T H E S O U N D T H A T C R E A T E S L E G E N D S
TwinAmp
,
OwnersManual
TYPE:PR266
P/N 047775
M. TREBLE — Adjusts the amount of boost or cut in the high frequen-
Tw in Fro n t Pa n e l Fu n ctio n s (Fig .1 )
cy range of Channel Two.
A. INPUT 1 — A high impedance, high sensitivity plug-in connection
N. BASS — Adjusts the amount of boost or cut in the low frequency
for instruments.
range of Channel Two.
B. INPUT 2 — A plug-in connection for instruments. This input
exhibits less input impedance and sensitivity than INPUT 1, making it
useful for guitars that have active pickups. This input will provide a
darker tone if used with guitars that have passive pickups.
O. MID — Adjusts the amount of boost or cut in the middle frequen-
cy range of Channel Two.
P. CHANNEL TWO INDICATOR — When this red LED is lit, Channel
Two is selected, and the Channel Two GAIN (item L) and VOLUME
(item Q) controls are active.
Note: INPUT 1 and INPUT 2 are inputs for both Channel One and
Channel Two.
Q. VOLUME — Adjusts the overall volume of Channel Two. As this
control is rotated clockwise from the “1” position, the volume comes
up slowly at first for additional control at lower listening levels; but
near mid volume settings, the volume comes up faster for perfomance
levels.
C. VOLUME — Adjusts the overall volume of the Channel One Clean
Sound.
D. PULL BRIGHT — This pull switch on the Clean Sound VOLUME
control (item C) boosts the highs. This has the sonic effect of adding
high end “sparkle” (to the Clean Sound only).
R. PULL CHANNEL SELECT — When this pull switch on the Channel
Two VOLUME control (item Q) is in the “in” position, Channel One is
selected. When it is in the “out” position, Channel Two is selected.
This pull switch is overridden when the footswitch is connected.
E. GAIN — Adjusts the gain for the Channel One Vintage Drive
Sound. Lower settings provide an “on-the-edge” clean sound, while
higher settings provide gradual compression, like a “cranked” vin-
tage amp, but at controllable volumes. This control works in con-
junction with the Channel One Vintage Drive Sound VOLUME control
(item J) to set the overall volume of the Channel One Vintage Drive
Sound.
S. MIX — Adjusts the amount of audible “wet” (processed) signal
when the variable level effects loop (located on the back panel) is
used. When the MIX control is in the full counter-clockwise position
(“1”), the “wet” signal will not be audible. When the MIX control is
in the full clockwise position (“10”), only the “wet” signal will be
heard (depending on the type of effect used). When nothing is
plugged into the EFFECTS RETURN jack (located on the rear panel),
the MIX control will have no effect on the sound. Also see the
“EFFECTS SELECT” switch in the Twin Rear Panel Functions section of
this manual.
F. TREBLE — Adjusts the amount of boost or cut in the high frequency
range of Channel One.
G. BASS — Adjusts the amount of boost or cut in the low frequency
range of Channel One.
F. MID — Adjusts the amount of boost or cut in the middle frequency
T. REVERB — Adjusts the amount of reverb present in Channel One
and Channel Two. When the footswitch is connected, the reverb can
be turned on and off remotely. Also see the “REVERB SELECT
SWITCH” in the “Twin Amp Rear Panel Functions” section of this
manual.
range of Channel One.
I. VINTAGE DRIVE INDICATOR — When lit, this yellow LED indicates
that the Channel One Vintage Drive Sound is selected, and that the
Channel One Vintage Drive Sound GAIN (item E) and VOLUME
(item J) controls are active.
U. PRESENCE — This is a true vintage-style PRESENCE control that
affects the way the power amplifier responds to upper high frequen-
cies. As the control is turned clockwise, the power amplifier (in inter-
action with the speaker load) enhances upper highs, giving the
Twin’s overall sound a “sparkling” quality.
J. VOLUME — Adjusts the overall volume of the Channel One
Vintage Drive Sound.
K. PULL GAIN SELECT — When this pull switch on the Vintage Drive
Sound VOLUME control (item J) is in the “in” position, the Channel
One Clean Sound is selected and the Clean Sound VOLUME control
(item C) is active; when in the “out” position, the Vintage Drive
Sound is selected, and the Channel One Vintage Drive Sound GAIN
(item E) and VOLUME (item J) controls are active. This pull switch is
overridden when the footswitch is connected.
V. PILOT LAMP — When this lamp is illuminated, the amplifier is
receiving power. Should the lamp burn out, turn off the amplifier and
unplug it from its power source, unscrew the red jewel, and replace
the lamp with type T47 light bulb.
L. GAIN — Adjusts the amount of gain in Channel Two. Lower set-
tings provide gradual compression, while higher settings provide
more sustain... lots more sustain.
