ZeroFive Audio Lowrider Review

It’s based on a portion of the circuit from Pultec’s EQP-1A, an outboard equalizer still considered a classic more than 70 years after its introduction. You may be familiar with the device even if you’ve never seen an original, because it’s been cloned endlessly as a software plugin. You’ve certainly heard the effect on countless recordings.

Equalization Homage

The original Pultec is a 3-band passive EQ paired with a tube-powered gain stage. The Lowrider replicates only the bass section, with a modern op amp in lieu of tubes. Bass boosts are the EQP-1A’s most celebrated sound, thanks to an intriguing design quirk. The original has separate controls for bass boost and cut, and they’re often used simultaneously. That may sound pointless. Don’t the two controls cancel each other out? Nope—due to their different cutoff frequencies and ranges, you can generate massive bass boosts with the gain knob, and then clarify the low mids via the cut knob. Result: walloping lows that don’t get woolly or muddy.

On the Lowrider, the boost and cut controls are combined in a single “intensity” pot. This disappointed me at first. Wouldn’t it be best to have separate controls for bass boom and low-mid clarity? Yet the single-knob solution, with its baked-in boost/cut ratios, simply works. Every setting yields the Pultec’s signature big-yet-clear bass sound. You don’t get the idiosyncratic tube coloration of the original gain stage, but the op amp provides clean and attractive volume boosts with variable amounts of low-end wallop.

As on the original, a rotary switch lets you select the boost frequency. The two lowest settings have been raised to slightly higher frequencies better suited to modern bass tones. There are also two additional settings where the cut frequency is shifted further above the boost frequency for even greater low-mid openness.

Boost for Body and Bigness

Audio Clip 1 demos the six settings on bass guitar. You hear a short phrase eight times: first with the effect bypassed, then with strong boosts centered at 30, 45, 60, and 100 Hz, and then the two custom settings. The clip concludes with a repeat of the bypassed sound. To my ear, all settings are attractive and usable, and it took mere seconds to dial them in. And man, I sure missed the bottom-end muscle when I switched off the pedal!

The Lowrider may also be useful for guitarists, depending on what styles they play and how low they tune. The Lowrider’s lowest-pitched settings reside below the range of most guitars, but the 60 and 100 Hz positions add muscle to low-register baritone guitar lines (Clip 2) and chunky drop-D power chords (Clip 3). Again, both demo clips begin and end with the effect bypassed.

The Lowrider is expertly handbuilt, using full-sized, through-hole components. It has no battery compartment, but it works with any standard 9-volt power supply. You can also run it at 18 volts, where it can accept line-level signals. (That is, you can apply it as an outboard mix effect without using a reamping device.)

The Verdict

There are many ways to add low-end muscle to bass and low-register guitar parts, from pitch shifters to subharmonic synthesizers to modern parametric EQs. But a Pultec-style solution, as capably conjured in ZeroFive’s EQP-1A, is both musically satisfying and nearly idiot-proof.