Dante: John, your
chronicles detail some early R&D work based on a Scope module called
'Rotor'. Could you explain the Scope Rotor, and your intentions of how to
add to that functionality ?
The original Rotor device came from an idea by the DSP coder at Creamware,
Klaus Peihl. I'm not sure if he named it, or another guy there (my immediate
boss, Michael Ruf), but the name is derived from the
Wankel Rotary Engine,
There are four inputs, and the output of this module is the sequence of the
four inputs, one after the other, like so: 1-2-3-4-1-2-3-4-1-2-3-4, etc..
The transition from one to the next can be abrupt, or a gradual cross-fading
of the inputs can had. The result is very much like a four-step 'wavestation
style' wave sequence.
One of the things I wanted to try was to see how it
sounded if I ran the Rotor at audio rates, and tracked the keyboard. The
wavestation can not run the wavesequences at audio rates, and I thought this
might produce interesting results.
Another thing I wanted to add was a way to sync the starting point of
the rotor's sequence of notes, so that for every time I play a note, I could
guarantee the start point. This did not happen until the Solaris keyboard
development, but this is still not in the standard Scope modules
Dante: Your chronicle outlines the development
of the original Rotor in 1999, but it was not adopted commercially at that
stage. Can you give us a brief timeline of the Rotor models after this and
how they culminated in this latest five Rotor (Rotor Ex) design ?
This module was in the basic building blocks of the Scope module library,
but had not been put into any synthesizer at the time. I had a couple of
ideas with it, which were pretty complex, and beyond the interest of my
bosses there at Creamware, so I didn't do anything with it until I had left
Creamware and was on my own.
Dante: So this led to the development of the
Rotor 48 ?
John: What I thought would be interesting
would be to have not one, but four of these rotor objects in one synth, with
the outputs of each feeding a fifth 'Master' rotor object. This way you
could have very extreme evolving pad sounds, since you could have the four
input Rotors slowly cross-fading, and then the Master Rotor also slowly
moving across the four Rotor inputs! Of course, this meant a fairly complex
layout, since you would have a total of 4 x 4 inputs, and with each input,
the choice of being an oscillator, a WAV (sample) playback, or External
Input. This is where I got the number '48' for the name of the first
plug-in, the Rotor 48, meaning sixteen total inputs, with RD, WAV, or
External as inputs. This version was released around March 2001.
Dante: So why was this scaled down to the
John: Because you have a lot of parameters for each input, it was a
bit of a large design to properly handle, so I made something simpler, the
Rotor Jr., which was only a one Rotor object. This was a few months later,
maybe June or July 2001. To keep things a bit more flexible at first, I only
implemented something called the 'RD system', which had the inputs for the
oscillator as blank inserts, with the user able to insert whatever type of
oscillator they wanted. Later versions had permanent oscillators installed,
as well as the RD choices.
Dante: And improvement on these designs as
well as a new Creamware 'User Interface Page Control' lead to the Rotor
John: These two plug-ins did not sell very
well, but I always thought they were unique. After I worked on quite a few
other plug-in ideas, I came back to the Rotor 48, to see what I could do to
really improve it. This was the Rotor EX, which I released July 2005. This
benefited from a new User Interface control that Creamware had added,
allowing one to page on the surface of the User Interface, and I was able to
get a lot more of the parameters on one surface, and a better layout for
everything. I also borrowed some things from my Quantum Wave synth, which
was a four-part Waldorf Wave emulation. I brought over the looping envelope
and some of the other ideas I had in the QWave, and also developed this idea
of using various colors for the little round bussing buttons to provide more
modulation routing and flexibility, which I called AMS routing (Alternate
Modulation Sources). Here's some explanation from the manual:
AMS makes it possible
to provide four different modulation paths to each of the synthesizer's 16
oscillators without creating a cumbersome or overly complex user interface.
Rather than providing 64 individual modulation sources, each with their own
amount, control and source list, AMS uses a generic modulation source and
allows the user to simply turn on the modulation destination with a switch.
The modulation source, amount, and control source for AMS 1-4 are set
at the Cntrl/Misc. page. Each oscillator has a set of
buttons that allows you to enable or disable modulation for each AMS source.
Each button has several states, which determine the destination of the AMS
source. These states are selected by clicking on the button repeatedly until
the desired destination is indicated. To make things simpler, color coding
is used for destinations:
BLUE for exponential frequency modulation.
for linear frequency modulation.
GREEN for shape modulation.
DARK BROWN for mix level modulation.
Holding the mouse cursor over a
button will list its destination colors. There is also a ‘Clear All’ button
to reset all AMS buttons per each Rotor oscillator group to the OFF
So just to re-iterate on the five Rotor design inherited from the Rotor 48,
I can see Rotors A, B, C and D on the GUI, they all feed into the fifth
Yes, the fifth one is the Master Rotor, and it uses the other four Rotors as
its inputs. It's primarily to give even more possible variation to long
evolving type sounds.