National Guitar Serial Numbers

Oct 12, 1999  Topic: National serial numbers Steve P Member. Steve, but if you want to date a National resonator guitar, look in the back of Bob Brozman's book on Nationals. If you're looking for something on, say, a 1960 Supro resoglass I think you are out of luck. Brozman does a good job of covering a lot of the pre-war resos, though. Most gear has a serial number, either printed on a label inside it or stamped into the headstock or neck plate. Use our dating guides below to figure out when your instrument was made and where it came from.

The Guitardater Project cannot verify the authenticity of ANY Guitar, this site is simply meant as a tool to satisfy the curiosity of guitar enthusiasts. This website possesses NO DATABASE of guitars made by manufactures, instead simple serial code patterns that are available on this site and in the wider guitar community are used.

When John Dopyera stormed out of the National shop in January 1929, his resignation stemmed from more than a spur-of-the-moment tantrum. For months, the inventor of the resonator guitar spent his evenings and weekends working with his brother, Rudy, on a secret project – a single-cone guitar they believed superior to the National Triolian. They called their new instrument the Dobro.

The Triolian’s bridge sat in a round wooden “biscuit” mounted in the center of a metal amplifying cone. John Dopyera developed the biscuit-bridge system for use in a ukulele, but felt the design did not sustain well enough when enlarged for a guitar. National’s president, George Beauchamp, overruled Dopyera and rushed the Triolian into production in late 1928. Beauchamp and Dopyera had been rubbing each other the wrong way for some time, and this came as the last straw. John and his brothers decided to split from National.

The Dopyeras turned the resonator upside-down and modified its V shape into a W, connected to the bridge by a long screw through the center. A radiating spider carried the sound from the bridge to the edges of the cone. Without a block of wood choking it, the inverted resonator vibrated freely and sustained notes longer than the biscuit-bridge cone.

Rudy and Emil (later called Ed) Dopyera left National soon after John.

The brothers named their new company Dobro (a shortened version of Dopyera Brothers). The word also meant “good” in their native Slovak language. Emil, the salesman, showed the prototype guitar to dealers in southern California and took the first orders. Two other brothers, Louis and Bob, helped finance the venture. In the spring of ’29 Dobro started production in the back room of Russell Plating Company. Within a few months the company moved to a new brick factory at 727 East 62nd Street in Los Angeles.

Dobro’s model numbers corresponded to list prices in a system that has long confused collectors. Because prices changed from year to year, guitars changed model numbers, and the same model number may have applied to several different guitars. For instance, 1929’s Model 45 was a dark, unbound student guitar, 1932’s Model 45 was a bound single-screenhole “Cyclops,” and by late ’33 the Model 45 was a spruce-top with two screenholes. This was not a progression of the same basic guitar. These were Dobro guitars that in those particular years carried a list price of $45. It was not a good system, and the company stuck it with until production ceased at the dawn of World War II.

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.

Custom Dobro guitars with gold-plated, engraved hardware and fancy inlay cost from $175 to $250. Round or square necks were available on all models.

Dobro also made mandolins, ukuleles, and “Tenortrope” banjo-guitars with round wooden bodies. By ’31 Dobro introduced the Model 50 tenor guitar, with a bound fretboard and a mandolin-size resonator in a guitar-size body.

Dobro started its serial numbers around 800. Later in the ’30s Regal in Chicago confused things by numbering a run of Dobros across the same range.

An early California instrument can be identified by square slot-ends in the headstock, coverplate screws in the points of numbers on a clock, and the lack of a dot at the 17th fret. The dot at the 17th fret was added in late 1930. By 1933 Dobro moved the screws to the half-hour points so a repairman could open a guitar without removing the tailpiece.

In ’32 Dobro modified its guitar line, with new model numbers ending in six instead of five. The unbound student guitar, its hardware painted silver instead of plated, dropped in price to become the Model 36. The Model 55 became the Model 56 (some ads specified hardware plated with nickel instead of chrome). The scrollwork Model 60 evolved into two styles: the Model 66, with a fretboard of red bean wood, and the Model 66-B, with a bound body.

Dobro introduced the Model 76, with a bound birch body and inlaid celluloid trademark, but made few of them. The Model 85 became the Model 86, with engraving added on the coverplate. Dobro’s Model 106 was a walnut guitar with a two-way matched back. The Model 156 was walnut with an inlaid fretboard and gold plating. Dobro’s tenor guitar came in three models, the 50, 75, and 100, with details corresponding to the Models 56, 76, and 106.

