National guitars are a unique and almost magical invention that are a fantastic welding of European craftsmanship, "modern" manufacturing techniques and that almost half-crazy, laterally thinking genius we are gifted with a few times every generation or two...Even the way the wooden neck of a National guitar disappears into the shiny metal body of the guitar is kind of cyborg-ish and futuristic to this day - 80 years after it's invention!
And the pure musical power it gives you is almost indescribable - it's incredible to think what it was like to play one before the invention of the electric guitar - but even now, in an acoustic environment a National guitar can often give you the impression of being the only person with a microphone at a public speaking seminar or something - but you better think of something to say or all that power can be your downfall - it's exhilarating but it's also scary - which is how every musical instrument should be really (believe me a concert grand piano - or a B3 - is a terrifying instrument at first!).
Paul Simon's song "Gracelands" begins with the line "The Mississippi Delta was shining like a National guitar" (which I thought was an evocative line long before I understood what it meant!) - but the bright nickel plating of National guitars has seeped into popular culture (in a very small way at least!) Most people recognize National guitars from the cover of Dire Straights' "Brothers In Arms" (it's a 1937 Style "O" Serial Number B1844).
If you want to find out a lot more about National guitars you really should buy Bob Brozman's book "The History & Artistry of National Resonator Instruments". It's the undisputed National guitar bible - with detailed information on every model and variation, the history of the company and the characters therin - as well as biographies of National artists, technical information for players/owners and all the information you need to date your National guitar (find the date of manufacture of your National guitar I meant...).Some of the common confusions are that a National is the same as a Dobro - (partly because both of these brand names have come to be used as verbs and partly because they were invented by the same guy) - that any metal guitar is a National - that a National is the same as a "steel guitar" etc., etc. - so that's what this page is about.
By the way, "steel guitar" refers not to the guitar and what it's made of, but to the fact that it's played on your lap with a steel bar - in other words it's a technique, not an instrument and is more common in Hawaiian or Country and Western than in blues.
To some people this stuff may seem overly obvious but I remember when I was growing up, being fascinated by these guitars and being able to find out next to nothing about them. Also I know there are a lot of sites with some information on National guitars now, but every site I looked at besides Notecannons, Vintage Guitars Info and the National Reso-Phonic website contained a lot of mis-information. So while I'm not the most focused and intelligible writer - everything on this page is absolutely, verifiably true! If you are looking for specific information on particular models or have any other National questions feel free to email me.
(Also if you email me a description and serial number of your vintage National I'm happy to give you a rough date for it - usually within a few months - but I don't have time anymore to give approximate valuations - I suggest you google the model and year and see what prices people are asking...it all depends on the condition of the instrument really...)
If you're looking for info on the new National company it can be found here - and no it's not actually the same company that existed in the 1920's, but the guitars really are every bit as good as the old ones. They're one of a very small handful of companies who's products are truly worthy of their history.
The original National guitar was invented by John Dopyera in 1927. The basic outline of the story is that in the 1920's with the jazz craze and the fact that music always gets louder and more popular after a war, guitarists wanted to be louder. They especially had to compete with banjos which are pretty darn loud if you didn't know.
In fact the volume of musical instruments has had a huge effect on the evolution of music because, before electrical amplification, to play in a band you had to play a lot simpler and pretty differently to how you'd play at home in order to be heard. Also a lot of instruments like banjo and accordion were chiefly popular because of their volume so that tunes were re-arranged to accommodate those instruments.
The banjo went through all kinds of enhancements to make it louder but the only thing you could really do to a guitar was to make a bigger guitar - but then after a certain size it's hard to play, expensive, silly looking and doesn't sound like a guitar! The other way - electric amplification - was being experimented with but was more than a decade away from being practical.
George Beauchamp, a guitarist, singer, entertainer and entrepreneur came into John Dopyera's music shop (he made and repaired violins, guitars and banjo's and had numerous patents for musical and other inventions) with the idea for a guitar with a horn on it. Stroh, an English company made violins with gramophone type horns on them - George had seen one at a gig (you can still buy them new from here). John Dopyera didn't think it would work but he made it - it reportedly looked really cool!
