Bass amplifier
A bass amplifier is a musical instrument electronic device that uses electrical power to make lower-pitched instruments such as the bass guitar or double bass loud enough to be heard by the performers and audience. Bass amps typically consist of a preamplifier, tone controls, a power amplifier and one or more loudspeakers in a cabinet.
While bass amps share many features with the guitar amplifiers used for electric guitar, they are distinct from other types of amplification systems, due to the particular challenges associated with low-frequency sound reproduction. This distinction affects the design of the loudspeakers, the size and design of the speaker cabinet and the design of the preamplifier and amplifier. Speaker cabinets for bass amps usually incorporate larger loudspeakers or more speakers and larger cabinet sizes than those used for the amplification of other instruments. The loudspeakers themselves must also be sturdier to handle the higher power levels and they must be capable of reproducing very low pitches at high sound pressure levels.
History
1920s–1940s
The bassists who first sought methods to make their instruments louder were upright bass players. While the upright bass is a large instrument, standing about six feet tall, due to its low register it is not a loud instrument when played acoustically and because human hearing is less sensitive at low frequencies. In the 1890s and early 1900s, upright bass players performing in bars and brothels often found it difficult to be heard by the audience over louder instruments such as trumpet. A partial solution was playing slap bass style, slapping the strings against the fingerboard to make a relatively loud percussive sound.In 1933, the Audiovox Manufacturing Company was founded by Paul Tutmarc, subsequently the inventor of the first electric bass, the fretted and solid-body Audiovox Model 736 Bass Fiddle, in 1936, which was designed to be played in a guitar-like horizontal manner. The instrument was sold with the first purpose-built bass amplifier, the Audiovox Model 936. Seen largely as a novelty, the few that were sold remained in the Seattle area.
1950s–1970s
The Ampeg Bassamp Company, founded in 1949 by Everett Hull, responded to the growing demand for electric bass equipment by producing a line of bass amplifiers. The first model offered was the Super 800, an 18-watt model with a single 12" speaker and a rear ventilation port. In 1951, Ampeg introduced a 20-watt version with a 15-inch speaker. In 1960, they introduced the B-15 Portaflex, a flip-top 25-watt tube bass amplifier with a single 15" speaker. While the Portaflex had a pleasing bass tone, and was used by studio bassists such as James Jamerson and Carol Kaye, it was not powerful enough to be used in a stadium or arena concert. Ampeg amplifiers were widely used by electric bass guitarists in the 1950s and 1960s.Leo Fender resurrected the solid-body "bass guitar" in 1950 with the Fender Precision bass. Unlike the upright bass, a solid-body electric bass does not produce acoustic sound from a hollow body; while an upright bass player often benefits from using a bass amp, a bass amp is a necessity for an electric bass player.
By the late 1960s, as electric guitarists in rock bands began using powerful amplifiers to play large venues, bassists needed to keep up. The Acoustic 360 was a "200-watt, solid state head designed to drive the 361 cabinet, a rear-firing 18" speaker enclosure". The engineers who designed the amp and cabinet in 1967, Harvey Gerst and Russ Allee, mounted the 18" speaker in a folded horn enclosure; the 360 amp had a built-in fuzz bass effects unit. The Acoustic 360 and its 361 cabinet "...got the bass world ready for the Woodstocks, Altamonts and giant festival concerts" and it was used by notable players such as funk bassist Larry Graham, Led Zeppelin's bassist John Paul Jones and jazz fusion player Jaco Pastorius. John Paul Jones used two of the amp/cabs in Led Zeppelin; Dave Brown used them with Santana; John McVie played with the amp/cab in the beginning years of Fleetwood Mac. In December 1967, the loud sound of the Acoustic 360 led to The Doors getting "...arrested for noise violations".
Another 1960s-era amp and speaker that was used for loud, large venue performances was the Ampeg SVT, a 300-watt amplifier head "powered by fourteen tubes" designed to be used with an 8x10" speaker cabinet.
The Vox T-60/AC-100 bass amplifier uses two 15-inch cabinets and thirty-to-forty watts of solid-state power using "germanium transistors". The Sunn Model T was used by The Moody Blues, Kiss, Queen, The Who's John Entwistle and Rush's Geddy Lee. The Sunn used a 150-watt amp with "four 12AX7WA tubes, followed by two 12AX7A tubes, and powered by four 6L6GC tubes".
The Gallien-Krueger 800RB was a solid state bass amplifier head introduced in 1983 that was liked by bassists for its loud, clean sound and durable construction. It introduced the concept of bi-amplification, as it sent 300 watts of low register sound to the bass speakers and 100 watts to the tweeter. The GK used a tube preamp simulator circuit called "boost". GK 800RB users include Red Hot Chili Peppers bassist Flea and Guns N' Roses' Duff McKagan.
The Marshall JMP Super Bass is a 100 watt amp. Lemmy, bassist/lead singer of Motörhead, used numerous of these amps to drive cabinets with four 12" speakers and others with four 15" speakers. His amps were labelled named "Killer," "No Remorse," and "Murder One". The Peavey Mark IV is a large, solid-state amp providing 300 watts at 2 ohms; the Mark IV was known for its affordable price and its reliability.
Fender developed a bass amplifier, the Fender Bassman, first produced in 1952. This was a 26-watt tube amplifier with a single 15" speaker. In 1954, the Bassman was redesigned to use four 10" speakers. This speaker cabinet was an open-back design; as such, it had poor low-frequency efficiency and was prone to blowing speakers when used for bass because of the lack of damping. The Bassman became very popular as an electric guitar amplifier. The circuit design also underwent repeated modifications. The "5F6A" circuit introduced in 1958 is regarded as a classic amplifier design and was copied by many other manufacturers, such as Marshall.