On the extreme high end was Dobro’s Model 206, with a spruce top, walnut back and sides, gold-plated and engraved hardware, and five-ply binding with a layer of gold sparkle in the center. Dobro made few Model 206 guitars – John Dopyera said no more than 12 or 15 – as showpieces for trade shows or by special order. Only three are known to exist today.

By this time the Great Depression had kicked into high gear.

Gold-plated guitars were hard to sell to people having trouble putting food on the table. Most of Dobro’s sales were in the lower end of the scale. To increase sales, Dobro had to make some even cheaper by simplifying the design and omitting some features.

In 1932, Dobro introduced a line of single-screenhole guitars, today known as the Cyclops instruments, which required less hardware and labor.

The least expensive was the Model 27, with an unbound body stained, painted silver, or brushed with a faux wood grain. Some ’33 square-necks had their frets painted on. The Model 45 Cyclops had a bound body with a rosewood finish. The Model 60 Cyclops had the same “carved” scrollwork and binding as the 66-B.

In mid ’33 Dobro replaced the Cyclops guitar’s full-sized screenhole with two smaller ones joined in a single frame. No model numbers for the double-Cyclops guitars have come to light, but there are two distinct styles. Some have no binding on the body, and others have ivoroid binding around the top and fretboard. Some double-Cyclops guitars, especially those sold through Montgomery Ward under the brand name Magno-Tone, have coverplates with radiating slots in a design called the poinsettia. Most of the double-Cyclops guitars date to ’33 and ’34, but Dobro apparently made a few as late as ’36.

California Dobro-made guitars appeared under a variety of brand names in the early 1930s, sold either through catalogs or by private music studios (guitar schools). Dobro often economized on guitars carrying other brands by installing no soundwells under the resonators or by cutting f-holes instead of installing screens. According to Emil Dopyera, part of the thinking was that if a guitar did not have the Dobro emblem it should not have the full Dobro sound. Budget Dobro guitars were sold under such brands as Hawaiian Radio-Tone, Michigan Music, Rex, and others. Emil later said, “If we got an order for 100 guitars with a special coverplate for a little less money, we did it.”

In Dobro’s 5,000-square-foot factory the production of guitar bodies was limited by space. According to John Dopyera, in about 1931 Dobro bought a shipment of guitar bodies from Regal, in Chicago. Dobro assembled between 60 and 100 guitars with Regal-made bodies in its Los Angeles factory before deciding that shipping the bodies from Illinois was too expensive, especially if Dobro had to send the finished guitars back to Chicago for distribution. So the Dopyeras decided to ship the metal parts east and let a Midwestern company assemble some guitars, as National already did with Harmony.

Gibson expressed interest in the deal, but their representative made no effort to hide his opinion that the Dobro was not a real guitar, but a gimmick. The brothers took offense at what they called Gibson’s “holier-than-thou” attitude. They decided to go with Regal, which at that time was producing its own line of guitars as well as Lyon and Healy and Washburn instruments. Dobro and Regal divided the U.S. into two territories, with the Mississippi River as the center line; Dobro would sell to jobbers in the West, Regal in the East.

The first Regal-made Dobros reached the market by the summer or fall of ’32. In January ’33, Regal announced in Musical Merchandise its own line of ampliphonic instruments built with Dobro parts. Regal made identical guitars under both the Dobro and Regal brands. Dobro in Los Angeles skipped over most of the 4000s in their serial numbering, reserving those numbers for Regal-made Dobros. Regal Dobros of the mid ’30s are most easily recognizable by their round slot ends extending straight through the headstock.

In 1933, Dobro introduced one of the first electric guitars. George Beauchamp’s and Adolph Ricken-bacher’s Electro frypan appeared in late 1932, but in Seattle a musician named Paul Tutmarc had been selling electric guitars under the name Audiovox since 1931. Dobro employee Victor Smith claimed he had been working on an electric guitar as early as 1929. Art Stimson, who had worked with Tutmarc, came to Los Angeles and told the Dopyeras the Audiovox pickup was his own invention. He sold them all rights for $600.

1933’s Dobro All-Electric looked something like a standard Dobro with a bound mahogany body. But its coverplate had no holes and was engraved with lightning bolts. Two pickup blades rose through a slot in the coverplate, one under the three bass strings and one under the treble.

Underneath the coverplate the blades connected to a large horseshoe magnet and a heavy transformer.

In 1934 Dobro combined the pickup with a resonator in a bound mahogany guitar. A horseshoe magnet was mounted inside the back, and the pickup blades rose on stems through holes in the resonator. According to John Dopyera, all but one of these guitars were returned to the factory for refunds because their owners didn’t understand how to use them. Only one, serial number 6845, is known today.

