GRM Tools 3 review: a classic reborn

It’s been a long time since I used GRM tools, from back in my University days at Birmingham UK, where I was lucky enough to study under the tutelage of one of the foremost electroacoustic composers of this generation: Jonty Harrison.

Ina-GRM as they are now known, come from a long heritage of electroacoustic music, tracing all the way back to one of the godfathers of Musique Concréte – Pierre Schaeffer. GRM, which stands for Groupe de Recherches Musicales, have just upgraded their fantastic GRM tools effects software, and with the release of the 3rd generation, have introduced a brand new bundle of effects – the Evolution bundle, comprising 3 new effects that complement and contrast with the other 12 effects, making 15 in total. Alongside the new effects, GRM have done a lot of work on revitalising their stalwart plugins, with some new features, new looks, and significant re-programming.

GRM tools have a reputation as an excellent group of sound manipulation and design effects plugins, and are used within a wide range of sonic art: from electroacoustic music, through commercial electronic music, to foley and sound design for film, tv and video games. Many of the GRM tools are based on FFT, or fast fourier transform; a mathematical analysis technique developed by Joseph Fourier back in the 1800’s for solving equations regarding heat and metal plates. But I digress..

Written using GRM Classic and ST

For those of you who are unfamiliar with GRM tools, I’ll quickly cover the older effects, and then review what new features come with the update, as well as cover the new bundle of effects in a little more depth.


CLASSIC: a bundle of 8 effects plugins

Band Pass
Is what it says. Stereo or mono, linked or unlinked, this effect plugin creates a strong bandpass on the incoming audio, and with the large XY parameter control window, it’s easy to adjust the bandwith and frequency range of each channel with a single control. It’s nice having dual mono channels – you can bandpass the audio separately in each channel, creating a lot more movement in the sound you’re working on.
Doppler is a panning effect on steroids. It enables you to position your audio in a stereo space, but also to automate its movement within the space, whilst at the same time altering the pitch and speed. One of the side effects is being able to create the doppler effect as something flies past your ears: hence the name.
Freeze is a lot of fun. The incoming audio scrolls by in the GUI main window. With a click of the freeze button, You can then stop the sound in its tracks, literally freezing a clip. You can create several loops of the audio to thicken it, and pitch shift and feedback the outgoing sound. You can narrow the clip selected down from a few seconds worth to a tiny amount of samples long, which in turn creates long spacious sounding drones or pads, regardless of the type of audio incoming.
Shuffling takes clips of the incoming audio and shuffles it around in time, moving it back and forth, so it’s not quite a delay, but can sound similar. You can choose the size of the clips to shuffle, and how far away from the original sound in time they appear. Can create a lot of movement to a sound.
Delays is taking the delay line idea to the max. You can choose up to 128 delay lines, choose when they appear, how the feedback looks, and you can create temporal variation as to when each delay line appears. It can create anything from a shuffling type sound, to a resonant buzz on the end of the incoming audio.
Pitch accumulation
Again, it does what it says on the label. The incoming audio is repeated as much as you like, and is re-harmonised all over the frequency spectrum. There are two transpose channels that take the incoming audio and repeat it up or down the frequency range, accompanied by feedback and delay. The parameters that can be manipulated enable you to create anything from a small doubling-type effect, to a huge wall of sound. You can turn a single voice into a crowd with not much effort.
Comb filters
5 band parallel comb filters on sliders enable you to pick the frequency of each filter, and add resonant feedback to each separate filter, enabling you to create anything from subtle boosts to certain frequencies, to turning short percussive sounds into long sustained chords.
Reson enables you to boost resonant frequencies. Up to 128 bands of resonance can be used. They can be distributed evenly or randomly across the frequency range.

THE SPECTRAL TRANSFORM BUNDLE: a group of 4 effects plugins

Is basically 2 effects in one, that can be used separately, or in combination. The first is a simple but great sounding pitch shift that goes up or down an octave. The second is a frequency scale effect. that scales each separate frequency band (from a range that you choose) up or down. The XY window in the middle of the GUI enables you to activate both effects at once.
Freqwarp is a very fun sound-design tool. I use this one a lot. Basically it’s an XY graph of the frequencies of the input sound running horizontally, and the output frequencies running vertically. There is a diagonal line that represents the intersection between the incoming original audio (horizontal) and the affected audio (vertical) you can place points on the line, and move them anywhere on the graph, so incoming audio frequency at that point changes to wherever you place it on the vertical access. It allows for wild timbre shifts, and frequency changes in small areas of the sound. This can TOTALLY change the sound you’re working with. Very inspiring.
A 32 fixed band mono or stereo equalizer. The advantage of this one is again in the real-time manipulation of the audio. I’ve posted a video showing what you can do real time, and also how simple it is to automate GRM tools within a DAW.

