The Aguilar Filter Twin Envelope Pedal brings the iconic Aguilar filter circuitry into a compact stomp box format, providing bassists with expressive analogue filter effects in a pedalboard-friendly size. As the name suggests, the Filter Twin utilises two filters sweeping in opposite directions to open up a wider range of funky, vocal-like tones. With just four knobs and a single foot switch, this pedal offers a streamlined interface while packing some powerful sonic shaping capabilities. Let’s dive in and see what this dual-envelope filter has to offer.

Initial Impressions

Right away, the quality construction of the Filter Twin is apparent. The heavy-duty steel enclosure feels sturdy and road-ready. The four no-nonsense control knobs have a smooth rotation with enough resistance to stay put when left alone. The single foot switch engages the pedal and a bright blue LED indicates operation. The jacks are securely mounted along the sides. It’s clear that his pedal was built to withstand the rigours of stage use.

Plugging my bass into the Filter Twin, I started with the controls at noon and switched the effect on. The familiar filter sound was immediately recognisable – a vocal, cocked wah-like tone enhancing the natural resonance of the instrument. Adjusting the Threshold knob brought more sensitivity and movement to the filter effect. Cranking up the Velocity knobs intensified the sweep rate, pushing the funkiness into overdrive. Faster “quack” sounds that would sound great on a guitar too. So far, very cool.

Here’s where things get interesting. The Blend knob allows you to pan between the up and down filters. With Blend turned fully counterclockwise, only the downward filter is heard, sweeping closed from bright to dark. Turned fully clockwise, now we get just the upward filter moving from dark to bright. At noon, both filters contribute equally to a more complex envelope interaction. This pan control essentially doubles the tonal palette, making it easy to switch between conventional and inverse filter effects on the fly. Very handy.

Into the Multi-Envelopeverse

To explore the full range, I maxed the Threshold and Velocity settings, then slowly blended between the filters. With aggressive playing, the filters danced together in a harmonic ballet, tracing the dynamics of my hands on the strings. You may find that lighter dynamics favour one filter over the other depending on how you intend to use the pedal. Easing off on the Velocity evened things out for more subtle textures. This interactive quality makes the Filter Twin come alive under your fingers.

Aguilar Filter twin

Activating some overdrive before the Filter Twin fattened up the core tone and introduced some gnarly edge to the envelope articulation. The filter effects also worked well after modulation and delay effects, adding animation to modulating effects.

Looking at the operation of the Filter Twin and envelope pedals, in general, it’s useful to note other pedals in your signal chain and the output level of your bass guitar. The Filter Twin operates by sensing the envelope of your instrument. That is, your loud sounds and your quieter sounds, and how that changes as a transient (when you pick a string) and as the note dies out over time. You may have a bass with active electronics with lots of bass boost which could affect the low-end sensitivity of the pedal, or a passive instrument with a much lower output level. In both of these cases, adjustment of the threshold will require different settings, especially when switching between these two instruments. In some ways, this is a good thing, as it can challenge a player to experiment with the new setting, rather than setting and leaving. On the subject of other effects pedals, place your Filter Twin at the start of your signal path, if you are using compression or distortion effects. Both, on heavier settings, smooth out and flatten your dynamics to an extent (depending on settings) which can affect the “triggering” of the filters on the Filter Twin.

The Bottom Line

On the whole, the Filter Twin nails the classic envelope filter sounds, while opening up fresh new possibilities thanks to the twin filter design. From funked-out slap riffs to tripped-out dub delays, this pedal brings interactive animation to your sound. Aguilar has homed in on the essential tone-shaping tools, while keeping the interface simple. For envelope filtering on the fly, the Filter Twin packs a lot of versatility into a small footprint.

Let’s break it down:

– Heavy-duty build quality stands up to abuse

– Iconic Aguilar filter circuit voiced for bass

– Separate upward/downward filters sweep together

– Blend control pans between the two filters

– Threshold sets sensitivity to playing dynamics

– Individual Velocity controls for each filter

– Highly interactive response puts control under your fingers

– Compact size with intuitive control set fits any pedalboard

From vintage swampy funk, to cutting-edge psychedelic dub, the Aguilar Filter Twin serves up an expressive array of envelope filter effects for modern bassists. This thoughtfully designed pedal makes it easy to unlock that chomping, wah-like animation perfect for sparking rhythmic grooves and taking solos into the stratosphere. If your sound could use some shake-appeal, the Filter Twin has you covered.


Manufacture:Aguilar Amplification
Model:Filter Twin
Controls:Threshold, Velocity x2 Blue LED and Footswitch
I/O:One ¼” input, one ¼” output, one DC power input.
Circuit Topology:Analogue
Housing:2mm (.080") thick 5052 aluminum alloy
Dimensions:93mm x 38mm x 45mm *including knobs.
Power Supply:9VDC battery or external PSU (not included) via 2.1mm DC jack.
Current Draw:10mA
Input / Output Impedance:1MΩ / 1KΩ
Max Output Level:+6dBu (1.6vRMS)
Noise Level:-94dBu (A weighted)
Warranty:3 year limited
Price:$249.99 ~ £282 UK