The History of the Legio Drum Kit

As part of our Legio firmware blowout, we released a series of percussive firmwares that we’re affectionately calling the Legio Drum Kit. Each one performs a specific percussive duty, and they easily chain together using the Legio audio inputs and outputs with no mixer required! We’ve got plenty of audio demos of all of the new Legio firmwares on our YouTube channel (with more to come!). In the coming weeks, we’ll talk about patching with a Legio drum kit, but today we wanted to dive into a little bit of the history of each of these firmwares.

Bos Legio

Bos Legio, our cowbell voice and a Noise Engineering favorite, was one of the most entertaining firmwares to work on. Surprisingly, though, the firmware underwent quite a few revisions as we dialed in the exact bell timbres we wanted. 

The FM bell was initially way over the top. We started out with a pretty standard bell patch, but it was a bit too ridiculous, even for Bos (which is saying something). We tweaked things down to a much more cowbell-esque realm by first switching to a Debel-inspired operator relationship, then using a frequency relationship inspired by the TR-808 cowbell.

The additive bell initially started out as more of a physical-modeling algorithm, using a series of tuned bandpass filters excited by a short burst of noise. This was too far the other direction: it was way too mellow and ended up sounding like a xylophone, despite some seriously cattle-inspired tweaking to the filter frequencies. We swapped over to sine oscillators, and were much happier (dare we say “moooooved by”) the results.

The x0x mode, while by far the simplest, also had a number of bugs. This style of bell uses two tuned square waves through a simple filter. The problem is, if the filter or oscillator frequencies are just the slightest bit off, it stops sounding like a cowbell and starts sounding like… well, two square waves into a filter. The idea was that with both potentiometers at noon and a fundamental frequency of 500Hz the result would be a relatively accurate implementation of an 808-inspired bell, and while we got there in the end, it took a number of revisions to fine-tune all of Hertz involved.

We could have kept tweaking the firmware until the cows came home, but we eventually settled on a set of sounds that we thought exemplified a nice range of synthetically bovine timbres.

Cymbal Legio

Cymbal Legio was by far the most difficult firmware to finish. Initially, we wanted to do everything from scratch, and we tried a lot of different synthesis methods: comb filters, modal resonators, additive voices, FM algorithms, hybrid FM/additive setups, and a host of different distortion and nonlinear-modulation algorithms applied to the end of it all and just couldn’t get anything that had more than a single (somewhat) sweet spot. 

After much debate, we asked longtime friend of NE Arthur Hnatek for a set of drum samples. He obliged with an extensive and unique library of one shots. We implemented a granular engine into Legio, and popped a few drum samples from Arthur into it. Immediately, things sounded a lot better. We still had a good bit of tweaking to do: the amount of sample storage on Legio is miniscule, so we had to chop out the best parts of two of our favorite metallic hits and build up a dynamics engine around them to create actual cymbal and hat sounds. We also had to fine-tune the randomness of the granular process quite a bit: not enough and subsequent hits sounded identical, but too much led to huge timbral shifts halfway through a tail.

In the end, we came up with a really cool metallic percussion voice that plays like a synth thanks to the fine granular controls, but sounds like a real drum kit thanks to the fantastic sample sources from Arthur.

Kick and Tom Legio

Kick Legio was a funny one: we’ve made a lot of kick drums over the years, so 90% of the work was done in an hour. The entire rest of the development came down to mapping the envelopes to the Impact knob. There are actually two pitch envelopes: a fast envelope that creates the impact, and a slow impact that slightly changes the pitch of the kick on long decays, adding in some nice movement. The relationship between the two, as well as the amplitude and speed of the pitch envelope, is all very sensitive to any change, so making the Impact parameter feel okay was a surprisingly big challenge that took multiple days.

However, much of the development was repurposed in Tom Legio: an early version created the basis of the Tom envelope setup. The envelope mapping and timings are quite different on Tom, since we wanted to create longer zappy sounds and those awesome cheesy synth-tom tones, but the core algorithm is quite similar.

Klang Legio

Klang was the easiest firmware of all. It’s a harmonic additive synth, very much inspired by the additive side of the original BIA, with some fun ways to get gnarly and distorted timbres thrown in. It plays a lot like a distorted Kick Legio, but it’s a very different synth under the hood. It was pretty awesome from the start, and with a little bit of polish it was ready for prime time.

Snare Legio

Snare, much like Cymbal, also went through a somewhat absurd number of revisions, this time with the help of the entire NE team and a few NE friends – Markus and Stephen never agree on what snares should sound like, so their initial timbre discussions were fraught and it was a team effort to find a happy medium. 

Initially, we started out with something somewhat like the BIA snare: a three-operator FM synth creates a snare body, and some decaying noise creates the snare rattle. The initial attempt left everyone underwhelmed, so we tried getting more creative with some ring modulation on the noise and different harmonic structure on the body synth. We tweaked this iteration for a long time and felt like we sort of had something cool, but it never had quite the range we wanted, nor the timbre we were really looking for.

Eventually, we scrapped everything we’d been working on and decided to use an entirely different approach: physical modeling. A set of tuned filters emulates the frequency response of the drum skin, which are in turn excited by a noise generator which also creates the noisy tail decay. While much more complicated, this got us pretty close to real snare sounds, and created a much more tweakable synthesizer. 

Bringing it all together

Making a bunch of drum noises is one thing, but finding a nice mixed balance with the whole drum kit together was another challenge. This gave Stephen an excuse to create a software emulation of all six drum voices followed by four types of loudness metering in order to find a nice balance for preset levels.