Review: BT Phobos from Spitfire Audio


Spitfire Audio in partnership with BT bring us what could just be the next Godfather of Synthesis. BT Phobos unleashes nearly endless tonal and rhythmix combinations for every musical pursuit imaginable from trailer and film work to electronic music of every genre. Imagine creating a complete cue with a single finger!

Jump to the Demos of  BT Phobos from Spitfire Audio

Jump to the Videos of  BT Phobos from Spitfire Audio


Review: BT Phobos from Spitfire Audio


Spitfire Audio has partnered with famed composer/performer BT (Brian Transeau) to bring us what could just be the new Godfather in the current Hybrid synthesis trend.

Using a revolutionary technology called Polyconvolution Synthesis, BT Phobos takes your music making to totally new places previously unheard of. With 40 Sextillion possible sound combinations at your fingertips, inspiring your compositions will not be an issue. Featuring custom sound design by BT, Richard Devine, Christian Henson, Paul Thomson and the entire Spitfire team

BT Phobos sells for $299.00 from Spitfire Audio



BT (Brian Transeau) should need no formal introduction here, but based on his current level of achievement in the music world you need to ask: What do you do after you have invented Trance, scored music for over 4 dozen movies and video games (including The Fast and the Furious, Laura Croft: Tomb Raider & Monster) and released a steady stream of albums, done sound design work and performed live? Well, you get together with Spitfire Audio and develop a new class of synthesizer that is out of this world.
For Spitfire Audio who also needs no introduction, this partnership gave birth to a unique opportunity to stand the world of composing and frankly synthesis as we know it, squarely on its head. While the venture took two long years, I think at the end of the day it has really paid off big!

This partnership gave birth to a unique opportunity to stand the world of composing and frankly synthesis as we know it, squarely on its head.

The pressing question for many is “What is Polyconvolution Synthesis?” BT came up with the idea of using convolution IRs and instead of using them in a conventional way, they are being used as tonal convolvers. This allows you to take a beat, pad or string noise and effect it via a selection of tonal convolutions which contain the same sounds as the sound sources themselves. By using three separate convolvers to modify the four potential sound paths, we arrive at Polyconvolution. Think about it simply like subbing in the sound of a pad or bell for the large room or cathedral IR which creates and entirely new sound by marrying that to a string or percussion sound. The results are actually quite amazing.

When I used to lecture I always joked about breaking out the complex diagrams and deep-diving on the technology. I am only going to do one of those here. I think that the slide that Spitfire Audio has made available to map the signal chain for BT Phobos is beyond impressive, if not a little menacing at first glance.

Back to the question at hand, “What does BT Phobos do?” So, the above diagram clears It all up for you then? I’m guessing not. I thought it was an important illustration of the overall complexity of the underpinnings over the engine behind it. What makes more sense is to look at the primary interface and dive in from there.


At first glance, the interface may seem a little bit ominous. There is a well-defined method to the madness at play here that will become increasingly clear as you work with it. Just as Spitfire Audio has developed a series of videos to cover the functionality of BT Phobos, I couldn’t possibly do justice to covering every nuance in a single review so I encourage you to watch the videos and read the documentation to get the most out of what is possible.

The main GUI is designed around a fairly logical layout. At the very top are four sound sources, each with their own ADSR, Waveform and Parameter controls for Dry, Wet & HPF the central section houses the three convolvers. The controls are nearly identical except for the Dry and Wet controls in this instance being swapped out for Output and Pitch. In the case of the sound sources and the convolvers you have total flexibility to sculpt the sound in the same manner. Each of the seven controls also has a Mute function so that you can bring sound sources in and out as you work.

The upside-down triangle shows you the relative position of each sound source to each of the three convolution paths. You can simply drag and drop the four triangles representing the sound sources wherever you wish. Dropdown menus or fly-outs provide selection for note only the sound sources, but also for the tonal sources for the convolvers and finally, the presets themselves.

If you want to start out slow and get used to the engine, there are over 700 crafted presets

If you want to start out slow and get used to the engine, there are over 700 crafted presets ranging from Harmonic, Rhythmic, Analogue, Atonal, Hybrid, Drones, Pads, Loops, Convolution Synths and combos. Using different presets will give you a sense of how BT Phobos functions at an interface control level. I spent a lengthy period of time experimenting with not only modifying the existing patches but also building new sounds and simply found myself losing track of time I was so intrigued You can really go down the rabbit hole with this one!

I found the very bottom section of the interface is a bit puzzling at first. Pressing a key is represented graphically on the grid, so it obviously represented the keyboard range. Here is where BT Phobos gets really cool! The top four lines represent your four sound sources and the bottom three lines represent your three convolvers. By clicking on the hollow dot at the ends of each, you can drag the start and end positions to determine where the playable range of each sound will be on the keyboard. This is really handy if you want to do keyboard splits or to subdivide the keyboard for pads and rhythmic elements and maybe a section devoted to atonal or drone sounds. You can also change the key range that you use each of the convolvers on for a specific sound to achieve variations that are frankly unheard of by my ears.

