Dobro

Dobro® is a trade name used mainly for guitars. The name was originally used by the Dopyera brothers and is now owned by Gibson Guitar Corporation.

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In common usage, however, the term "dobro" has come to refer to any acoustic guitar with a metal resonator set into the body (also known as resonator guitars or resophonic guitars). The bridge of a resophonic guitar over which the strings pass is attached to a metal resonator which produces and amplifies the sound; the body of the guitar does not play a significant role in sound amplification.

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The name came into being when John Dopyera and his brothers ("Dobro" also means "good" in their native Slavic language) left the National company (which they had helped co-found in 1927) to strike out on their own in 1929. While trying to make a louder instrument John had pioneered a mechanical amplification system consisting of three small spun-aluminum cones (similar in shape and size to modern 6" loudspeakers) which he had perfected and patented as the National "tricone" system (U.S. patent #1,741,453). While primarily used in guitars, the system was also used to amplify ukuleles, mandolins, and tenor and plectrum guitars.

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The cost of manufacturing tricones was very high, pricing the instruments out of the reach of many players. In an effort to produce more affordable instruments, a single-cone design was developed. Sadly, while John Dopyera always claimed that this single cone was his invention, it was patented by George D. Beauchamp, one of National's directors (U.S. patent #1,808,756), so John and his brothers left to found their own company which they called Dobro.

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Since National held the patent on the single cone, the Dopyera brothers had to develop an alternative design, which they did by inverting the cone so that rather than having the strings rest on the apex of the cone as per the National method, they rested on a cast aluminum "spider" which had 8 legs sitting on the perimeter of the upside down cone (US patent #1,896,484). Both Dobro and National built a wide variety of metal- and wood-bodied single-cone guitars until World War II halted production.

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Thus both National and Dobro brand guitars of the prewar years shared a common inventor, but their mechanical amplification systems were different. Actually, resonator guitars can be grouped into three major sets: National tricones, National single cones and Dobros. National and Dobro merged in 1934, bringing the Dopyeras and their resonator guitars full-circle.

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The first picture here is of a guitar fitted with a Dobro style cone. The last one is actually of single cone National guitar.

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Many more of these instruments are pictured at notecannons.com.

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As can be seen from the ukulele advert below, the model name was the price. So some instruments, while remaining unchanged physically, were sold over several years and therefore actually have catalogue model numbers that get progressively larger as time went by and their prices went up! This makes it nearly impossible to identify most instruments, although the higher the model number (price) the more ornate the instrument would have been as a rule of thumb.

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Towards the middle-to-late 1930s Dobro licensed most, if not all, of their instrument building to Regal in Chicago. Regal, beside making instruments incorporating the "Dobro amplifier" under the Dobro brand, also made them with Regal, Old Kraftsman, and Ward brands, to name but a few.

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In this sense, the resonator guitar is actually more akin to a banjo with its resonating skin than a guitar, and the tonal quality of the resonator guitar reflects this. The original intent was to produce a louder sound that could compete with the rest of the band, but because the electric guitar was developed around the same time, resonator guitars never became widely popular. (In another ironic twist, Beauchamp — who had helped found National with John Dopyera and was forced out prior to the merger with Dobro — worked with Adolph Rickenbacher, whose company had made metal guitar bodies for National, in developing some of the earliest production electric guitars.)

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Modern resonator guitars are typically played with a steel bar or slide, rather than by fretting the strings with the fingers. The instrument is also sometimes refered to as a "Hawaiian guitar". Resonator guitars come in either a "squareneck" (or "bluegrass") style, or "roundneck" variety, more often used in blues music. The squareneck has strings which are raised a centimeter or more over the fingerboard. The playing position of this type of resonator guitar is with the instrument held turned on its back with the strings facing up.

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Trade name: A trade name, also known as a trading name or a business name, is the legal name of a business, or the name which a business trades under for commercial purposes....

Guitar: The guitar is a stringed musical instrument. It is generally played with the fingers of the left hand. The right hand plucks the strings with either the fingers or a plectrum, (guitar pick). The sound is produced by vibrating strings, which in turn resonate the body and neck....

Gibson Guitar Corporation: The Gibson Guitar Corporation, of Nashville, Tennessee, USA, is a manufacturer of acoustic and electric guitars. Gibson also owns and makes guitars under such brands as Epiphone, Kramer, Valley Arts, Tobias, Steinberger, and Kalamazoo. In addition to guitars, the company makes pianos through its Ba...