How to Choose a Guitar Amp (part 2)

An overview of the technology inside of guitar amps

In the previous part of this series on choosing a guitar amp, we discussed the pieces in an amplification chain to help better educate the guitar player when going to buy his or her first guitar amp, or for an intermediate player, when looking to upgrade to a more significant guitar amp set-up. In this second part, we will discuss the common ways that guitar amp systems are “stacked” or housed, and review the 4 different technologies available in the “guts” of a guitar amp system.

The 3 or 4 parts of the guitar amp system can be combined in 1 box or shell, and this configuration is called a combo or combination amp. This is the most common amp one would see, where the pre-amp / processor, power amp and speaker are all combined in one convenient box called a “cabinet” (see diagrams below). Most beginner and intermediate players, and many medium size gig playing professionals will own a combo amp and can be served quite well with just a combination amp, from practicing at low volume levels in an apartment room to playing to a few hundred people in a small performance venue. Some small to medium combo amps can serve a moderate professional player in a recording studio, and can also be “miked” into a PA system for playing to larger audiences as with a band in a performance or solo gig.

The preamp / processor in a combo amp is inside the same cabinet as the power amp and speaker, but sometimes the preamp / processor is in a separate box our housing referred to as the preamp cabinet or more accurately the “amp head”. When you see a speaker in a single cabinet, with a separate small box on top containing the pre-amp / processor (amp head), this is also referred to as a “half-stack”, because it has only 1 speaker and 1 amp head.

amplifier-stacks

A full stack contains at least 3 separate boxes or compartments divided as the “amp head” on top of 2 speaker “cabinets”. In larger concerts serving large audiences, you will often see this combination, although the amp head is often hidden or controlled by the sound engineer /technician and all the audience sees are the large speaker cabinets.

In terms of “watts” this is a basic rating for the amount of power output capabilities for the speakers. A 10 Watt amp is very small and is good for practice and a small room, or recording. A 15 to 20 watt amp can be used for practice as well, if turned down, and can be “miked” to a PA system for medium sized crowds. It would be best to start with at least a 20W amp, because a person might be disappointed with a 10 or 15W amp once they begin playing small venues or want a larger sound.

The Fender Champion 20 is an example of a combo or combination amp (all in 1 cabinet), and is great for both practice and small gigs. It has several EQ knobs including 2 effects for digital amp modeling and tube effects simulation as well for a variety of sound styles. It is recommended for beginners and intermediate players who do not need to perform for large crowds, and want a lot of options for a modest budget around $100. This amp could also be “miked” and balanced into a PA system for a larger crowd if necessary.

Most guitar player needs are met with a combination amp, and unless you are going to be a serious touring professional or recording professional, you can do quite well with a 20W, combo amp for between $100 and $300. Just get familiar with the technology combinations and listen to different examples to make sure the amp has the effects and amp modeling you desire.

 

The “Guts” of the amp – it’s what’s inside that counts!

Essentially, there are 4 kinds of amps you can buy when dividing them into categories based on their “guts” or inner technology.

The inner workings of an amplifier can consist of tubes (think old tv tube technology), solid state technology (think LEDs), digital processors, and hybrids or combinations.   Combination (hybrids) in this reference has nothing to do with the number of cabinets as described above, but has to do with having more than 1 technology inside the amp itself. Most amps that amateur guitar players use are combination amps or all solid state and digital combinations. Many professionals use combination amps and also desire higher end tube amps for classic electric guitar sounds that are hard to model perfectly with solid state and digital technologies.

Tube amps are the original amp technology which gave us the classic guitar sounds of the 50s, 60s and some of the 70s including early rock and roll, British crunch sounds, and classic warm blues and jazz sounds. Tube amps are great in that they can give a robust, warm sound that cannot quite be matched by digital modeling or solid state, although they come close. Tube amps are of often the choice of professional players because of the robust warmth and “fatness” or “creaminess” or “buttery” quality of sound for certain genres of music, although many pros will use combination amps to give them access to more diverse sound modeling available at various volume levels.

The cons of owning a tube amp are that they generally cost more, weigh more, and have higher maintenance issues because the tubes wear out and need replaced. Tube amps also need a bit of time to warm up before they can deliver the full sound, and they cannot create full distortion and thickness of classic tube sounds at low volumes because volume is the only way to saturate pure tube amps and create distortion. They have to be cranked up a bit in order to get that classic, rich tube distortion sound.

