Today, most electric guitars seem like conservative variations on a master theme. Body shapes don't veer too far from established precedents. Pickups are neatly divided into several proven designs. Basic volume and tone controls haven't changed in over half a century.
This narrow range of design permutations isn't due to a lack of imagination. Guitar concepts have standardized to a degree because of wild and uncanny experimentation. We just don't see - or remember, for the younger readers - the failed experiments anymore.
Guild's built-in guitar "kickstand." Rickenbacker's 12-to-6-string conversion "comb." Gretsch's string mutes. Amps built into the guitar or case itself. Modular onboard effects. Vibrato units that actually split the guitar in half. The list goes on.
Gibson's Varitone circuit was born during that same innovation-rich period of the late '50s and early '60s. Somehow, it has survived, like a vestigial organ or appendage. Players continue to regard it with mystery and question its usefulness, but the natural selection of the free market still hasn't deleted the Varitone from the electric guitar's master DNA.
What the Varitone Circuit Does
Below that chicken-head knob lies a notch filter with six separate capacitors soldered to switch decks. The first position (1 on the dial) is true bypass, allowing the signal to go straight to the volume pot from the pickup, with no resistors or capacitors in the way. The other five steps on the switch remove certain frequency ranges of the tonal spectrum, creating different EQ maps for each.
There are no specific names for these maps, leaving players to use terms like squishy, underwater, and guitar-in-a-box.
The exact frequency slices taken out at each step vary by company (Gibson or Epiphone) and era (the '70s produced notably different circuits), but the basic idea has always been the same: the Varitone allows for pre-set frequency "scoops" that you can dial in with the flip of a switch.
What the Varitone Circuit Doesn't Do
The Varitone circuit is not a compressor. It would also be false to label it as "just another tone knob" or "something like a wah pedal." It is a switch, not a potentiometer. Unlike the tone pot in your guitar or your wah pedal, which roll off higher frequencies in a progressive way, the Varitone switch jumps to predefined frequency scoops, preserving the lows and highs on either side of that scoop.
Sadly, many vintage Gibson ES-345 specimens have had their original Varitone circuits ripped out due to the persistent gospel that it "sucks out the tone."
As the owner of a modern Gibson with a Varitone switch and someone who's checked with reps from the company, I feel confident in saying the "1 position" on the switch is indeed true bypass and does not negatively impact the fullness or voice of the '57 Classic humbuckers in my guitar. As for the other positions, well..."sucking out" a range of frequencies is exactly the point.
The Case for the Varitone Circuit's Continued Existence
The Varitone switch first appeared on the Gibson ES-345 circa 1959. It has remained a standard feature of that model for its entire existence. It is also appears on some Gibson ES-355 specimens. Most famously, though, it is a feature on Gibson's B.B. King Lucille model. And this provides a window into why it has survived.
B.B. King had the Varitone switch on his guitar because he used it, not just because it happened to be a feature on a model that looked nice. See Scott's "The Thrill Is Gone" recommendation in the video above. Other players like Freddie King and Elvin Bishop also put the switch to good use. The models these players used - the ES-345 and Lucille - have driven Varitone-equipped guitar sales.
Gibson tried including the Varitone switch on newer models, such as the fantastic ES-137 Custom in the '00s and the Blueshawk in the '90s. Neither of these models lasted very long (though Epiphone still produces a Varitone-equipped Blueshawk Deluxe). Was it because players rejected the Varitone feature?
It's definitely not for everyone. If you get bored easily with experimentation or enjoy the comfort of having one familiar voice come from your guitar, then a Varitone circuit probably seems like an unusable distraction. For the rest of us, it provides voices and colors on the fly that are hard to achieve in any other way.