For example, the serial number 90237XXX corresponds to a production date of 1/23/97. The last three (or four as of 2005) digits signify the location of production and batch number, respectively, but this information isn’t necessary to accurately dating your instrument. Outside Appraisals. The serial number of an acoustic guitar may be on the back or on the label in the sound hole. The guitar's serial number also may give you a clue to its value. Generally speaking, a lower serial number (for example, '0001') indicates an older guitar that will be worth more than one with a higher serial number (for example, '0987').

• Dobro Serial Number List
• Dobro Serial Number Dating
• Guitar Serial Number Dating
• Dobro Serial Number On Headstock

The National String Instrument Corporation was formed to manufacture the first resonator guitars, known as resophonic guitars. National also produced resonator ukuleles and mandolins. The company was originally formed by John Dopyera, the luthier who invented the resonator, and musician George Beauchamp, a steel guitar player who had suggested to Dopyera the need for a guitar loud enough to play a melody over brass and other wind instruments.

Serialization of Dobro instruments is far less tangled, but there are different forms of the numbers to contend with. Dobro serial numbers should always be used in conjunction with other identifying features for dating pur- poses. Thanks Prof; took off the resonator and sure enough the label's serial No. I'm supposing that means it's the 33rd off the line but I'm still looking for the year.

In Los Angeles, the early 1920’s was quickly becoming the entertainment capital of the world. In this era, many guitarists sought instruments that could complete in volume with other instruments in the orchestra. Guitars were un-amplified string instruments in those days and were relegated to just adding to the rhythm section. It was not loud enough to be a lead instrument. Many frustrated guitar players that wished they could be compete with brass and reed instruments like the banjo did, but sound sweet like an acoustic guitar.

Musician and vaudeville promoter George Beauchamp, sought a louder, improved guitar to play at his gigs. Several inventors had already tried to build louder stringed instruments by adding megaphone-like amplifying horns to them. Beauchamp saw one of these and went looking for someone to build him one. John Dopyera, a violin repairman with a shop fairly close to Beauchamp’s Los Angeles home was asked to innovate and build a guitar that was louder and better than when was already available.

In 1908, the Dopyeras emigrated from Slovakia to California, USA sensing a war would erupt in Europe. In the 1920s, Dopyera founded his own store in Los Angeles where he worked making and repairing fiddles, banjos, and other wooden string instruments. Around this time, Dopyera patented several improvements on the banjo. John Dopyera was one of 10 siblings.

John Dopyera, a Slovak-American took up the challenge. Dopyera was already a recognized inventor that had several patents for various ideas. Some were for improved Banjos, that Dopyera and his brother Rudy were building in the small shop. Beauchamp wanted his own idea built that featured an Hawaiian guitar that sat on a stand; a Victrola horn attached to the bottom and pointed towards the audience. The Dopyera’s did not think much of the idea, but built it for George Beauchamp as requested. It was a failure as it did not sound great.

John Dopyera had been thinking about resonator guitar for some time, so the Dopyeras then started experiments with thin, cone-like aluminum resonators attached to a guitar bridge and placed inside a metal body. The early prototype utilized a large aluminum single-cone resonator, but working through the issues John Dopyera found that using three smaller cones produced a smoother more balanced guitar sound. They called this the tri-cone resonator, sometimes referred to a triplate.

John Dopyera had experienced with several prototypes using from one to four resonator cones. He found that as one cone was a bit louder, three produced a nicer musical tone. He had also tried several materials including paper, pressed fibre, glass, tin and other sheet metal to make the resonant cones. Thin Aluminum that looked like a loudspeaker worked he best. He used a cast aluminum bridge and an inserted wood saddle as he saw it transmitted the sound from the strings to the resonator cones best.

Beauchamp, impressed with the tri-cone design, suggested forming a manufacturing company with the Dopyeras, who had already started making the tri-cone guitars in their small workshop. The Dopyeras called these guitars Nationals, the same name they used on their Banjos. They probably made about 40 or more guitars before a factory was established.

