5 Characteristics to Look for When Buying an Amp

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5 Characteristics to Look for When Buying an Amp

Amplifiers take sound that has been converted to an electrical current, boost its power and make it possible to instantly re-play it at a much higher volume. Amplifiers are part of stereo systems and karaoke kits, but the type of amplifier that this article focuses on is used to increase the volume of the sound from a musical instrument.

Musicians who play electric instruments depend on an amplifier to produce their basic sound. Many musicians who play acoustic instruments rely on their amp to produce the sound that the audience hears at every gig. Buying the right amplifier is almost as important to the way a musician sounds as their instrument, which is always chosen very, very carefully. Here are five factors that every musician should consider before buying a particular amplifier.

1. The Right Kind of Amp

Many instrument amplifiers are designed with electric guitars in mind, and they can plug directly into a port on the guitar. The frequencies of sound that they can amplify cleanly and accurately correspond to a standard guitar's range. Guitar-based musical groups are the most common type of band and they almost always have at least one, sometimes two or more, standard electric guitars.

However, bands also have electric bass guitars and electric keyboards. There are amplifiers designed to work well with the bass's lower range, and those amplifiers are a good choice for a bass player. There are also amplifiers designed specifically to work with electric keyboards.

Increasingly, popular bands are incorporating instruments other than guitars, basses, and drums, and classical, jazz, and folk groups sometimes use amplifiers, as well. Look for an acoustic amp for acoustic guitars, fiddles, and classical or jazz instruments. Remember that acoustic instruments will also need microphones.

2. The Right Technology

It is possible to purchase new and used amplifiers that were manufactured at various times in musical and technological history. That means that a variety of technologies are available at affordable prices. The two most important to know about are vacuum tube, or valve, amps, and solid state amps.

Vacuum tube amps have a warm sound and distort the sound at high volumes in a way that many people like. They were the first type of amplifiers developed and mass-marketed to musicians, and they have a classic sound. Solid state amplifiers were introduced later, and they have a cleaner sound that is more faithful to the un-amplified sound of the instrument. However, some musicians feel that the sound of solid state amps lacks character.

Today's most advanced amplifiers can be adjusted to sound like classic vacuum tube amplifiers or like clean, clear solid state amplifiers. Some use multiple, layered technologies and some allow real-time digital manipulation of the sound. However, many musicians looking for a signature sound still prefer a straightforward, classic amp. The best way to choose an amp will always be to try it out and see how it sounds with a specific instrument and musical style.

3. The Right Amount of Power

The power of an amplifier is expressed in watts. In general, an amp with a lower power rating will begin to sound distorted at lower volumes. The maximum volume where the amp can create a clear, clean sound increases in a logarithmic curve. As a rule of thumb, the wattage must be multiplied by ten in order to double the volume. A one watt amp is approximately half as loud as a ten watt amplifier, and a 100 watt amp is roughly twice as loud as a 10 watt amp. In general, amps up to 10 watts are used for practising, 15 to 30 watts amps are good for rehearsing with a band or playing a small venue, and amps of 50 amps or more are needed for larger gigs.

Another thing to be aware of is that tube amplifiers are more powerful than solid state amps. In fact, a tube amp at the same power rating might be twice as loud as the corresponding solid state amp. Speaker sensitivity and the number of speakers used with the amp also affects the sound volume. Finally, it is possible to tone down high powered amps with volume controls and power attenuators. It is important to be aware that these controls can affect the amp's sound quality. A more powerful amp is not always a better choice, as it can be challenging to quiet it down without sacrificing the character of the sound.

4: Effects

Many modern amplifiers come with a variety of effects such as reverb, delay and wah-wah. These effects can change the instrument's tone, timing, pitch, volume, and modulation. Below are descriptions of what some of the common effects are and what they sound like.

Tone effects

Tone effects like wah-wah pedals and equalisers change the volume of various frequencies to change the character of the sound.

Distortion effects

Distortion effects like overdrive and fuzz mimic the sound of an overdriven amp.

Timing effects

Timing effects like reverb and delay change the timing of the output to produce dramatic results.

Pitch effects

Pitch effects like pitch bend pedals, harmonisers, pitch shifters, and octavers change the pitch of the instrument or layer on changes in pitch.

Volume effects

Volume effects like noise gates, limiters, compressors and volume controls affect the general loudness, dynamic contrast, and noise level in the signal.

Modulation effects

Modulation effects such as chorus, phaser, flanger, panning, tremolo and vibrato vary the frequency, volume, or output of the sound in a characteristic pattern.

Although a wide variety of effects can open up creative possibilities, they are only worth having if the tone quality of the amplifier is not sacrificed. The learning curve on effects can be steep, and it is a good idea to be comfortable with and in control of the basics before experimenting with effects.

5: Size, Shape, and Portability

Most amplifiers used in gigs are suitcase-sized or larger, and many are heavy as well. However, mid-sized and mini-amps are also available for small venues and for practising at home or on the road.

When choosing an amplifier, think about where it will be used and about how it will be transported. For example, choose a mini-amp that will fit into an existing backpack or gig bag. Choose full-sized amps that can be carried along with the instruments and that will neatly fit into the vehicle that is used to transport the equipment to gigs. It seems like a trivial thing to consider and usually it will not be a deciding factor in the purchase, but it is a good thing to verify fit and portability before buying.

It is also good to be aware that some amps include a speaker and others do not. Using a variety of speaker configurations with the same amp can provide greater flexibility, but it may be more expensive and less convenient than having an all-in-one package.

Buying an Amp on eBay

On eBay, amplifiers can be found in under the All Categories list, under Musical Instruments. From the Musical Instrument category, proceed to Pro Audio Equipment, to Amplifiers and finally to Instrument Amplifiers . Under Instrument Amplifiers, use the search box to find guitar amps, bass amps, keyboard amps or acoustic amps. Scroll to the bottom of the left hand column to limit the search to the local area.


When buying an amplifier, always remember that it will be part of the group's standard equipment and that it will have a huge effect on the way the instrument sounds to the audience. Before buying, remember to consider the type of instrument or instruments it will amplify, the relationship between the musical style and the amplifier technology, the features that are needed or may be needed in the future, the amount of power that may be required and the size, shape and weight of the amplifier and how that will affect portability.

Reverb is a popular ambience type effect pedal that produces an echo of the sound. Reverb is generally used to add depth to the sound and imbue it with some ambient character. Reverb is difficult to use in real-world venues as they usually have some echo-producing properties of their own. 'Voodoo Child' by Jimi Hendrix used reverb in combination with wah-wah pedals. Many guitar amps also include in-built reverb effects.

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