At the 1934 NAMM show Dobro presented a revamped line of guitars, mandolins, and ukuleles. The shift from the old line was gradual, with some of the new models produced as early as 1933. By mid ’34 all previous models were discontinued. Because the mid ’30s were Dobro’s peak production years, the new line contained what are today the best known prewar Dobro models. All these guitars had bodies roughly 31/2″ deep at the butt, where earlier Dobros had measured closer to 31/4″.

The Model 19 was Dobro’s cheapest resonator guitar – so cheap that it didn’t carry the Dobro emblem. Its decal said, “The Angelus, a Dobro Product.” It had no soundwell and smooth-sided f-holes instead of screenholes. The Angelus coverplate had a simple design of 12 round holes at the clock points.

Jackson Serial Number Decoder

The birch Model 27 proved Dobro’s biggest seller and remained popular through the decades. This was the model played on the Grand Ole’ Opry in the post-war years by both Bashful Brother Oswald and Josh Graves. In the ’70s, Jerry Douglas made his mark playing a Regal-built Model 27. Modern dealers and collectors usually identify a Model 27 as having binding on the top only, but rare early examples had no binding at all and most Regal-made Model 27s were bound top and back. The true identifying mark of a Model 27 is its lack of the three holes under the strings between the screenholes, an economy suggested by Regal and adopted by Dobro (Regal apparently never liked bothering with the three holes and even on high-end models never beveled the edges, as Dobro did). Many players hold that omitting the three holes improved the sound of the Model 27.

Dobro’s 1934 line included the Model 37, with a mahogany body bound top and back and along the fretboard, the Model 45, with a spruce top and mahogany back and sides, the Model 60, its scrollwork “carved” in a new pattern with a more prominent letter “D” on the back, and the walnut Model 100. Dobro in California marketed some budget flat-tops with trapeze tailpieces and 14-fret Spanish necks, using the name Dobro Jr. Regal produced only the Models 19, 27, 37, and 45, by far the more common models.

Both Dobro and Regal built tenor guitars with full-size resonators, shortened bodies and 14-fret necks. Dobro called theirs the 37T and 45T, with details corresponding to the Model 37 and Model 45 guitars (a Model 37 guitar was a 37G, and a mandolin a 37M). Regal offered more tenor guitar models but used a different numbering system, calling their tenors the 191/2, 271/2, 371/2, and 451/2.

In September ’34 Dobro introduced a line of metal-body guitars.

Rudy Dopyera wanted Dobro to build metal instruments from the beginning, but John was not satisfied with the soldering method used by National. The solder of the era was weak, and heliarc welding was not yet invented. When John Dopyera found a local shop making metal boxes by crimping the edges together, he learned the technique from the foreman and applied it to metal guitars. The crimped rims of Dobro’s metal guitars gave them the name “fiddle-edge.”

The first metal Dobros had solid headstocks and individual gear machines, at that time an expensive feature. Dobro’s metal guitars had “crossed window” soundholes; Regal’s had five-sectioned f-holes. The Dobro M14 (Regal 14M) “Leader” had a body of nickel-plated brass, the M15 Professional was of German silver, and the M16 “Artist” was of German silver, “…elaborately engraved.” Regal and Dobro used different engraving patterns. Serial numbers on the metal guitars ran in a new sequence with the prefix “M.” These instruments were the quality single-cone guitars John Dopyera wanted to build at National in 1929. But times had changed. Few of the M guitars sold in the Depression market.

In 1935 a less-expensive line of Dobro metal guitars replaced the M series. The Model 32 had a painted steel body. The Model 46 was made of “Dobro-Lite” aluminum, finished in translucent silver-gold or, later, painted.

The Model 62 had a body of nickel-plated brass with stencil-sandblasted designs on the front and back.

In January ’35, following a bitter lawsuit and a lot of wheeling and dealing, National and Dobro merged into one company under the control of Louis Dopyera. Two months later National-Dobro moved into a new factory at 6920 McKinley Avenue in Los Angeles, where the two lines came to share much equipment. The characteristic square slot ends of the earlier Dobros gave way to rounded slot ends passing through the headstocks at a slant, cut by the same router used on National guitars of that period. McKinley Avenue Dobros typically have spun cones instead of stamped ones and serial numbers in the 8000s. They include the Model 27 square-necks prized by collectors today.

At the ’35 NAMM show, Dobro introduced the prototypes of its new electric line: the No. 1 Hawaiian Guitar, with a one-piece body of cast aluminum, the No. 2 Standard Guitar, with a Regal archtop body and a pickup mounted in an oval metal housing, and the No. 3 Mandolin. The earliest aluminum lap steels had no knobs. Later Dobro added first a volume and then a tone control. The aluminum guitar was discontinued by 1937.

