FLEX 15 TM
Owner’s Manual
Revision 1.0
Description
The FLEX 15 is a 15 watt (Triode) or 25 watt (Ultralinear) vacuum tube
guitar amplifier. The circuit configuration is Class A single-ended. There
are 2 channels and an effects loop, all footswitchable. The tube-buffered
effects loop is both series and parallel with send and return level controls
and a wet/dry mix control.
Inputs and Outputs
INPUT: This ¼” jack is used to connect to a guitar or the output of an
effects pedal.
SPEAKERS: These three ¼” jacks are used to connect to a speaker
cabinet. The Rock Block can drive speakers of 4, 8 or 16 ohms
impedance. Only one speaker jack should be used at a time.
SEND: This ¼” jack is used to connect to the input of effects pedals or
rackmount effects.
RETURN: This ¼” jack is used to connect to the output of effects pedals
or rackmount effects. If no cable is connected to the RETURN jack then
the SEND is internally connected to the RETURN.
FOOTSWITCH: This ¼” jack is used to connect to the dual footswitch box.
The footswitchs control the channel selection and the effects loop.
AC POWER: This jack is used to connect a 3-prong power cord.
Controls
POWER: This is the ON/OFF power switch. Push to the up position to
powerup the tube heater supply.
STANDBY: This is the Standby switch. Push to the up position to
powerup the amp.
GAIN: These knobs are used to control the gain of the preamp for each
channel.
BRIGHT: These knobs are used to boost the upper treble response for
each channel.
CHANNEL: This switch is used to select the channel. It is nonfunctional if
the footswitch is connected.
BASS FREQ: These 3-way switches are used to set the bass rolloff
frequency for each channel.
BASS LEVEL: This knob is used to set the bass level for both channels.
BOOST: This 3-way switch is used to boost the gain of the amplifier for
both channels.
MID (CH1): This 3-way switch is used to set the mid frequency level for
channel 1.
MID (CH2): This 5-position rotary switch is used to set the mid frequency level
for channel 2.
TREBLE: This knob is used to set the treble frequency level for both
channels..
EFFECTS LOOP: This switch is used to enable/disable the effects loop. It
is nonfunctional if the footswitch is connected.
VOL: These knobs are used to set the master volume for each channel.
SEND: This knob is used to set the level for the SEND output.
RETURN: This knob is used to set the level for the RETURN input.
MIX: This knob is used to control the amount of the effects loop signal mixed
into the direct signal.
OUTPUT POWER: This switch is used to select the maximum output power
(5W or 15W). In 5W mode only 1 output tube is used. The 4 ohm speaker
jack should not be used in the 5 watt mode.
TRIODE/UL: This switch is used to select the operating mode of the output
tubes – Triode or Ultralinear. The maximum output power is 15W for Triode
mode and 25W for Ultralinear mode.
Operating Instructions
Connect the guitar or effects pedal to the INPUT jack using a guitar cable with
a ¼” mono plug. Also connect a speaker cabinet to the SPEAKER jack using
a speaker cable with a ¼” mono plug. If a speaker cable is connected to the
SPEAKER jack, then a speaker must be connected to the speaker cable to
avoid possible damage to the amplifier.
Turn on the amplifier with the POWER switch. After about 30 seconds toggle
the Standby switch to PLAY. When turning off the amp reverse the turn-on
sequence.
For a clean guitar sound: Turn the VOL knob maximum clockwise. Set the
BOOST switch to the left (minimum) position. Adjust the GAIN knob for
maximum volume without distortion. Adjust the BASS switch and TONE
knobs to taste.
For a “bluesy” or “crunchy” guitar sound: Turn the VOL knob maximum
clockwise. Set the BOOST switch to either the left or center position. Adjust
the GAIN knob for the desired amount of distortion.
For a “hi-gain” or “lead” guitar sound: Turn the VOL knob maximum
clockwise. Set the BOOST switch to either the center or right position. Adjust
the GAIN knob for the desired amount of distortion, sustain and feedback.
For reduced volume with high gain: Turn the VOL knob counter-clockwise.
This will reduce the overall volume of the amplifier. The distortion will
transition from output tube to preamp tube distortion as the volume is reduced.
To Next Page
Need help?
General