Kurzweil K2661, Musician’S Reference Manual

Page: 171 / 500

KDFX Reference
KDFX Algorithm Specifications
10-89
714 QFlange
Digital quantization followed by flanger
PAUs: 1
Digital audio engineers will go to great lengths to remove, or at least hide the effects of digital quantization
distortion. In QFlange we do quite the opposite, making quantization an in-your-face effect. The
quantizer will give your sound a dirty, grundgy, perhaps industrial sound. As you’ve already gathered
from the name, the quantization is followed by a
fl anger. QFlange is a stereo effect.
Quantization distortion is a digital phenomenon caused by having only a limited number of bits with
which to represent signal amplitudes (
fi nite precision). You are probably aware that a bit is a number
which can have only one of two values: 0 or 1. When we construct a data or signal word out of more than
one bit, each additional bit will double the number of possible values. For example a two bit number can
have one of four different values: 00, 01, 10 or 11. A three bit number can take one of eight different values,
a four bit number can take one of sixteen values, etc. The 18 bits of the K2661’s digital to analog converter
(DAC) represents 262144 different amplitude levels (2
18
). Let’s take a look at how fi nite precision of digital
words affects audio signals. The fi gures following are plots of a decaying sine wave with varying word
lengths.
Figure 10-33 A decaying sine wave represented with different word lengths: (i) 1-bit, (ii) 2-bit,
(iii) 3-bit, (iv) 4-bit.
Clearly a one bit word gives a very crude approximation to the original signal while four bits is beginning
to do a good job of reproducing the original decaying sine wave. When a good strong signal is being
(i) (ii)
(iii) (iv)