Theory of operation – Source Audio Soundblox Pro Multiwave Distortion Pro User Manual

Page 4

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Theory of Operation | 7

6 | Theory of Operation

The shapes of the distortion curves are also different from standard
distortions. Normally, as the input signal voltage rises, the output voltage
also rises, but begins to level off and finally pins (or clips) at a maximum
value. With a foldback curve, for large enough values of the input, the
output will begin to decrease. With more extreme amounts of foldback,
after decreasing for a while, the output can begin to increase again. Maxi-
mum foldback has many regions where the output alternates between
increasing and decreasing. These kinds of curves add a lot of high fre-
quency content to the output. It also can provide a lot of control over the
sound, based on the level of the input signal. With heavy foldback, chords
containing only octaves and fifths tend to sound best. Other intervals can
cause some strange, although not necessarily undesirable sounds.

Using a special shape of the distortion curve, strong second harmonics
can be created, sounding like a note an octave higher. Rolling off the
guitar tone control will help maximize the octave impression. Complex
chords don’t typically work well for octave settings. The result is very
sensitive to the input signal level (as long as the

SUSTAIN

and

DRIVE

controls are not set too high) and can give a sort of auto-wah effect. Try
dialing down the guitar volume for some interesting effects.

A conventional distortion effect tends to turn the guitar signal into square
waves. Playing harder only makes the transition from negative clipping to
positive clipping a little bit steeper. With our foldback and octave algo-
rithms, a slightly higher input can have a radical effect on the shape of
the output signal.

The

MWD

Pro features the same type of algorithms as the original Mulit-

wave Distortion but adds user presets and a 7-band equalizer and many
other control and parameter options.

THEORY OF OPERATION

The Soundblox Pro Multiwave Distortion provides some unique distortion
sounds. In creating this effects pedal, we didn’t intend to duplicate, mod-
el, or emulate any existing types of distortion. The types of algorithms
we use to create the distortion are quite different from the standard set,
although with certain settings the result can sound similar.

One of the techniques used is to divide up the input guitar signal into
multiple frequency bands. Each band is separately distorted, and then all
are recombined. Because of this, you can achieve a lot of clarity between
notes on chords with complex harmonies. It’s possible to leave several
notes droning, while a melody is played on top. A normal distortion tends
to reduce such playing to mush by compressing and distorting low and
high notes together. Because of the multiple bands, it’s also possible to
get several notes feeding back at the same time. The first

15

settings

(labeled

MULTI BAND

) on the effect knob use band splitting while the last

8 (labeled

SINGLE BAND

) do not.

17

MULTI BAND

SINGLE BAND

02

03

04

05

06

07

08

09

10 11

12

13

14

15

16

18

19

21

22

CLEAN BOOST / EQ

00

20

01

OCTAVE

NORMAL

FOLDBACK

OCTAVE

NORMAL

FOLDBACK

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