It might surprise you to learn that the relationship between round back and flat back guitars is actually quite similar to how solid state amps relate to their tube brethren. (And the debate around the two is equally as hot!)
As far as history is concerned, the lute is arguably the most recognizable round back guitar. But that design didn’t really last, and contemporary round back guitars didn’t appear until the 1960s in direct response to the amplification boom.
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The Fight Against Feedback
Modern round back guitars are practically synonymous with The Ovation Guitar Company, which was literally started by rocket scientists. Aerospace engineer Charles Kaman was an avid guitarist who believed that the design of the acoustic guitar could benefit tremendously from advances in modern science.
Citing the known benefits of a semi-parabolic shape in nature and architecture (think amphitheaters and the human ear), Kaman and his team concluded that the best shape for a guitar included a round back.
As any luthier will tell you, bending wood is no small feat, and additionally, the braces and baffles used to create this effect serve only to dampen and absorb sound. So Kaman and co. began experimenting with various fiberglass composites they had been using on helicopter rotors and missile noses.
The end product was a smooth and incredibly durable fiberglass composite known as Lyrachord. To this day, Ovation guitars are made with Lyrachord, and other round back guitar manufacturers use similar fiberglass or plastic composites to get that curvy bowl shape without the use of braces or baffles.
Guitarists in the ‘60s and ‘70s welcomed this new design as the answer to their on-stage sound struggles. The original flat-backed acoustic guitar produces a glorious timbre and resonance that we all know and love. But when you place a microphone in front of it (the only amplification technology available at the time), that coveted resonance creates a frustrating level of feedback.
Ovation delivered an acoustic guitar whose round back and fiberglass material projected sound evenly. This guitar was designed to be amplified, and the likes of Josh White and Glenn Campbell welcomed it with open arms.
The company would continue to use acoustical engineering to improve their guitars for on-stage performance, introducing clustered sound holes and built-in preamps in the decades following its first release.
Round vs. Flat Comparison
Given that the round back guitar was developed specifically to be used for amplified performance, it is important for today’s guitarists to understand the noticeable differences, both in sound and function, between the two body styles.
Tone
Despite its technological advances, there are just some things the round back guitar cannot replicate. The timbre produced by wood instruments like the flat back guitar is undeniably richer and more textured, especially when played without amplification.
As noted earlier, flat back guitars produce more resonance than round back guitars and enjoy longer sustain. Again, this is highly desirable in acoustic settings, but difficult to mitigate when amplified.
That said, round back guitars are quite capable of producing a full sound that is brighter in tone than flat backs, even when not plugged in. When amplified, you will enjoy a built-in equalizer that allows you to adjust your tone to your ear, your songs’ stylings and the room.
Physical Considerations
Due to their thin wood construction (ideal for resonance) and smaller surface area, flat back guitars are lighter in weight than round backs. (Great for hauling, bad for shipping.)
However, the thin wood construction that produces the rich sounds we love is also prone to damage. Flat back guitars can chip, crack and split if not handled with care. Furthermore, it is not at all uncommon for these guitars to warp under conditions where temperature and humidity vary drastically.
For these reasons, round back guitars are generally considered sturdier – it would take a monumental force to crack or warp Lyrachord. However, it is worth noting that round back guitars still feature wood faces, and the seam where the fiberglass meets the wood can fail without proper care.
Finally, if you’ve visited any guitar forum thread on round back guitars, you’ll encounter numerous guitarists sounding off about how these guitars like to slide down into your lap when playing seated. (Of course, as with any online forum, you’ll hear from the other camp which seems to have no problem at all with slippage. “Just use a strap.”)
Play
Keeping in mind that modern round back electro-acoustic guitars were designed to be plugged in, they are often touted as being capable of pulling double duty, as both an amplified acoustic and an electric guitar.
To that end, their bodies are often shallower than a traditional flat-back acoustic, their necks are narrower, and they use lighter gauge strings. This can be extremely appealing to electric guitarists who want to expand into the acoustic guitar realm.
However, it should be noted that these guitars are still acoustic at heart. As noted above, round back acoustic-electrics can lack the nuance of your beloved Martin, and similarly, you’re not going to be doing any shredding on it like you can on your Strat.
When to Use a Round Back Guitar
In the end, round back acoustic electric guitars offer a desirable versatility to performing musicians. Rather than lug around both a hefty flat back acoustic and an electric, round backs can offer the best of both worlds with minimal compromise in sound and play.
They are bright, optimized for amplification, and just plain unique.
Plus, just look at that super space-age, futuristic design!
