Players wanting to change the sound or timbre of an acoustic guitar, or just clear up any nasty tone issues or feedback, can look to digital processing or post-production for help. But Keeler Sound's Performer Series sound processors for nylon and steel string instruments make use of pipes and ports for the promise of an as-the-music-happens "perfectly balanced tone." Swapping out a unit's diaphragm, or not using one at all, will also alter the tone of the guitar.
The Jumbo and Shorty sound processors have been engineered to take on the roles of passive equalizer and dynamic enhancer. They feature a number of sound ports, brass chime pipes, intake and exhaust tubes, with a removable diaphragm to the rear.
The handcrafted units are said to grab hold of the sound produced by a player's picking and massage, manipulate and multiply the harmonic structures of the sound waves for improved or colored tone. The latter can be achieved by changing the diaphragm material to bring the acoustic properties of tone woods or carbon fiber to the sonic mix.
The Performance Series has been designed to fit most instruments out of the box, though Keeler Sound may be able to undertake custom builds for non-standard configurations. Installation is reported tool-free, with the strings being loosened, the unit lowered into the soundhole and kept in place courtesy of an anti-vibration shock mount.
Musicians are promised tightened bass registers and enlivened higher reaches. The units are reported capable of taking control of unwelcome sounds and feedback at the guitar itself, rather than in the engineer's booth at the studio, to make post-production tweaking a thing of the past.
The Jumbo unit is available for steel-stringed guitars only at a cost of US$299, while the Shorty comes in steel and nylon string flavors for $249 each. The sound processors are currently only available direct from Keeler Sound.
You can see (and hear) a Keeler sound processor in action in the video below.