Combo amplifier

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Case amplifiers from the US manufacturer Fender belong - along with devices from other brands - to the early combo amplifiers that were successfully mass-produced commercially. The picture shows a Fender Deluxe, built in 1953, in the textile covering of the wooden amplifier housing, which is typical of the manufacturer's devices at the time, known as tweed

The combo amplifier , in professional circles also shortened to the Combo , in German and trunk amplifier called, is a combination of devices of an electrical audio amplifier with one or more loudspeakers in a usually box-shaped housing made of wood , fiber board , composite materials or plastic . Combo amps have been made since the late 1920s. They are used as a compact solution for sound reinforcement purposes for amplifying the signal from musical instruments with electrical pickups . These include the electrical instruments electronic piano , pedal steel guitar , electric guitar and electric bass, as well as acoustic plucked instruments such as acoustic guitars and mandolins , provided they are equipped with pickups. Depending on the model and in combination with one or more microphones , combo amplifiers can also be used to amplify audio signals from any acoustic musical instruments and to amplify the voice. Some of the early devices had connections for both electrically amplified musical instruments and microphones.

history

Two Magnatone brand combos from 1953 (front) and 1957 (rear). On the right edge of the image distortion - effects pedal type Big Muff

Combos were the first electrically powered amplifiers for musical instruments. The design was developed in the USA and has existed since the late 1920s. The first series-produced combo amplifier was the Tone Amplifier, launched in 1928 , developed for the musical instrument manufacturer Stromberg-Voisinet (later renamed Kay Guitars ) in Chicago . This radio speaker combo was used in combination with a contact pickup that could be attached to the ceiling of an acoustic guitar or to the bridge of a banjo .

At the beginning of the 1930s, other companies also began serial production of instrument amplifiers. The US musical instrument manufacturers Rickenbacker (from 1932), National Guitars, Dobro and Gibson (from 1935) were among the first to offer combos . Usually these case amplifiers were offered together with a guitar. One example is the Rickenbacker Frying Pan lap steel guitar , which was priced at $ 175 with amplifier in 1933. Three years later the Gibson company brought their first “Spanish” electric guitar model, the Gibson ES-150 archtop guitar together with a guitar amplifier for US $ 150. The device had an output of 15  watts , had a 10-inch loudspeaker and was advertised by Gibson as a “High Fidelity Ultrasonic Reproducer” .

The circuits of the amplifier unit in the first combo amplifiers corresponded to those of tube radios , but without their high-frequency components. All of these devices had only a few watts of output power. For about 35 years since their invention, combos have been the only available format for instrumentation amps. Since then, the combo design has established itself as a widespread type of guitar amplifier.

Equipment and forms of construction

A combination of preamplifier and power amplifier as well as at least one loudspeaker is integrated in the combo housing . The purpose of the compact design is often to improve the transportability through lower weight and smaller dimensions than with multi-part devices in stack design ( English : stack ). Many combo amplifiers have a handle attached to the top of the housing for easy transport - hence the name case amplifier . Some of the first combos from the 1930s also looked like a small suitcase with a built-in speaker. However, with increasing demands on the performance and resilience of the devices, combos were developed in later decades which, due to their equipment with several larger speakers and / or with a particularly stable housing construction, are so heavy that the compact design loses its advantages. In individual cases, combo amplifiers can weigh more than 40 kg.

The half-open back of a combo amplifier with exposed, hanging-mounted electron tubes and speakers

The rear of the housing plays an important role in shaping the sound of combo amplification. Devices with a closed back radiate the sound pressure of the loudspeakers in a more concentrated manner towards the front, and the low frequencies of the sound are emphasized more, whereas combos with an open or half-open back also radiate the sound pressure to the rear, which creates a more spatial and treble-rich sound. The open and half-open design date back to the early days of combos in the 1930s to 1950s, when many musicians (especially guitarists , for example in big bands ) sat behind their combo amplifier during stage performances . The purpose of the open case back was that they could hear their own playing on the instrument better. A combo housing that is open to the rear also offers some additional storage space for its power cable and small instrument accessories and the like when transporting the device. One of the most important manufacturers of combo amplifiers with half-open back panels is the US company Fender . The loudspeakers in combos are mostly high-performance woofers, in many devices with a diameter of around 25 cm (10  inches ) or 30 cm (12 inches) and with a hard-mounted membrane .

