Kurzweil K2500 - RELEASE NOTES V2.5 Release Note page 3

Introducing KB3 Mode
Introducing KB3 Mode
KB3 Mode is a ground-breaking upgrade for the K2500. You can now create and play organ programs that
offer superb realism and unprecedented flexibility. If you are using a keyboard model of the K2500, you'll also
be able to use your instrument's mod wheel and sliders to emulate the nine drawbars found on traditional tone
wheel organs. Similarly, if you're running a K2500R, you'll be able to respond to external drawbar commands
from MIDI (e.g., a MIDI drawbar device).
Although KB3 Mode is an extension of the V.A.S.T. operating system, its programs work a little differently
than other K2500 programs. You'll want to read through these release notes to make sure you take full use of
all these new capabilities.
First Some History
Countless blues, jazz, and rock recordings have centered around the distinctive sound created by classic tone
wheel organs (such as the Hammond B-3) played through rotating speaker systems like the Leslie . Not
only is the sound great, but it's supremely versatile, since the player can control timbre in real-time by
adjusting drawbars that add or remove harmonics from the fundamental tone. Other cool sound-shaping tools
include a percussive emphasis that can be added to each note and the capability to change speaker rotation
speed. Many people, in fact, feel that the tone wheel organ was the first popular synthesizer. And although
these organs haven't been made for years, they are still sought after, restored, and lugged about by legions of
dedicated keyboard players. This despite archaic electronics, inscrutable wiring, and an unwieldy heft that tops
400 pounds.
Duplicating the sound and flexibility of these organs – without the nasty side effects – is the goal of KB3 Mode.
A Little Science
In creating KB3 Mode, we've done extensive testing, measurement, and analysis on several tone wheel organs.
From there we've done our own physical modeling to emulate these organs, taking into account even such
esoteric matters as the way older organs sound different (and arguably better) as their capacitors begin to leak.
(Of course we let you decide if you want your K2500 to sound like an old or new organ.) We've also recruited
the best organ players we could find to try out these programs, and have used their feedback to make sure that
all of KB3 Mode's real-time controls are as convenient as they were on the organs of yore.
To make it all work, we've created a new type of program – the KB3 program – that is built around a totally
new model. In a nutshell, KB3 programs use up to 96 oscillators simultaneously, each oscillator having its own
pitch and amplitude. The K2500 has 48 voices, and KB3 Mode provides two oscillators per voice, for a total of
96. To get the voices it needs, KB3 Mode employs these oscillator pairs independently of each other.
Furthermore, all voices start up – albeit silently – when you select a KB3 Mode program. In a regular K2500
program, on the other hand, voices only start when you play a note. You can see this if you go to the Voices
display (Master mode Util page) while a regular K2500 or KB3 program is selected. While a KB3 program is
selected, you'll see that a number of the K2500's voices are active, even when no notes are being played. And
since these voices are always active, KB3 Mode can rely on tone wheel sharing, as opposed to note stealing, to
maximize usable polyphony.
One more thing. When you create your own KB3 Mode programs, you can use any samples you want for the
upper tone wheels and a variety of waveforms for the lower tonewheels. Not only that, but you can swap the
upper and lower tone wheel groups. The creative possibilities are limited only by your imagination.
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