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The
SESSION just might be the best jazz amp on
the planet!
So
you just want to play in a band? One room needs
a lot of power, so you bring your big amp with two
12"s. The next place needs something really quiet,
so you bring your little amp with a single 12".
Then you play another room with your medium-powered
4x10" amp. Every room sounds different, and each
time you must contend with different speaker complements,
different amp tones, different levels of satisfaction
and inspiration.
Power
Scaling and other goodies
The
SESSION amp will put an end to "difference"
forever! It's the working musician's dream. Dial
up only as much power as you need. Like all of the
new line of LONDON POWER instrument amps,
Power Scaling is the secret to having the same tone
and touch responsiveness at all power levels. Set
the POWER SCALE to MAX and have 50W of glorious
guitar tone - classic, sweet and clean. Overdrive
it and live on the edge - or beyond. Dial the POWER
SCALE down and you can achieve this same magic
at lower SPLs. It helps if your speaker is up to
the task! On stage, use the SESSION 112 cabinet,
or experience the full London Power tone with a
pair of separated cabinets! This allows you to keep
up with drums, even at low Power Scale settings.
We
added the LIMIT control to literally limit
the amount of output tube distortion that can occur
as you dial down the power down. LIMIT assures
the proper interface between the output stage and
the rest of the amp. Of course, you can use the
LIMIT control independently as a master volume
to create some fat distortion tones from the preamp.
For an "automatic" limiting function, flick the
tracking T switch. This Power Scales additional
circuitry and keeps the tone more consistent with
"single-dial Power Scaling".
Of
course, you don't have to use the Power Scale to
get output tube distortion. You can decide how loud
you wish to play with everything set for maximum
clean loudness, then dial down the POWER SCALE
control. Stop when you hear distortion, and then
nudge it up a bit. Now you are playing at the amp's
compression point, which can really add to the singing
quality of your guitar.
The
magic of Sustain
There's
another way to tap into that compression, using
the SUSTAIN control. This gives a variable
supply impedance - sometimes called "sag", but that
is so demeaning - which is inherently a signal-dependent
phenomenon. Here's what happens: When a power supply
is loaded down, its output voltage drops. In an
amp, it is the audio power stage that loads the
supply down, which it only does when you drive the
amp harder. You would suppose that a Power Scaled
amp would exhibit no sag at all, but this is not
the case. Even without the SUSTAIN control,
our Power Scale circuitry is designed to provide
a soft rectification effect similar to a tube rectifier.
It also filters out diode rectification noise, so
most amps sound better dialled down than at full
power. The SUSTAIN circuit provides further
softening of the supply but in an infinitely variable
way that the player determines.
"What
if I leave POWER SCALE at MAX and
just dial up the SUSTAIN?"
You
will get an increasingly spongy sound. At the extreme
it may not be useful, or be merely so as a novelty
sound. But using it more conservatively, it will
change the "feel" of the amp. Especially when combined
with Power Scaling, SUSTAIN will let you
hold notes forever and roll them easily into feedback.
Hey, that sounds like my kind of jazz! Since music
is all about... you know... you should know that
more women prefer 'sustain' to 'sag'. Who wouldn't?
EQ
& Drive
The
all-tube SESSION uses a pair of 12AX7s in
a three-stage preamp architecture that produces
a magnificent, sweet clean tone for electric or
acoustic. The DRIVE control can dial up rich
"throaty" tones perfect for jazz, blues or rock.
The 3-way EQ offers HIGH, MID and
LOW controls that offer a familiar feel.
This is the same circuitry as the clean channel
of the SUSTAINOR preamp. Yes, it actually increases
the sustain of your guitar sound!
The
smart loop
The
parallel - or "mixing" - effects loop is switchable
to series mode using the front-panel S switch. The
effects loop has variable SEND and RETURN
controls right on the front panel where you can
access them quickly during a gig. The loop accommodates
both line and instrument level devices, so plug
in whatever you have. Unlike effects loops on mass-produced
amplifiers, both the SEND and RETURN
jacks on the SESSION are transformer isolated. This
prevents ground loops between the amp and any unit
plugged into the loop.
The
effects loop can also be used as a switchable gain
or level boost. A footswitch is included, and is
plugged into the back of the amp using a regular
guitar cord. This is great for performance situations
where you may want two different volume levels,
or even a switch between clean and dirty sounds
within a song.