Beauchamp, trying to find investors, took the tri-cone prototype and the Sol Hoopii Trio (a world-famous Hawaiian group) to a lavish party held by his millionaire cousin-in-law, Ted Kleinmeyer. Sol Hoopii was a top steel guitar player and was being paid $500 to entertain the guests. The guests were mesmerized by the sound of the new tai-cone in the hands of Sol Hoopii. Kleinmeyer was so excited about the guitar and the prospects for a new company that he gave Beauchamp a check for $12,500 that night. That was quite a lot of money in the 1920s.

National Tri-cone

In 1927, National produced the first resonator instruments and sold under their new National brand. They had metal bodies and a tri-cone resonator system, with three aluminium cones joined by a T-shaped aluminium spider. Production of the metal-body guitars began almost immediately. Beauchamp, acting as general manager, hired some of the most experienced and competent craftsmen he could find, including several members of his own family and the Dopyeras. They were quite popular in the days before electric guitars, but were relatively time consuming and expensive to manufacture. Many of these guitars are quite ornate and engraved with scenes like palm trees. Art-Deco meets superior and innovative design that made guitars louder in the era before electric guitars. Nationals not only sounded great they looked fantastic.

Sol Hoopii was the first musician known to record using a National Tri-cone. He was a top Hawaiian steel guitar player.

Tampa Red was the first African-American Blues player to record with a National. He developed a clean bottleneck style on his gold-plated style 4 Tri-cone. With three resonator cones in this model, he hits us with a lot of single-string sweet sustain.

The National line of metal-bodied resonator instruments are the most uniquely American guitars ever made. These louder, shiny instruments were built to satisfy the need for a louder guitar for jazz bands and recording. They were intended for use by Hawaiians and white dance orchestra guitarists, but wound up in the hands of black blues performers, white hillbilly performers jazz and various ethnic guitarists. National made nickel silver, Hawaiian guitars, mandolins, tenor guitars, and ukuleles. Their design shows a strong Art Deco influence, very modernistic, and a true blending of art and industry.

The new tri-cone was a huge hit for the new National Company. A Chicago Musical Instrument Company, one of the country’s largest distributors, ad from December 1927 boasted that the National Silver Guitars were fastest selling items since the Saxophone. The tri-cone were being sold as Hawaiian and Spanish style guitars and later Tenor models arrived.

National’s partners decided to form a corporation and issue stock to raise more capital. The Dopyera brothers sold the trademarked National name to the corporation in exchange for common stock. The members of the organization were Ted Kleinmeyer, George Beauchamp, John Dopyera, Paul Barth, and Murray Ferguson. The first Board of Directors meeting was on February 29th, 1928.

The new factory and purchased equipment was located near Adolph Rickenbacher’s tool and die shop. Rickenbacker (later known as Rickenbacker), was a Swiss born and highly skilled production engineer with experience in a wide variety of manufacturing technique (also a relative of WWI flying ace Eddie Rickenbacker). Beauchamp was first introduced to Rickenbacker by Ted Kleinmeyer. Rickenbacker owned one of the largest deep-drawing presses on the West Coast. Rickenbacker was also a good businessman and had invested in National. Soon National asked him to help manufacture metal bodies for the National guitars. Later, Rickenbacker had the title of engineer in the National Company in 1930 catalog.

By 1928, business was booming at National with every major steel guitar artists playing a tri-cone. Almost an overnight success. Wild parties and big spending followed, that did not look kindly by John Dopyera. The freewheeling spending and excesses pained him.

Unfortunately, internal disputes within the National company that were present from the very beginning, boiled over. One big dispute between George Beauchamp and John Dopyera was over a single-cone resonator. Beauchamp wanted them as they would be less expensive am a bit louder, but the perfectionist inside Dopyera had yet to find one that pleased his ear. This was already after a few failed attempts Beauchamp had with some of his other ideas, like a Bakelite (early plastic) neck. Dopyera felt lots of money was wasted on crazy unfounded ideas already by Beauchamp.

