How Resonator Guitars Work and Sound So Cool
Resonator guitars are the literal bright shiny objects of the six-string world. Once you’ve heard and seen one, it’s hard to not be mesmerized by the sizzling, crisp ring of its tone or the look of that metal pie plate in the middle of the body that all of that sound comes from.
Resonators have been a favorite instrument of blues players from Son House to Joe Bonamassa, but they’re also a staple a bluegrass, where they’re typically square necked models played flat, much like a steel guitar. Resonators have also made indelible contributions to country music classics, like Johnny Cash’s “Southwind.” And they provide one of roots music’s coolest ways to add a distinctive sonic flair to an arrangement without plugging in — although today plugging in a resonator is always an option.
The distinctive sound of a resonator guitar, sometimes called a resophonic guitar, is derived from the spun metal cone or cones under the instruments’ round faceplates, which serve both a protective and decorative function. The wooden or all-metal body of the guitar itself certainly plays a role in generating that tone and in sustaining notes, but not anywhere near as significantly as in conventional acoustic guitars, where the top of the body is the instrument’s essential tone-generating component.
Like most good inventions, the resonator addressed a specific need — for guitar players to be heard in loud, multi-piece ensembles or in noisy locations like juke joints and house parties. This was well before plugging in was an option, in the mid-1920s. That’s when the National company first began mass producing these singing beauties, which took particularly well to the slide playing of such Delta greats as Son House and Bukka White.
Initially resonator guitars were built as lap steels, to capitalize on the Hawaiian music craze of the mid-1920s. Those Hawaiian-style guitars led directly to the square neck resonator six-string that’s most common in bluegrass and country music, with the Gibson Hound Dog Squareneck being a good contemporary example.
Quickly, however, the most commonly used resonators became round-neck models, early ancestors of contemporary resonators like the Gibson Hound Dog Deluxe. They were either wood bodied and necked, to produce a warmer tone, or all steel except for the neck, to cut through rooms with the authority of a switchblade. And their round necks made them easy to play for musicians who’d learned on conventional acoustic guitars. The blues musicians who embraced these guitars are primarily responsible for the continued popularity of resonators today.
The magic of resonators lies in metal’s ability to resonate hotter than a wooden guitar top. The trick is in translating the energy of picking and strumming into the instrument’s resonating frequencies, and the keys to that are cones and biscuits (yum!) and bridges.
When you see Delta bluesman Son House playing his classic “Death Letter” — which has been covered by the White Stripes, Gov’t Mule and a host of others — on YouTube, he’s frailing away at a resonator guitar with a tricone design. The tricone resonator was the brainchild of John Dopyera, a Slovakian immigrant and son of a violin-maker whose surname led to the term “Dobro,” which was initially a brand of resonator guitar and now is often used as a generic tag for the instruments. He attached three metal cones facing downward into the guitar’s body to the undercarriage of a T-shaped bridge. This allowed the energy of the strings of the guitar being struck to be distributed evenly among the three cones before being projected into the body. The result then emerges through the sound holes in the top of the guitar. Tricone models are the most high-pitched, brittle and ringing instruments in the resonator family.
The so-called “biscuit” resonator relies on a single cone, and the biscuit — which is mounted to the base of that inverted cone – translates the energy of picking and strumming from the bridge to the biscuit to the cone. The tone produced is more even-tempered and lower than that of tri-cone models, and single cone resonators are typically less costly as well.
The other popular resonator style relies on the spider bridge, which actually looks more like a fat-threaded web than an arachnid. Dopyera also invented this bridge and resonating system. In guitars equipped with spider bridges the single resonator cone actually faces up and the bridge is suspended over the cone by the webbing. That makes the resonator cone act more like a direct speaker, and makes spider-bridged resonators the loudest.