Contrast is the only Compression/Expansion-based effect in the bundle. Not your regular compressor expander, it gives you the capability of getting very creative in the way that you use the plugin to mellow or excite the audio from subtle to extreme ends. The effect groups the incoming audio into strong, medium and weak amplitudes, and then lets you manipulate each group separately. This is a very useful plugin for adjusting the energy of a sound. Depending on which group you manipulate, you can mellow the intensity, or energise the intensity of the audio.


Well, actually quite a lot. For starters, the GUI has been updated nicely. It’s easier to read, and is frankly prettier than the slightly utilitarian older plugs. You can now re-size the windows too. Bigger’s always better right?

GRM tools place a lot of emphasis in the design and structure of their plugins for real-time manipulation of sound. There are several universal parameters that are present on every plugin with this in mind. These features have been massively improved, and added to. Here’s the list:


X-Y window – the main features of each effect are present in the main window in the GUI. These enable you to manipulate the main parameters with a mouse, or other XY midi controller.

ELASTIC BAND – This is a new feature to enable smoother control of live manipulation – if you hold down the apple/option key while using the mouse, a ‘rubber band’ appears between the control knob and the position of the mouse. the knob/slider/point will then begin to move smooothly towards the mouse position. So if you’re wanting slow steady movement, this is the tool to use.

PRESETS – on the right hand side of the window there are 14 preset points that you can save, as you improvise and play with all the different parameters of an effect. These can be saved, and even morphed between, either manually with the performance slider (at the bottom of the window), or within a timeframe that you set yourself.

TEMPO MATCHING – when used within a DAW, the tempo based parameters can be matched to the tempo of the host DAW, by shift clicking on the parameter.

AGITATION – Another new feature adding a further element of randomness and manipulation to most parameters in the effects – there is an agitation amount and time that can be applied to any parameter with a pink button next to it (selecting the pink toggle button allows that parameter to be affected by the agitation). Agitating the selected parameters increases and decreases the amounts according to the percentage and speed you’ve chosen.

MIDI IMPLEMENTATION – a very simple to use, but comprehensive midi implementation allows you to ‘learn’ any hardware control element to any parameter, just by moving the parameter and midi control element at the same time. Very useful for quick integration between hard and software. There is a useful midi control window that can be opened from the bottom of every effect – to manage any midi control you’ve implemented.

MULTI-FORMAT – I love this new feature. GRM now has a much wider platform and user base potential: Every effect is standalone, and also comes as a VST, AU, RTAS plugin version too, for integration into any DAW. One new addition I loved about the standalone is the ability to record .wav files as you go – drag and drop the audio you want to manipulate, start a new recording from the file menu, and it records and saves audio of everything you do as you play around in the effect. This for me is excellent, as it really speeds up my workflow.

MULTI CHANNEL – some of the plugins include the ability to utilise multi channel output, in several different formations; Quad, 5.0, 5.1, and 7.1. Not all the plugins have this ability at this point, but this has a lot of potential for sound-design.

All these features really are what GRM tools are all about – real time manipulation of sound in very powerful and simple ways. Some of these features have been present since the incarnation of GRM tools, but in this version, they are much more flexible, powerful, and above all, very stable. I don’t know if the effects have been re-written since I last used them, but it sure seems like it. They didn’t crash or freeze once while I was using them.


With GRM tools3 comes a bundle of 3 new effects that complement and contrast with the original set:


Evolution is used to obtain continuous evolution of timbre by frequential sampling of the input signal.’

As soon as I started using Evolution, I fell in love with it. It is a beautiful piece of algorithm that enables you to slow down audio to the point of freezing it, but also to evolve slowly between sampled points in the audio file. For creating slowly evolving smooth sounds, as organic, or electronic as you want them, this is a perfect plugin. It’s similar to the freeze plugin, but with more variety and dare I say it, evolution of sound within it. In terms of creating audio, it performed flawlessly. Smooth beautiful sounds that hold no glitching, and don’t seem to tax the CPU of the macbook pro I was using to create the sounds. Here’s a video of Evolution in action, with audio taken from a recent road trip to Santa Fe.

Evolution samples the incoming audio at periodic intervals. It then interpolates (kind of morphs) between the present sample, and the previous sample. You control how it morphs, and how long it takes to morph. You can control how many bands you want to sample with (sort of like bit rate) from a very organic and smooth texture with 65536 bands, to a more digital and bit-reduced sound of 128 bands.