So by late 1928, the Dopyeras became very disgruntled with the management of the company and what they perceived was the wasting of resources. Probably the last straw for John Dopyera was he found out that Beauchamp claimed the patent for the single-cone resonator for himself.

Dopyera and Beauchamp lived in different worlds and apparently were at odds on every level of personal, business and social interaction. Dopyera was a frugal inventor that was very health conscious, while Beauchamp was more or an entertainment type that was free wheeling and liked to party. They found that they could not work together successfully. Another problem was Ted Kleinmeyer, who had inherited a million dollars at 21 and was trying to spend it all before turning 30 (when he would inherit another million). A Roaring ’20s party animal, successful losing money faster than he could make it, he started hounding Beauchamp for cash advances from National’s till. Beauchamp did not know how to handle him, creating a huge strain on the company.

John Dopyera, quit National in January 1929 assigning his stock interest to Ted Kleinmeyer. Basically, he signed away his patent rights in disgust and planned his next venture.

National also sold resonator Mandolins, Ukuleles and 4-string Tenor guitars based on resophonic technology. This was mechanical amplification before electric guitars were readily available.

The resophonic guitar reined supreme in the late 1920s and into the late 1930s. First played by Jazz players in dance halls because they were louder than a standard guitar. Later picked up by Hawaiian and Blues musicians because of the expressive nature and dynamics resonator guitars have.

National saw business slow during the depression years, but orders kept coming which is not easy as they were selling a luxury item. Recreation and entertainment were both great escapes from the economical realities people were experiencing. National guitars likely survived for the same reasons the movie industry stayed successful. Even Sears Roebuck distributed Nationals, even dictating some cost saving production changes as using less screws and fewer coats of lacquer be used.

Dobro

John Dopyera quit National and formed the Dobro Corporation with four of his brothers. The name was based on Dopyera Brothers. DOBRO has five letters for the five Dopyera brothers – John, Rudy, Emil, Louis and Robert. Plus the word Dobro which means “good” in Slovak.

The Dobro Manufacturing Company produced a competing single resonator design, with the resonator cone inverted. The Dobro design was both cheaper to produce and louder than the tri-cone. He innovated the the inverted single resonator cone with a spider bridge, named because it had eight legs. Beauchamp had went ahead and patented the original Dopyera single-cone resonator prototype in his own name. The new Dobro design was both cheaper to produce and louder than the tri-cone. Some feel it is not as well balanced, but became part of its appeal. John Dopyera had confidence in his new design.

John Dopyera once called the Dobro resonator his second good design. Since he had to leave his patents with National when leaving the company he needed to come up with a new resonator design. Dopyera felt this new invented design as better. National had soon introduced their own single resonator design, the biscuit, which is the one John Dopyera claimed to have designed before leaving National, though the patent was now registered by Beauchamp. National also continued to produce tri-cone designs, which some players preferred. The single-cone resonator were cheaper to build, therefore allowed for a less expensive resophonic guitar.

John Dopyera fearing Beauchamp and National would try to claim credit, registered the new resonator patent for Dobro in his brother Rudy’s name. The Dobro was made with a wooden body as Dopyera could not afford to purchase the machinery for metal body guitar making.

National Single-Cone Patent

This triggered a war between National and Dobro. Beauchamp was fighting and telling customers that Dobro was infringing on National’s patents and could be sued. The Dopyera’s reaction to Beauchamp’s anti-Dobro campaign was to start a legal action against National. Since John and Rudy had started years before meeting Beauchamp making Banjos and guitars on the strength of John’s ideas and not Kleinmeyer’s money and Beauchamp’s work they felt they were on some good legal ground. Beauchamp was actively trying to put Dobro out of business.

