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Stephenson Amplification
40 Watt Reverb Combo:
Click
on Image for larger pictures
Features:
- 2 channel
pre-amp
-
Effects
loop
-
Dual
power scale
-
4
power tube power amp with 3 mode select
-
Ultra
linear / pentode operation
- Gain boost
on both channels
-
Fat
control
-
6SN7
driver tube in power amp
-
6SN7
tube-driven reverb
-
Plexi-glass
panels
-
Heavy-duty
custom transformers
-
Welded
seams steel chassis
-
Birch
cabinet
-
Marine
-grade mahogany ply speaker baffle
-
Figured
pine high gloss front and rear panels
1x12
combos use the new Jensen NEO speaker
•
100 watts
•
Light weight
•
Full bottom with smooth highs
Common
features of our 40 watt reverb amps:
-
2
channels independent EQ’s
- Dual
power scale master volume (each channel has its own wattage control)
- Tube
driven parallel effects loop
-
Footswitchable gain boost for both channels
-
Fat
control. Feedback attenuation. Controls gain and body of power amp.
-
4
tube power amp with 3 modes:
- Mode
1: 20 watts from dissimilar tube
operation of a 6V6 and a EL84.
- Mode
2: 30 watts from a pair of EL 34’s.
- Mode
3:
All 4 tubes operating.
Stephenson
Amplification 40 Watt Amplifier Operation:
Front Panel:
Clean
channel:
Gain - preamp level control for channel A
Treble - high frequency control for channel A
Bass - low frequency control for channel A
Distortion
channel:
Gain - controls amount of preamp distortion for channel B
Level - controls channel B’s preamp signal output to power amp
Treble - high frequency control for channel B
Bass - low frequency control for channel B
Mid - midrange frequency control for channel B
Fat:
Feedback attenuation – controls the amount of negative
feedback employed in the power amp. Negative feedback is a common guitar
amplifier method to control the tightness and gain of the power amp. Too
much negative feedback can cause a thin, constricted sound, and too little
can cause a bloated sound. With the Fat set to minimum, a great deal of
negative feedback is employed, which keeps the power amp tight with less
body and gain. With the Fat set to maximum, the power amp is running "open
loop" (no negative feedback), for maximum gain, body and wattage
from the power amp.
Power
Scale Ch.A and Ch.B
Power Scaling (PS) is the world’s best and most transparent
master volume. PS varies the amount of wattage the power amp produces
by proportionally varying the voltages applied to the power tubes. With
the PS set to minimum, the wattage output is only a fraction of a watt,
and with the PS set to maximum, the power amp produces full wattage. Power
tube life is greatly extended with the PS on settings less than maximum.
Each channel has its own PS control and is automatically activated with
the footswitch channel button.
Rear Panel:
ON/OFF
Power switch:
Turns power On or Off
Ultra Linear / Pentode:
This switch selects what mode the power tubes are running in:
- Ultra
Linear is a 50’s hi-fi deal that requires a custom output transformer
with an extra set of taps that run the power tube screen grids at near
the same potential as the plates. Ultra Linear has a smooth, warm sound,
and the lower internal resistance of the power tube allows the Fat control
to be set higher.
-
Pentode is the classic guitar amp method of power tube operation. Pentode
produces more wattage and generally more grind. This mode prefers the
Fat control to be dialed back to keep the bottom tight.
Dual Power Tube Select
V6
/ 34 / Quad:
- V6
: This setting activates two of the 4 power tubes, the tubes
activated are the 6V6 and the EL84. This dissimilar power tube combination
produces 20 watts power output.
- 34:
This setting activates the pair of El34’s for 30 watts power output.
- Quad:
This setting activates all four power tubes for 40 watts power output.
Footswitch:
This 5 pin jack is where the footswitch is connected to the amp.
Speaker impedance selector:
Use this selector as a tone control. The output transformer is more than
twice over-rated, so there is no harm in running the selector set to the
wrong impedance.
*** Do not change the impedance while the amp is being
played.
Speaker jacks:
These two ¼ inch jacks are wired in parallel.
Reverb:
Each channel has its own reverb control. The reverb is footswitch activated.
FX
Loop:
The loop is a tube-buffered parallel type with a transformer-isolated
phase-reversible send. Some effects processors and effects pedals reverse
the signal's phase, so use the phase switch to put the effects signal
back in phase with the amp. The loop can also be used as a solo boost.
Plug a short ¼ inch cable between the send and receive jacks, and
adjust the send and return levels for desired amount of boost. The volume
boost can now be activated by using the footswitch's EFX button.
Footswitch Operation:
Chan.:
This button controls which channel is activated. When the LED is on, the
distortion channel is activated. When the LED is off, the clean channel
is activated.
Gain:
This button boosts the gain in the preamp. The amount of gain is internally
set and non adjustable. When the LED is on, the gain boost is active.
The gain boost works on both channels.
Reverb:
This button activates the tube driven spring reverb.
EFX:
This button activates the parallel effects loop. When the LED is on, the
loop is activated
Tips for use:
Channel
A Getting a clean sound:
-
Channel footswitch LED off.
-
The
Gain, Treble and Bass controls are now active.
-
The
fullest clean sounds are achieved by having the amp's Gain set fairly
high (about 5), and the guitar's volume rolled down.
-
Having
the guitar's volume rolled back and the amp turned up has the benefit
of not overloading the preamp, keeping the signal cleaner.
-
For the loudest clean wattage, turn the channel A Power Scale to max.
Channel
B Getting a distortion sound:
- Channel
footswitch LED on.
-
The
Gain, Level, Treble, Bass, Midrange are now active.
- The Gain
knob controls the amount of preamp distortion generated. Settings of
5 and higher have the most body.
- The
Level knob controls the preamp volume sent to the power amp.
-
Set the Level in conjunction with the Power Scale. The higher the Power
Scale, the higher the Level can be set. In other words, if the Power
Scale is set low, then the Level needs to be set low as well, or excessive
distortion is generated.
Using
the V6-34-Quad:
This switch
selects what power tubes are active.
- The V6
position activates the 6V6 and the EL84 power tubes. This mode produces
20 watts.
-
The
34 position activates the pair of EL34s for 30 watts. This mode is the
familiar guitar amp push/pull class A.
-
Quad
position activates all 4 power tubes for 40 watts. This mode has the
fullest sound tonally from all the even-order harmonics generated from
the mismatched tube combination. When in the Quad position, experiment
with the different tonalities of the different speaker impedance settings.
Using an 8 ohm cabinet and setting the speaker selector to 16 ohms will
produce more mids and highs.
Using
the Pentode/Ultra Linear:
This switch can be used with any of the power tube modes (V6/34/Quad).
-
The
Pentode position produces the most wattage and is the more familiar
guitar amp sound. The Pentode position works the power tubes the hardest,
especially the 6V6 tube.
-
The
Ultra Linear position is warmer sounding, and is easier on the power
tubes. Expect longer power tube life when in Ultra Linear mode of operation.
Using
Power Scale:
The Power Scale control is the amp's
master volume. It controls the wattage output. Stephenson Amplification
amps are designed to run reliably at full wattage settings; however, much
longer tube life can be expected by having the Power Scale set below maximum.
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