The early rock bands of the 1960s used the PA system only for vocals. The electric guitarist and electric bassist had to produce their sound for the hall, club or other venue with their own amplifiers and speaker cabinets. As a result, bass players from the 1960s often used large, powerful amplifiers and large speaker cabinets. Some bass players would even use multiple bass amplifiers, with the signal from one bass amp being sent to one or more "slave" amps. In the mid-1960s John Entwistle was one of the first major players to make use of Marshall stacks. At a time when most bands used 50- to 100-watt amplifiers with single cabinets, Entwistle used twin stacks with new experimental prototype 200-watt amplifiers. This, in turn, also had a strong influence on the band's contemporaries at the time, with Jack Bruce of Cream and Noel Redding of the Jimi Hendrix Experience both following suit.
Entwistle also experimented throughout his career with "bi-amplification," where the higher frequencies of the bass sound are divided from the lower frequencies, with each frequency range sent to separate amplifiers and speakers. This allows for more control over the tone, because each portion of the frequency range can then be modified individually. The Versatone Pan-O-Flex amplifier used a different approach to bi-amplification, with separate amplifier sections for bass and treble but a single 12-inch speaker. The Versatone was used by well-known bassists such as Jack Casady and Carol Kaye.
Grateful Dead bassist Phil Lesh used an unusual method of bass amplification which was part of the band's 1970s
Wall of Sound PA system. The signal from each string on the bass was sent to its own amplifier
and speakers. This added a wider spatial effect to the bass and also reduced the Intermodulation distortion
between the strings.
In later years, Lesh's bass signal was so powerful that fans dubbed the area in front of his speakers the Phil Zone,
which was referenced in the band's CD Fallout from the Phil Zone.
1980s–2010s
In the 1980s the role of bass in popular and rock music evolved to become more melodic rather than simply providing a rhythmic function. The amplifier brand strongly identified with this new, 'scooped' sound was Trace Elliot. There were several features which made their amplifiers unique: the GP11 pre-amp featured 11 graphic EQ bands which were very broad bands, overlapping each other, thereby enabling massive amounts of frequency cut or boost when adjacent bands were boosted or cut. Secondly, the frequency bands were spaced closer together towards the bass end allowing even more variation for bass guitarists to alter their sound like no other amp had previously allowed. Added to this were MOSFET poweramps of 250 or 500 watts and the option of bi-amplified systems where bass and upper frequencies are filtered before being separately amplified and fed to dedicated high frequency and low frequency speaker cabinets. Trace Elliot gained a reputation for themselves; rumour has it that early users were John Paul Jones of Led Zeppelin, Andy Rourke of The Smiths and Brian Helicopter of punk band The Shapes. Mark King of Level 42 was also an early adopter of the brand. The company, now dedicated to manufacturing, moved to new premises in Witham, Essex, in 1985 to satisfy the growing demand.As PA systems improved, horn-loaded "bass bins" and subwoofers were added and were often well-equipped to amplify directly fed bass guitar and keyboard frequencies. As well, in the 1980s and 1990s, monitor systems were substantially improved, which allowed sound engineers to provide on-stage musicians with a loud, clear, and full-range reproduction of their instruments' sound.
File:The Police 02.jpg|thumb|left|alt=A bassist/singer, Sting, is shown at a performance. A number of speaker cabinets are shown onstage.|In this 2007 photo of The Police's singer-bassist Sting, several Ampeg cabinets with multiple 10" speakers can be seen on the left side.
As a result of the improvements to PA systems and monitor systems, bass players in the 2000s no longer need to have huge, powerful bass amplifier systems to play stadiums and arenas. Instead of playing with two 8x10" bass stacks and one or more huge, powerful bass heads, in the 2010s, many bass players perform at large live venues with relatively small and less powerful bass amplifiers. The reason they can do so is that most higher-priced 2010s-era bass amplifiers usually have DI output jacks that can be patched into the audio snake cable, and then plugged into the mainstage mixing board and amplified through the PA system or sound reinforcement system.
In the 2010s, virtually all of the sound reaching the audience in large venues comes from the PA system or sound reinforcement system, the huge speaker systems pointed at the audience. As well, in the 2010s on-stage instrument amplifiers are more likely to be kept at a low volume, because when band members have their onstage amps "cranked" to high volume levels on stage, this makes it harder for the audio engineer to control the sound mix and blend. For example, if a heavy metal bassist had two 8x10" cabinets and several 1x18" subwoofer cabinets and several thousand watts of bass amplifier heads, and these amps are set to a very high volume level, this bass player will be creating very significant onstage bass volume. If the sound engineer wished to turn down the bass in the PA/sound reinforcement system, this bassist's loud onstage volume would make it hard for this engineer to control and/or reduce the volume of bass in the FOH sound mix. Another issue that can develop with bass players who have very high onstage volume is that it can be hard for the audio engineer to produce a clean sound through the PA/sound reinforcement system. For example, if a bassist was driving his bass amp speaker stacks into clipping to create a fuzz bass tone, if the audio engineer wished to have a "clean" bass sound, this could pose a challenge.
As a result of requests by audio engineers to reduce onstage volume, in the 2010s, in many large venues. much of the on-stage sound reaching the musicians now comes from the monitor speakers or in-ear monitors, not from the instrument amplifiers. Stacks of huge speaker cabinets and amplifiers are still used in concerts in some genres of music, especially heavy metal, but they tend to be used more for the visual effect than for sound reproduction.
In some small to mid-size venues, such as bars and nightclubs, the PA system may not have the capacity to provide the bass sound for the venue, and the PA system may be used mainly for vocals. Bass players in bands that play at a variety of venues, including these types of small to mid-size venues, may need to be able to provide the bass sound for the venue, and so they will require a large combo amp or bass stack with this capability.