In some documents it was said that instrument dealer while visiting National was told by Beauchamp that Dobro infringed on some of Nationals patents and National had won a lawsuit. This of course was completely false. Beauchamp also claimed that the unique spider bridge found on Dobros originated at National. Also false. These fake claims did result in some loss of orders for Dobro from some instrument dealers. These wild and untruthful assertions by Beauchamp got National into a legal mess as he even brazenly committed his claims in writing to some visiting dealers.

National was having cash flow problems and due to the pending legal issues with Dobro found Beauchamp in a odd position. Beauchamp had bee dabbling with electric guitar pickups since around 1930, but rather than launching an electrified instrument at National, he chose to work closely with Adolf Rickenbacker. This showed the precarious position National found themselves in.

The Dopyera brothers would eventually win in a court settlement. Then Ted Kleinmeyer, nearly broke (and a few years away from the rest of his inheritance), sold his controlling interest in National to Louis Dopyera, brother to John and Rudy. In the shakeup that followed, Beauchamp and several other employees were fired. Beauchamp firing was probably partly because of the enterprise he had started with Rickenbacker and seen as a conflict of interest. Now out of National, George Beauchamp needed this new opportunity. Beauchamp even took night courses to learn more about electronics.

Dobro was also experimenting with magnetic pickups in the early 1930s. Arthur J. Stimson was responsible for Dobro’s first electric guitar designs. Victor Severy also worked on Dobro electric instruments. Dobro did release an electric guitar in 1933, but had little impact until years later. National had an electric guitar around 1934 right before the merger with Dobro.

Beauchamp enlisted his friend Adolf Rickenbacker to build the first fully electric guitar nicknamed the “Frying Pan,” which was a Hawaiian style lap steel. Adolph’s help, know-how, ideas, and capital made this possible. The first name of the company was Ro-Pat-In Corporation but was soon changed to Electro String. Adolph became president and George secretary-treasurer. They called the instruments Rickenbackers because it was a famous name (thanks to cousin Eddie) and easier than Beauchamp to pronounce. Rickenbacker’s other company still made metal parts for National and Dobro guitars and Bakelite plastic products such as Klee-B-Tween toothbrushes, fountain pens, and candle holders.

George Beauchamp died of a heart attack in 1941 while deep-sea fishing near Los Angeles. He was only 42.

National-Dobro Corporation

The history of Dobro and National is long and complicated and full with instability. However in 1934, the Dopyera brothers secured a controlling interest in both National and Dobro, and merged the companies to form the National-Dobro Corporation.

Soon the electric guitar and amplifier was invented and it began to challenge the resophonic guitar in popularity. Big changes were coming. After the merger, National-Dobro Corporation offered some electric instruments in their 1935 catalog.

The company was eventually moved from California to Chicago as much of the instrument manufacturing was based there. The move started around 1936. This was a re-birth for the company. Every major electronic company was in Chicago and it was probably clear that National-Dobro future would have to be soon be producing electric guitars.

During WWII the National, like many other companies found it hard to get raw materials to build their products. No metal body Nationals were made after 1941. The government even ordered a halt to guitar manufacturing. They survived making model airplanes for the war effort to help train pilots. When the war ended, the technology had changed and electric guitars took over in popularity. National resophonic guitars were loud, but electric guitars were louder.

At one point they contracted Regal to build their guitars as the exclusive builder of resonator guitars. They lost the rights to the names during World War II which led to a number of other names. The Original Musical Instrument Company was the last name used with Hound Dog being a brand of resonator guitar when Gibson eventually purchased them in 1993. Gibson currently owns Dobro and manufactures single-cone, spider bridge Dobros resonator guitars and Hound Dog brand guitars. Epiphone has also made resonator guitars at a lower price point.

Today Dobro brand is owned by Gibson and manufactures them in Nashville.

Valco

Valco was formed in the 1930s by three business partners and former owners of the National Dobro Company; Victor Smith, Al Frost, and Louis Dopyera (John Dopyera’s brother). The company name was a combination of the three partner’s first initials (V.A.L.) plus the common abbreviation for company (Co.). It was 1943 and the National-Dobro Corporation was dissolved with the new partners buying out the remaining stockholders.