Twin Rear Panel Functions (Fig. 2)
A. FUSE — The fuse is in the AC supply of the amplifier and will pro-
tect the amplifier and the operator in the event of an electrical fault.
Fig. 1
Fig. 2
If a fuse blows, it should be replaced only with a fuse in accordance
with the listing at the fuse holder. If the amplifier repeatedly blows
fuses, it should be checked out by a qualified technician. UNDER
NO CIRCUMSTANCES should a fuse of a different type or higher
rating, or a fuse bypass be used, as this could damage the equip-
ment and present a serious safety hazard.
F. EFFECTS SEND JACK — Provides an unbalanced output signal
from the preamp, pre-reverb. It is used to patch into effects.
G. EFFECTS RETURN JACK — This jack provides a pre-reverb return
from effects gear. Plugging into this jack makes the MIX control on
the front panel active.
B. POWER SWITCH — This switch turns the AC power on and off.
H. PRE-AMP OUT JACK — The PRE-AMP OUT JACK, in conjunction
with the POWER AMP IN JACK (item I), provides a post-reverb patch
point at the power amplifier input. This jack can be used to provide
an unbalanced, line-level signal (1.3dBV) for recording and sound
reinforcement consoles, and for driving external power amplifiers, or
another TWIN used as a slave amp. To use another TWIN as a
slave amp, simply run a guiter cord from the master TWIN’S PRE-
AMP OUT JACK to the slave TWIN’S POWER AMP IN JACK .
(Note: this output is best for driving tube type slave amps. See item
P, BALANCED LINE OUT, for driving solid-state slave amps.)
When the switch is off (down), the amplifier is completely shut down.
C. STANDBY SWITCH — When in the STANDBY position, the ampli-
fier is off; however, the tube filaments are left on as to eliminate
warm-up time, provided that the POWER SWITCH (item B) is ON.
Use of this feature during short breaks versus using the POWER
SWITCH will increase tube life.
D. OUTPUT SWITCH — When in the OUTPUT HIGH position, the
maximum output power of the Twin is set to 100 watts RMS, when in
the OUTPUT LOW position, 25 watts RMS. The OUTPUT HIGH posi-
tion is normally used in most applications, and the OUTPUT LOW
position is useful for simulating a smaller amplifier, especially when
the power amp is overdriven.
I. POWER AMP IN JACK — This jack connects directly to the input of
the power amplifier. It automatically disconnects the preamp signal
when used. This is useful for using the Twin as a slave amp.
J. OUTPUT BIAS ADJUST — This trim adjustment is used in conjunc-
tion with the OUTPUT BALANCE ADJUST (item L) and the BIAS TEST
POINTS (item K) to set the output tube bias. See Output Tube Bias
Adjustment Instructions below.
E. EFFECTS LEVEL — This switch directly affects the signal level
appearing at the EFFECTS SEND JACK (item F) by boosting or atten-
uating the signal being sent to the effects. External rack effects usual-
ly require a setting of 3dBV. Use the highest setting possible that
does not produce distortion for the best low noise performance.
K. BIAS TEST POINTS — Used to measure output tube bias and balance
with a digital voltmeter. See Output Tube Bias Adjustment Instructions below.
CH. 1
L. OUTPUT BALANCE ADJUST — Used in conjunction with the BIAS
TEST POINTS (item K) to set the balance between the push/ pull tube
sections of the power amp. See output Tube Bias Adjustment
Instructions below.
footswitch. The footswitch GAIN SELECT button switches between the
Channel One Clean and Vintage Drive sounds, the CHANNEL
SELECT button switches between Channel One and Channel Two,
and the REVERB button turns the reverb on and off. Note: Any good
patch cord will work with the remote footswitch; however, a speaker
grade cord, when it’s available, is perferable to a coax guitar cord.
When the footswitch is connected, it overrides the front panel PULL
GAIN SELECT and PULL CHANNEL SELECT switches.
Output Tube Bias Adjustment Instructions —
1. Turn on the amplifier and let it warm up for at least two minutes
with the STANDBY SWITCH (item C) in the ON position and the
OUTPUT SWITCH (item D) in the OUTPUT HIGH position.
2. With a digital voltmeter set to its most sensitive DC voltage scale,
measure the voltage between the two BIAS TEST POINTS (item K)
labeled “BIAS” and adjust the OUTPUT BIAS ADJUST control (item J)
for a reading of .08 VDC (80 mVDC).
N. REVERB SELECT SWITCH — This three position switch assigns the
reverb to Channel One, Channel Two, or to both channels. For
example, if the switch is set to “CH. 1”, reverb will be available for
Channel One ONLY. This switch is used in conjunction with the front
panel REVERB control and the reverb on/ off footswitch button.
