Specifications

THE EFFECT DEVICES
245
PH-90 Phaser
The PH-90 Phaser is a classic phaser effect with some special features for fine-
tuning the sound. It can create the classic sweeping phaser sounds suitable for
pads or guitars, but also more extreme effects if you like. The phaser is best
used as an insert effect.
Theory
A phaser works by shifting portions of the audio signal out of phase, and then
adding the processed signal back to the original one. This way, narrow bands of
the frequency range (“notches”) are filtered out. When these frequencies are ad-
justed, a sweeping phaser sound is created.
The PH-90 is a four-stage phaser, which means that there are four “notches” in
the frequency response curve (this is a little like using four notch filters with dif-
ferent filter frequencies - see page 108 for an explanation of notch filters).
When the phaser frequency is adjusted (manually or by the built-in LFO), these
notches will move in parallel in the frequency spectrum. Furthermore, you can
adjust the distance between the notches (Split) and their Width. Adding feed-
back raises the filter gain just below each notch in the frequency range, creating
a more pronounced effect.
Parameters
CV Inputs
The following CV inputs are available on the back panel of the device:
D Freq CV.
Adjusts the frequency parameter. Use this e.g. for creating envelope con-
trolled phasing (preferably with LFO Freq. Mod turned off in the device).
D Rate CV.
Lets you control the speed of the modulating LFO from another device.
About Stereo and Mono connections
The PH-90 can be connected using mono or stereo inputs, as shown by the
graphs on the back panel. Note the following:
D A “moving” stereo effect is only obtained when you use a mono in-
put and stereo outputs.
With a stereo input, the two sides are processed in parallel, maintaining the
stereo image of the original sound.
D When you are using a mono input and stereo outputs, there will
only be a stereo effect if the internal LFO is used.
If you turn LFO Mod Amount to zero, both stereo outputs will carry the same
signal (mono). This is because the “fake stereo” effect is produced by invert-
ing the modulation for one of the output channels.
| Parameter | Description
Frequency Sets the frequency of the first notch. Adjusting this will move
the other notches correspondingly. This is the parameter mod-
ulated by the LFO to create phaser sweeps.
Split This adjusts the distance between the notches in the frequency
range, thereby changing the character of the effect.
Width Determines the width of the notches. Raising the Width deep-
ens the effect and simultaneously makes the sound more hol-
low and thin. This will also have an effect on character of the
feedback “tone”.
LFO Rate This is the speed of the LFO modulating the frequency param-
eter. The higher the value, the faster the phaser sweeps.
LFO Sync This button lets you activate/deactivate LFO sync. When it is
activated, the frequency of the LFO is synchronized to the song
tempo, in one of 16 possible time divisions. The LFO Rate knob
is then used for setting the desired time division. Turn the knob
and observe the tooltip that appears for an indication of the ti-
medivision.
LFO Freq.
Mod
This determines the depth of the LFO modulation, i.e. by how
much the frequency parameter should be modulated.
If you turn this to zero, the effect will be a static, formant-like
sound (most effective if you add a little feedback).
Feedback This is similar to the resonance control on a filter. Raising the
feedback gives a more pronounced “tone” in the effect. For
“singing” phaser sounds, try raising this to the maximum.
| Parameter | Description