K&K Sound Pre-Phase Product Manual

PRE -PH A S E PRE A M P
Thank you for choosing the Pre-Phase! This little
preamp provides an astonishing sound quality. The
addition of the phase switch is one of the most
important tools for live sound amplification of any
acoustic instrument.
The super lightweight of the Pre-Phase will not affect
the acoustic tone of your instrument and the battery
life is about 150 hours with a standard alkaline
battery.
The volume control wheel allows for convenient
adjustment during performance. With the Pre-Phase
you should be able to plug your acoustic guitar into
any amp or PA directly. Simply use the EQ on the
amp or Mixer channel to adjust your tone.
HOW THE PHASE SWITCH WORKS
The Pre-Phase has a miniature phase switch
mounted on the left side of the volume wheel. It is a
sliding switch and you can slide the little white tab
left and right with your finger. There are only two
settings.
Phase switches are usually marketed as a feedback-
controlling device, but they accomplish more than
just that. Phase determines at what point in time a
sound wave has its peak or trough.
the wave on the left (1). Interestingly, if these two
waves were played back simultaneously from the
same speaker source with the same volume, they
would completely cancel each other out and no
sound would be heard. There would be silence.
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This picture shows two
(basically identical) waves,
but the wave on the right (2)
is inverted with respect to
When you amplify your guitar, your sound will also
suffer from a degree of phase cancellations.
Amplification systems, effect units, or any electronic
audio device may or may not invert the phase of the
signal coming in. In most cases the manufacturers
do not specify.
Every acoustic instrument projects sound waves in a
certain phase when it is played unplugged. The
phase that is projected from the amplified speaker
source needs to be "in phase" with the acoustic
instrument's own sound waves or the result will not
be optimal.
An out-of-phase problem is indicated by early
feedback and tinny, unbalanced sound. This may be
tolerable in some tone ranges (positions on the fret
board) and quite noticeable in others, even resulting
in sound cancellations on some notes.
The Pre-Phase's phase switch allows for instant
correction of this problem. By toggling the phase
switch back and forth, you will notice fuller, warmer
and nicely balanced tone with less feedback in one
setting. This is the correct phase switch setting.
Keep in mind that it may be different with different
amplification systems.