Valco made airplane parts throughout the war. When the war ended, they made a few prewar style resonator guitars mostly from leftover parts.

Valco manufactured electric Spanish and lap steel guitars, and vacuum tube amplifiers under a variety of brand names including Supro, Airline, Oahu, and National. They also made amplifiers under contract for several other companies such as Gretsch, Harmony, and Kay. In the 1950s they began producing solid body electric guitars.

This is a completely different from early Nationals from this era. Other than the name the art-deco metal body resophonic guitars of the early Nationals was over. During this period the National brand was used on all sorts of innovated Spanish style guitars and lap steels made from all sorts of materials like plastics, bakelite, fiberglass and wood.

Valco established itself as an important electric guitar manufacturer until the mid 1960s. Valco merged with Kay Musical Instrument Company in 1967, however the merged company quickly went out of business in 1968 because of financial difficulties greatly fuel by the large flow of inexpensive imports and the Vietnam War.

A number of manufacturers have reissued several different reissues or derivatives of Valco instrument and amplifier models since their demise. Eastwood Guitars produces a variety of reissue Airline and Supro guitars. Several of Valco’s earlier amplifier models are currently reissued by Vintage47 Amps of Mesquite, Nevada.

In late 2013, it was announced that Absara Audio of Port Jefferson Station, New York, had purchased the rights to the Supro trademark from noted electronic engineer Bruce Zinky. A series of new Supro amps were launched at the Winter 2014 NAMM Show in Anaheim, California. The new Supro amps are cosmetically reminiscent to their progenitors from the 1960s.

Rudy Dopyera passed away in 1978. John Dopyera passed away on January 3rd 1988 at age 94. He was actively tinkering and playing music well into his 90s.

National Reso-Phonic Guitars

The National resonator era started in the roaring 1920s, survived the Great Depression and ended with World War II. No original style National resophonic guitars were made between 1942 and 1989. During this period you could only find them in attics, pawn shops, under beds or in closets. For some time there was little recognition of their aesthetic or intrinsic value.

Mark Knopfler

Resophonic guitars did grow back in popularity. Players like Mark Knopfler, a renewed appreciation for Delta Blues and American roots music helped a great deal. Hawaiian music also was being played again. National resophonic guitars soon new popularity and became highly regarded and appreciated for their art-deco looks, unique sound and American ingenuity. Dire Straits Brothers in Arms album cover featured Mark Knopfler’s 1937 National Style “O” guitar. This opened up the instrument to a whole new generation.

1937 National Style “O” guitar on Dire Straits Brother In Arms album

Vintage examples eventually became sought after and prices rose. These vintage Nationals were usually found in poor condition and needing restoration. Don Young and McGregor Gaines started the National Reso-Phonic Guitar Company in 1989 after doing restorations for a number of years on vintage Nationals.

Nationals have a much wider dynamic range than either electric or conventional wooden acoustic guitars, with a profound tone that is unique among instruments. This still makes them quite popular as it is not all about pure volume anymore as we now have electrified instruments, including electrified resonator guitars.

In 1989 the new company in San Luis Obispo, California named National Reso-Phonic Guitars began manufacturing excellent reproductions of resonator instruments based on designs originated by John Dopyera. They have also added some original guitars representing more than 50 different models.

Donald Young passed away on June 15, 2016 at the age of 63.

Resophonic Guitars

In the relatively short life of National, an amazing variety and models were built. Since a good part of this era was during the Depression and had poor business conditions it is remarkable accomplishment. Some of the core models were in continuous production from 1927 to 1941 like the tri-cone Hawaiian and Spanish resonators. Others were only were in production for a short time. At their peak, National was churning out about 50 instruments a day and it is estimated the thousands were produced. No one knows the exact numbers. Every once in a while a rare model shows up in the vintage model that was long forgotten. There were probably over a one hundred models produced.

