Back when I had hair, I joined Project Karnak. They needed my bass to sound more like a synth. The best way to achieve this was an envelope pedal. I opted for the Aguilar Filter Twin which I liked very much. I later made this Aguilar Filter Twin demo video to show how much I liked this envelope pedal.
This video demo will demonstrate why I like this envelope pedal so much. If you prefer to read, the post continues below this video.
Why use a bass envelope pedal?
I was looking for an envelope pedal that would help me recreate a synth bass sound on an electric bass guitar. When I started playing for Project Karnak, I could hear that the bass parts had all been played on a keyboard synth bass. Some of these patches had a filter envelope shaping the sound.
In this case, the envelope controls a low-pass filter that would start out very open so the high frequencies are easily heard. As the synth plays a phrase, the envelope lowers the frequency of the low pass filter and starts to cut out the high frequencies. When the player ends the phrase the envelope resets. When playing legato, the envelope is spread over several notes without restarting. When the synth is played staccato, the filter resets for every note.
Aguilar Filter Twin Demo
Aguilar Filter Twin’s Filters & Blend controls
The Aguilar Filter Twin has simple, solid controls. When activated, the pedal applies two envelope filters, hence the ‘Twin’ part of the name. Each filter is essentially an EQ sweep, one travelling up the frequency spectrum, and the other down it.
The ‘Up’ filter has a similar effect to a wah-wah pedal being moved from the heel position to toe position. The ‘Down’ filter is exactly the same effect, but in the opposite direction. You could say, the ‘Down’ filter goes ‘OO-WW’ and the ‘Up’ filter goes ‘OO-WA’. Trust me, it makes sense when you hear it.
Each filter has a velocity control, these are the bottom two knobs of the four available. These control the speed at which the filter effect travels up or down the frequency spectrum. For example, with the ‘Up’ filter velocity set low, it takes about a second for the filter to get from ‘OO’ to ‘WA’. With the velocity set high, the movement of the filter is almost immediate.
The Blend control sets the mix of the two filters. It’s not a blend of dry and wet signals. It’s a mix of how much ‘Up’ and ‘Down’ filter you want to hear. If you only want to hear the effect of one of the filters, turn the blend all the way in one direction. By setting different velocities for the filters and then blending them to taste, you can easily create interesting envelope filters.
The Aguilar Filter Twin is a solid pedal with simple controls.
Aguilar Filter Twin’s Threshold
The threshold control sets the portion of the frequency spectrum you would like the pedal to work within. The filters don’t work across the entire frequency spectrum all of the time and it’s a relatively narrow bracket compared to other filter pedals.
When the threshold is set low, the filters are at the lower end of the spectrum and the effect can be quite subtle, even buried. With the threshold set high, the filter is more trebly. I prefer to have this setting between 9 o’ clock and 1 o’ clock. Depending on your dry sound and the notes your playing, you can really catch the transients of your notes and get a particularly punchy sound.
Using an envelope pedal to create a synth sound for bass
When recreating the synth sounds on bass, I would start with a generally downward filter envelope and this would be relatively slow. Setting both the blend and the ‘Down’ filter to 9 o’ clock achieves this.
Meanwhile, the ‘Up’ filter is set much faster, around 3 o’ clock. This adds a slappy squelch to the start of the envelope, adding to the attack of the notes played.
Staccato vs. legato playing
For me, the Aguilar Filter Twin’s greatest asset is how it triggers the envelope. Remember that the synth sounds being emulated wouldn’t retrigger the envelope on every note if the synth was playing a legato phrase. The envelope would only restart once there is silence between the notes.
Interestingly, the Aguilar Filter Twin does this really well automatically. It’s very intuitive to play and makes it a lot easier to get a predictable filter sound.
Why the Aguilar Filter Twin is better than the EBS BassiQ and MXR M82 envelope pedals
Whilst shopping around for the Aguilar Filter Twin I also tried a couple of other popular envelope pedals, the EBS BassiQ and the MXR M82. I felt that the Aguilar Filter Twin out-performed both of these pedals.
The MXR uses a decay control to set the speed of the filter sweep, however as the filter moves through the spectrum the pedal seems to boost the frequency a little too high and the signal seems to distort a little.
The EBS BassiQ is a better envelope pedal than the MXR M82, but it’s sound is very distinct and the filters a lot more aggressive than those of the Aguilar Filter Twin. The EBS BassiQ might be a better choice for the heavily stylised filtered bass you might hear on an old funk record, but for imitating a synth bass, it just sticks out too much.
I soon dismissed the MXR, but whilst testing the EBS I also found that I’d spend a bit of time adjusting the dry tone on the amp to make the filter tone closer to what I wanted. Another plus for the Aguilar Filter Twin is that the dry tone never needed to change to make the filter sound better.
Conclusion: Aguilar Filter Twin demo
In conclusion, I hope this Aguilar Filter Twin demo shows that this is a simple, robust envelope pedal that just sounds nice and always sounds nice. Some users might find that this pedal can’t achieve all the filter sounds they might want and you could argue the simplicity of the controls is limiting.
However I think it’s important to note that this pedal never sounds bad. The sound is never distorted or too weird or out of control as it can be with some other pedals. I originally recorded this Aguilar Filter Twin demo several years ago, and this pedal is still on my board at every gig to this day.