As the acoustic guitar became popular in the early 20th century, players needed ways to increase the volume of their instruments so they could be heard when playing with other musicians in large performance spaces. In the mid-1920s, John Dopyera developed an amplifying system, which he used when he founded the National String Instrument Corporation in August 1926 with his brothers Rudy, Robert, Louis, and Emil. Their company would use Dopyera's system to produce “ampliphonic” or “self-amplifying” guitars, known today as resonator guitars. John received a patent for his design on December 31, 1929.
More-advanced designs soon followed, including one which utilized a single aluminum cone to turn the entire guitar into a speaker cabinet. The guitar strings sat on a thin wooden saddle (or “biscuit”) at the peak of the volcano-like aluminum cone. The biscuit transferred the vibrations of the strings to the speaker cone, which would then resonate, thus amplifying the sound.
John, however, did not think that this single-cone design was well-suited for guitars, since they were so much larger than ukuleles. In frustration, he resigned from National in February 1929 to found Dobro Manufacturing; he derived the name “Dobro” from the first letters of Dopyera Brothers. Dobro modified National’s biscuit design by flipping the cone upside-down and connecting the broad base to the strings with a four- or eight-armed “spider”; unlike the biscuit, the spider conducted the vibrations from the strings directly to the edges of the speaker cone, allowing the cone to vibrate freely.
In addition to the cones, Dobro bodies featured sound holes between the resonator and the neck; in every model except Model 35, which featured segmented F-holes, these sound holes were circular and resembled the portholes of a ship. Because of its overall design, Dobro resonator guitars had longer sustain than single-cone Nationals of the same period.
In fact, the sound of these vintage Dobro guitars much more closely resembled that of the tri-cone or tri-plate National resonators, which, as their name suggests, had three resonator cones, rather than just one. Each resonator cone was six inches across, and the three were arranged in a triangle with two on the bass side and one on the treble side of the body. The three peaks of the cones were connected with a T-shaped bridge topped with a wooden saddle, which allowed all three cones to vibrate in unison, thus amplifying the sound.
As with nearly all resonator guitar designs, these cones were hidden under a sound plate, which were sometimes engraved for artistic effect. Because the vibrations had to travel farther from the bridge to three cones than in single-cone designs, tri-cone guitars were not as loud as single-cone guitars, but they boasted longer sustain and a sweeter tone.
Dobro and National merged in 1935 to form National-Dobro, but by the late 1930s resonator guitars had become less popular, as electric archtops and steel lap guitars became more accepted. National-Dobro made its last resonator guitars in 1940 0r '41. The company continued to sell a few models into 1942, when National-Dobro reorganized as Valco under Vic Smith, Al Frost, and Louis Dopyera...
Today, collectors can find resonator guitars under a variety of brand names besides National, Dobro, and National-Dobro. For example, Dobro built instruments which other distributors like Ward, for Montgomery Ward, sold under their own brands. In 1932, Dobro granted a Chicago-based company named Regal a license to manufacture guitars with a Dobro resonator, and in 1966 Mosrite purchased Dobro and began to produce resonator guitars under the brand Replica 66.
Dobro and National themselves produced a wide array of models and styles, but unlike Martins and Fenders, vintage Dobro guitars are a headache to date with much accuracy. For many years, Dobro model numbers corresponded to prices in the Dobro catalog. As a result, the same guitar could be listed under different model numbers in different years, and multiple designs could be listed under the same model.
Model 45, for example, simply meant that the guitar cost $45. By far the most collectible Dobro, however, is Model 206, only three of which are known to exist today. The instrument's design featured gold-plated and engraved hardware, with a gold sparkle in the center of the body. Most Dobro models were more modest, especially with the onset of the Great Depression.
National manufactured a variety of models in both the single-cone and tri-cone styles. Some of these models featured wood bodies, while others were metal with nickel-plating. These nickel-plated National guitars are extremely collectible for both their excellent sound and their dazzling look—those with round necks allowed different techniques than those with square necks, which are most desirable.
Single-cone National models included the Triolian, Duolian, Style O, and Style N; tri-cone models included Styles 1, 2, 3, and 4. Style 1 was simpler, while Styles 2, 3, and 4 featured intricate engravings and decoration. Style 4, for example, boasted Art Deco-style geometric shapes, surrounded by a chrysanthemum design credited to George Beauchamp, one of the original incorporators of National in 1928. Players today differ over whether they prefer the sharper, louder sound of the single-cone models or the softer, sweeter tone of the tri-cone guitars.
In contrast with Dobro guitars, Nationals have serial numbers that can be easily tied to a year of production. These numbers are generally found either on top of the headstock, on the body by the end of the tailpiece, or on the back of the bridge.
Best of the Web (“Hall of Fame”)
Vintage Guitars Info
Vintage Guitar and Bass
Clubs & Associations
Other Great Reference Sites
Most watched eBay auctions
Recent News: Resonator Guitars
Source: Google News
Listening Room celebrates year anniversarySouthwest Virginia Today, July 28th
After receiving that high praise, Ireland picked up his resonator guitar and started writing and performing again. His live performance schedule began in 2007 at Mason Dixon and at Piano's in New York City, also at Musica in Hudson, New York. In...Read more
John Cee Stannard & Blues HorizonMusic News, July 28th
'Poverty Blues' sees John Cee playing an Ozark resonator guitar with massive backing featuring double bass and electric guitar from Mike Baker – this one was inspired by a BBC documentary about the middle class Americans who had lost their jobs after ...Read more
News Briefs: Delmonico Insurance Agency moving into new Syracuse officeAuburn Citizen, July 27th
The band specializes in close two- and three-part harmony with solid instrumental backup and features Shirley Stevens as singer/guitarist, Ed VanCott on mandolin, Dick DeNeve on resonator guitar, Karen Campolieto on bass, Chuck Simmons on lead guitar, ...Read more
Nitty Gritty Dirt Band Plays Ryman Auditorium Sept. 14Cybergrass Bluegrass Music News, July 27th
With instrumental greats Sam Bush on mandolin, Jerry Douglas on resonator guitar, and Byron House on bass. With contributions from Country Music Hall of Famer Vince Gill, Nashville Songwriters Hall of Famers John Prine and Rodney Crowell, legendary ...Read more
Bluegrass, Beef and Corn Festival returns to Baudette Aug. 1Walker Pilot Independent, July 27th
Porcupine Creek consists of six teenagers: Jacob is on banjo; Ben plays the flattop acoustic guitar; sister Dulcie Ashworth plays fiddle; Derek is on mandolin; Sarah Birkeland plays bass; and Holger Olesen is on the resonator guitar. Their debut live...Read more
GHS Strings Introduces the Americana SeriesPremier Guitar, July 27th
The Americana strings are suitable for a wide range of instruments including acoustic guitars, banjos, mandolins, pedal steel guitars and resonator guitars. The series has been developed drawing on GHS' decades of knowledge in string design and ...Read more
Classic Rockers Who Might Actually Make Good Country RecordsWide Open Country, July 26th
holds her own on the ballads. And let's be honest, Benatar led the movement that paved the way for strong solo female acts like Miranda Lambert. But mostly, just imagine how beautiful “Love Is A Battlefield” would be with some resonator guitars and...Read more
New name, same great showAustin Herald, July 26th
In addition to Marty himself on the electrified Resonator guitar and vocals, the band features native Austinian Chris Lynch on the fiddle, Jeff Kissell on upright bass, and Matt Goff on the drums. All three have been said to possess “raw musical...Read more