However John made a second guitar, the principle of which more sensibly focused on the disc of a gramophone than the horn. (gramophones have a mica disc to which the needle is attached - it's actually the disc that amplifies the sound, the horn basically just projects it.)
All these things so far were things other people were working on as well - in fact, the principle is pretty much the same as a banjo and not too dissimilar to the washtub bass! - but somehow what came out of John Dopyera's mind was altogether different to anything anyone had come up with! It's a great piece of art-deco industrial art - it's futuristic and mechanical looking, un-symmetrical, shiny - much shinier in real life than in the pictures. But then the engraved ones have got the oldey worldy flowery patterns, kind of at odds with the futuristic shape but it works anyway.
These first guitars, called tri-cones (or sometimes tri-plates) used three spun aluminium "cones" which are very much like speaker cones (in appearance and function), joined by a "T" shaped bridge. In fact speaker cones were not invented until 1925 so the idea was not as obvious then as it may seem now (actually it still doesn't seem very obvious really). The body of the guitar is made of "German Silver" which is what fret-wire is made of (which is what frets are made of! 65% copper, 10-23% zinc, and 10-20% nickel). The reason for the metal body is that, all the energy of the strings was intended to be amplified by the cones, a wooden body vibrating would have soaked up some of this energy - and also so it wouldn't warp or split - guitar makers in the 1920's were paranoid about warping and splitting - there's almost always some kind of "guaranteed not to split" sticker inside old guitars.
The bodies were made in three pieces, the sides were actually one piece and the front and back were very neatly and expertly soldered to it.
What makes them have so much more sustain and volume is the fact that the thin aluminium cones vibrate much more easily than a wooden top (on a normal, wooden guitar, the volume comes mainly from the top or front of the guitar vibrating). Much like a gramophone, the cones don't produce a lot of bass, so the body of the guitar was designed to act like a speaker box and all the bass comes out of the grilles (or the f-holes on the single cone guitars). For this reason the twelve fret models have more bass than the later fourteen fret models because, instead of lengthening the neck, they shortened the body (all Tri-cones had 12 fret bodies).
John Dopyera and George Beauchamp went into business making these guitars and they sold very, very well. They were not only far louder than a normal guitar, but they have a unique tone which was particularly suited to Hawaiian music. In particular they have much longer sustain than a wooden guitar (the wooden top absorbs a lot of the energy of the string causing it to die out sooner) which is extremely useful for slide playing, enabling many notes to be played from a single pluck of a string.
In 1915, 17 million Americans visited the Panama-Pacific Exposition in San Francisco, hearing Hawaiian music for the first time. By the time the National guitar came along, everyone was playing Hawaiian.
But the depression was on it's way and National guitars were extremely expensive due to the materials and particularly the labour involved in spinning the cones and engraving the engraved ones. A "Style 1" tricone, meaning one with no engraving, cost $125 in 1930, a Style "2" - $145, Style "3" $165 and style "4" $195 (to put this in perspective it was possible to buy a cheap, wooden bodied acoustic guitar for $1.50 during this period!).
So a cheaper model was called for and it's invention caused a furore in the National company. John and George had huge personality conflicts and I think John was sick of the business side anyway - similarly to Leo Fender he preferred to invent and make things rather than sell them.
Anyway John quit and signed over all his patents to the company. Three months later George Beauchamp filed a patent for a single cone resonator guitar. This was what all the fuss was about because clearly he didn't "invent" the single cone - John Dopyera had already made and sold single cone mandolins and ukuleles and really, a guitar is just a big ukulele - anyhow George got the patent and is listed as the inventor, as well as being described in other publications as the inventor of the tricone! But quite probably the single cone Nationals would never have been made without George Beauchamp because John Dopyera claimed to not like the tone of them. So while it was maybe a bit sneaky and un-ethical, we're eternally grateful to him for giving us this -
Whereas the tricone has three small cones connected by a "T" shaped bridge, the single cone Nationals have one large cone, on top of which sits a round wooden "biscuit" which holds the thin wooden bridge. The fragile cone is protected by the round coverplate and the bridge is protected by a metal cover or "strap".
