Audio clips were recorded with a PRS SE HBII into a Fender Hot Rod Deluxe mic’d up with a Shure SM57 into Logic Pro X.
Rhythm guitar (right side): Bridge pickup, peak at 3 o’clock, gain at noon, band pass mode, hi range
Lead guitar (left side): Middle pickup, peak at 1 o’clock, gain at 1 o’clock, low pass mode, hi range
RatingsPros:Authentic vintage-style tones. Handy output level feature. Cons: A bit thin sounding in the high-pass mode. Street: $179 Keeley Neutrino rkfx.com | Tones:  Ease of Use:  Build/Design: Value: |
Keeley’s latest iteration of their dynamically funky envelope filter is addictive, musical, and just plain fun. This version includes a handy output-gain trim pot on the side, a direction control switch, and the expected gain, mode, and peak controls. The Neutrino is based around an optocoupler, much like the classic Mu-Tron, which gives it a more nuanced (and pleasing) dynamic range. In other digital-based circuits the tracking can be questionable, with harsh high end, but Keeley’s Neutrino design squashes those concerns.
In short, an envelope filter responds to the output of your instrument to emulate how your foot would sweep a traditional wah pedal. Think of Jerry Garcia on “Shakedown Street” or Steve Wonder’s clavinet sound on “Higher Ground.” Each mode of the Neutrino offers a different tonal take: some are funky, others more atmospheric and lo-fi, but they are all musical and deep. I jumped in after the Garcia “quack” tone and was stoked to see how close the Neutrino could get. The response felt immediate and satisfying. For harder funk-style strumming, I backed off the gain a bit and upped the peak control. Watch out Nile Rodgers! Keeley has once again improved on a beloved classic and made it affordable, rugged, and accessible.
Test Gear: PRS SE Hollowbody II, Schroeder Chopper TL, Fender Hot Rod Deluxe
If 3 Were 6
With six times the controls found on the 1 and 2 versions (if you discount the original’s on/off slider switch,) the LPB-3’s control complement offers pre-gain, boost, mid freq, bass, treble, and mid knobs, with a center detent on the latter three so you can find the midpoint easily. A mini-toggle labeled “max” selects between 20 dB and 33 dB of maximum gain, and another labeled “Q” flips the resonance of the mid EQ between high and low. Obviously, this represents a significant expansion of the LPB’s capabilities.
More than just a booster with a passive tone, the LPB-3 boasts a genuine active EQ stage plus parametric midrange section, comprising the two knobs with shaded legends, mid freq and mid level. The gain stages have also been reimagined to include a pre-gain stage before the EQ, which enables up to 20 dB of input gain. The boost stage that follows the EQ is essentially a level control with gain to allow for up to 33 dB of gain through the LPB-3 when the “max” mini toggle is set to 33dB
A slider switch accessible inside the pedal selects between buffered or true bypass for the hard-latch footswitch. An AC adapter is included, which supplies 200mA of DC at 9.6 volts to the center-negative power input, and EHX specifies that nothing supplying less than 120mA or more than 12 volts should be used. There’s no space for an internal battery.
Power-Boosted
The LPB-3 reveals boatloads of range that betters many linear boosts on the market. There’s lots of tone-shaping power here. Uncolored boost is available when you want it, and the preamp gain knob colors and fattens your signal as you crank it up—even before you tap into the massive flexibility in the EQ stage.
“The preamp gain knob colors and fattens your signal as you crank it up—even before you tap into the massive flexibility in the EQ stage.”
I found the two mid controls work best when used judiciously, and my guitars and amps preferred subtle changes pretty close to the midpoint on each. However, there are still tremendous variations in your mid boost (or scoop, for that matter) within just 15 or 20 percent range in either direction from the center detent. Pushing the boost and pre-gain too far, particularly with the 33 dB setting engaged, can lead to some harsh sounds, but they are easy to avoid and might even be desirable for some users that like to work at more creative extremes.
The Verdict
The new LPB-3 has much, much more range than its predecessors, providing flexible preamp, boost, and overdrive sounds that can be reshaped in significant ways via the powerful EQ. It gives precise tone-tuning flexibility to sticklers that like to match a guitar and amp to a song in a very precise way, but also opens up more radical paths for experimentalists. That it does all this at a $129 price is beyond reasonable.
Electro-Harmonix Lpb-3 Linear Power Booster & Eq Effect Pedal Silver And Blue