The Mappings control allows you to use either a dozen standard preset functions for Velocity, Pan, Cutoff, Envelope Attack & Release, etc. or you can also build as many of these custom mappings as you choose. This functionality applies to both the Mapping control in the sound sources and convolvers.

Exploring presets for the sound sources and convolvers to modify existing ones is clearly the way to go in order to get used to the BT Phobos engine. Spitfire Audio’s crack development team have made it easy for you to get started and find what you are looking for. The design of the preset system for sound and convolver sources is beyond clever.

In addition to searching for sounds by narrowing them down to specific sound type like Brass, Choral, Drums, Electronic. Evolving, Guitar, Loop, Orchestral, Organ, Pulsing, Seq, Strings and Vocals amongst many others, you can also narrow them by combinations of each of those or by Key or Tempo. The perfect examples of this would be clicking on Ethereal and then Choral or Pulsing and Guitar. This one is sort of a very cool mind maze. That’s why there are over 40 Sextillion combinations possible!

Each of the convolvers has a deep control set that is exposed by clicking on the W, X or Y. Underlying this is controls for IR Offset, IR Envelope, Filter and Gates. This is one area where a trip to the manual is going to help you get the most out of the potential, but fear not, this is not a deal breaker by any means. This is going to be more useful once you want to fine tune beyond everything covered thus far or create your own presets.

The Global LFO page is another section where you are going to want to get some practical experience under your belt and probably refer to that handy manual. With great power comes great responsibility – or something like that!

Well, with all of that hopefully I haven’t scared any of you off the path as that would be a shame. BT Phobos is a phenomenal groundbreaking synthesizer and as an Omnisphere fanatic, I don’t make comments like that lightly. I have not been able to stay away from the keyboard since I got this wonderful new muse. Is it really all I have made it out to be? Yes and SO much more.

So where does it find its place in the musical spectrum for composers and musicians? My honest answer is that I don’t think you can make polka music with it!

BT Phobos is so versatile that it will fit in any kind of trailer, score, video game, electronic music or to add unique timbres to a plethora of unusual suspects.

One of the enormous strengths here is the ability to independently control the four sound sources on the keyboard mapping sliders and then apply the convolvers where you want them. The results are beyond amazing and I am sure you will find that the sky (and your imagination) are the limit to what you can do.

If I had to come up with one con here it would be that the screen can be a little hard to read on certain screens depending on the brightness settings. While it is aesthetically pleasing, I would almost like a black and white option for ease of reading some of the smaller parameters.

There are a number of new soft synths popping up in the $200+ range that couldn’t hold a candle to BT Phobos in functionality, content or broad ranging capability.

One question you may be asking is whether it is a good value for the asking price. In a word: Yes. There are a number of new soft synths popping up in the $200+ range that couldn’t hold a candle to BT Phobos in functionality, content or broad ranging capability. I am so pleased with BT Phobos that I am awarding it the coveted SLR’s Top Pick Award! This will be a staple of my studio and sessions for a long time to come. I can only hope that this will have expansions created for it in the same manner as eDNA Earth and/or open development for third party sound designers to just keep making this better and better.

As with all of my reviews, please check out the audio and video demos to make sure that this is the right tool for your studio.



This is the very first venture into the Plugin space for Spitfire Audio and they could not have picked a better partner. BT is truly a man on the cutting edge of musical technology. You may be asking, “Why a Plugin?” The simple answer is that the technology requirements are just too far afield from what can be accomplished in Kontakt scripting at the present time.

BT Phobos downloads at 22.9 GB and requires double the space during the install. It comes with 2,381 samples and 716 presets allowing over 40 Sextillion possible sound combinations. The significant technical highlights are:

Revolutionary Polyconvolution synthesizer, across 3 separate convolvers
Contains more than 2000 unique sounds, created by BT, that can be used both as a source or as an impulse response
Over 650 presets showcasing the possibilities of Phobos
Plugin that loads directly into any DAW that supports VST / VST3 / AU / AAX.
IRs in Convolvers are polyphonic, track pitch played and render in real-time
Loops as sound source / or as IR track host tempo
MPE Compatible (for use with multidimensional controllers such as ROLI Rise or Roger Linn Linnstrument)
Dedicated Gate Stages and Filters on each sounds source / convolver unit
All controllers mappable to controller and / or multiple LFOs

Please note that you MUST use the latest version of Spitfire Audio‘s Library Manager

BT Phobos sells for $299.00 from Spitfire Audio


 Demos BT Phobos from Spitfire Audio

Videos of BT Phobos from Spitfire Audio