The "Triolian" was the first single cone guitar, named Triolian because the prototypes actually had a mini tricone set-up under a single, round coverplate - this turned out to be too complex for a budget model but the name stayed the same - initially made of wood they were changed to painted steel - these paint jobs were really corny, pink or yellow with surfers or hula girls stencilled on them!
Inexplicably nowadays, some later steel bodied Triolians had quite realistic woodgrain paint jobs, like those old kerosene heaters!
The extra-budget model was the "duolian" - named to sound like a triolian but less - which had a steel body, painted in varying styles over the years and costing $32.50 originally. National also made even cheaper wooden bodied single cone guitars as electric instruments took over and acoustic amplification went out of style (for a while!). As can be expected they sound a bit mellower and are quieter than the metal bodies. The wooden bodies were not actually made by National, they just had National cones and coverplates on them, so many of them seem the wrong shape, the sides of the guitar don't match the curve of the coverplate as well as on the metal bodies (the earliest ones are very nice though).
As the single cones gained in popularity, the range of models expanded upwards with the style N, O and Don models. The "N" was a nickel plated German silver single cone introduced in 1930 with no pattern or engraving but with tricone features and quality.
Also released in 1930 was the style "O" with a nickel plated brass body with a wonderful Hawaiian scene etched into it - the detail of the pictures is matte looking (you can't feel it though) while the background is the normal mirror finish of the nickel. The pattern was sandblasted into the brass through a stencil before being nickel plated. No one knows who designed the pattern but there are actually seven different Hawaiian scenes that were used between 1930 and 1941. The very first etched Style O's had an abstract lightning bolt pattern similar to the "exploding palm tree" tricones.
The "Don" was the fanciest single cone model - introduced in 1934 with a 14 fret German silver body, ebony fingerboard with diamond shaped pearloid inlays, pearloid headstock overlay and made in three styles of engraving - plain with engraved border, an art deco geometric floral pattern or a tricone style engraving. Because of the brass body and the simplicity of the sand blasting process, the style O was very much cheaper than the "N" or "Don" models, accounting for their rarity now.
While it's true the single cones were more popular later on, especially as cheap electric guitars came on the market, they didn't replace the tricones, all the models were available at the same time. National also made super-cheap models for Sears mail order company.
As well as guitars, the company made mandolin, (four string) tenor guitars and ukuleles in each of the styles (except for Duolian and Don styles) - ie there were Triolian Tenors, Style O Ukuleles, Style 3 Mandolins etc.
Meanwhile John Dopyera (who had left National) invented the Dobro (named because his brothers helped make them - Dopyera brothers, and Dobro means "good" in Slavic languages)
Probably partly to avoid infringing George Beauchamp's patent on the single cone National, the single cone in the Dobro is the other way around, the peak of the cone is towards the back of the guitar and the vibration of the strings is transmitted to the edges of the cone by a complicated "spider" bridge. They sound very, very different to National guitars, much mellower for one thing, which possibly reflects John's preference for the tricone tone over the National single cone.
Technically speaking Dobros probably are an improvement (as John Dopyera believed) to the resonator concept, their attack is less harsh and they have a more controlled decay with lovely "woody" overtones. Accompanying a bright, strumming guitar of the Martin/Gibson type, Dobros epitomise country music - to country music the Dobro is exactly what the National was to Hawaiian or blues.
While Dobros are sometimes used on blues album covers and Nationals are sometimes mistakenly described as Dobros - they were almost never used by blues players. By the time Dobros were becoming popular, most blues players were playing electric guitars whereas the more acoustic-orientated country and western music embraced the Dobro and the brand name became a description of a playing style.
Dobros are almost always wooden bodied and I don't think they've ever been out of production whereas the last metal bodied Nationals were made in 1941 and the company switched over to making cheap wooden archtop guitars, fairly successful electric violins and plastic solid body guitars!
