Review: Tonsturm SPCTRL EQ

Draw your EQ curve, modulate it and then modulate the modulators for good measure in this flexible sound design rabbit hole of a plug-in.

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Tonstrum SPCTRL EQ

Review Overview

Our rating


Our verdict

A comprehensive vector curve editor for simple and complex shapings
Four powerful modulators cover all the angles
Easy assignment and editing of modulators
Thoughtful selection of transformation parameters

You do need to read the manual first!
No I/O metering

A sound design tool made by sound designers for sound designers – and anyone else wanting to break away from the standard filter format.

Price $99
Contact Tonsturm

SPCTRL EQ is an FFT-based filter plug-in made for sound design. By marrying an ‘anything goes’ curve editor with a bank of assignable modulators, SPCTRL EQ is designed to filter, shape and transform incoming audio in many complex-sounding ways without becoming over-complicated in operation.

The cool, spacious interface features many recognisable parameters, from input/output levels and dry/wet mix to a real-time spectral display, mid/side processing and low/high-cut filters. The less familiar parameters – FFT bands, Clean and Response – quickly flag that this is not a plug-in you can simply dive into. Touring the presets and reading the manual is necessary to navigate SPCTRL for the first time and gain entry to a world of creative tone shaping, modulating and mangling.

Tonstrum SPCTRL EQ

Vector and shape

The first stop in SPCTRL is the vector editing window. You can effortlessly carve the initial straight line into the line graph from hell, or something more elegant. There’s more than the standard click-and-drag breakpoint editing, too. Tonsturm has fleshed it out with curve anchor points and a shape generator. The generator will drop a linear shape (triangle, square, ramp up/down) in the vector editor, which you can then skew, stretch, move and even create multiple subdivisions within. You can alter the EQ curve as a whole with the five controls that appear in Transform mode: Amount, Shift, Stretch, Skew and Spread. These not only define how your curve affects the audio, along with three scaling modes (lin, log & custom log) but also form the main modulation targets. This may all seem rather complex, and sonically it can be, but in practice, it is easy to work with (undo/redo helps), and the scalable spectral display provides all the feedback you need.

It’s worth noting that the FFT bands (128 to 4096) and associated Clean/Response knobs add overall control of the digital processing for clarity and spectral noise-gating. You can set the upper and lower EQ range limits to run up to a clip-inducing +48dB, which can serve up plenty of sonic sauce in conjunction with the soft-clip output limiter.

Transformational modulation

There are four flavours of highly flexible modulator: LFO, custom LFO, random and envelope follower. You can add any number in the modulator panel to create almost any imaginable combination of outputs. Though primarily intended for EQ curve manipulation, these can be assigned to their co-modulators’ parameters and even themselves. For example, an LFO can modulate its own cycle frequency. Assignment is simple, and the destinations of each module are shown in the Assignments panel, as are the modulation origins of any selected transform parameter, such as Skew or Stretch.

There are no limitations on what you can assign besides your tolerance for mangled chaos. The gentlest of phasings and filter sweeps are as achievable as the most intense oscillating comb filterings and distorted sonic slice-ups. SPCTRL is a well-designed toolbox that can render almost any EQ/filter modulation imaginable and is as musical as it is sound effects friendly.

SPCTRL EQ is not the only plug-in of its kind. Still, it approaches the modulated filter model with ingenuity and economy to deliver a highly flexible and creative tool that does not overwhelm or hinder the user. It is also sensibly priced for any serious sound designer, musician or producer looking for something beyond the standard filter plug-in.

Tonstrum SPCTRL EQ

System Requirements

  • Mac OSX 10.11+ (64 bit) or Windows 10+ (64 bit)
  • Intel Core i5 CPU, 4GB RAM
  • iLok account

Key Features

  • AU, AAX, VST, VST3 and Audio Suite
  • FFT (Fast Fourier Transform) processing
  • Control over 4096 frequency bands
  • Flexible Curve Editor
  • Modulation system from FRQ Shift plug-in
  • Preset and custom LFOs as modulation sources
  • 6 Banks of presets
  • 14-day free trial

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