In early ’36 National-Dobro opened a branch office in Chicago, the center of the nation’s musical instrument business. National and Dobro instruments shipped from Los Angeles to Chicago were numbered in the same series with the prefix “A.” By ’37 the Chicago office grew from a warehouse to a full-fledged factory, building National and Supro instruments and handling so much of the company’s business that the Los Angeles plant finally closed.

In August ’37, National-Dobro contracted all Dobro assembly to Regal, agreeing to sell Regal hardware by the unit. By that time National-Dobro’s attention was focused on production and profitability.

Louis Dopyera had bought out all his brothers and, except for a few odd shares, was sole owner of the company. All five brothers continued to collect royalties for use of the Dobro brand name.

The introduction of a cheap, efficient gear machine in ’36 allowed solid headstocks on lower-priced guitars. Regal began using solid headstocks on all models of Dobros in a new serial number sequence beginning apparently at one and continuing into four digits. Mike Auldridge played a Model 37 from this series with the Seldom Scene in the ’70s and ’80s, and kept another only a few serial numbers different as a backup.

Once Regal took over all Dobro production, it ceased numbering any guitars except for a occasional enigmatic marks like “J” or “HH25.”

National-Dobro, however, continued the Dobro number series, which had reached the 9000s, usually with an “L” prefix, on National guitars. Regal never numbered resonator guitars carrying its own trademark, except by accident.

Regal mixed and matched hardware freely on all its Dobro guitars, apparently using whatever tailpieces or coverplates were handy at the time.

After ’37 Regal used the f-hole and crossed-window dies on metal guitars and sold them with or without pickguards. Distributors, studios, and mail-order houses sold Regal-built resonator instruments under brand names that included Alhambra, Broman, Bruno, Gretsch, Magno-tone, More Harmony, NIOMA, Norwood Chimes, Old Kraftsman, and Orpheum.

In ’37 the Dobro Model 75, with a walnut body and engraved coverplate, made a brief appearance in Regal’s catalog. That year Regal replaced the budget Model 19 with the Model 25, which had top and back binding and pointed f-holes, and introduced the Model 6, a small, two-tone guitar with f-holes and a mandolin-size resonator not specified as genuine Dobro, although many of them were. The Model 6 had a moon-and-stars or 12-diamond coverplate.

In 1937 Regal introduced the Dobro Hawaiian Electric Guitar, with a solid, square-ended wooden body. The Dobro Spanish Electric Guitar had an archtop body with a two-blade pickup mounted in a square metal housing.

In 1939 Regal revised its prices and changed the Dobro line once again. The blond Model 5, with a mandolin resonator, joined the Model 6 in the bargain basement. The former Model 25 got a $2 raise to become the new Model 27, and the former Model 27 went up $5 to become the Model 32. The steel-bodied former Model 32 became the Model 35. The mahogany Model 37 disappeared from the line. The aluminum Model 47 dropped $1 to become the Model 46, and the plated-brass Model 62 rose $3 to become the Model 65. A measure of the Great Depression was that the most expensive wood-body Dobro of ’39, the spruce-top Model 45, had the same price and model number as the cheapest student Dobro of ’29.

Regal made a few Dobro guitars for which no model number is known. Some spruce-tops had f-holes instead of screenholes. In ’38 Regal made Super Auditorium Size Dobros using archtop bodies bought from Harmony or Kay. These required 13-fret necks to get the scale right. In ’41 Regal made an f-hole resonator guitar with maple top, back, and sides in a natural finish.

The U.S.’ entry into WWII was a death blow to resonator guitars. President Roosevelt issued a limitation order restricting the use of critical materials. Louis Dopyera saw the handwriting on the wall. Within weeks of the bombing of Pearl Harbor, he sold all the assets of National-Dobro to himself and with his former employees Vic Smith and Al Frost started the Valco Corporation to go into war work. According to Smith, Valco sold the Dobro hardware it had on hand to Gibson.

Gibson experimented with a few resonator guitar prototypes in the 1940s, but never put any into production. After the war Valco returned to the instrument business, building electric guitars. Regal struggled along and declared bankruptcy in 1954.

Vintage National Guitar Serial Numbers

Not until the folk music revival of the ’60s would anyone make another Dobro.

This article originally appeared in VG‘s June ’99 issue. All copyrights are by the author and Vintage Guitar magazine. Unauthorized replication or use is strictly prohibited.

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National Guitar Serial Numbers

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