3. Connect the digital voltmeter to the two BIAS TEST POINTS (item
K) labeled “BALANCE” and adjust the OUTPUT BALANCE ADJUST
control (item L) for 0 VDC.
O. EFFECTS SELECT SWITCH — This three position switch assigns the
EFFECTS RETURN JACK (item G) to Channel One, Channel Two, or
to both channels. For example, if the EFFECTS SEND and EFFECTS
RETURN jacks are being used to patch in an effect, and the EFFECTS
SELECT SWITCH is set to the “CH. 1” position, the effect will be
heard ONLY when Channel One is selected.
Notes:
1. Make bias and balance adjustments only when necessary. If you
are unsure about setting bias and balance, it is best to LEAVE THIS
FEATURE ALONE, as it is pre-set at the factory.
2. For optimum sonic performance, set bias to .08 VDC, then set bal-
ance.
3. For optimum sonic performance with increased tube life, set bias
to .06 VDC, then set balance.
4. For optimum tube life, set bias to .04 VDC, then set balance. If a
bias measurement of .04 VDC cannot be obtained, replace the
6L6GC output tubes.
P. BALANCED LINE OUT — This XLR jack provides a transformer
coupled, balanced, floating ground output which can be used to
drive slave power amps, or with proper equalization, used as a send
to a mixing console for recording or sound reinforcement.
5. If the output tubes can’t be balanced, check the bias setting
and/ or replace the 6L6GC output tubes.
For optimum performance when driving slave amps, use high power
solid-state amplifiers of 300 watts minimum rating, and set the gain
M. FOOTSWITCH JACK — Plug-in connection for the remote
of the slave amps such that they NEVER clip with full output from the
Twin. Here’s why: Since the signal at the BALANCED LINE OUT is
derived directly from the output transformer, the signal is a replica of
the voltage present at the speakers in the Twin. If the output of the
slave amps never clip, then the voltage at the output of the slave
amps will also be a replica of that on the speakers in the Twin. This
will preserve the Twin sound. As for the 300 watt minimum rating...
T. IMPEDANCE SELECTOR SWITCH — Sets the output impedance of
the amplifier. The setting should equal the total load impedance as
determined above using the three speaker jacks. (The Twin is sup-
plied with two 8-ohm speakers connected in series; therefore, the
IMPEDANCE SELECTOR SWITCH is set to 16 ohms at the factory.)
LOW POWER OPTION
The Fender Twin can be run with only two output tubes instead of
four. This is done by removing the inner two 6L6GC tubes (the 2nd
and 3rd large tubes, counting left to right), and setting the IMPED-
ANCE SELECTOR SWITCH to one-half of the total speaker load; e.g.,
with a total speaker load of 16 ohms connected, the OUTPUT IMPED-
ANCE SWITCH should be set to 8 ohms. (Remember — half the
tubes, half the impedance.) This will produce 60 watts RMS in the
OUTPUT HIGH setting, and 15 watts RMS in the OUTPUT LOW setting.
In order for a “slaved” solid-state amp to reproduce the sound of a
tube master amp, a solid-state amp needs lots of headroom. For
example, because of the way a tube amp interacts with a speaker
load, a 20 watt tube amp, when driven into heavy clipping, can pro-
duce output signals equivalent to a 180 watt solid-state amplifier.
This nine-to-one ratio can get excessive when a 100 watt tube master
amp is used. But, if the solid-state slave amp has enough headroom
to never clip, and if the speakers used on the slave amp are the same
as those used in the Twin, voila! You now have the capability of
obtaining large amounts of on-stage Twin sound. We recommend
using a Fender Electronics SPL9000(s) with an additional Fender
speaker enclosure(s).
LINE CORD
Your amplifier is equipped with a grounding type supply cord to
reduce the possibility of shock hazard. Be sure to connect it to a
grounded AC receptacle. DO NOT ALTER THE AC PLUG.
If the BALANCED LINE OUT is used as a send to a mixing console, it
should normally be pre-equalized before going to the console input.
What works well is to run the BALANCED LINE OUT signal through
a low-pass filter set to 5 to 6 kHz. The slope of the filter needs to be
steep, 18 dB per octave minimum. A handy way to do this is to use
the low-pass output of an active crossover, or to use a parametric
equalizer. By tweaking the equalization, some very useful sounds
can be obtained.
TUBES
The Fender Twin tube complement consists of four Fender Special
Design 6L6WGC/ 5881’s (part number 039214), three Fender
Special Design 12AT7’s (part number 023531), and five 12AX7A’s
(part number 013341). Fender’s Special Design Tubes provide opti-
mum performance in the amplifier. For best results, replace with
Fender original equipment tubes only. Tube location lable is in cabinet.
