A resonator guitar, also called a resophonic guitar or commonly known as a "Dobro," is an acoustic guitar that makes sound by sending string vibrations through the bridge to one or more metal cones (called resonators) instead of to the guitar's soundboard (top). These guitars were created to be louder than regular acoustic guitars, which struggled to be heard over horns and drums in dance bands. Over time, they became popular for their unique sound and were used in bluegrass music and the blues, even after electric amplification made loud volume possible.

Resonator guitars come in two main styles:

There are three main types of resonator designs:

Many different versions of these styles and designs have been made by various brands. The body of a resonator guitar can be made from wood, metal, or other materials. Usually, there are two main sound holes, placed on either side of the fingerboard extension. In single-cone models, both sound holes are either round or shaped like an "f" and are the same on both sides. The older tricone design has sound holes with irregular shapes. Some models with cutaway bodies may have one sound hole or none on the lower side.

History

John Dopyera, responding to a request from steel guitar player George Beauchamp, created the resonator guitar to make an instrument loud enough to compete with brass and reed instruments. Dopyera tested different designs, including up to four resonator cones made from various metals.

In 1927, Dopyera and Beauchamp started the National String Instrument Corporation to make resonator guitars under the "National" brand. The first models had metal bodies and used three conical aluminum resonators connected by a T-shaped aluminum bar that supported the bridge, a system called the tricone. National also made wooden-bodied tricone models in Los Angeles, California, called Triolians, but only produced 12 of them. Later, they changed the tricone body design to single-cone models but kept the name.

In 1928, Dopyera left National to form the Dobro Manufacturing Company with his brothers Rudy, Emile, Robert, and Louis. The name "Dobro" came from "Dopyera Brothers" and means "good" in their native Slovak language. Dobro released a resonator guitar with one cone shaped like a bowl, covered by a circular metal plate with a bridge in the center. This design was cheaper to make and louder than National’s tricone.

Over time, the word "dobro" became a common term for any resonator guitar. National responded by making its own single-resonator model, which Dopyera had designed before leaving the company. Both National and Dobro continued producing tricone models, which many players preferred for their sound. Both companies used parts from Adolph Rickenbacker, including aluminum resonators.

After legal battles, the Dopyera brothers took control of National and Dobro in 1932 and merged them into the "National Dobro Corporation." However, they stopped making resonator guitars after the U.S. entered World War II in 1941.

Emile Dopyera (also known as Ed Dopera) made Dobros from 1959 before selling the company and trademark to Semie Moseley, who later combined it with his Mosrite guitar company. In 1967, Rudy and Emile Dopyera formed the Original Musical Instrument Company (OMI) to make resonator guitars, first branded Hound Dog. They later regained the Dobro trademark when Mosrite went out of business temporarily.

In 1993, the Gibson Guitar Corporation bought OMI and claimed exclusive use of the Dobro trademark. As of 2006, Gibson made several resonator guitars under the Dobro name, including models with round or square necks.

After forming the National Dobro Corporation, the term "National" was often used to describe instruments with non-inverted cones, different from the inverted-cone Dobro. This term was especially used for single-cone biscuit designs, as tricone models were expensive and not widely produced. Players and collectors also used "National" to refer to older tricone instruments, which some preferred despite being softer and rarer.

In 1942, the National Dobro Corporation changed its name to Valco and later made many fretted instruments under the National brand. By the 1960s, Valco produced resonator guitars again under the National name, using wood and fiberglass.

In the late 1980s, National Reso-Phonic Guitars was formed to make traditional resonator guitars, focusing on recreating the sound and feel of older models. The company also makes 12-string guitars, ukuleles, and mandolins.

Casa Del Vecchio Ltda. in São Paulo, Brazil, started making guitars and string instruments in 1902. In the 1930s, they began making resonator guitars, including their famous model called the Dinâmico. They also made Dinâmico cavaquinhos (a type of small resonator ukulele) and resonator mandolins. They continue to make standard acoustic instruments and Hawaiian-style lap steel guitars.

In the late 1990s, Amistar, a Czech Republic company, started selling tricone resonator guitars.

Wayne Acoustic Guitars made spider bridge resonator guitars in Australia during the 1940s and 1950s. These guitars used cheap Australian wood and a tone ring instead of a tone well. They lacked neck reinforcement and used a pressed cone, often called a "pillow cone." Many of these guitars remain today. As of 2010, Don Morrison made resonators under the Donmo brand.

Asian companies like Regal, Johnson, Recording King, Republic Guitars, and Rogue also make or import many affordable resonator guitars. Johnson also makes resonator ukuleles and mandolins.

A company called Gallotone in South Africa produced resonator guitars in the 1950s and 1960s.

Playing

Resonator guitars are commonly used in bluegrass music and blues. Bluegrass musicians traditionally used square-necked Dobro-style instruments, played like steel guitars. Blues musicians often preferred round-necked National-style guitars, which were frequently played with a bottleneck.

The resonator guitar is most often played as a lap steel guitar. The square-necked version is typically used only in this playing position. Square-necked instruments are set up with high string height, which is preferred by steel guitar players. They are also tuned to an open tuning that works well for this style.

The round-necked version can be played in either the lap steel position or the Spanish guitar position. It can be set up with different string heights, ranging from a half-inch (which makes it hard to use the frets) to a very small fraction of an inch (used by traditional guitar players). A middle ground is often chosen, allowing the use of a bottleneck on the top strings while still using the frets when playing in the conventional position.

Many different tunings are used. Some tunings that work well for square-necked guitars are not recommended for round-necked resonator guitars because they require high string tension, which needs the stronger square neck. Slack-key guitar tunings are best for bottleneck playing. The standard E-A-D-G-B-E tuning is also widely used.