To further confuse the story, after bitter, sometimes nasty competition and law suits, National and Dobro merged into the National Dobro Corporation in 1935 (the National board of directors had removed George Beauchamp in the lead-up to this, possibly over the bitter law suit with Dobro).
National Dobro made mostly electric instruments, including guitars and amps with the Supro name. Many of these designs were innovative, even world firsts but they had really lost the high end of the market with the decline of the resonator guitar. The original Tricones especially were played by the most famous and successful musicians of the day and were the "Duesenberg" of Hawaiian guitars (when I wrote this I didn't know there was a guitar company called "Duesenberg"! I was of course referring to the Duesenberg car - I don't know what the guitars are like!) Incidentally the Duesenberg car company is that from which the phrase "Doozy" or "Doosey" comes from. A Doosey is an exceptionally high quality example of it's type (by 1926 the car was the most expensive in the world and had had a mechanical computer which automatically lubricated the greasing points and advised when refilling was needed as well as suggestions to check engine oil and battery water level!)
The National/Dobro/Supro and later Valco instruments however were not seen as being much different to the Kay and Harmony type mail order instruments and those companies had more experience with the lower end of the market. Valco continued on though and traces of it can be detected through the sea of Teisco's, Eko's and other plastic guitars until I think it finally died out in 1968.
I've often been asked about National's connection with the invention of the electric guitar and yes, there are a few connections although none of them had anything to do with John Dopyera at all. It must be remembered that there were hundreds (or thousands) of people experimenting with electrifying guitars from the late 1920's to the general commercialization of them in the early 1940's. Who invented the first electric guitar is, therefore, an infinitely debatable topic.
However, many people would know that Rickenbacher features heavily in electric guitar history but it is less well known that our friend George Beauchamp, having left National, worked for Rickenbacher, particularly in the field of electric instruments and that the "Frying Pan" and other Rickenbacher inventions are clearly his work.
The other National/Rickenbacher connection is that all the metal bodies for the National guitars were made by Rickenbacher's factory (this was long before Rickenbacher made guitars of their own). National was an early entrant into the electric guitar market and while George Beauchamp was one of the earliest electric pioneers, he wasn't working for National at the time. Apparently National made the first electric guitar with a fully compensating bridge though...
Blues guitarists who played National guitars include Son House, Booker White, Blind Boy Fuller, Bo Carter, Tampa Red, Walter Vincent, Bumble Bee Slim, Scrapper Blackwell, Black Ace, "Kansas" Joe McCoy, Memphis Minnie, Peetie Wheatstraw, Brownie McGhee, Ernest "Whiskey Red" Brown, Henry Townsend, Henry Johnson, Archie Edwards, Sister Rosetta Tharpe, Robert Petway, Hammie Nixon, Tarheel Slim, Robert Johnson (reportedly), Blind Arvella Grey, Oscar "Buddy" Woods, Reverend Gary Davis, Babe Stovall, Kokomo Arnold, Gus Gibson and Doug Quattlebaum. Most of those guys (and gals) played Duolians or Triolians but there's some Style O's, Style N's and a number of Tricones and wood bodies in there as well.
National guitars were by far the loudest guitars you could buy in the 1930's so I guess it's no surprise they were used so much in the blues. Hawaiian musicians rarely (possibly never except for King Bennie Nawahi, who played a wood bodied Triolian) used the single cone guitars for slide playing because they don't have enough sustain (the notes die off too soon) and they have much less complex and quieter harmonics compared to the tricones. Some single cones have less sustain than an ordinary guitar so they're no good for those long slides that make Hawaiian guitar so great.
As well as the volume, the tone of National guitars means they are clearer and more defined than most wooden guitars, even at very low volumes. Also they have a huge dynamic range, (the range between loudest and softest) but the most noticeable difference between a National and a normal guitar (after the volume and appearance!) is the huge amount of percussion. You can get a really loud attack to the notes as well as the percussive effects of metal fingerpicks on the strings and the gunshot sounds when you snap the strings against the frets - all of these things making them ideally suited to blues.
