Spitfire Audio Phobos Review – BT’s Polyconvolution Sample Synthesizer Stands Out From The Crowd

  • Sound
  • Features
  • Ease Of Use

Spitfire Audio Phobos

BT and Spitfire have come up with something that stands out from the crowd. Phobos is a touch fiddly but once you’ve got your head into it, it’s very rewarding.

– Phenomenal sounds
– Perfect for creating dynamic drones and pads

– Not the most intuitive interface
– Sample loading time (for those without a SSD drive!)

Phobos is Spitfire’s first foray into the plugin world outside of the comfort of Kontakt libraries. It’s a big step, and I spent quite a bit of time with Phobos, learning it’s ins and outs to see how Spitfire have entered the fight. Phobos is a ‘polyconvolution sample synthesizer’. Bit of a mouthful, I know, but bear with me. For this synth, Spitfire collaborated with world renowned DJ and composer BT (not to be confused with the British Telecoms company).

Phobos comes downloadable as the standard formats of AU VST and AAX. You need about 30GB space to fit Phobos in your sample library, and to get you started there are over 700 presets, created by BT and other big hitters. There are over 2000 source samples to play with, varying from percussive, tonal, instrumental and field recording. As a double whammy, if you’re a big fan of BT – this instrument gives you access to a large chunk of BT’s own archive of samples.


In audio, convolution is usually applied to reverb – using the algorithm created from one recorded space, to create the identical reverb on that space to a new instrument. You want a piano playing in the Taj Mahal, there’s probably a convolution algorithm out there to fulfill your dream.

In the case of Phobos, Spitfire and BT use the same idea, but instead of using it for reverb, the characteristics of one sound are convolved, or have an affect on other sounds, kind of mashing/morphing together to create a new sound entirely. In Phobos, there are 4 source sound slots, and 3 convolve slots, into which you can load any of the 2k plus sounds provided.

The GUI is fairly clear in showing the routing of the sound. 4 sound sources along the top of the GUI, and the 3 convolve slots are based around a triangle in the middle, with mod controls, keyboard range, preset selection and others all based at the bottom of the GUI.

I don’t particularly like the GUI, finding it hard to tell the difference between parameters and little logos with random artsy writing. Call me spartan, but it put me off initially.

Anyway grumbling aside, the sounds really are quality. When you load a source, there are two streams of tonal and looped sounds – each with a wide variety of descriptors, so you can hone the type of sound you’re looking for.

There are some really nice droney pad sounds, micro glitch loops, drum breaks, massive taiko patterns, and all sorts of synthesised or recorded tones. Loads of interesting sounds that wouldn’t crop up on your average plugin synth.

All of the sources have ADSR, HPF, volume and mute buttons. The sources have wet and dry volumes that allow a mix of the original sound, and the convolved sound coming back to the source. If you hit the number or letter indicators over each module, you open a further parameter window, that includes gates, more detailed attention to the envelopes, sample starts and offset, Low and Hipass filters, and in the case of the convolvers, the size of the FFT window you’re working with.

If you’re struggling to get inspired (you really shouldn’t be!) then there are randomisation buttons for each. The convolver slots additionally have an output volume and a pitch shift, so you can send the convolved signal back at a different pitch to the original source.

Convolving them:

Once you’ve selected your sources, and your convolve signals, you can then use the triangle in the middle of the GUI to move the sources around and allow them to be convolved to different convolvers. So you can allow one source to be affected by 1, 2 or 3 of the convolve signals, by placing the source (demonstrated by a little white numbered triangle) within the larger triangle representing the three convolver signals. You get a little visual notification that the source is hitting the convolve as the relevant sides to the triangle start vibrating. Make sense? It’s tough to explain, so you should probably go ahead and watch the demonstration here – one of many that Spitfire put up to help you get the hang of the instrument.

It is possible to automate the movement of the ‘pucks’ within the triangle, to give some movement to the convolutions. It’s a little complicated, and has to be done in the DAW, but it is possible. If you’re looking to do that, then you need to watch this video,

Modulation mappings

If you click the mappings button on the sources, then you are presented with a list of default mappings for the source sounds. Default is the level, and pan. But you can add an unlimited amount of mappings to modulate an almost unlimited amount of sources, to affect 24 targets, from envelopes, levels, gates, Hipass and lowpass filter cutoffs, etc. The same can be said of the Convolver slots. If you don’t want to modulate with Midi, there are 4 LFOs available, with 4 different shape waves, to automatically add movement to your modulations.


Wow, that was a wordy description of BT’s Phobos. It’s kind of apt though. Phobos is an interesting beast, with phenomenal sounds, and great quality to it. But it requires some proper attention. It won’t come up trumps if you just skim the surface (aside from the presets I suppose. But who wants to use them!).

It’s a touch fiddly, which reminds me of other BT-related plugins. But once you’ve got your head into it, the work is very rewarding. I found that I had most success creating drones and pads that had a lot of evolution and subtle movement in them, which is what they were aiming at with Phobos, I think. BT and Spitfire have come up with something that stands out from the crowd, for sure.

It’s not the most intuitive interface, and you have to wait for samples to load (SSD recommended to avoid irritation) But the sound is worth the wait, and worth diving into the manual for. It’s Sci-Fi all the way. And the ‘BT’ness is very evident sonically, with the clean sound, and subtle glitch and quirk to the rhythm. Great partnership, and great, er, ‘convolsamplesynth’. Recommended!!

Spitfire Phobos is £269 direct download. For more info, check out the product page.

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