The Development of Eclipsa — From Reference to Instrument

As you can probably tell if you have been keeping up with my work for a while, or if you know me in real life, I have always been interested in vintage and rare music equipment, and I have, in fact, been able to collect some myself. Moreover, I have, over time, come to be interested in the history behind some of this equipment, how they were made and what led to their creation.
One such unit that has always stood out to me is the Yamaha® RA-200 rotary speaker cabinet. What has fascinated me, in particular, was how Yamaha has taken a completely unique approach to their rotary system and paired it with a static speaker section.

You might ask what makes it such a significant piece in the history of rotary speaker designs. Originally intended for keyboard use, its design differs fundamentally from the more widely known Leslie®-style speakers. It features three vertically rotating midrange drivers alongside four 12" stationary speakers. Each rotary driver spins on its own axis, powered by an individual motor, while the speed of all three is controlled by a single potentiometer and footswitch. The signal is transferred to the drivers via a brush-based system, similar to the way an electric motor operates. The end result is a thick, swirling, three-dimensional chorusing sound with a somewhat unpredictable panning behavior. It does not simply modulate a sound, but creates a sense of true motion- alive in the room and constantly moving around the stereo picture. The RA-200 was never produced in large quantities, and it has been out of production for a very long time, making this a rare device in today’s world.

For a while, I have had the idea of recreating this sound in pedal form, but I was also aware that this was not something to be taken lightly and would take more experience, knowledge, and eventually, access to the original unit itself. Naturally, my first step was to get this masterpiece into our workshop somehow. It turned out that was not an easy task and our quest for one would take quite a while to accomplish. Jelena was finally able to locate a well-maintained unit within Europe. But that was only part of the challenge — at well over 100 kg, transporting it required proper crating and reliable handling, all coordinated remotely. I’ll admit, there was a bit of anxiety about what condition it would arrive in. With the help of some good friends, the cabinet finally arrived safely in our workshop a few weeks later. And as it turned out, it was indeed in pristine condition, with the previous owner having replaced the front grille cloth, one of the 12" static speakers in the lower cabinet, and the drive belts for the rotary drivers. The end result was a cabinet that sounded exceptionally good, effectively noise-free, with sound filling the room the moment I turned it on. The top part delivered rich rotary chorusing, while the lower 4x12" section was loud and punchy. To say the least, glorious.

So, after several days of just messing around with it, I started thinking about how I could incorporate all of its nature into the DSP and design the best possible emulation of it, and the form and name of the pedal came to me pretty quickly: Eclipsa! I already designed a Pulse™ pedal, which is a Doppola® revolving speaker emulator, and these effects are no stranger to me. The physics behind rotary cabs is something I am familiar with. However, RA-200 is quite more complex than the Doppola. Emulating it involves not only reproducing the effect of the rotary speakers, but also the full acoustic signature of the cabinet. One of the most difficult aspects to emulate, however, is the physics of the moving sound source. The three rotary speakers produce a lot of reflections; they're not quite balanced, and their rotational inertia isn’t totally predictable. They each have their own little imperfections because of their individual motor drives and speaker counterbalance weights. They also create a complex phase relationship that's always changing and somewhat random in terms of stereo image. Recreating that sort of thing in a deterministic DSP system is not trivial.

Alongside the complex rotary system, the preamp stage also plays an important role in the overall sound. The original Yamaha RA-200 includes its own amplification (one for the rotary side and two for the lower 4x12” static cab), which sounds excellent but leans somewhat toward the darker side. For that reason, some well-known guitarists, particularly members of Pink Floyd, paired the Yamaha RA-200 with the Alembic® F-2B tube preamp to introduce a brighter, more articulate character. My goal was to take a similar approach in the Eclipsa design. I focused on recreating the character of the Alembic F-2B but in a solid-state form and adapted it to more suitable frequency ranges for a guitar, minimizing the noise floor as much as possible. I was very satisfied with how it turned out - on its own, it has a great warm tube-like response with a nice crisp top end and a controlled low end with plenty of depth. Together with the rotary part, it makes a great combination. I stuck to my initial idea of having a switch option to always have the preamp on as a buffer bypass.