Review – Destructor by Blue Cat Audio

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Blue Cat has a brand new plug in: a distortion and amp sim module that amply demonstrates Blue Cat’s typical flair for depth, elegance and flexibility in their software design.


by David Baer, Nov. 2016


We had promised to bring you part 3 of our review of Blue Cat’s Crafters Pack bundle in this issue of SoundBytes, but have decided to cover a brand new plug-in from Blue Cat instead.  The final Crafters Pack installment will appear in our next issue.

The new plug-in is Destructor, a distortion and amp sim module providing considerable control of many aspects of generating distortion.  The software is available in virtually all formats as is true with all Blue Cat offerings.  The list price is $99 USD.  An introductory discount of 20% will probably no longer be available by the time you read this, but occasional sales have been known to happen.

Although the amp sim aspect of this plug-in might lead non-guitarists to disregard it, I would suggest that any mixing engineer would find use for it, both on individual tracks (of all variety) and for master-bus applications.  It is capable of much more than just amp simulation and its range is everything from the gentlest, pleasing “warmification” to brutal audio annihilation.



There are several ways in which distortion can be introduced into audio.  The principal one is signal processing that will turn a pure sine wave into something other than a sine wave.  Obviously, such processing will also turn complex wave signals into something other than what they started as.  Signals can also be degraded with simulated sample bit reduction and sample rate reduction.  These techniques can be combined, of course.

The distortion module in Destructor is at the heart of the process, but there are other parts.  First we have a front end consisting of a gate followed by a compressor.  Next comes a pre-distortion equalizer module, followed by the distortion engine, and that followed by another equalizer module.  A final brick wall limiter completes the processing chain.

The Destructor gate and compressor do not have a switch to disable them, but setting the respective ratios to 1:1 accomplishes that.  Both EQs and the distortion module have enable buttons (although turning off the distortion module seems rather beside the point).  The gate and compressor are entirely serviceable modules that get the job done, but as they are quite conventional, we will spend no time discussing them here.

The EQs and distortion module have two modes of UI display, so-called “easy” mode and full-edit mode.  The UI image at the top of this article shows all three modules in easy mode.  A skinning capability can be used to apply different looks to the EQ and distortion mode, some examples of which appear below.  Personally I prefer the standard Blue Cat “look” but some may appreciate the visual references to real-life hardware.


Inner Workings

Let’s dive right in to the heart of things by analyzing the distortion module itself, and what a marvelous creation it is.  There are actually two edit screens, one with most of the adjustable controls and an advanced one to further specify dynamics and other parameters.  One of the things that makes Destructor so very impressive is that one can use an envelope follower to have the distortion respond in real time to the dynamics of the signal being followed.  So, we can tell Destructor to only apply distortion when things get loud or even only when things get soft.  We’ll look more closely at this in a moment. 

The advanced distortion edit panel is seen below.  The grid panel shows signal alteration.  The straight line from lower left to upper right represents no distortion.  The white curve is what the user (distortion preset designer) sets.  The green line is dynamic and shows the transformation actually being applied.  For reference, in the lower right are a blue sine wave and a depiction (pink line) of the alteration of that sine wave due to the current settings .


The shaper curve (essentially the green line) can be made symmetric or asymmetric.  It can be rectified (all input results in output in the upper half of the grid).  Smoothing, which reduces the harshness of the distortion, can be specified.  Bit depth reduction can be simulated as well as sample frequency reduction.  The Shape Mix control acts like a wet/dry level (but to the shaper curve only).

To the right we have more controls, including a Mix knob – not to be confused with Shape Mix.  The main Mix control is the overall mix of dry (undistorted) and distorted content.  The Gain knob to the right does just what you’d expect.  The Drive control at the top is effectively an input gain control.  Decimation can be used simulate reduction in sample rate, and corresponding aliasing can be specified.

