10
11
LOADING
The soul of the P331 Tube Loading Amplifier is its LOADING
controls. It’s where the tubes live and allows you to vary
at which point the audio hits the tube along its response
curve. This is accomplished in a few different ways
depending on your settings. It gets even more interesting
as you experiment with the different modes...as well
as the level of signal you feed into the unit. You’ll find
different recordings are affected in slightly different ways
even with the same settings. The enhancement is very
much program dependent.
MODE
There are two main modes to the LOADING circuit.
CLEAN
or
BLOOM.
While in
CLEAN
you are operating in “feedback”
mode, utilizing the manipulation of feedback to affect
internal tube gain. While in
BLOOM
, you’re operating in
“feed-forward” mode, utilizing the manipulation of plate
loading to affect internal tube gain. Two different ways to
add subtle harmonics to your signal. Your ears will tell you
which is right for the material you’re working with.
AUTO-PADDING
(PRE, POST, OPEN)
One of the key elements of the P331’s LOADING circuit is its auto-padding feature. As gain is increased
to the tubes, the signal is padded down in equal measure. This allows for precise and repeatable
loads to be applied to the tubes. It also ensures minimal level gain or loss during operation, giving
you the ability to audition what the tubes are doing without distraction from drastic changes in level.
It’s a cool feature and essential to the concept of the unit. To make it even cooler, we provide the
ability to control where in the circuit the padding occurs (
PRE
or
POST
) or disable the auto-padding
all together (
OPEN
). When in
PRE
, the auto-padding occurs to the signal before it hits the tube. In
POST
, the auto-padding occurs after the tubes. While in
OPEN
the auto-padding is disabled and your
Loading knob allows you to crank it up while using your output Gain as a “master volume” of sorts
similar to how a guitar amplifier with a master volume would function. It’s all about experimenting
and letting your ears guide you.
The toggle switch is a “momentary” switch. As you move the toggle actuator to the right, you notice
it will “snap back” to the center position. Move it to the right again and you’ll notice the LED next to
PRE
,
POST
and
OPEN
will change color.
PRE = GREEN
POST = ORANGE
OPEN = BLUE
You can operate in
CLEAN
(toggle left) or
BLOOM
(toggle center) within any of the three auto-padding
modes.
XFORMER
The P331 is designed to run fully transformerless in its default state. The
OUT
setting is a hard wire bypass. This provides the purest, cleanest and most
unaffected audio path through the unit. However, in keeping with the P331’s
versatility, the operator may switch in output transformers and select two
optional settings to load them in different ways. This provides additional
options for enhancing the subtle textures of your audio.
LIFT
GAIN
The LIFT circuit is a gentle parallel filter that enhances the highs, lows or
both the highs and lows of the signal. Audio passes through the LIFT circuit
before the LOADING circuit. With any of the LIFT filters engaged, the audio
is passed unscathed through the fully balanced P331 circuitry and blended
with harmonic content of the LIFT and LOADING circuits working in concert.
OUT
= Hard Wire Bypass
HF
= Gentle High Frequency Lift
LF
= Gentle Low Frequency Lift
DUO
= Both High and Low Frequency Lift
We hesitate to specify exact frequencies designed into the LIFT circuit as depending on your settings
(and how much the signal is being affected by harmonics) the lifted frequencies can shift slightly. As
with all settings and controls on the P331, it’s best to simply use your most valuable assets...your ears
when determining if the LIFT circuit is working for the audio you’re presenting it with.
We decided to give the P331 a clean, fully-balanced solid-state
output gain. We weren’t interested in coloring the sound here.
We wanted the ability to faithfully reproduce what was happening
in the
LOADING
and other circuits while providing the ability to
boost or cut up to 11dB in 1dB increments.
For even finer control we added a
RESOLUTION
switch that allows
you to “back-off”
0.25dB
or
0.5dB
to whatever your current setting
is on the rotary switch. Use this for even finer level matching
between your P331 settings and your bypassed signal, or for getting
that little bit of extra level out of your analog chain before clipping
your A/D.
LIFT CIRCUIT
OUTPUT GAIN
TUBE
LOADING
CIRCUIT
XFORMER
Lift Circuit Engaged
Lift Circuit Engaged
Lifted frequencies are affected
by tube loading harmonic content
Lifted frequencies are affected
by tube loading harmonic content
IN
IN
OUT
OUT
Signals are
blended
(optional)
Signals are
blended
Input signal passes through 100% unscathed
Input signal passes through 100% unscathed
CAUTION:
Be careful when selecting the
OPEN
mode, as you are disengaging the
auto padding. Depending on where you have the
LOADING
and
GAIN
knobs set,
switching to
OPEN
can unexpectedly and dramatically increase the output level.
Summary of Contents for P331
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