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Palmer PGA-05 Users Manual
PGA-05
Manual
ADIG-ST Advanced Direct Injection for Guitar-Stereo
BACKGROUND
The
PGA-05
is one of a special series devoted to the direct injection of guitar
amplification. A DI box should normally transfer a linear signal through its circuitry.
The guitar amplifier’s loudspeaker, however plays a very important role in forming the
electrified sound, and therefore must be taken into account when replacing the
miked-up sound. While the PGA-04 (ADIG-LB) has a built-in Load Box (loudspeaker
substitute) for connecting directly to the amplifier, the
PGA-05
does not. Instead, it is
a two channel (stereo) DI box that can accept the full power speaker output of an
amplifier or a line level pre-amplifier/multi-effect output signal using the Line/Spkr
Input level switch.
Some preamps and multi-effect units have a built-in “Recording Output” which is
designed to reproduce a miked cabinet. While this may be convenient, it frequently
does not sound very good. This will not be the case using the analogue technology of
the
Palmer PGA-05
. The subtle phase changes and conflicts that a normal
loudspeaker generates is reproduced via the
PGA-05
’s filter circuit--thus producing a
more lively and diversified sound.
Warning! The PGA-05 does not contain a Load Box. When used with a tube amplifier,
there must be a load connected to the amplifier output. See section - Guitar Amplifier
and PGA-05.
CONCEPT
As stated, the
PGA-05
has two completely separate channels which can be
individually adjusted for sound and tone. This is ideal for a stereo DI guitar set-up. In
each channel, the input signal is powered up using a very small built-in amplifier. The
mini-amplifier has an operating voltage of about 60V and therefore guarantees an
excellent dynamic sound. This signal is then led through the LC-filters which form the
speaker “sound”. It is then routed through a transformer-isolated line-out stage to give
a ground-free balanced XLR output, or unbalanced jack output. Parallel to this, a
second unfiltered signal, that we’ll call a “Full Range” signal, is also fed to the final
stage. Without using up a second channel on the mixing desk, these two signals can
be mixed internally using the separate “Filter” and “Full Range” volume controls. Very
often this technique is used in the recording studios when a direct (clean) signal is
mixed with the speaker output to create a “cutting” bright sound. The extreme highs
can be filtered out to give a smoother sound by using the 6kHz Hi-Cut-Filter. This
method can be used to reproduce the sound of a 12” loudspeaker or a brighter 10”
speaker.