important. This is because the idea of a good distortion, in general, is to have an amp that pushes as much clean bottom end into your overdriven sound as possible without getting flabby or muddy, which is what creates the hugeness of the sound. The lower in wattage that you go, the quicker your bottom end will mud out. This is not always the case.

As a rule of thumb, the amount of wattage need for Solid State amp is of follow:

• 10-30W: practice on your own.
• 30-50W: practice with a band or recording; gigging (small club)
• 50 to 100W (or more): Large Gigs (as much wattage as you ever need). Even using that 500w MetalHead amp for your blues music could be necessary.

For valves, it's a bit more complicated:

• <10W clean:, Self Practice, Recording
• <10W overdriven: Self Practice, Recording, Gigging (small club)
• 10-20W clean: Self and Band practice, Recording, Gigging (small to medium club)
• 10-20W overdriven: Band practice, Recording, Gigging (small to medium club)
• 20-30W: Band practice, Gigging
• 30-50W: Gigging
• 50W-100: Freakin loud. Please use a pair of earplugs.
• 100W+: Earthquake and noise pollution. Prepare to deal with the police.

Power Ratings

When reading an amp's rated watts (this is more the case with solid state amps), not all manufacturers adhere to a universal standard in stating the wattage. For example, an amp manufacturer may say Amp A is rated at 400 Watts. But when you go to an oscilloscope the measure its true wattage, you may find that it is only a 100 watt amp. But at several points of the sound wave it may have spiked (transients) up to 400 watts. So, the manufacturer goes with the max reading. On the other hand, more than a few 100 watt Marshalls (and other brands, I'm sure) have tested at 150 watts clean. Distortion compounds this problem. Due to the nature of distortion, tube and solid state alike, the amp might be putting out 100 watts, but the speaker sees it as 140 watts (see short explanation below). This is why it's important to buy speakers rated for more than your amplifier is rated.

RMS is .707xPeak voltage. In distortion, the sine wave becomes a square wave, resulting in a power output that is closer to the full peak voltage. A 100w RMS sine wave has peak voltage of 141.4w

Types of Unit (smallest to largest)

The combo amp is a one piece unit containing both the preamp, power amp, and the speaker(s). Typically they do not exceed more than 100 watts, as they are designed to be "relatively" portable. Most combos have just a single speaker, ranging from 6" to 15" but some have two or even four speakers. The most common is a single 12" with a pair of 12" being the next most common.

Micro/Headphone amps

Danelectro Honeytone amplifier

Micro amps usually have 1 watt, and do not exceed 10 watts. This class of amplifiers is known for its small size (no larger than a computer speaker), designed for extreme portability (such as carrying them in your guitar bag). While some may have built-in speakers, they usually cannot be heard during Jam sessions. As they are solid states and generally low wattages, if they do not utilize FET circuitry they tend to go into an unpleasant distortion very quickly. Aside from homemade solutions (such as the famous Ruby amplifier), Danelectro Honeytone and Vox amPlugs are all good choices.

DI Unit (including amp modelers)

Rockman headphone amplifier

Many "amp modelers" or "micro-amps", like the Rockman, are actually DI Unit hybrid with effect units. A DI unit transforms the unbalanced, high impedance signal from the guitar into a balanced, low impedance signal for use with a mixer; however, some desiged for use with guitar have amp modelers within them, and may have multi-effect processors for additional effects. Most often these are used with headphones, but they also allow direct input of the guitar to the mixing desk in a recording studio, while retaining some of the tone and quality of an amp. There are two kinds: analog modelers, which is most common, and digital computer modeling, such as Line6's POD 2.0.

The main benefit of using a DI unit is that they are compact, and they can get "loud enough" and have a particular tone. This is particularly true for amp modelers and "headphone amplifiers", as their embedded electronics frequently have a somewhat decent approximation of a tube amp. You can also use these in recording, or use it like a pre-amp and plug it into a larger amp for volume. Also, if you are often going to hook up to a P.A. system with your amp, these may provide a cheap option and quicker setup than a larger amp. The Behringer V-Amp 2, is a good example at less than $100 USD.

The main downfall of DI units is that they cannot completely capture the tone of a guitar amplifier. The ultimate way to connect an electric guitar to a PA is to use a microphone in front of the speaker.