Another reason they were used so much for blues could be that they can sound a bit like a banjo (which is what some people don't like about them!) because the banjo was really the first blues instrument.
It's amazing to think of the solo acoustic guys (and gals) in the 1930's playing and singing un-amplified in noisy clubs or on the street. Even the guys with National guitars - if you play a National as loud as you can it's much louder than a "normal" singing voice and as soon as you play un-amplified in a pub you can hardly hear it! I know audiences were accustomed to much quieter music then but I just can't imagine doing a gig in those conditions without a National guitar!
Of all the types of National guitars, the style "O" is my personal favourite. The tricones have a fantastic huge sound, very even tonally, huge dynamics and lot's of sustain. The steel bodied single-cones (duolians and triolians) have a more trashy, bluesy sound, they have louder, more "middy" sound, with more echo to it than the tri-cone, a louder, more percussive attack but much less sustain. The Style "O" (single cone, brass body) has a sound somewhat in between these extremes - it may not have enough sustain or harmonics for Hawaiian music or too much sustain for some Delta blues depending on your tastes (and technique) but I believe I can play a wider variety of music on them than any other style. And of course there's the palm trees! I think it's a wonderfully optimistic, idyllic picture. I mean, you'd describe it as nostalgic if it were on paper - but it's sandblasted onto a metal bodied guitar!
Actually it's an interesting comment on the range of National tones that the Style O is some people's least favourite. Some say that the brass bodies soak up too much of the string vibrations that should be going to the cone but I think they tend to have a more mellow bass tone that suits my playing more. It just shows that there's a National model for everyone!
I should also say that, while the different models do have different sounds which you may prefer for one style or another, you can play any style of music on them. It is a common misconception that you have to play slide or blues or Hawaiian on a National guitar. The exceptions are the "Hawaiian" or "square-neck" models. National (and most other contemporary companies) offered guitars in Hawaiian or Spanish configuration - Hawaiian guitars have square necks to increase sustain for slide playing and for the increased strength required for higher string action. You can of course play "Hawaiian" or "lap style" on a Spanish model but not the other way around.
The Hawaiian tricones generally had square metal necks (which look really cool), and the single cone Hawaiians had square wooden necks. I've seen wooden square necks that have been crudely whittled down by frustrated Spanish players!
Because National stopped making metal bodied guitars in 1941 and only started again in the 1990's, many companies and individuals have sprung up making copies. The re-birth of the National company polarized these companies into making either luxurious, expensive, handmade guitars or very very cheap ones. There are a number of companies making cheap metal bodied guitars. Most of them are the wrong shape, they just look ugly, they have gaps and messy welds, loose bits etc. but they're affordable so maybe they'd sound good if you could put a National cone in them? I don't know, I had a steel bodied copy and it sounded like a rubbish bin.
The new National company however makes FANTASTIC guitars - I would have paid a lot more for mine if I had to!
Besides their great respect for the history and soul of the old instruments, the new company have made some NEW models as well, much as the old company would have done if their market hadn't disappeared. They make steel tricones and baritone and twelve string versions of all the models, which the original company was experimenting with in the 1930's.
You'll hardly ever see a (vintage) Tricone - but you can't miss them if you do - ALL the original Tricones were nickel plated German silver or nickel plated brass (Styles 35 and 97) - so they're all shiny, chrome-ish looking things with a triangular cover plate (not round) and with criss cross grilles on the front.
Tricones came in six different models. The relatively rare Style 35's and 97's (1936-1940) were nickel plated brass - like the Style O - with sand-blasted scenes on them. Style 35 has a minstrel playing a lute on a bridge (!) and Style 97 has a girl surfing on the back. They're quite strange pictures and unlike the Style O - they're in colour! I'm not sure how they're done - I guess it's just paint because I've seen old ones with little or no colour left on them. (The last ones were made with no colour.)
