Seymour Duncan SFX-11 User Manual
TM
Two Channel Tube Overdrive / Distortion Pedal
Congratulations on your purchase of the Seymour Duncan
Twin Tube Blue™. You can start using your Twin Tube Blue right
away after reading the safety precautions below, and you’ll
immediately enjoy the versatility of having two channels of gain
and a wide range of great tones. However, you might want to
read through these instructions in their entirety rst, to gain
valuable information, which will enhance your enjoyment of your
Twin Tube Blue.
SFX-11
1
Safety Precautions
Hazardous voltages are present. For your protection, and to reduce the risk
of electric shock and danger to personal health, please observe the following
safety precautions when setting up and using your Twin Tube Blue. Most of this is
common sense, but please read it anyway.
Your Twin Tube Blue is designed to work with typical power systems utilizing a
three-prong outlet. To reduce the risk of electric shock, do not plug your Twin
Tube Blue into any other type of power system. Contact your facilities manager
or a qualied electrician if you are not sure what type of power is supplied
to your building or performance stage. Do not use your Twin Tube Blue with
ampliers or other gear that have two prong AC plugs. Do not overload wall
outlets, extension cords, or multiple power strips as this can result in a risk of re
or electric shock.
Never open the chassis. Do not attempt to tamper with or service your Twin Tube
Blue yourself. You’re just asking for trouble. Opening or removing the cover may
expose you to dangerous voltage or other hazards, which could result in serious
injury or death – not to mention damage to the Twin Tube Blue. Wouldn’t that
suck? Refer all servicing to qualied service personnel.
Do not block or cover the side vents on your Twin Tube Blue. Never push objects
of any kind through openings in the equipment. No drummer jokes, please.
Dangerous voltages may be present. Conductive foreign objects could produce
a short circuit that could cause re, electric shock, or damage to your Twin Tube
Blue.
Never place a Twin Tube Blue near a radiator or heat register. Failure to follow
these guidelines can cause overheating and affect the reliability of your Twin
Tube Blue.
Unplug your Twin Tube Blue from the wall outlet before cleaning. Do not use
liquid cleaners or aerosol cleaners. Use a damp cloth for cleaning.
Do not use your Twin Tube Blue near water - for example, near a bathtub,
washbowl, kitchen sink, or laundry tub; in a wet basement; near a swimming
pool; on stage with water effects or precipitation; and the like. Do not expose
the Twin Tube Blue to dripping or splashing liquids and do not place objects
lled with liquid on or near your Twin Tube Blue (yes, unfortunately, this includes
bottled malt beverage liquids). And for heaven sakes, don’t use it while you’re
sitting on the can… OK, enough of that.
2
General Information
The Twin Tube Blue is designed for years of solid performance. One of the
secrets is the duo of type 6111 tubes. These sub-miniature triodes represent
the pinnacle of tube technology advancement. The 6111s were designed and
manufactured to meet the MIL-E-1 spec for reliability under conditions of severe
shock, vibration and temperature. They provide extremely long service life with
virtually no tendency towards microphonics (see USA Department of Defense
Standards, Test Methods for Electron Tubes). Also, unlike some “tube” stomp
boxes that only use the tubes as a clipping diode, the Twin Tube Blue employs
a 100% vacuum tube signal path with a high voltage power supply. This allows
the tubes to operate to their fullest potential and provides the most gain and the
smoothest tone. The result is the classic tube sound, smooth distortion, and low
order harmonics you expect from a great tube preamp.
Tube Life
The 6111 tubes will typically last many times longer than even the best 12AX7s.
For most Twin Tube Blue owners, this means you’ll never have to change your
tubes. However, nothing lasts forever. Should you nd your Twin Tube Blue in
need of new tubes (e.g., exhibiting erratically uctuating signal levels, spurious
increases in noise, sputtering, low level whistling, extreme loss in frequency
response), contact Seymour Duncan or your favorite authorized Seymour
Duncan dealer for your options.
Changing tubes on the Twin Tube Blue is more complicated than plugging pins
into a socket and could be dangerous. Make sure a professional does the work.
Do not try changing the tubes yourself.
Two channels means versatility. When coupled with (true) bypass, this effectively
provides three-channels: Rhythm, Lead and bypass. Separate gain and volume
controls allow Lead and Rhythm Channel levels to be independently set. The
meticulous internal layout minimizes cross coupling and unwanted circuit
interactions that can be a major problem in high gain-high impedance vacuum
tube circuits.
3
Explanation of Controls
11
8
7
10
Top Panel
1
2
3
4
5
6
9
1 Rhythm Gain – Inter-stage gain control for the Rhythm Channel. Provides varying
degrees of overdrive, from clean tube tone to crunch.
2 Rhythm Channel Status Indicator – When lit, it indicates that the Rhythm
Channel is active or staged for activation if the unit is bypassed.
3 Rhythm Volume – Master volume control for Rhythm Channel. Positioned at the
end of the gain chain, it regulates the loudness relative to the other channel, and to
the bypassed sound.
4 Lead Gain – Inter-stage gain control for the Lead Channel. Provides varying
degrees of overdrive, from bite to super hot lead tones.
5 Lead Channel Status Indicator – When lit, it indicates that the Lead Channel is
active or staged for activation if the unit is bypassed.
6 Lead Volume – Master volume control for Lead Channel. Positioned at the end
of the gain chain, it regulates the loudness relative to the other channel, and to the
bypassed sound.
7 Bass – Controls low frequency content in both channels with greatest effect in the
range of 40 Hz to 200 Hz.
8 Treble – Controls high frequency content in both channels with greatest effect in the
range of 2 KHz to 20 KHz.
9 Channel Selector – Selects between the Lead and Rhythm channels. It is possible
to pre-select the gain or volume for a channel when in bypassed mode. This allows the
exibility of transitioning from bypass to either channel without having to step through
4
different sounds.
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