Ver. 1.0 - © Phædrus Audio Ltd. 2017 All rights reserved.
the proximity-effect. Thus, the first position on the DRIVE control permits simple selection of
the HPF into the circuit: a luxury not easily afforded to the engineers working with The
Beatles!
GAIN and +
The ability to select the higher gain regime of +46dB was included in the design of the Type 47
amplifier because the standard module played various duties in the console and, in some
instances, this meant driving lower loads or making up for more loss in the mixing electronics.
Thus, when the Type 47 amplifier was operating at 46dB, it was not to give more gain in the
sense we understand today, it was to work the amplifier harder to overcome more loss or to
drive a lower load. This is the essence of the DRIVE control in the PHAB-S. In positions 3 and 4
of the DRIVE control, more gain is liberated from the amplifier, but the amplifier is also double,
and then triple, terminated.
Thus, the DRIVE control needs to be used in conjunction with the input attenuation control.
When GAIN is selected, you will notice a small loss in volume caused by the extra load, this
needs to be overcome by advancing the INPUT ATTEN' control. You will notice a "hardening" of
the tone when operating the preamp in this way. The final position, exaggerates this effect.
Still more gain is required to overcome the extra load and you will notice that the tube
amplifier really starts to "show the strain".
Even more distorted effects may be obtained by reducing the master fader and driving the
preamplifier even harder when GAIN/+ are selected.
Pad switch
The Pad switch introduces 20dB attenuation on the primary side of the input transformer.
Stereo Shuffling
(For information and history on Stereo Shuffling go here:
http://www.phaedrus-
audio.com/intro_to_shuphlers.htm
)
The PHAB-S incorporates the
Stereosonic
shuffler invented to correct for various shortcomings
in conventional two-channel stereo. It is simply selected by switching the STEREO SHUFFLER
control downwards.
As with the SHUFFLER in the original 1960s mixer, the correction circuit is entirely passive and
therefore has some static
insertion loss
. That’s to say that the signal level drops by about 2dB
with the SHUFFLER in circuit. Compensate for this loss by advancing the master faders by one
click when the SHUFFLER switch is operated.
Note that stereo shuffling is not appropriate when the preamplifier is being used as a two
channel device, for example for a microphone and a guitar.