Practice/Studio amps

Their wattage may range from 5 to 50, though from 30 on its hard to say whether it is purely practice alone or can also be used for small gig (see below). Generally, they are designed to be used in a small space, because the small size demands a small space for a suitable volume for practice or recording. While they come in various size, for a solid state amplifier, one should need at least a 10-inch, suitable for jam sessions. On the other hand, if you have a 5 watt tube amplifier, most people will accept your amp in a jam session.

Small gig amplifiers

From 30 watts upward, these combo amplifiers the smallest package which is considered suitable as a stand-alone amplifier for small gigs. The standard is usually 50 or more watts of power and one 12 inch speakers, though some manufactures may use less wattages of 30 and 40, while employing more than one speakers. For tube amplifiers, even a 30 watts is enough, though with better models, sound quality of solid state amplifiers begins to approach levels acceptable to professional musicians.

Quality is always important, but perhaps even more so in the case of the 1x12 inch 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. These cost about 180 to 450 USD.

While a 2x12 combo may be seen as simply an amplifier with one more speaker, the volume of air moved essentially double, and thus make it louder. Benefit of using two speaker instead of one is that it allows stereo effects. Some consider these to be the absolute minimum serious amplifier.

Busking amps

In essence, these are practice/small or gig amps that have a battery attached. Naturally, that means they are more expensive. 15 watts on average, but Pignose Hog 30 can go to 30 watts, while Vox's DA20 have 20 watts and 2x 8" speakers, and Crate's Taxi Series have some that have 50 watts with 10 inch speakers.

They will usually provide 6 to 10 hours in one charge, but also, make sure they can take AC power too when needed. Do note that they are actually quite weak in terms of overdrive. On the other hand, rock and metal music is not exactly busking music, either — soft and light music that add to the atmosphere (usually a park or something) is usually preferred, and thus, the watt are usually enough. A good one is Vox's DA series, which uses modeling processors for an approximation of a tube amp while having a small package.

Heads, Cabinets, and Stacks

Marshall amplifier without the speaker cabinets plugged in. Commonly referred to as the "head".

One of the greatest symbol in rock and metal is the stack combination basically, it was made up of the following:

• The head: Basically the amplifier without the speakers
• The cabinets: Contain the speakers in an enclosure

Due to the fact that they are always at least two pieces (even if they can be locked together), they are bulky and not really known for their mobility.

When purchasing the two, make sure of the impedance of the cabinet, and the power rating for the head at that impedance. Make sure the cabs RMS rating is about the same as the head's power output at the impedance of the cab. A head can be solid-state or tube, the latter being less durable, but sounds better and is more expensive. A good solid-state head costs 200 to 600 dollars and a good tube head costs 500 to 1400 dollars. In general, a single cab would have a 4x12 for guitar, though other arrangements, such as 1x15, a 2x12, a 4x10 or a 6x10 had also appear. A cab typically range from 250 to 650 dollars.

Low wattage

Why would someone want to make an amplifier with low wattage, which is usually 5 to 15 watts – making them practice amplifiers, but in a stack format? Some of them, such as MG15MSII by Marshall, is a mere showpiece, for people who want to own a stack but do not have space and room for one. While they may be in a stack configuration, these low wattage solid-state heads are still nothing more than a practice amp, and depending upon who you are talking to, they may even invoke an image of wannabe. Then again, Zakk Wylde uses a modified Marshall MS15MSII microstack (now available as Microstack Zakk Wylde edition) for his practice, which when played by the demo person (see it in Marshall theater), does quite well for a metal sound.

However, for many <20w tube amplifiers, such as Epiphone Valve Junior's Stack configurations and its numerous clones, such as Crate Blackheart BH5H, or the Marshall 20w Lead and Bass Head, it provides much more flexibility that cannot be provided in a combo. A hot rodded class-A tube amp– which can go up to 16 watt RMS with 2x 6v6 and proper output trnsformer, pumped out a 4x12 cabinet, can be as loud as a 50 watt solid-state amp, and thus it provides potential to upgrade in the future. Furthermore, by separating the speaker from the amplifier, customizing (hotrodding) the amp is actually easier than a combo. Since pumping sound through more speakers produces more volume but has a softer sound, it may be even better than a fully cranked 50 watt tube amp during a performance. By separating the amplifier and speaker into two pieces, it could also be easier to carry, as in the case of Orange Tiny Terror (15 watt), which comes with a shoulder bag. This is due to how human bares a load: the same piece of equipment could be very heavy or "lightweight" depending upon where (on the body) and (how) you carry it.

