Amplifiers are an essential device in the production of music, both for professional musicians and for those who are just getting started into the music scene or who play as a hobby. Amplifiers allow instrument players to draw on a wide range of sound effects, with the advantage of not having to buy separate pedals to that purpose. This makes amps convenient devices in terms of portability and functionality.
About Musical Amplifiers
An amplifier is a device used with musical instruments that do not have speakers or that require an external source of sound. In addition to producing a louder sound output, amplifiers can also be used to modify the sound of certain musical instruments and to add extra effects to their sound, or to remove unwanted sound effects, like distortions or high frequencies. Although amplifiers are commonly used with electric or acoustic guitars and with many string instruments (such as bass), other musical instruments that can benefit from an amp device are keyboards, syntethisers, harmonicas, and harps. Amplifiers are also used by sound or recording engineers to modify or remix existing recordings. Lastly, amplifiers that have an integrated headphone jack allow players to practise with their musical instrument of choice without disturbing others.
The first guitar amplifier was created in the beginning of the 1930s by a Texan guitarrist and inventor called George Beauchamp. The first amplifier worked as a guitar pickup that transformed the vibrations of guitar strings into an electrical current, and its functioning was based on the same principles used to design record players or electric generators. The invention of amplifiers and of electric guitars came hand in hand, and as electric guitars gained in popularity from the 1940s onwards, so did amplifiers. However, it was not until 1949 that the first guitar amp as we know them today was invented. The creator was Leo Fender, who designed an amplifier with the 50-watt output that has become so common among musicians today.
Basic Components of Musical Amplifiers
In addition to the wooden box or cabinet in which amplifiers are housed, there are three main components that make up an amplifier. These are:
- The Grill - The grill covers the front of the amplifier and protects the speakers, which are located immediately behind. Amp grills are made of cloth.
- The Electronic Amplifier - This is the main component of a musical amp and consists of an electrical circuit that magnifies voice or any other audio signal through a series of complex energy conversions.
- The Speakers - The size of amp speakers is measured in inches. Usually, amp speakers range between 3 and 15 inches, depending on whether they have been built for practice only or for full studio performance.
Types of Amplifier Available on the Market
Musical amps can be classified into three main types: practice amplifiers, combo amplifiers, and head amplifiers. As their name suggests, practice amplifiers are suitable for quiet practice only. As such, they are characterised by a low watt output, usually in the range of 10 to 20 watts. Practice amps also come equipped with speakers, but these are small in size (usually ranging between 3 and 8 inches). The limited watt output and speaker size of practice amps means that they can only handle basic sounds, but cannot be used to create or remove sound effects like distortion or audio gain. On the other hand, practice amps have some clear benefits, which include portability and a generally lower price.
Combo amplifiers, also known as combination amps, consist of a rectangular shaped box which integrates the electronic circuit that amplifies sound and the speakers in the same unit. One of the key characteristics of combo amps is their audio input jack, which allows users to plug in a guitar or other musical instruments. In addition to the audio input jack, some combo amplifiers are also equipped with secondary speaker jacks, RCA connectors, and / or FX send and return jacks. These allow players to connect additional speakers or portable audio devices (like CD players) to the amp, and to connect additional sound effects, pedals, etc. Some types of combo amps are suitable for playing in small or medium sized venues, and these feature a line out jack that can be connected to the venue's PA system. There is a wide variety of watt output in combo amps, which ranges betweeen 10 to 350 watts. Practice amps are one type of combo amplifier.
Unlike combo amplifiers, head amps consist of an amplifier head, or circuit, that is connected to the speakers through external cabling. A key charateristic of head amps is that they are stackable over one or various cabinets so that the intensity, wattage, and volume of the sound output can be adapted to the specific requirements of a venue. Head amps also come equipped with a microphone jack or three-pinned connector. As a general rule of thumb, the more power a player needs, the more suitable head amps will be.
Choosing Between Solid-State and Vacuum Tube Amplifiers
There is another consideration that must be taken into account when buying an amplifier. Musical amplifiers can be divided into four types, depending on their sound output and the technology involved in their design. Solid state amps use analogue technology, which results in a clean sound, free of distortion, compression, and other sound effects. It could be said that solid-state amplifiers deliver sound in a raw state.
On the other hand, vacuum tube amps (also called valve amplifiers) consist of several glass tubes or valves, which produce a warmer sound effect than in the case of solid state amplifiers. Some tube amps are equipped with a dual setting that allows users to switch between warm and raw sounds, so tube amps are preferred by many players due to their versatility. Another feature of tube amps is their generally louder volume output, even when compared to solid state amps of equal wattage. Tube amps were the first type of musical amps ever invented, so their design makes them bulkier and heavier than solid state devices. The internal glass tubes are very fragile and may not be suitable for players who need to be very mobile.
Modeling amps (sometimes called digital amplifiers) are the modern equivalent of tube amplifiers, but they use digital technology to produce an extensive range of sound effects, including phase, distortion, chorus, reverb, delay, and many other digital tone effects. Their digital capabilities mean that modeling amps can be programmed to incorporate certain effects at specific times. This type of amplifier can assist in the production of all musical styles, as they combine the best features of solid state and tube amps. Modeling amps are generally a good choice for beginners, as they are affordable and not too limited in their range of settings.
Lastly, there are hybrid amplifiers, which can be considered another type of modelling amp without the digital component, as they combine the advantages of both tube and solid state design. Hybrid amps tend to be cheaper than tube amplifiers, while being capable of delivering warm sounds and other enriching sound effects. Some of the most popular hybrid amps include the Marshall Valvestate.
Additional Considerations when Buying a Musical Amplifier
Apart from technological design issues, there are other factors that need to be considered in order to choose the most suitable musical amplifier. Some of these factors include:
Frame or Cabinet Design
Amps are basically wooden cabinets fitted with speakers and an electronic circuit. It is worth noting that the relative thickness or thinness of the wood used can have an effect on the quality of sound produced. It is recommended to look for amps with a minimum thickness of one-half inches, since going for anything thinner may result in the speakers becoming loose as an effect of continued vibration. Another element of cabinet design is open vs closed back. Closed back amps have a less complex and more directional overall sound, while open back amps sound more airy and are more commonly used in small venues.
Speaker Size / Power Output Combination
Larger speakers do not necessarily produce better sound. The most common amp speaker size is 12 inches, as they have a better balance of elements like dispersion, harmony, and tone complexity than some 15-inch speakers. Practice amps have a lower speaker size-output combination, but for other purposes, a 50-watt/12-inch speaker amp will be sufficient.
Finding Amplifiers on eBay
There is a wide range of amps available on eBay. Click on the All Categories link on the left hand side of eBay's homepage. Scroll down to Musical Instruments and click on the Pro Audio Equipment link. On the left hand side of the page, under categories, there is an Amplifiers section. The search results can be further refined by brand, amplifier type, condition, power output, and price.
Buying musical amplifiers online is a convenient option that can save time and money. When using eBay to find an amp, always ensure that the seller has positive feedback and that the amp's specifications are suitable in order to enjoy a hassle-free shopping experience.