Review: Leapwing Audio RootOne

This new subharmonic generator plug-in supposedly offers the cleanest low end yet. Time to find out just how low it can go.

Price £180
Leapwing Audio

We all like full-sounding low-end in our mixes but it can be a tricky thing to achieve while retaining clarity and punch. There are a number of tools on the market to help boost the bottom, from Waves’ classic MaxxBass to more recent tools such as Brainworx’s bx_subsynth. Now Leapwing Audio has entered the fray with RootOne; a multi-band subharmonics generator with pitch tracking and phase alignment that claims to
offer the cleanest low-end yet.

Sub club

The traditional technique used by subharmonic generators is to use a band-passed pitch-shifted signal. But the engineers at Leapwing Audio felt that this resulted in a sound that was detached from the original audio, so they set to work on developing a new analysis-synthesis algorithm for generating the cleanest subharmonics possible. The trick was in making sure it was phase-aligned to the original sound, a task that took them the best part of a year-and-a-half to achieve. The result is RootOne, which has three low-frequency bands (labelled Sub, Thump and Punch), with variable crossover points. The algorithm checks for the presence of a frequency an octave above each band, and then generates a
pure tone that pitches track to the original.

The subharmonics range from 10Hz to 196Hz, and you can blend all three bands together. Setting the crossovers is confusing at first, as you have to double each figure to work out which frequencies will fall into each band. You get three sliders to blend in the generated signals, plus a fourth saturation band for adding additional low-mid harmonics. This section has a drive amount, colour control for choosing between tape and tube style distortion, and a low-pass filter that goes from 100Hz to 1kHz to reduce the top end. You can also drive individual subharmonic bands into the saturation for more thickness. The sliders have been well calibrated to give more extreme processing at the top end of the scale too but you have a lot of control around the sweet spot to create more subtle and natural sounding results. It’s extremely smart.

Stay on track

On top of the pitch tracking, you also have volume tracking, which helps the signals hug the original audio and thus create a more natural result. This can be controlled on a per-band basis using the dynamics control, with 100 being full tracking,
and 0 being a more solid signal.

There’s also a decay amount, which increases the tail beyond the original length and can be used to control the sub-decay of things such as kick drums. Other features include solo buttons for each band, undo/redo, A/B comparison, and separate faders for the original audio and main output. As with Leapwing’s other plug-ins, the retina GUI is clean and easy to use. That said, it would perhaps be useful to have some sort of visual representation of the input signal frequency spread and the generated harmonics. That way you could quickly dial in the crossover points without having to resort to using a spectrum analyser on the track in question, and also get a better sense of where the new energy is being added. In terms of functionality, it would be useful to have individual band-bypass buttons to switch them in and out, and a low-cut filter on the final output to rein in unwanted super-low frequencies.

We put RootOne to the test on a bunch of audio material. First, we play a clean sine and dial in some subharmonics to see how the pitch tracking works. Using a spectrum analyser, you can clearly see the added sub frequencies moving as notes are played.

Initially, when we solo the subharmonic output, the sound wavers and garbled.
It turns out this is due to an issue with the first version, which was quickly remedied
by Leapwing shortly after release. A quick update later and the solo’d output sounds much cleaner and more stable.

LeapWing RootOne

Next, we try a bass guitar part, and are able to dial in a thick and even-sounding sub that tracks the original guitar perfectly. Drums and percussive instruments work well and you’re able to massage the different parts of the signal into place to thicken things in a natural-sounding way. In theory, you could also use it on vocals, although we find it sounds more disconnected from the original on the tracks we test.

Though RootOne can be driven hard, it’s more effective and transparent if you use a lighter touch. If you go overboard with the saturation slider, you can quickly make things muddy. You have to be careful about driving the lower subharmonics too hard too, as these can distort quickly when combined with the other signals.

RootOne works wonders on signals that are lacking low end, as it generates it for you. It’s very useful for helping sub-heavy tracks cut through on smaller speakers too. However, if you have a sub or kick that’s already bass heavy and want to beef if up, you probably don’t want to generate additional harmonics an octave down, as they will be too low. You’ll probably find that traditional saturation techniques will give better results here. With that in mind, it might be interesting to have an option to synthesise harmonics at the same pitch as the input signal, just as a thickening tool.

Best in show

Leapwing Audio’s plug-ins are on the more expensive end of the scale, which obviously prices many users out. There are some alternatives out there that are cheaper and do similar things but, with Leapwing, what you’re really paying for is the quality of its algorithm. RootOne a professional tool for generating the cleanest possible low-end harmonics, which is easily worth the investment if you’re making money from music and want the best of the best. It won’t necessarily be the most effective tool for the job on
all material but when it works well, it’s a marvel of transparent processing.

Do I really need this?

LeapWing RootOne
If you’re serious about low-end mixing, then you’ll probably have a few tools for the job already. RootOne will not cover all the bases but it’s very good and clean at what it does. It seems to excel at adding weight to more traditional basses, guitars and drum parts and could prove an essential tool for mix engineers that do a lot of band-mixing work. It’s also a sensational tool for electronic producers looking to make their sub-heavy tracks cut through on smaller speakers. If you’re dealing with electronic sources though, then you might find that a little more work at the sound-design stage will grant you more powerful results when it comes to scientifically crafting sub frequencies, as opposed to relying on a plug-in to add it in later on. Though not quite adept in all departments, RootOne should be your route-one in many.

Key features

  • Multi-band subharmonics generator and shaper
  • 3 phase-aligned low-frequency bands
  • 4th band for harmonic saturation
  • Variable crossover frequencies
  • Tracks pitch and dynamics
  • Drive control for additional low-mid harmonics
  • Clean and transparent sound
  • Retina interface


bx_subsynth £140

This is combination of modern software tricks such as a mix dial and M/S width with a model of the dbx 120XP Subharmonic synth’s engine. It has three generated bands plus Squeeze and Drive.

Submarine £70

This is fairly similar in that it includes two subharmonic generators powered by Waves’ Organic ReSynthesis tech, and drive and dynamics features. But it doesn’t have the same level of control.


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