Premier Guitar features affiliate links to help support our content. We may earn a commission on any affiliated purchases.

Keeley Filaments Review

Keeley Filaments Review

Keeley’s first metal-oriented distortion excels—even beyond heavy realms.

Robert Keeley’s adventure as a boutique-pedal-world fixture began by modding overdrives and compressors. Since then he has also dabbled in fuzz and just about every other effect type. But the new Filaments pedal marks Keeley’s first concerted venture into pedal-driven, high-gain realms that make metal players drool and snarl.

Maxing the gain, I was first impressed not by the crunch, but by the quietness of the Filaments.

If you’re the kind of heavy player that savors fine-tuning and microscopic tone tweaking, Filaments will make you feel like a kid in a candy store. Tone options are abundant thanks to six knobs (level, presence, gain, bass, body, and treble) and three mini-toggle switches (boost, bright, and crunch). And it only takes a quick tour and twist of the knobs to hear that the Keeley can summon the essence of just about every metal style from djent to classic—and more than a few non-metal styles, too. Even better news: If you’re a plug-and-play guitarist and the presence of so many controls gives you option anxiety, you can skip the Xanax. It’s nearly impossible to make Filaments sound bad.


Extremely powerful pedal. Very wide range of sounds.

Metal-oriented package means other musicians might overlook this fantastic pedal.


Playability/Ease of Use:




Keeley Filaments

Lighting Up
I tested Filaments using an Ernie Ball Music Man Axis Sport through the clean channel of a Mesa/Boogie Lonestar Special and got going on my evaluation with all knobs on the Filaments at noon, save for the level. Here, at what you’d assume were middle-of-the road settings, the tones were aggressive and modern with excellent sustain. At first I had all three mini-toggles in the off position and brought them up one-by-one, to gauge their impact. The boost mini-toggle added a subtle but noticeable bump in volume. The bright mini-toggle dramatically changed the pedal’s character from a dark and creamy sound that was killer for liquid solos to a head-slicing tone that was perfect for articulate leads, pinch harmonics, and low “Master of Puppets”-type riffs, where clarity is mandatory. Engaging the crunch mini-toggle was the most ear blasting move you can make with the three mini-toggles, and resulted in a ton more volume and presence.

Maxing the gain, I was first impressed not by the crunch, but by the quietness of the Filaments. I was also blown away by just how much power it puts at your fingertips. It turned my Lonestar into a monster that remained amazingly articulate. (It’s worth noting that Filaments runs at 9V DC, but you can use 18V DC for more power and volume if you need it—an impressive notion.) Even with the gain cranked, the pedal cleaned up reasonably well when I moved my guitar’s volume knob down to about 4. The output was still plenty loud and had a lot of sustain, but it was clean enough for non-metal applications.

Slayed by Subtlety
If you need evidence that the Filaments can be more than a one-trick metal pony, try this maneuver: turn the gain all the way off, disengage the bright mini-toggle switch (keeping the boost and crunch mini-toggles active), and set all the other controls (other than level) at noon. At this setting, I got an incredibly sweet and singing overdrive sound—again with crazy-long sustain that would be perfect for modern blues or fusion. Notes were smooth sounding and chords sounded clean with a slight edge if I rolled the guitar’s volume knob back to about 7 or 8, softened up my attack, or used my fingers to pluck the strings.

The Verdict
With three gain stages, Filaments has the capacity to be a fire-breathing dragon. But even if you’re not a metalhead and just want a powerful compliment to a mid- or low-gain pedal in your setup, Filaments should be at the top of your short list.