Basics are:
1) Resonator: three-cone or single-cone
2) Body material: German Silver, Brass, Steel or Wood
3) Neck-to-body Joint: 12-fret or 14-fret
4) Neck: Hawaiian (square neck) or Spanish (round neck)
5) Headstock: Slotted (1927-1935) or Solid (1936-1941)

Hawaiian style (square neck) is made to play on lap or on a strap. Have high string action and markers, not frets. Spanish style (round neck) is meant to be played like standard Spanish style guitar. String action is lower and can be played fretted.

Collectors of vintage Nationals can break down the models via major historical periods:
1) Prototypes, false starts and earliest produced
2) Models of the John Dopyera era 1928-1929
3) Models of the Depression era 1929-1935
4) Models of the Chicago era 1935-1941

All models were nickel plated except Triolians, Duolians, and the wood body resonators. All styles except the Duolians have ivory celluloid fingerboard binding. The Style numbers indicate the materials and ornamentation that the model has. Usually, the more more ornate the more expensive the guitar would be. National did make some one-offs, custom orders and one-of-kind instruments. Many of the fanciest most expensive Nationals were highly engraved. Some with Hawaiian scenes. They are considered great art.

Unlike companies today, National’s selling prices stayed pretty consistent for their 13 years of production.

Some examples of National Models (not meant to be an extensive or complete)

Tri-cones
Tri-cones were made of german silver with a three piece body construction. The three cones give it less volume but more sustain than a single-cone. Engraved tri-cones are very collectable. Any National made of german silver is very desirable and has sweet tone. They are produced with round and square necks. Includes the Style 1, 1 1/2 ,2, 2 1/2, 3, 4, 35, 97 nickel plated models, and the style M-3 painted tai-cones.

Dobro Serial Number List

Some details on Style:

• Style 1, 1 1/2: plain body, early examples with unbound fingerboard, dot fingerboard inlays. After 1930, “wriggly” lines engraved around outer edge of body. Note this is sometimes refered to as a “Style 1 1/2”. Available 1927-1942.
• Style 2, 2 1/2: Wild Rose engraving, no engraving on coverplate, dot fingerboard inlays. Note some 1927-1929 examples have roses engraved on the coverplate. This is sometimes refered to as a “Style 2 1/2”. Available 1927-1942.
• Style 3: Lily of the Valley engraving, diamond shaped fingerboard inlays, some with ebony peghead veneer and pearl logo, some with celluloid peghead veneer and engraved logo. Clear pickguard added 1936. Available 1928-1942.
• Style 35 squareneck tricone where the enameled air brushing has worn off.
  On the back you can just barely see the “Lute player” sandblasting, and
  the remains of the enameled air brushed color.
• Style 4: Chrysanthemum engraving, diamond shaped fingerboard inlays, some with ebony peghead veneer and pearl logo, some with celluloid peghead veneer and engraved logo. Clear pickguard added 1936. Available 1928-1940.
• Style 35: Known as the “Lute Player” model. Brass body with nickel plating, back sand blasted etching of Renaissance musician under willow tree, palm trees sand blasted on front and sides, airbrushed enamel coloring over sand blasting, maple neck, bound ebonoid fingerboard on squareneck model, bound rosewood fingerboard on roundneck model, dot fingerboard inlays, solid peghead. Enamel coloring discontinued 1939. Available 1936-1942.
• Style 97: Brass body with nickel plating, back sand blasted etching of surfer, airbrushed enamel coloring over sand blasting, maple neck on squareneck, mahogany neck on roundneck, ebonoid peghead veneer, slotted peghead with point at top, sheild logo with 3 vertical line. Clear pickguard added 1937. Available 1936-1940.
• Style M-3 (Marino): Introduced in 1937, this plain nickel plated brass body model has a square neck (Hawaiian). By 1942 the body is no long nickel plated but is instead painted with a oak looking wood grain finish. Discontinued by 1943. Almost all were made with square necks. Are rare round necks were made.