The combination of preamplifier and power amplifier in combos is produced in different versions. The oldest and most widespread design until the 1960s is the tubular construction . This combo design can have the disadvantage compared to devices in multi-part stack form that exposed electron tubes are directly exposed to the vibrations generated by the sound of the loudspeakers. The service life of the tubes, which are sensitive to vibrations, can be shortened as a result, and the vibrations can cause undesirable background noises during operation, such as a "thump" of the power amplifier tubes. Since around the mid-1960s, combos have also been manufactured in transistor construction, later also in hybrid construction (amplifier preamp with tubes, power amplifier with transistors). Modern digital combo amplifiers are able to reproduce the sound of several other models ( emulation ).

A special form of combo amplifiers are small devices for home use such as this Danelectro HoneyTone in a plastic housing, which has been built since the 1990s . The “ retro ” -style design alludes to the shape of the first combo amplifiers from the 1930s

Regulator and connections

The control of the sound and volume of the devices is usually carried out using several rotary controls ( potentiometers ) on the amplifier unit. The knobs of the potentiometers are grouped on the top or on the front of the combo in a control panel that is labeled with the functions of the knobs. Depending on the size and features of the device, these are controls for input sensitivity and volume , single or multi-band tone controls for frequency processing ( equalizer ) and, if necessary, controls for integrated sound effects such as reverb , echo and others. Sockets for 6.35 mm jack plugs are usually used as connectors for instruments or microphones to be connected - but also mostly three-pin (mono) or five-pin (stereo) sockets for DIN plugs , especially with older European devices . Some combo amplifiers also have the option of routing the audio signal via cables to external loudspeakers and / or to an audio mixer . Some combo amplifiers for home use also have a connection socket for audio playback devices (such as portable CD players and MP3 players ) and an output for headphones . The amplifier component of most combos is powered by an integrated power supply unit with mains power, but there are also small models that can be operated with an external power supply unit and, alternatively, with batteries - for example, to be used for street music and the like outdoors. The smallest combo models whose front about the size of a DIN A6 - postcard has been able to, are mostly operated with batteries and are best suited for relatively quiet practicing on the musical instrument.

Three combos on stage, each with a microphone. A Fender device on the left and in the middle, and a VOX AC30 amp on the right

Performance capacities of combos

The requirements and demands on the nominal power of combo amplifiers differ according to their purpose - size of the room to be covered, number of listeners, desired volume, music style. The offer on the market ranges from small devices with a few watts of power - for practicing on a musical instrument and for home use - to medium-sized devices with medium power, which are suitable for audio monitoring in recording studios and for live demonstrations , for example to powerful models that can be suitable for the sound reinforcement of larger rooms with a large audience. Combo amplifiers are hardly suitable for high-quality sound coverage in very large rooms and crowds; here the combo loudspeakers are usually microphones (see photo on the right), and the audio signal is directed to the audience via a much larger public address system (PA) . In such cases, combo amplifiers are usually counted as part of the backline , the stage sound system used by musicians. The recommendations and views regarding the required power reserves of combo amplifiers in different situations vary greatly depending on individual experience and needs.