BLACK TOLEX COVERING CARE
Q. EXT. SERIES JACK — Plug-in connection for extension speakers.
This should be used in conjunction with the MAIN SPEAKER jack
(item R). By using the EXT. SERIES JACK, the extension speaker is
placed in series with the main speaker; therefore, the impedance of
the extension speaker adds to that of the main speaker. For exam-
ple, by connecting a 4 ohm speaker to each jack, the total load is
4+4=8 ohms. The IMPEDANCE SELECTOR switch (item T) would
then be set to 8 ohms. (Note: an additional 8 ohm speaker could be
added to the EXT. PARALLEL JACK (item S) for a total of 4 ohms, with
the IMPEDANCE SWITCH set accordingly.)
The exclusive Fender Tolex covering on your cabinet is especially
designed to provide years of lasting beauty. A very light soapy solu-
tion on a sponge may be used to remove dirt and residue that may
accumulate in the grain. Be careful not to let any liquid come in con-
tact with the operating surfaces. DO NOT have the amplifier
plugged into a power outlet when cleaning.
TROUBLESHOOTER’S CHECKLIST
- Is the power cord properly plugged into an electrical outlet?
- Is there power at the outlet?
R. MAIN SPEAKER JACK — Plug-in connection for speakers. For
proper operation, this jack should always be used first as connection
to the primary speaker(s). If this jack is used alone, set the IMPED-
ANCE SELECTOR switch (item T) to equal the total speaker load
impedance connected to it.
- Is the fuse blown?
- Is the speaker(s) properly connected to the amplifier?
- Is the amp on standby?
- Are all the control knobs turned up above “4”?
- Is the volume control on the instrument turned up?
- Is the instrument plugged into the amplifier?
(Eliminate any effects devices and try another cord.)
S. EXT. PARALLEL JACK — Plug-in connection for extension speak-
ers. This jack should be used in conjunction with the MAIN SPEAKER
JACK (item R). By using the EXT. PARALLEL JACK, the extension
speaker will be placed in parallel with the main speaker; therefore,
reducing the total load impedance. For example, by connection a
16 ohm speaker to the MAIN SPEAKER JACK and a 16 ohm speaker
to the EXT. PARALLEL JACK, the total impedance will be
If, after checking all of the above, the system is still not operating
properly, consult your authorized Fender Service Dealer.
(16X16)/ (16+16)=8 ohms. The IMPEDANCE SELECTOR SWITCH
(item T) would then be set to 8 ohms. (Note: An additional 8 ohm
speaker could be connected to the EXT. SERIES SPEAKER JACK (item
Q) for a total load of 16 ohms, with the IMPEDANCE SWITCH set
accordingly.)
Twin Block Diagram
1
2
Gain
2
3
Sp e cifica tio n s
PART NUMBER:
120V version: 21-4809
230V version: 21-4889
TYPE:
PR 266
DIMENSIONS:
Height: 20-3/ 4” (52.7 cm)
Width: 26-3/ 8” (67 cm)
Depth: 11-1/ 2” (29.2 cm)
Weight: 77 lbs. (35 kg)
POWER REQUIREMENT:
FUSE TYPE:
120V version: 120 volts AC, 60 Hz, 360 watts.
230V version: 230 volts AC, 50 Hz, 360 watts.
100V and 120V versions: 4A SLO-BLO, 125V min.
230V and 240V versions: T2A, 250V.
INPUT IMPEDANCE:
EFFECTS LOOP:
Input 1: 1M ohm.
Input 2: 136k ohm.
Pre reverb.
Nominal level: +2, -5.5, -13 dBV.
Output impedance: 4.2k ohm maximum.
Input impedance: 130k ohm minimum.
EFFECTS MIX CONTROL:
Continuously variable between the signal at
the EFFECTS SEND and EFFECTS RETURN jacks.
REVERB:
Post effects loop.
PRE-AMP OUT:
Post reverb, +1.3 dBV nominal level.
Recommended load: 22k ohm minimum.
POWER AMP IN:
+1.3 dBV sensitivity, 130k ohm input impedance.
BALANCE LINE OUTPUT:
Derived from the output transformer, fully balanced.
+3 dBV nominal level into 600 ohms or greater.
Pin 1 floating, pin 2 (+), pin 3 (-).
AMPLIFIER LOAD IMPEDANCE:
Switch selectable for 4, 8, or 16 ohms.
POWER OUTPUT:
OUTPUT HIGH setting: 100 watts RMS, 5% THD.
OUTPUT LOW setting: 25 watts RMS, 5% THD.
into 4, 8 or 16 ohms.
SPEAKER COMPLEMENT:
Two Fender P/ N 026488 Special Design 12” 8 ohm
speakers wired in series.
A PRODUCT OF:
FENDER MUSICAL INSTRUMENTS CORP.,
CORONA, CA 9 1 7 2 0
MADE IN U.S.A.
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