The correspondence between the easy mode controls is straightforward: easy Drive to edit Drive, easy Mix to edit Mix, and easy Gain to edit Gain.  The final easy mode knob, Dynamics, takes us to the advanced edit panel (a “+” icon in basic edit mode switches the UI into advanced edit mode.

The main thing in this advanced area is the shape dynamics control on the left.  This is where Destructor truly shines in relation to most of the competition.  It is here we can tell Destructor when to apply distortion and when to back off.  An envelope follower can follow one of several signals: Destructor input, post-gate signal, post-compressor, post pre-EQ or external sidechain signal.  The envelope is similar to that in a compressor, having attack time and release time both adjustable.  Range controls the amount of dynamics applied to the curve.  The adjustable threshold and ceiling slider controls to the right tell the dynamics processor at what point to start adding distortion and at what point to max out.  If the ceiling is lower than the threshold, distortion increases as the signal gets quieter. 

But wait … there’s even more.  The two shape controls affect the shape of the follower curve.  Think of both the attack and release levels as straight lines from minimum to maximum (or vice versa for release).  A Shape setting of less than zero makes that level change happen more rapidly toward the end of the segment.  A positive value setting slows down the rate of change as the end of the segment approaches.  All this allows for much nuanced distortion design and can contribute to much expressivity in final tone. 

Continuing in the advanced edit area, we next have ability to dial in oversampling.  The first time I saw a distortion unit with oversampling, I had a fairly sarcastic reaction about thinking distortion needed to be avoided when introducing distortion.  But perhaps when going for only gentle warming the presence of this control has merit.

Lastly there is a phase control, which I found to be too subtle to make an audible difference, apart from when the phase knob was actually being adjusted.  Blue cat describes it thusly: This is a phase shifting filter that continuously shifts the phase, and the frequency you choose is the center frequency for the shift. So all frequencies are delayed with a different amount, resulting in very strange “wah-ish” effects around the center frequency when using large amounts.

You hopefully see just how deep Destructor is for application of distortion.  Next we look at the two EQ modules, which are identical.  That we have a pre- and post-distortion module means that distortion schemes can be designed that emphasize specific portions of the frequency spectrum.  If we wanted to limit distortion to mids and below, for example, we could just reduce the highs in the pre-EQ and restore them in the post-EQ.  the distortion would still be applied to the highs, but the amount of it could be considerably curtailed. 


Like the distortion module, the EQs are nicely conceived, but are considerably easier to explain.  We have low-cut and high-cut filter, a low-shelf and high-shelf filter, three peak filters with positive or negative gain and a comb filter.

The EQ easy mode UIs will have either four or five knobs, corresponding to advanced EQ controls as follows.  If the high-cut filter has a non-zero slope, then we get a tone knob that controls the cutoff frequency.  Otherwise there is no Tone knob shown.  The Bass and Treble easy controls govern the gain of the two shelf filters.  The Mid knob controls the gain of the middle peak filter (the one with the pink icon).  Finally, Gain does what you’d expect.  The corresponding control in edit mode is the blue slider on the right.

In addition to full presets for overall distortion designs, local presets for the distortion module and EQs can be saved.


Is Destructor for You?

The one thing I haven’t mentioned is the very generous number of factory presets.  Although Destructor might appear a bit intimidating, there are such a wide variety of well-organized presets that you will likely find something close to your needs.  A bit of modest tweaking can get you all the way to where you want to go, but in most cases there’s already a preset that will do that.

Speaking of appearing intimidating, I’m happy to report that the documentation is quite good.  There might be a few corners of this plug-in that you may find challenging to understand, but most of it is entirely intuitive, especially after a careful reading of the manual.

So, what’s missing?  I think I’d like to see a global wet/dry mix control more than anything else.  It would also be nice to disable the gate and compressor with a lock when auditioning presets.  These are pretty minor complaints, though, in relation to all that I like about this software.

A demo download is available for checking Destructor out.  It won’t allow preset saves and will interrupt the sound (some users would argue for too long a time).  But it’s easy to take Destructor for a test drive – something that may be an entirely rewarding investment of your time.


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