Shopping for the right resonator can be a nightmare but I've tried to condense some important information and resources on this page to help you understand the difference between various models, brands and features. Without getting into the quick sand of resonator history the main inventors of the resonator guitar are National and Dobro. Dobro is now owned by Gibson and National is a small shop still producing instruments in California. You can read more about the history below. In general there are metal and wood body resonators. They come with round necks and play just like a regular guitar or a square neck model that lays down flat when played. They are all driven by a resonator cone and make very loud and durable instruments that can put out a huge sound. I decided to play a round neck model. At that point I had to choose a single cone model or a tricone model with a wood or metal body. That lead me to a couple of years checking out various brands until I found the best match for my needs. When I finally found the right instrument I knew it was the right one. Hopefully after you run through this page you will understand the differences and will have a better chance finding the right kind of resonator. You may already own one and simply enjoy reading more information. In any case good luck.
COMMON COMPONENTS AND FEATURES OF RESONATOR GUITARS
THE SPUN CONE - The single cone or tri-cone is created by starting with a blank piece of aluminum and spinning on a machine that's much like a phonograph spinning a record but as the die moves from the inside outward it forms the metal around a cone shaped metal or wooden dye. The first resonators ever invented had 3 smaller cones then the single cone resonator was patented in the 1930s. SEE HOW NATIONAL SPINS CONES
Single cones come in several standard sizes and the tricone comes in one standard size (see sections below). The best way to test the sound of a cone is to stick a small screwdriver or punch up through the small hole and suspend it in the air then tap the rim with another small hard object. The super high quality cones will ring like a bell with sustain and clarity while the cheaper ones sound (clack) like you are hitting a cheap aluminum pie plate (see video). The main reason for the huge tonal difference is the method used to make the cone. The cheaper cones are simply stamped out in a machine and lack the consistency required to ring like a bell. You can usually tell which cones are stamped and not spun because they lack the little circular lines around the cone where they were spun. Hear the difference in cheap cones by watching the video.
Having a spun cone is not a guarantee you have a great cone. It has to be a well made spun cone such as those made by John Quarterman. In fact he began stamping his cones with a special logo because it's rumored that some other ambitious resonator builders were selling their own cones using his brand name. Here is an example of the stamp you'll find on the real Quarterman cones.
National resonators also spins their own cones and can usually be spotted by the 3 swirl shaped indentions they've begun stamping into the cones for extra strength. I think both their single cones and tri-cones are outstanding. Especially if you are going for blues. See the video on Luttrell Resonator Guitars and watch the master luthier compare the sound of cheap vs expensive cones and other useful information.
Cone Types and Sizes
SINGLE CONE - The single cone comes in a few standard diameters ranging from 9.5" to 10-3/8" for biscuit style bridges and 10.5" for spider bridge guitars. The strings transfer their vibrations to the single cone through either a spider bridge or a biscuit bridge. The large single cone usually has big open bass and a wide frequency response. They can have explosive volume and very quick punchy attack. The single cone can take on a little different personality based on the type of bridge used such as a biscuit bridge or a spider bridge. See and hear more details in the examples and the sound test. Even though they tend to be used for specific styles you can't really pigeon hole any model.
TRICONE - The tricone is a configuration that uses three smaller 5-5/16" aluminum cones. National not only spins the best tri-cones but they also add a small swirl design (see photo) which I believe adds strength to the cone. This configuration in contrast to the single cone design only has one kind of bridge which is a T shaped aluminum bar that sits on top of them and transfers the string energy from the saddle into the cones. The tricone configuration has less of the quick BANG attack of the single cone but offers the same energy spread out over a longer time period giving you the sustain needed for fantastic slide work. But contrary to what people think you can use any style resonator for any style music by modifying your technique. The tricone also seems to generate a fatter warmer tone with more overtones. Meaning when you strum the open D and then sweep up the first string with the slide it sounds like a whole band due to the complex overtones and increased sustain. If you want to sound more like Mike Dowling and you don't have his skill a Tricone in open D can be wonderful way to get that rich sound he seems to get with any reso guitar.
SPIDER BRIDGE - (single cone) - This bridge like all bridges transfers string energy or vibrations down into the cone. They call it the spider because it has multiple legs that span the diameter of the cone and apply the string vibrations to the outer ring and the center of the cone. This cone is shaped a little different and rises in the center to meet the saddle. This is where you begin leaving the National arena and getting more into the Dobro designs. In my limited experience Bluegrass players almost exclusively use this design in square neck resonators or Dobros. In my opinion the larger 10.5" single cone and design produces a very full bass and brilliant sustaining high end with a noticeable bluegrass twang in the middle of the neck. These still sound fantastic for blues but I lean more toward the biscuit bridge for a more raunchy style with a fatter midrange. I would certainly not limit yourself without trying both. This design usually uses a maple saddle with or without an ebony cap. This spider bridge just sits on top of the cone and held by string tension. Most of these have a small adjuster screw in the center of the saddle for adjusting the height. These are among the loudest instruments I've ever heard.