Just before the Styles 35 and 97 there were a very small number (possibly only three or four) experimental guitars believed to be brass bodied but with very strange, abstract sandblasted patterns on them featuring comets, stars, explosions or palm trees. These few guitars are known as "exploding palm tree" models - they possibly all had wooden square necks.
All the other tricone models (1928-1941) were nickel plated "German silver" which is also known as white brass and apparently sounds quite different to yellow brass (I have played a German silver tricone and it was the most amazing guitar I've ever played but it was so long ago I really can't remember enough to compare it with a brass one). The German silver tricone styles are numbered according to the pattern of engraving - style 1 has no engraving, style 2 has roses on it, style 3 has the more elaborate lily-of-the-valley design and style 4 has a very elaborate chrysanthemum pattern. (Many people including John Dopyera believe the style 4 has too much engraving - John Dopyera may have objected also because George Beauchamp is said to have designed the pattern. It does look a bit busy though...I think.)
The engraving is very well done and although it did add a fair bit to the cost of the guitars, I think a style 3 tricone is one of the most beautiful guitars ever made.
If it's a metal bodied single cone - it's either a Duolian, Triolian, Don, Style N or Style O. Duolians are steel bodied (although you can't tell by looking at them unless they're rusty) and either have a weird "crystalline", semi-transparent painted finish (1931-1937) which ranges from green-ish to brown-ish to gold-ish depending on how they've dried. There has long been debate as to what this finish actually was but it is now believed to be a mixture of Naphthalene (a mothball ingredient) and Shellac - several people have made good replicas with this recipe although I believe it is prohibited for commercial manufacture in the U.S. by environmental and health laws. The later models (1938-1940) have a quite realistic wood-grain paint job. Also it says "Duolian" on the headstock!
The first Triolians (1928-1929) were wood - then steel (from 1930) and were painted PINK or YELLOW with hula girls and surfer decals on them - you can't miss them - then they were yellow with a crudely stencilled black palm tree scene on them (1929-1930) - then the stencilled scene models were continued (in slightly toned down hues) but there was also offered a lovely brown sunburst finish (1930-1936) that was lighter over the centre of the coverplate and over the f-holes - then they had the realistic wood-grain finish from 1937 to 1941 - they also all have "National Triolian" on the headstock.
If it's a single cone and it's shiny (i.e. not painted or "crystalline") it's an "O", a "Don" or an "N". The Style O (1930-1941) is by far the more common of these and has the (relatively) subtle palm tree scene sandblasted on it - the Style N (1930-1934) looks the same but with no patterns on it at all (it's actually made of German Silver and is very rare because it was plainer and more expensive than the Style O) - The Don (1934-1936) is the other German Silver single-cone but has sort of geometric art deco floral designs engraved on it. It also has "Don" engraved on the coverplate strap (Why? We don't know!).
All the early single cone guitar styles had "flat-cut f-holes" and the neck joined the body at the twelfth fret. The f-holes were changed in 1933 to a "rolled-in" design, which is also slightly shorter - the edges of the cuts are folded in, rather than just flat. Then all the single cone guitars were changed to fourteen fret models in 1935 with the same length neck but shorter bodies. For one year only twelve-fret guitars were made with rolled in f-holes so you'll hardly ever see one - although the new Style O's are modelled on the 1933-34 model - I think it's the best looking one - I don't like the short body as much.
There's an argument that they're the best sounding ones too - although it's all subjective - the rolled-in f-holes strengthen and stiffen the top, sending more vibration through the cone and also the longer body gives a bit more bass than the fourteen fret models. That's the theory anyway.
Any guitars that have "National" on the headstock, are metal-bodied but are different to the above are probably new ones - or really valuable rare ones I don't know about!
No National page would be complete without a "playing considerations" section so here 'tis. It's quite hard to explain how different a National is to a "normal" guitar, but you find you have to alter your technique quite a bit. Because of the huge dynamic range you find that how hard you pick makes much more difference than on a normal acoustic or an electric guitar and you have to pay attention to much smaller changes in your picking style. This is most pronounced when using fingerpicks.