Style O
Typically nickel plated brass bodies, but some early models are made of either brass, steel, or german silver…. or a combination of the three. Most after the first 600 or so tend to be consistent brass two piece bodies. When National converted to a 14 fret guitar in late 1934, they kept the same scale length and shortened the body height to achieve the two extra frets. Brass body used instead of steel, nickel plated after 1931. The specs changes a bit over the years of production.

Style N (1930-1932)
National’s highest quality single cone resonator, German silver body with nickel plating and no etching or sand blasting, round shoulder, upper F-holes, pearloid peghead veneer with engraved National logo, mahagony round neck, dot inlay fingerboard, bound ebony fingerboard, 12 frets clear of the body, slotted pegged. Replaced in 1934 by the 14 fret Don model.

Don (1934-1936)
National’s highest quality single cone resonator replacing 12 fret Style N model, German silver body with nickel plating, round shoulder, upper F-holes, pearloid peghead veneer with engraved National logo, round mahogany neck, slotted peghead, bound ebony fingerboard, 14 frets clear of the body, “DON” engraved on handrest.

Duolians
Was a lower cost steel bodied model that typically came with an unbound mahogany neck and nice Duco Frost finish in Grey, Green, Walnut, Brown, and Gold. Most were grey or green. The earliest were Dark Walnut. This model has a nice growl and an incredibly raw steel tone.

Supro Collegian vintage Resonator (1939-1941)
Basically a pale yellow colored Duolian with a different coverplate. Sold under the Supro brand name (but still sometimes has the National nameplate), this model replaced the Duolian and Triolian models in 1939. Discontinued in 1941.

National vintage Wood Body Resonators (1928-1942). Wood body Nationals are not as desirable to many collectors, but they are quite cool anyways.

Triolian – first wood body resonator was the Triolian in late 1928. By 1929, this model converted to a metal body instrument. The very first wood body Triolians had a tri-cone resonator system. Less than 10 of these examples were probably produced. Much like the metal body version, the wood body Triolian has a single cone resonator, round shoulder, upper F-holes, bound single layer fingerboard, dot fingerboard inlays, 12 frets clear of the body.

Triolians were upper level steel bodied models. It came in several varieties. Polychrome with yellow/pea green and palm tree scene, a Walnut sunburst finish, or even a piano grain painted finish. It featured a bound maple neck and fretboard and engraved tuners. Early ones were made of wood with floral scene then hula girl motif on the back, but quickly went to steel body with a palm tree scene and sunset.

Rosita (1933 to 1939)
Maple veneer body probably made by Harmony, lyre-shaped holes in upper body, trapeze tailpiece, bound top and back, 14 frets clear of the body, ebonized fingerboard, dot fingerboard inlays, slotted peghead, 2-tone mahogany finish, round or square neck. In 1937 F-holes replaced the lyre shaped holes in the upper body.

El Trovador (1933 for 8 months only)
Body made by Kay, mahogany top, 2 piece matched mahogany back, upper F-holes, triple bound top and back, trapeze tailpiece, 12 frets clear of the body, bound fingerboard, dot fingerboard inlays, slotted peghead, serial number beginning with “K”.

Trojan (1934-1942)
Maple veneer body, upper F-holes, trapeze tailpiece, bound top, 14 frets clear of the body, slotted peghead, shaded walnut finish. Introduced 1934. In 1937 Trojan specs changed to Dobro-type tailpiece, ebonoid pickguard with stripes and letter “N”, bound top and back, rosewood fingerboard, solid peghead, bound ebonoid peghead veneer.

Estralita (1934-1942)
Mahogany top, 2 piece matched mahogany back, upper F-holes, 4-ply binding around coverplate, 4-ply binding on top and back, unbound fingerboard, 14 frets clear of the body, varied pattern fingerboard inlay, solid peghead, shaded brown finish. Available 1934 to 1942.

Havana (1938-1942)
Spruce top, upper F-holes, roundneck or squareneck, bound fingerboard, dot fingerboard inlays, ebonoid peghead veneer, natural top finish, sunburst back finish. Available 1938 to 1942.