It's
a smart loop, too!
You
might imagine that if you had the loop in 'series'
mode and then switched it 'off' that your sound
would disappear. Not in our amps. The switching
circuitry automatically enables the 'dry' path,
bypassing the loop in this instance, but correctly
switching back to just the 'returned' sound when
the footswitch is activated again. See our Effects
Loop Truths for more information about effects
loops.
Get
jiggy (or jazzed) with Bias
Low
voltages in the power section assure peak performance
and safe operation with any age or grade of tube.
This is a classic tube power amplifier fitted with
a few "power amp only" features. You can choose
the fast attack of fixed-bias, used in 99% of guitar
amps, or select the round sound of cathode bias
with the 'K' switch. This is "true" cathode bias
without a bypass cap, so the sound is round. Power
in this mode is limited to 5-8W, so any tube you
plug in will be safe and happy. You can alter the
bias level in either mode with the 'H' switch; 'up'
means "heat". The BODY control allows you
to dial up any tone from low-powered single-ended
to high-powered push-pull. Combined with the bias
switch, you can also create a half-power asymmetrical
distortion that is very smooth, for jazz.
But
wait! The BODY control is no longer labelled
with SE (single-ended) at one end and PP (push-pull)
at the other, as it was in the past. It says 'BRN'
and 'BLU'. Brown sound and blue sound? Not
quite. This is our new double-ended BODY
control with a single-ended sound at each end, and
push-pull in the middle. This lets you take advantage
of the amp's ability to can run dissimilar tubes,
accessing the sound of either as single-ended. Output
transformer primaries are colour-coded with a 'brown'
end and a 'blue' end, which is very obvious when
you look inside the amp. You will
know which tube is the "brown" one and which one
is "blue".
Match,
Triode & Vibe - oh my
The
massive Hammond output transformer allows the output
tap MATCH switch to be set for whatever tone
sounds best. Don't worry what the tap impedance
ratings are - we won't tell you anyway! - just hook
up your cabinets and play.
And
then there is the TRIODE switch that minimizes
odd-order harmonics, effectively rolling off "highs"
in the triode position. Lots of players think they
don't like triode sound, or ultralinear sound, but
they have not usually heard either with the amp's
feedback loop dialled out. You can do this on the
SESSION using the VIBE control. With VIBE
dialled all the way up, and TRIODE selected,
the amp has the same damping factor as with VIBE
fully counter-clockwise and pentode operation selected
(TRIODE switch 'down').
Fun
with tubes
A
pair of 6L6s will give you classic North American
sounds, while EL34s provide a more British sound.
6550Cs impart a cleaner sound, where 6V6s are creamier.
You can even use two different tubes for completely
new sounds. The bias tool and meter are included
with the amp, and the bias procedure is in the owner's
manual. You get three sets of output tubes with
the SESSION, so you can start experimenting right
away. Now you can leave all your tweed and Tolex
amps at home, and just use the SESSION through a
detuned cabinet to get any sound you want at any
loudness.
Reverb
reverb
The
best finish for smooth overdrive tones is spacious
reverb. The SESSION amp has a full-length
Accutronics delay line driven by LONDON POWER's
proprietary push-pull reverb driver. Amazing dimension
and air! Our reverb is very clean so it won't muddy
up your distortion or your clean tones.
and
our usual Ironclad Durability
Power
is served up by a Toroid Tech toroidal transformer
with dual primaries for worldwide mains voltage
compatibility. Full-bandwidth potted Hammond transformers
are used in the effects loop for isolation. Solen
polypropylenes and Philips and Wima capacitors
are used throughout the supply and audio circuitry.
Extensive choke filtering, DC heaters and DC-standoff
heater operation keep hum to a minimum. A quiet
DC fan keeps things cool. Military-style sealed
pots from PEC and high-quality 1/4" jacks last
virtually forever. All mounted in a 3U rack-mountable
Hammond steel chassis with detachable rack ears.
The
SESSION family of amps is covered by our Twenty
Year Warranty, excluding tubes and the reverb tank.
Clean
is its forté. But you get forty shades of
purple to kiss the sky.
- SESSION rear panel - [note:
loops controls are on the front panel]
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