BISCUIT BRIDGE - (single cone) - This bridge design usually consists of a wooden (maple) disc with a slot in the top where a saddle is glued in and the strings ride over the top (see photo). The saddle is often held in place with a screw that comes up from beneath through a hole in the center of the cone. This is a very simple and reliable design that has the big open sound of a single cone resonator but slightly more bluesy funk and a little less bluesgrass twang than the spider. Also a little less volume and sustain than the spider. It does however sound much more like Son House, Blind Boy Fuller or all the old bluesmen. As you can see in the photo to the right I have the cover plate removed on an old 1970s Dobro brand resonator guitar. That I overhauled for a friend. You can see the entire process here. To lower the action on a biscuit bridge you have to file the slots deeper for each string and slope the back side slightly so they will ring clearly. To raise the action you either have to fill those slots with wood slivers or bone dust and cyano glue and refile the slots but the best way is to simple purchase another 10-12.00 dollar biscuit and replace it. Once the action is set on these beasts you typically don't ever have to mess with it again. See my article on how to replace and adjust the action on one of these designs.
TRICONE BRIDGE - As mentioned before the tricone typically has only one style of bridge. It's a casted aluminum T-bar with three small tits that sit down into the holes of the three aluminum cones. National was the company that invented this design and still even today have the same design cover plate which conforms to the T-shaped bridge causing the player to have to lay their palm of the picking hand on top of the cover plate channel. For some people this has always been an aggravation but a clever Aussie luthier named Don Morrison developed and refined his own tricone bridge system that can utilize a standard single cone style cover plate seen in the photo below with the green and yellow Donmo. Can you see the tricones hiding under the hole there? Not only does this tricone sound fantastic but only weighs in at a feather weight 6.3 pounds versus the 9.5 pounds of back breaking National. Plus it feels more balanced and doesn't slide off your lap while playing. After playing many tricones I knew I had to own one but most of them sounded too warm and I hated that National cover plate. So by going with the Donmo custom order I got the old relic look with a steel body that brightened up the tricone sound and the design eliminated the crossbar hassles.
COVERPLATE STRAP - This is usually something you can remove on newer National resonator guitars to access the saddle for minor adjustments but many older guitars have this cover welded on. Most Dobro style cover plates also have a permanent non removable cover strap. That can be the worst hassle when adjusting or setting up a resonator and a valid consideration when buying. If the resonator is poorly setup or designed you won't be able to make the strings and saddle line up properly. You also need to pad this area when shipping or the pressure coming down on the top of the guitar can crush the cone and coverplate or simply bend them downward and ruin the setup entirely and require some minor repair work. Place a foam cutout around the face of the guitar before closing the case so the bridge area cannot touch the inside of the case lid during shipment. Almost all dealers ship without this type of extra packing care. Then they act surprised the strings are all buzzing when it arrives.
TRAPEZE TAIL PIECE - This is the trapeze tailpiece which simply holds the strings in place on one end. This part has to lay down on the surface of the guitar and is usually padded with a small piece of felt. Otherwise it can be a source of rattles and noises. Many old time players rake their pick across those strings during songs for a special "ching-ching-ching" effect. This must sit down lower than the height of the saddle so the string break angle remains as steep as possible and applies maximum down pressure from the strings to the saddle. When filing the string slots in the saddle I usually sweep downward with a few light strokes of the file on the rear of the saddle string slot to maximize the tone and reduce minor deadness in the strings.
THE SOUND WELL - In many older Dobro designs and also many cheaper brand resonators you will find the sound cavity beneath the cone is not much more than a wooden cylinder. This in my opinion highly restricts the sound in the sense that the body and tonewoods used in the construction of the body have less affect on the tone. Additionally you can have total failure of the instrument if the structural elements and cheap design allow the sound well and the surface the single cone sits on to warp or become unround. That would be the time you realize the cheap Asian model was not such a great investment and not worth the price of major repairs. So you once again have some great wall art. As you see in the photo (right) this wooden sound well has holes cut in it but they don't all have that feature. Unlike the wooden resonator guitars the metal body resonators don't require a sound well and the whole body plays that role. See the photo on the left and notice the strong supports and metal lip that the single cone rests upon. I believe when buying an extremely cheap resonator guitar the metal bodies provide more natural reliability. The neck also has a stick that runs the complete length of the body providing strength and sustain.
ALTERNATIVE DESIGNS - Some people have a pretty wild imagination and great sense of humor when it comes to resonator design. I've heard of a hot guitar design but I wouldn't want to grab that resonator the wrong way! Although you can feed a family cooking with it.
On a more serious note master luthier Ralph Luttrell of Atlanta Ga has decades of guitar building and restoration experience and a special talent for building incredible tone with is L-100 and T-100. Although he learned from some of the finest resonator builders in the industry such as Tim Sheerhorn he soon went his own direction with the design. The heart of the tone, power and sustain of the Luttrell resonator guitar comes from the neck stick being anchored into a specially tuned truss that transfers vibration to the back bracing. The entire body is used as the sound chamber maximizing the woody timber and quality of the hand chosen master tonewoods.