Aragon de Luxe (1939-1942)
Archtop body made by Kay, spruce top, maple back and sides, bound upper F-holes, radial pattern wood coverplate with semi-rectangular holes in groups of 3, board plate tailpiece, clear pickguard, triple bound top and back, bound rosewood fingerboard, double parallelogram fingerboard inlays, rosewood peghead veneer, bound peghead, chrome plated metal parts, light brown sunburst finish.

Dobro/Regal Vintage Resonators

Most Dobros have wooden bodies which includes all the early ones produced. They all use the spider bridge with an inverted single-cone. Dobro’s original 1929 line included the unbound student Model 45, the Standard Model 55 with a bound fretboard, the two-tone French scroll carved (actually sandblasted) Model 65 with a bound ebony fretboard, the Professional Model 85 with a triple-bound mahogany body, and the Model 125 “De Luxe” with a walnut body and four-way matched back.

Dobro also made some metal body guitars from 1935 to 1940. Regal (which was Dobro’s exclusive licensee) made metal body resonator guitars with their brand name and also the “Old Kraftman” name. Several other resonator brand names were also used such as Ward, but these are in fact still Regal/Dobro made resonator guitars. All metal body Regal/Dobros have 14 frets clear of the body.

Some Examples of Painted Metal body Dobro Resonators:

• M-32 gold painted vintage resonator
• M-35 sunburst painted vintage resonator
• M-46 “Lumalite” silver painted vintage resonator
• M-47 “Lumalite” mahogany grain painted vintage resonator

Some Examples of Nickel Plated Metal body Dobro Resonators:

• M-14 nickel plated vintage resonator
• M-15 nickel plated vintage engraved resonator
• M-16 nickel plated vintage engraved resonator
• M-62 “Spanish dancer” nickel plated vintage resonator
• M-65 “singing ladies” nickel plated vintage resonator

Today’s Resonators

Today, we see the three major designs from National and Dobro resonators still available in metal and wood bodies sold by several builders. There are many different styles and options available. Most all come in square neck that you would play on your lap or attached to a strap or round neck that are played like a standard Spanish style guitar.

Still we see the original Tri-cone (three 6″ diameter cones), Single-Cone (9 1/2″ diameter) and the Dobro inverted single-cone guitars. All of these resophonic guitars can be used in any style of music and they have a unique sound. Tri-cone and single-cone resophonic guitars are quite popular in Hawaiian music, Blues, Folk and Country. The Dobro inverted single-cone wooden body resonators are particularly popular with Bluegrass players.

National Single-Cone Resonator

Single-cone models are available in wood, steel and brass. The tri-cones come in steel and in brass. The tri-cones and single-cones have essentially equal overall volume, however the attack of the single-cone is stronger than the tri-cone, and conversely, the sustain of the tri-cone is much longer. The wood bodied Dobro has a nice attack that is well focused due to the body design. When played with bare fingers the attack and volume is quite different. Most times resophonic guitars are played with fingerpicks and a metal or glass slide. Of course this may vary from instrument to instrument. Although, they can be played in standard tuning. open tunings are also quite popular.

Dobro Serial Number Dating

Republic Tri-cone from my collection

Many Asian imports are available at much lower price points that are based on the early designs of John Dopyera and National. Some of these can be great beginner guitars and a decent value. If you are looking for a high quality Resophonic guitar, you could not go wrong with a new National Resophonic model or a bouquet maker. Vintage Nationals are usually pretty expensive and since they are quite old at this point may need extensive restoration to be a good playing instrument again.

National guitars HUGE in the Delta Blues

Hawaiian Steel Guitar Classics 1927 – 1938

Sol Hoopii Trio

Guitar Serial Number Dating

Resonator Documentary – RESONATE 2008 FULL MOVIE

Dobro Serial Number On Headstock

Jerry Douglas Elite Dobro Player