It's often been said before and I completely agree with Bob Brozman that you should use fingerpicks on a National. Partly because, with bare fingers you put much more sideways pressure on the strings which can move the cone about a bit and cause rattles, but also to take advantage of the huge variation of tones along the string length. Picking near the fingerboard or the bridge is like two different guitars, much more so than a normal guitar and it adds a whole new palette of expression you can use, but only with fingerpicks.
The other major consideration is string damping - if you just let each note ring you'll find it's like playing the piano with the damper pedal down, if you don't let it up you'll get a blurry clanging mess! So you have to damp the strings with both your left and right hands, more than on a normal guitar.
However this leads to another playing consideration, that of right hand position. On a single cone National, the coverplate strap is directly over the bridge - where on a Martin type acoustic you might rest your hand on the bridge to dampen strings, you can't do this on a National. In order to dampen strings you need to put your hand in front of the coverplate strap - meaning you can't dampen strings while picking near the bridge (because to pick near the bridge your hand is on the coverplate strap...make sense?). On a Tricone this is even more pronounced because the coverplate strap is T-shaped with the top of the T facing you - so to rest your hand on the strings you have to pick even further towards the fingerboard or adjust the angle of your hand.
One aspect that causes a lot of debate is string gauges. There are all kinds of theories about this but the easiest way to think of it is this - the neck angle, the strength and thickness of the cone, the height of the bridge etc. on National guitars were all designed to work with 1920's string gauges.
The cone is not physically attached to the guitar, it is held in place by the string pressure and in order to amplify properly it must be compressed a little by the strings, like a drum skin. If you use light strings, not only will there be buzzes and rattles, but the guitar will be much quieter.
The optimum amount of pressure was determined in the 1920's when guitar strings were like piano strings and the new models are made the same way. When tuning to open D or G you should use even thicker strings. I always tune to either open D or open G and I use those Martin Bluegrass Resonator strings which go .016, .018, .026, .036, .046, .056 and they're pretty cool (I have used the Michael Messer National strings made by Newtone in England and they are probably the best you can get - I just found the Martins were 80% as good and 50% of the price - but they're well worth checking out). You can still easily bend the thinner strings (especially the B string when tuned to A) and you get a huge, chunky National tone - the .056 could be thicker though, when tuned to D it's a bit quiet-ish (much thicker though and it wouldn't fit through the tailpiece!).
Many people have asked me how you get used to the 12 fret necks but all the acoustic guitars I own are twelve fret models - I learnt on one so I couldn't say. All these things are quite easy to get used to, as is the weight and the fact that you can't play them without a shirt on ('cause they're so damn cold!).
If you're thinking of buying one I would very strongly recommend you save up a little bit more and get a genuine (new) National - they really are better in every way and you will be rewarded with a real lifetime guitar (how many new Style O's have you seen second hand?).
It's impossible to recommend old National guitars because they are governed by the same rules as any old guitar but more so! All the original metal bodied Nationals are between 63 and 77 years old and while many have been treasured family heirlooms that play as good as new ones, many more have been almost completely destroyed. A quick search on eBay reveals models with "a 10cm square jagged hole in the top below the fingerboard" or "fingerboard and headstock replaced" or "small neat hole in the side of the body" (not pictured!) etc. etc.
Similarly to old Volkswagens, because they're built so tough and seem indestructible, previous owners have often "had a go" at their own repairs and modifications - more so than on a Gibson or a Martin or whatever. All that aside, they are built like tanks so if you are prepared to spend money on repairing one, there isn't much that couldn't be fixed. I'd love to have an old "crystalline" Duolian or a sunburst Triolian.
If you've just bought one I would say (congratulations!) bear in mind it may take a few weeks or months to get the hang of it - even a year or two later you start to figure out how to really play it. Also new models take a couple of months of playing before they really start to sound good - like really much better than they sound in the shop. And if you want it to look like Son House's guitar just play it on a really hot day and leave the sweat on there for two or three days and you'll never get it off! Looks great! Have fun!
If you want to buy a National guitar you could look here -