This design not only uses the entire body of the guitar as a sound well but the design makes the entire guitar very woody sounding, more responsive and they project much better than any other wood body resonator I've heard. Just listening to him play a T-100 in this shop tour video gives you some idea of how far the tonal envelope is being pushed with modern resonator designs.
GENERAL BODY MATERIALS - I think the first thing to consider is the design of the guitar. If the entire body is used as the sound cavity you may see a bigger difference in the overall sound based on the wood or metal choices. I can give you some of my impressions. Brass is a very balanced and warm metal for musical instruments and one reason why cymbals and horns are made from it. Compared to steel it has a less edgy and less tinny sound. Steel sounds like you would expect with a tinny quality and a little brighter edge. These qualities can work with and against you based on the type of instrument, cones and what kind of sound you like. A single cone biscuit National like a Style O in brass has a huge warm slightly twangy sound without any harshness on the trebles. The exact same guitar made in steel with nickel plating has a more bite and edge, slightly more tinny and old rag timey sound. They both sound great but you can hear the difference in brass and steel. Please see the finishing section below for more details on how the inside finish of the guitar can alter the tone. On a more warm sustaining tricone resonator the brass can sometimes be pretty warm. Almost too warm at times and the edge and bite the steel gives you might be an option to consider. In any case it's important to realize the body materials whether wood or metal will make a difference if the whole body is used as the sound cavity. Just go tap a piece of brass then a piece of tin roof and it won't take a luthier to hear the difference. Same with woods which we can cover in the next section.
WOODS, BASS, PROJECTION - The same general qualities I've seen in guitars and various back and side woods seem to play a similar role in how these resonators project and sound in the bass and mids. If the body is used as a critical part of the sound chamber you may experience these general qualities. I base much of this information on my tests of Luttrell guitars constructed with identical specs and resonator components but with different tone woods. These various qualities did not surprise me at all. Any of them with a sitka top and rosewood back had metallic big trebles with piano deep reflective bass. The maple models had clarity on the high end with a very fundamental tone and punchy bass that punched more in the lower chest area than the gut. Mahogany models did have the deeper bass with a nice throaty sound but were more woody and warm than the rosewood models and the highs were more smooth. I even tested a mahogany top and back model with an even more warm huge throaty sound. Some of these wood based reso designs aren't too far from sounding like a very powerful flat top acoustic guitar. On the flip side of this coin some resonators have laminated (glued layers) backs and sides and some have sound wells blocking some of these effects. There's no way to tell how great a resonator might sound. So don't think too hard about this stuff. Go play some and make your own judgements.
BODY FINISHES - Not a huge difference what the outside finishes are as long as they are easy to maintain, strong and thin. The inside of almost all wood and metal resonators is unfinished with the exception of a two models from National known as the Delphi Steel and Polychrome Steel series. This powder coated finish inside the steel body warms up the sound and certainly tames some of the tinny or bright sound brought on by the steel body. So if you bought the exact same guitar as the Delphi with a steel body but a nickel finish like the VS model you would not have the powder coated texture inside taming the biting tinny sound. Likewise the tricone Polychrome model would have more bite and trebles without the powder coating inside. The Brozman and National sites go into much detail on finishes not making a difference and I agree with that most of the time but in this specific scenario the powder coating inside makes a difference. Imagine hearing a guitar with fresh bright strings and then hearing it again with warm used strings. That's a good way to think of the amount of difference in tone when the powder coating is inside. If I had the powder coated models I would more than likely have to stick with fingerpicks to get the attack and brightness I like. The only real difference in outer finishes is the look and durability. Nickel does wear faster but it also looks more warm and golden tinted in the light. The chrome plating models have a colder blue tint but they are more durable and don't tarnish. You can wipe all these down with windex window cleaner or metal polish but you cannot make them shiney and new all the time. They actually look better just letting them go.
TUNING MACHINES - You are constantly tuning and retuning resonators from open D, standard and open G. Why would you own a $ 2-3K resonator then use 25.00 dollar chinese tuners? I try to use the Waverly 3 on a plate tuners when having a new instrument made. I would never put a cheap set of tuners. I'm not that crazy about the stock tuners National uses either.
STRING CHOICES - Please don't buy 10 sets of resonator strings with your new round neck. Just save yourself a whole lot of pain and buy 2-3 sets of DAddario EJ-17 Mediums PBs. They sound fantastic and make slide playing easy but also can be played like a regular guitar. Your new National Style O round neck is not just a slide guitar. It's a whole guitar. Play it in standard tuning, drop D, open D and G. Remember it needs decent action. Just increase your slide skills a little bit and work with the mediums 13-56. If those aren't working great for you and still want bigger strings just swap out the first two with a 14 and 17 and see if you like that. Slapping massive reso strings might choke the tone right out of your cone and if not careful you might mess something up in the process. When you first get a new reso clean the strings and try to get a good bearing before you begin changing things. Talk with some other players and get some recommendations before jumping the gun. Bluegrass Dobro players use entirely different setups than many Delta Blues players and so on.
LB's own resonator FAQ