I was very impressed with how smooth the interpolation was. There was no clicking, unless you changed the band rate mid sound, which is to be expected. The XY parameter window enables you to change the pitch shift and pitch scale of the audio file. moving it around quickly created smooth slides and sounds that remarkably to me had no digital grit, clicks or pops.

I really liked the purity slider. This basically filters out the less prevalent frequencies as you increase the purity, which means that the frequency bands narrow and narrow until you’re listening to pure sine waves at whatever frequencies are strongest in that sample. To be able to go back and forth from a wide spectrum organic sound, to narrow wave bands that sound much cleaner and more ‘electronic’ is very nice indeed. Definitely my favourite aspect of this plugin.


Fusion modifies a sound by playing on delays, filters offset and frequential sliding.’

Fusion is a sonogram-based delay manipulation tool. The main window shows a smooth moving sonogram of the audio file, moving left to right.

There are 8 ‘playheads’, or bands that intersect with the sonogram as delays, at any point in the audio. These playheads’ parameters can then be manipulated in terms of bandwidth, feedback, frequency sliding – which is sort of placing the ‘playhead’ at an angle, so the sound slides up or down the frequency range, creating a kind of glissando effect.

One small bug I found with the software was when trying to manipulate the GUI elastic bands when the delay times were set to the clock of the external DAW, the software responded in a strange way – it couldn’t cope with the delay time changes. Not too big a deal, and I’m sure that is something that can be worked out.

Fusion seems to work best to me on percussive sounds. It’s harder to pick delay times out when its used on ongoing sweeping sounds. However, it’s not to be limited there. Here’s a video of me using Fusion with a simple groove in Ableton live.

I really liked Fusion. I didn’t find it immediately as appealing as evolution, but with a bit of messing around, it did come up trumps with some interesting sounds, especially on rhythmic material.


Grinder is used to degrade a sound by freezing its frequential or time changes, and by modifying its spectral resolution. It also enables interesting vocoder effects.’

Grinder is an interesting plugin. Sort of like a vocoder, sort of bit reduction. The maths behind it is fairly complicated, but it still manages to fit in a sound-design gap that hasn’t been filled by much else. It definitely creates some interesting sounds. One of the things I like about Grinder is that you can modulate the sound with the amplitude of an auxiliary input audio file, as you would with a vocoder. This can create some interesting sounds indeed – half-way between a vocoder and bit reducer.

Here’s a video using the Grinder plugin:


Many of the issues I used to have with GRM have been significantly reduced, if not resolved. As I mentioned briefly above, plugin stability used to be a problem. Because these plugins sometimes needed a LOT of computer processing power, my computer could not always handle them, and it would regularly freeze (not intentionally!) or crash. Now, it seems like this is under control, and a combination of greater computer power, and improved programming (maybe?) has massively stabilized the software. In fact, I didn’t have any glitching, freezing, crashing or any other issues whilst using the plugins fairly intensively.

64 bit implementation is not available yet, but that is not GRM’s issue. they’re waiting on dongle makers Ilok to come out with 64bit implementation, and as soon as that is ready, they’ll be good to go. There’s also no TDM support at the moment, or PPC, but I think that’s to be expected now (well, PPC anyway)


I think that GRM has taken software that ruled the roost in university sound labs and sound-design studios, and with new features and improvements have made it much more accesible to the project studio, to more commercial mainstream music, and even to live performance, with the addition of new formats, midi implementation, and much better stability. In my opinion, there is nothing else that comes close to GRM in terms of simple yet unique real-time creative manipulation of sound. There are of course many other programs that do similar things, but you’re going to need to know how to program, or really take time learning your way around software such as Max for Live, to get effects that in this case are instantly at your fingertips. The update brings a much greater level of flexibility, accesibility and stability to this already fantastic bundle of sound manglers. Instantly into the top 5 plugins I’ll find a way to use on absolutely everything I do. Brilliant.


All the bundles are still on introductory pricing at Don’t Crack Audio:
$689 for the complete GRM bundle
$289 for the Classic bundle
$289 for the ST bundle
$389 for the Evolution bundle

… In my opinion, there is nothing else that comes close to GRM tools in terms of simple yet unique real-time creative manipulation of sound…

Product page


  • Incredible sound quality
  • Instant and simple to use real-time manipulation
  • Did I mention how good it sounded?


  • Maybe if you were looking for bread and butter mix plugins this might not be the right choice


  • No TDM
  • Fairly pricey

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