Serious gig

These are the types that most people talk about, with a head unit from 50 watts, that's good for a small club, to the standard 100 for large auditorium. For a small auditorium, a half stack – connected to one 4x12 speaker cabinet– is more than enough, and can still establish creditability or seriousness.

For a larger venue, or even an arena, you may run a full stack – that is, you'd have two 4x12 cabinets, one stacked upon another vertically. The size, however, is tremendous; when fully deployed they are as tall as a grown man, and even when disassembled, you will still need a van to carry them. In case the volume is not enough, you can either hook up to even more speakers, or better yet, use another stack as a slave.

Obviously, these are not really good for practice, as not only are they hard to transport, but also too loud. My neighbor received a notice for turning his half stack a bit too high, and I start to get uncomfortable on volume above 2.

One that is good is the Crate's PowerBlock, which is as small as a DI unit, but is actually a 150watt RMS pure solid-state goodness. Plug in any FX you want, and you will have a perfect companion for your guitar.

Unless you need extreme loudness, you probably won't need these 200+ watts amplifiers. On the other hand, that 550watt Fender MetalHead is definitely tempting, and so is the Randall Warhead (300 watts). Oh well, if you want metal, you can always just go for the Warhead Combo configuration.

It is recommended that players always wear earplugs when playing a full stack. Tinnitus can develop from long periods of exposure to loud sounds with Pete Townsend being a notable sufferer and an example of the lack of awareness about the dangers of wearing no ear protection during the early days of stadium rock. Earplugs and accessories are available from reputable dealers and manufacturers.

Head and cabinet match up

As mentioned before, a speaker out will have a certain acceptable impedance. For solid state amps, you should only plug in speakers that have the same impedance, even though larger amount of impedance is also somewhat acceptable (e.g.: a 8ohm plug can only accept 8ohm or 16 ohm) Plugging in a speaker with lower impedance will very likely burn your amp.

Tube amps are much more sensitive to speaker impedance. Any mismatch between the speaker impedance and the impedance set on the amp will cause higher strain on the output tubes and transformer. It is more acceptable to plug in a speaker of lower impedance, however, the opposite of what you can do with solid state amps. A higher speaker impedance might be ok as far as it is no more than twice than the one set on the amp. NEVER TURN ON A TUBE AMP WITH NO SPEAKER CONNECTED. This might cause severe damage to the output transformer. Always turn off your tube amp before disconnecting the speaker. Some amps have shorting jacks (e.g. Hiwatts), these may allow you to change speakers on the fly, but always at the amp side of the cable, never at the speaker side. Furthermore,having more speaker only increasing the volume somewhat; using a 5w to push a 4x12 cab will be slightly louder than 1x12, you can push more watt through such cab, and you'll have a broader tone, with the sound thicker and fuller. Hower, to actually increase the volume, you do need more wattage.

No amp here!

Marshall cabinets

One of the iconic images of heavy rock and metal is a "Wall of Marshall" standing behind the entertainer. However, chances are that only 4 of these speakers (a double stack) are real, if at all. Some artists may even use amp modelers in secret. Brian May, for example, uses only 6 Vox AC30s even though he has a "Wall of Vox"

Rack-Mounted Products

Rack mount units are the ideal setup for live arena playing. Rack mounted units gives the player maximum control of the tone and the ability to access different effects patches during a live performane. These units are mounted in standard 19-inch rack. The fact they each unit is a dedicated separate component allows the guitarist a high degree of flexibility in regards to tone and the order in which the units are chained.

A typical rackmounted setup would consist of a pre-amp unit, equalizer, speaker/cabinet simulators, power amplifiers, power unit and effects. Additional units such as tuners and MIDI switchers can be added. The routing options are more complex than those of a standard stack setup allowing the guitarist to draw upon a vast range of sounds either in stereo or mono.

Quite commonly, these are all controlled by a MIDI pedal, plugged into the MIDI switcher.

Tips

• Visit the manufacturer's site for information and then compare their description to forum or online reviews by independent sources. Comparison allows a more balanced view to be formed especially with regards to the quality of on-board effects and the general performance of the amp.
• Buy the best amp that you can afford stretching your budget to the limit of what you personally consider expensive.