Players

The resonator guitar was introduced to bluegrass music by Josh Graves in the mid-1950s. He played with Flatt and Scruggs. Graves used the fast, rhythmic three-finger picking method created by Earl Scruggs for the five-string banjo. Modern players often use this style, except for Tut Taylor, who used a flat pick.

In bluegrass music, the resonator guitar is usually tuned to an open G, with strings set to D G D G B D or G B D G B D, from the lowest to highest string. Sometimes, other tunings like open D (D A D F# A D) are used.

Other well-known bluegrass players include Jerry Douglas, Mike Auldridge, Rob Ickes, Phil Leadbetter, Andy Hall, and Sally Van Meter.

The resonator guitar was used in older country music, such as by Bashful Brother Oswald in Roy Acuff’s band. However, it was mostly replaced by the pedal steel guitar in the 1950s. Despite this, the instrument is still often used instead of the steel guitar. James Burton and Grady Martin played the resonator guitar with a flat pick on many recordings. Leon McAuliffe first played a dobro before switching to electric lap and console steel guitars.

The resonator guitar is also important in blues music, especially the Southern style of country blues from the Mississippi Delta and Louisiana. Unlike bluegrass and country players, most blues musicians hold the resonator guitar in the standard guitar position. Many use slide guitar techniques with metal slides.

In the 1920s and 1930s, players like Bo Carter, Bukka White, Son House, Tampa Red, and Blind Boy Fuller used resonator guitars because they were louder than regular acoustic guitars. This allowed them to play for bigger audiences in places without electricity for amplifiers. Street musicians, such as Arvella Gray, also used resonator guitars while busking, for example, on Chicago’s Maxwell Street.

One of the few Delta Blues players who used the lap style in the 1930s was Black Ace, also known as B.K. Turner. He toured and recorded with his mentor, Oscar "Buddy" Woods, who also played the lap-style resonator guitar and lap steel guitar. Woods, who was fifteen years older than Ace, taught him his guitar techniques.

Today, some blues musicians still use the resonator guitar, including Taj Mahal, Eric Sardinas, Alvin Hart, The Deacon Brandon Reeves, Warren Haynes, Derek Trucks, Doyle Bramhall II, Roland Chadwick, John Hammond Jr., Roy Rogers, John Mooney, and Megan Lovell of Larkin Poe. Mark Knopfler has also played the instrument, and his National resonator guitar is shown on the cover of the Dire Straits album Brothers in Arms.

Varieties

Single resonator guitars with a bowl-shaped resonator and spider (Dobro style) are often used in bluegrass music. Tricone (National style) guitars are still favored by many blues musicians. Single-resonator biscuit (also called National style) guitars are also made and produce a different sound.

Bluegrass players often choose wooden bodies, while blues players may use either metal or wooden bodies. Early metal-bodied guitars were usually of higher quality than early wooden-bodied ones, but this may not be true for newer models. Metal bodies can be made of brass, aluminum, or steel. Fiberglass is also used for guitar bodies. Both metal and wooden bodies are often painted, or wooden bodies may be stained or coated with lacquer. Metal bodies may be plated or left plain.

Bluegrass players usually play guitars with square necks, while blues players often prefer round necks. Square-necked guitars allow for a bit more variety in tuning, while round-necked guitars offer more options for playing positions.

Single-resonator guitars can have round sound holes with screens or without screens. Some players remove the screens to improve the bass sound. They can also have f-holes, often with gauze screens. These screens help strengthen the guitar's body, especially if the body is made of wood.

Many different combinations of features are possible. These can be found on both old and new instruments, and many types of music can be played on any resonator guitar.

Although resonator guitars were originally designed to increase volume, some modern models include electric pickups and other technology. Many makers produce guitars with various types of pickups, and some players add pickups to non-electric guitars. Most resonator guitars use piezoelectric pickups (contact sensors) placed under the bridge or on the instrument, or specialized microphones placed inside the guitar or near the resonator to keep the unique sound.

However, all acoustic and semi-acoustic resonator guitars are very sensitive to feedback, so the design and placement of pickups must be carefully planned. Some modern models include both piezoelectric and magnetic pickups. Some piezoelectric pickups are active, meaning they have a preamplifier to boost the signal for amplifiers. Recently, solid-body electric resonator guitars have been made. These guitars use magnetic pickups and are played through amplifiers.

Other resonator instruments

Resonators are also found on the following instruments:

• Basses made by Regal
• Ukuleles (see Resonator ukulele), made by National and Dobro between 1928 and 1940
• Banjos
• Tenor guitars
• Mandolins and mandolas
• Mountain/Appalachian dulcimers
• Viola guitars

Brands

Historic brands of resonator guitar still in use today include National, Dobro, and Regal. None of these brands are owned by their original companies. Each brand returned to production after one or more long breaks in manufacturing:

• The National name is now used by National Reso-Phonic Guitars, a company founded in 1987. This company is not related to the original National. It makes reproductions of historic instruments from many brands, not only National-style instruments.
• The Dobro name has changed ownership several times throughout history. Since 1993, Gibson Guitar Corporation has owned Dobro. Gibson produced Dobro-branded instruments through its Epiphone division until 2020. No Dobro-branded instruments have been made since then.
• The Regal name has been bought and sold multiple times since its original owners stopped operating. Since 1987, Regal has been a brand of Saga Musical Instruments.

• #1,741,453 covering the tricone.
• #1,896,484 covering the Dobro.
• #1,808,756 covering the biscuit single cone resonator, registered in the name of Beauchamp.