In other words, with tube amps, distortion is usually less achievable at lower volume levels, and this is one of the advantages that solid state and digital pre-amp technology has over tube amps, although some professionals would rather have the pure, classic, warm and fat sounds provided by a tube amp.

A great example of a very popular classic style tube amp is the Peavey Classic 30/112 Tube Combo Amp Tweed – these sell for about $700 and are called a combination amp because they are all in 1 cabinet, but use all classic tube technology for the sound shaping and distortion effects.

You can easily identify many tube amps when looking under the pre-amp controls or dials inside the cabinet, you will see what look like small light-bulbs. These are the tubes that use electron flow and magnetic field to alter or shape the flow or signal originated from the guitar strings, thereby affecting the signal and the sound. Tube amps usually have fewer effects / controls or output options, and you can easily pay twice as much for a tube amp that is comparable to a solid state amp of the same size and watts or power output.

After tube technology came solid state technology (beginning in the 1970s) which replaced most tubes with processors (computer chips), transistors and LEDs (light emitting diodes). Think of an LED light versus an older incandescent light with a filament, or think about how most heavy Cathode Ray Tube televisions have been made obsolete by lighter, high definition LED television technology. The technology is very similar, although it is configured to shape and amplify sound versus images.

Many of the upsides of solid state amps are that they are lighter in weight, they’re generally more durable, require less maintenance and are more resistant to environmental changes for performance setups. They are also cheaper and can offer more options on a lower budget.

Most low to mid-priced guitar amps use solid state technology or a combination of a tube for pre-amp shaping and solid state technology for the power amp, and some add digital processing for effects modeling to replicate new sound effects as well as old tube amp modeling. Modeling is simply a term whereby digital technology and solid state technology work together to create a sound similar to classic tube amp models from earlier decades. Therefore, whenever you hear the term “modeling” in amp technology, this is referring to using digital processors to replicate sounds created by other analog tube amp models and configurations.

Digital amps / processors can be included in amplifiers these days, and can also be used in effects pedals and effects processors that are often in an amp head or stack set up outside of the amp. Many combo amps use all 3 technologies as well to try to deliver the best of all worlds in amp technology, sound shaping, modeling and effects. Essentially, digital amps / processors use software and processing chips to digitally model sounds produced by classic tubes and other solid state sounds. They are also often programmable so you can alter and save your own combinations or combine your preferences to model / fabricate similar sound shaping from classic tubes including complete classic amps as well as individual controls like distortion, reverb, delay, chorus, tremolo, vibrato and other effects.

The fourth kind of amp technology is called hybrid or combination technology, which is seen in the majority of middle and lower budget market amps today. By using a combination of tubes, solid state and digital technology, one can have access to quite an incredible variety of sounds in 1 amp ranging from soft ballads, to 60s crunch sound, to country twang, classic blues, jazz and heavy metal.

Many of these combination amps or hybrids today have a tube amp for the pre-amp, and use solid state technology for the power amp, instead of all tubes. By combining tubes with solid state and digital, one can still access the warmth of a tube amp at lower volume / gain levels, but can also over-drive the solid state technology or use digital modeling at very low volume levels to be able to get some massive distortion at low volume levels, as well as including a much wider variety of sound shaping options.

With only tubes, one cannot access full distortion at low volume levels because distortion requires that the signal is “clipped” or essentially turned up too high for the technology to handle or process. The peaks of the wave of the signal are too high to be processed, giving the distortion or edgy clipped sound signals that can be modified to create all kinds of distortion. You can distort or clip signals at low volume levels with solid state or model it easily with digital effects processing because these do not require that a tube is “saturated” by turning the volume or gain all the way up. Tube distortion is often described with terms like warm, full, rich, buttery, creamy and even dirty. Solid state distortion is often described with terms like clean, crisp, and sometimes thin or edgy.

In the third and final part of this series, we’ll talk about testing an amp and cover some of the different effects to help you make the most informed decision when you decide to buy an amp.

 

 About the author: Aaron Schulman is an avid music composer, guitar player and enthusiast who has helped many people learn more about guitars and amps to help them make a more informed decision when buying. He publishes thorough acoustic guitar reviews on his site, Strumviews.com, about guitars in different budget ranges, including his pick for best acoustic guitar under 500 dollars.

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