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P331 TUBE LOADING AMPLIFIER IN USE
There’s really no “right” or “wrong” way to use the P331. We believe in experimentation and that
trusting your ears will guide you to the settings that sound “right” to you. With that said, the following
may be a helpful guide to getting started and becoming accustomed to the P331’s controls.
FINDING UNITY
The below settings are calibrated to provide unity gain at the output. It’s a good starting point.
When processing stereo sources, we suggest ensuring your settings on the P331 are matched on the
Left and Right channels.
Begin with the unit in
BYPASS
(OUT) with the
LIFT
,
XFORMER
and
GAIN
sections in their
OUT
(bypassed)
position and the
LOADING
knob set all the way down (to the left) in its first position.
In the
MODE
section, set the auto-pad to
PRE
by ensuring the GREEN LED is illuminated. If the LED is
any color other than GREEN, flip the momentary toggle all the way right as many times as necessary
to get to GREEN, then set the toggle to the
CLEAN
position.
Take the unit out of
BYPASS
(IN) and you will be at unity gain.
GETTING LOADED
Now that you have a starting point it’s time to start experimenting with how the
LOADING
circuit
will affect the audio source. Start clicking through settings on your
LOADING
knob. You’ll notice little
to no level gain or loss as you run through different settings. This is due to the auto padding which
is working in the background before the signal hits the tube (
PRE
). Even though you are affecting
internal tube gain, you are not hearing drastic changes in level. This helps when using your main
BYPASS
to A/B between the processed and unprocessed signal without being influenced by drastic
level changes.
Try changing the
MODE
from
CLEAN
to
BLOOM
and experiment some more with the
LOADING
knob.
Now, instead of manipulating feedback to affect internal tube gain, you’re manipulating plate loading
to affect internal tube gain. Again, all being automatically padded behind the scenes to keep levels
fairly matched.
Frequently use your main bypass switches to A/B between the processed and unprocessed audio.
Now try flipping your
MODE
switch to the right to change from
PRE
(GREEN) to
POST
(ORANGE). The
auto-padding is now occurring after the tube as opposed to before the tube. Running through the
same settings you used in
PRE
now take on a slightly different vibe...and driving the input with louder
or quieter signals adds additional possibilities.
OPEN UP WIDE
When you switch to
OPEN
(BLUE) you’re completely disabling the auto padding. This is a good time
to start getting acquainted with your solid-state output
GAIN
section.
Before engaging
OPEN
, put the
GAIN
circuit into
CUT
mode and turn the knob all the way to the right.
This starts you off with 11dB of attenuation. Since in
OPEN
you now have no auto-padding going on,
the
LOADING
knob turns into a tube gain control. As you turn up the
LOADING
knob your level will
increase with each switch position. Using your
GAIN
control in
CUT
mode to manually pad the signal
functions like a master volume on a guitar amp. Now you are in full control of the tube gain (
LOADING
knob)...and the padding (
GAIN
knob). And of course, you still have your
CLEAN
(feedback) or
BLOOM
(feed-forward) modes to switch between. Pretty sweet!
GETTING A LIFT
Don’t let the simplicity of this control fool you. What’s going on behind the scenes took us a whole
lot of experimentation to ensure the integrity of the original signal remains intact while gently lifting
either the highs, lows or both the highs and lows of the source.
Like all the other features of the P331, the effect can be more or less subtle depending on the source
and what settings you’ve chosen on the
LOADING
control. Sometimes it’s just what’s needed...
sometimes the best position is
OUT
. It’s your call.
GETTING TRANSFORMED
We allow the user to hit the optional output transformers in two different ways which changes their
load and, in turn, provides additional sonic options. This control is also heavily dependent on the
audio source it is being fed and the level of the signal. Experiment between the
1
and
2
settings to
find the sweet spot or
OUT
for hard wire bypass.
MORE TO GAIN
Although we’ve left the
GAIN
section for last, it’s an integral part of using the P331 effectively. It’s a
fully-balanced, low-distortion output amplifier which allows you to take all that you are doing with
the
LOADING
,
LIFT
and
XFORMER
circuits and boost or cut up to 11dB.
The
GAIN
knob gives you 11dB of
BOOST
or
CUT
in 1dB increments, while the
RESOLUTION
switch
allows you to back-off 0.25dB or 0.5dB from whatever setting you’re at on your
GAIN
control. The
first position on the
GAIN
knob is 0dB. This allows you to select just 0.25dB or 0.5dB as a starting
point if necessary by utilizing the
RESOLUTION
toggle. After that first position the resolution switch
is “subtractive”. For instance, if you are in
BOOST
and are adding 2dB on the
GAIN
rotary switch, by
engaging the toggle switch to 0.25 you are REDUCING the level by 0.25dB.
The
RESOLUTION
switch really lets you fine tune your level-matching to A/B your processed vs
unprocessed signal while experimenting with the other circuits in the P331 or to squeeze out every
last bit of analog level at the end of an analog mastering chain.
Summary of Contents for P331
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