The Tech 21 Killer Blue Wail Bass Wah is a wah pedal built specifically for bass. Where a guitar wah can thin out a bass signal as it sweeps, Premier Guitar notes that "unlike guitar wahs, the Killer Blue Wail for bass keeps the low-end intact"1. Tech 21 says the pedal "preserves the original tonal integrity of vintage wahs and overcomes familiar shortcomings," naming excessive noise and unreliable mechanical parts among them2.
How the filter works
Rather than the simple band-pass or low-pass filters found in many wah designs, Tech 21 says the Killer Blue Wail's emulation uses a specially-designed filter that changes both the frequency and the Q, meaning the sharpness of the filter, as the pedal rocks2. For a bass player, that is the part of the design the maker points to when explaining how the pedal sweeps without hollowing out the note underneath.
What the maker says the design does:
- Changes both the filter frequency and the Q as the pedal rocks2
- Preserves the original tonal integrity of vintage wahs2
- Overcomes familiar shortcomings of vintage wahs, including excessive noise and unreliable mechanical parts2
- Keeps the low end intact, where guitar wahs do not1
The rocker and the light sensor
The Killer Blue Wail features a spring-loaded rocker that returns to its resting, or bypass, position when you remove your foot, and it automatically engages when you press forward on the pedal2. That is a different feel from a conventional wah, where the pedal stays wherever you leave it.
Inside, the pedal uses light sensor technology rather than a pot turned by the rocker. That speaks to the common failure point on older wah pedals, where the internal pot gets scratchy or cuts out2.
"Utilizing light sensor technology, there are no clunky pops, no irritating scratching sounds, and no pots to wear out."
Housing and power
The housing is machined from solid billet aluminum, which Tech 21 says will provide long life2.
| Specification | Detail |
|---|---|
| Dimensions | 3.375″w x 8.0″l x 1.75″h2 |
| Weight | 24 oz.2 |
| Housing | Machined from solid billet aluminum2 |
| Battery | 9V alkaline, not included2 |
| External power | Former Tech 21 power models #DC2 and #DC42 |
The pedal takes a 9V alkaline battery or Tech 21's former #DC2 and #DC4 power models2. Players planning a daisy-chained supply should check what their adapter offers against those model numbers before relying on it.
Background and release
The Killer Blue Wail for bass arrived as part of a move by Tech 21 to take the Killer Wail, previously a Private Stock limited edition, into full-scale production. Premier Guitar reported the lineup as three pedals1:
- Killer Wail v2
- Richie Kotzen Signature RK Killer Wail
- Killer Blue Wail for bass
Tech 21's product page lists anticipated availability as August 20252.
Tech 21 makes a range of other bass pedals, including the SansAmp Bass Driver DI V2, the dUg Pinnick signature distortion, and the Geddy Lee Amalgamation Signature Chorus. For more on the effect type, see Wah-Wah Pedals and Bass Pedals.
Videos
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Questions
Does the Killer Blue Wail Bass Wah have pots that wear out?
No. Tech 21 uses light sensor technology in the Killer Blue Wail Bass Wah, and the maker says that means no clunky pops, no irritating scratching sounds, and no pots to wear out. That addresses a familiar complaint about vintage-style wah pedals, where the pot that the rocker pedal turns can get noisy or scratchy over years of use.
What size is the Killer Blue Wail Bass Wah?
Tech 21 lists the pedal at 3.375 inches wide, 8.0 inches long, and 1.75 inches high, with a weight of 24 oz. The housing is machined from solid billet aluminum, which the maker says provides long life.
Why does a bass need a different wah from a guitar?
A guitar wah is voiced for a guitar's range and can pull the low end out of a bass signal. Premier Guitar notes that, unlike guitar wahs, the Killer Blue Wail for bass keeps the low-end intact, so the fundamental of the bass note survives as the filter sweeps.
Is the Killer Blue Wail Bass Wah true bypass?
The pedal uses a spring-loaded rocker that returns to its resting, or bypass, position when you remove your foot, and it automatically engages when you press forward on the pedal. Tech 21's product page does not use the term true bypass, so the bypass type is not described beyond that spring-loaded design.
Sources (2)
- Tech 21 Killer Wail Wah Pedals Unveiled, Premier Guitar, 2025-03-03
- Killer Blue Wail Bass Wah, Tech 21 NYC, 2025-07-30