A Roland Jazz Chorus Combo with two speakers, each 12 "in diameter. The 28 kg heavy device is mounted on castors for easier transport

Combo models and manufacturers

Early case amplifiers made in Germany appeared since the early 1950s under the brands Dynacord , Echolette , Hohner and Schaller , among others . Since the 1960s, the international market has been dominated by models from the USA and Great Britain ; since the 1970s also from devices from Japanese manufacturers. The companies Glockenklang and Warwick are currently well-known companies of German origin when it comes to combo amplifiers for electric bass. The best-known and widespread models of combo amplifiers include the American Fender Bassman (which, however, was also built in a two-piece stack form; at that time also known as Piggyback - " piggyback ") and a few other Fender models, the British VOX AC30 and the Japanese Roland Jazz Chorus JC-120 . Other well-known series of combo models are manufactured by Marshall , Mesa / Boogie , Laney , Line 6 , Ampeg and others.

literature

  • Tony Bacon, Dave Hunter: Totally Guitar - the Definitive Guide , Guitar Encyclopedia. Therein: Chapter Amplification , pp. 42-53. Backbeat Books, London 2004. ISBN 1-871547-81-4
  • Guitar Basics - Everything Guitarists Need to Know! In it: Chapter Combos & Tops, pp. 98–105. Press Projekt Verlag, Bergkirchen 2003. ISSN  1430-9769
  • Helmuth Lemme: Guitar amplifier sound . Pflaum Verlag, Munich 1995. ISBN 3-7905-0717-2
  • Carlo May: Vintage guitars and their stories . Therein: Chapter Since the transistor looks into the tube - A look into the history of guitar amplifiers, p. 96 ff. MM-Musik-Media-Verlag, Ulm 1994. ISBN 3-927954-10-1
  • Udo Pipper: Amp Station - Bedroom Amps . Series of articles in the guitar & bass journal on the subject of combo amplifiers for home use, starting with issue 1 / January 2010. MM-Musik-Media-Verlag, Ulm. ISSN  0934-7674

Web links

Individual evidence

  1. ↑ a b c May: Vintage guitars and their stories, p. 97
  2. ↑ George Gruhn & Walter Carter: Electric Guitars and Basses, p. 6 f. Presse Projekt Verlag, Bergkirchen 1999. ISBN 3-932275-04-7
  3. ↑ Thomas Kosche: Wire up the sound so that they can hear you playing! - Article in: Electric Guitars ; Special issue of the magazine Guitar & Bass on the history of the electric guitar, p. 43. MM-Musik-Media-Verlag, Ulm 2004. ISSN  0934-7674
  4. ↑ Lemme: Guitar Amplifier Sound, p. 14
  5. ↑ Guitar Voodoo Guide - The Lexicon for the Guitarist, p. 48. Press Projekt Verlag, Bergkirchen 2006. ISSN  1430-9769
  6. ↑ May: Vintage Guitars and Their Stories, pp. 98–99: Illustrations of several early combo amplifiers
  7. ↑ Guitar Basics - Everything Guitarists Need to Know! P. 99
  8. ^ Ebo Wagner: Mesa / Boogie - Royal Atlantic RA-100 . Test report on a combo guitar amplifier in: Guitar & Bass, issue 6 / June 2011, p. 152 ff. MM-Musik-Media-Verlag, Ulm. ISSN  0934-7674
  9. ↑ Bacon / Hunter: Totally Guitar , p. 49
  10. ↑ Guitar Basics - Everything Guitarists Need to Know! P. 108
  11. ↑ a b Lemme: Guitar Amplifier Sound, p. 21
  12. ↑ Udo Pipper: Amp-Station - FAQs on Fender amps, in: Guitar & Bass, Issue 9 / September 2016, p. 153. MM-Musik-Media-Verlag, Ulm. ISSN  0934-7674
  13. ↑ Guitar Basics - Everything Guitarists Need to Know! P. 127
  14. ↑ Guitar Basics - Everything Guitarists Need to Know! P. 129
  15. ↑ Udo Pipper: Amp Station - Bedroom Amps, in: Guitar & Bass, issue 1 / January 2010, p. 230 ff.
  16. ↑ Guitar Basics - Everything Guitarists Need to Know! P. 104