Kurzweil 150 Faq Manual

KURZWEIL MUSIC SYSTEMS

Questions and Answers About the
Kurzweil 150 Fourier Synthesizer

What is the Kurzweil 150 Fourier Synthesizer?

The Kurzweil 150 Fourier Synthesizer is a multi-timbral sound source, designed to work with any MIDI controller, be it
keyboard, guitar interface or personal computer.

Is it a sampler?

No. The Kurzweil 150FS produces its sounds using additive synthesis technology and a highly advanced form of Contoured
Sound ModelingTM, Kurzweil’s proprietary technique for analyzing and encoding the characteristics of natural sound. The
process of converting a sampled sound into a 150FS sound model is so complicated that even we are amazed that we can do
it.

It’s called a Fourier Synthesizer. Does this mean it only does harmonic sounds?

Actually it should have been called a "partial synthesizer" but then customers might think they weren’t getting a complete
machine. Each "partial" (sine-wave component) of a sound may have any arbitrary frequency which can either be fixed or a
function of the fundamental pitch. "Noise" partials are also available, which is one reason the piano and other acoustic
voices are so realistic. One voice may have as many as 64 partials and the total aggregate may be up to 240 partials. When
the polyphony exceeds this limit, individual partials (marked as optional in the sound models) are stolen, rather than whole
notes.

What about the sounds?

The Kurzweil 150FS comes with 27 Kurzweil-quality acoustic and electronic instrument voices (plus ramp, square and sine
waves), including an incredible acoustic piano, and three expansion sockets for adding more sound blocks as they become
available. The Sound Modeling Program, a standard feature of the 150FS, enables the musician to develop original sounds.

Is it the same piano sound that’s in the Kurzweil 250?

The piano sound is different but just as high quality. It has certain additional features due to the technology used to create the
sound. For example, there’s more change in timbre from soft to loud and more change in the sound as it decays -- there is no
looping as with samplers. There are actually 8 timbre levels in the piano and 5-8 in the other sounds (except the organs).

How do I use the 150FS?

The instrument comes with 93 preset programs for accessing the instrument voices alone or in combinations of splits and
layers. In addition, a simple front panel interface allows you to create and store your own preset programs.

What kind of programs?

You can split the keyboard into two or three regions and define up to seven sound layers in each region. Each sound layer
can select a different instrument voice and can be separately tuned, transposed and balanced. For example, you can put the
acoustic bass on the left side and have piano layered with guitar on the right. Or you can make a great twelve string guitar
sound using two guitar layers with one transposed up an octave and slightly detuned.

Can I use the 150FS with my Kurzweil 250 to reduce channel stealing?

The 150FS is a fine complement to a MIDI setup that includes a Kurzweil 250. Nevertheless, the 150FS will not increase the
number of channels available for your K250 sounds.

What else can I do?

Each sound layer can be timbre shifted (which alters the harmonic content of the sound). You can also control how effects
such as pitch bend, chorusing, vibrato and graphic equalization are applied.

What’s timbre shift?

Timbre ShiftTM is an effect that alters the harmonic content of a sound. It is a combination of transposition in one direction
with an equal amount of pitch shift in the opposite direction. For example, with one octave of timbre shift, when you play
middle C, the sound you get has the harmonic content of the C an octave below, but played at the pitch of middle C.

What is it good for?

It lets you change the tone color of the built-in instrument voices. For example, timbre shift lets you turn the acoustic grand
piano into a bright rock ’n’ roll piano. You can also select a particular timbre (such as the piano sound at the low A) and play
it over the entire keyboard.

How about chorusing?

The 150FS chorusing is software chorusing, not the kind you get with an external effects box. It works by generating extra
notes (up to seven) for each MIDI note. Each extra note may be successively detuned, delayed and attenuated so you can
create a variety of effects such as phasing/flanging, chorusing and echo. The detune range is enormous (up to 2000 cents) so
you can chorus in musical intervals such as fifths -- i.e., 700 cents.

How about vibrato?

The vibrato LFO is a variable symmetry oscillator. There are two waveshapes available: triangle and square; a symmetry
control acts like pulse width modulation. You can also select whether the vibrato works above, below or about the nominal
pitch.

How do I control the effects?

Each sound layer has parameters that control how the chorusing and vibrato effects are applied. Either (or both) effect can be
switched on or off or enabled by the mod wheel and/or by mono or polyphonic afterpressure (aftertouch). Another parameter
controls pitch bend, which can be disabled, controlled by the pitch wheel, afterpressure, or both.

You mentioned a graphic equalizer?

Yes. Each program has an eight-band graphic equalizer. Each sound layer has a parameter to turn the equalizer on or off.

How many programs can I have?

The 150FS allows program numbers from 1 to 255. But the size of a program varies with the number of sound layers. A
typical number of user programs is 100. This does not include programs provided in the 150FS’s ROMS.

255 programs? MIDI allows only 128!

We’ve thought of that. The 150FS includes a 128 element program list that lets you map MIDI program numbers to 150FS
programs. You can split the list two or four ways if you like (e.g., to create four banks of thirty-two programs each).

What about polyphony? How may notes can it play?

The 150FS can produce up to 16 notes at once. You can start up to eight notes simultaneously; beyond that, you’ll start to
hear delays.

Delays?

Yes, delays. If you create a program with four sound layers, each MIDI note will actually produce four notes. So if you play
a six-note chord, you trigger 24 note events. The 150FS will immediately play eight of these voices, and the remainder of the
voices (up to 240 partials simultaneously) will be heard as previously-triggered notes are released.

Does this mean I can’t use the layering and chorusing?

No. It just means that your demands must be reasonable. Excessive chorusing and layering should be used to create sounds
that you would play monophonically (i.e., one note at a time). For polyphonic playing, you should limit the number of notes
per MIDI note to three (e.g., three layers or one layer with two-note chorusing or two layers with one-note chorusing on one
of the layers).

So how does it work with MIDI?

The 150FS features OMNI, POLY and the Kurzweil MULTI modes of MIDI operation. In Multi Mode, the 150FS is multi­timbral. You can assign separate programs to all 16 MIDI channels. Each channel has separate controls (pitch wheel, mod
wheel, etc.). The 150FS is also one of the few instruments that is responsive to polyphonic afterpressure.

Polyphonic afterpressure?

Yes. Afterpressure can be used to control pitch bend, chorus detune and/or vibrato depth on a per-key basis.

What synthesizers produce afterpressure?

Many synthesizers produced within the last few years produce monophonic (channel) afterpressure. The Kurzweil
MIDIBOARD is the only one, however, that produces polyphonic afterpressure.