Effects Loop
Of course, you can use pedals and rack-mounted effects between your guitar and the amp. In fact, that’s
where most wah-wahs and other pedals sound exceptionally good.
However, rack signal processors are often best suited to being
placed after the preamp’s tone-shaping circuitry. Your Hundred
Duo Twelve’s Effects Loop is designed to give you the best match
between the amp and the processor by allowing you to set the level
of the signal going to the effect, as well as the one coming back.
Therefore, you can tailor your amp/effects levels for best signal-to-
noise ratio and the amount of distortion you want. Note: The Effects Loop send can be used to route a signal
to a guitar tuner.
The Effects Loop comes after the preamp and reverb sections. In addition, its low-impedance circuitry lets
you drive everything from the simplest stomp-box effect to the most sophisticated pro signal processor with
excellent results. It’s also fully buffered, meaning that it can drive long cords and line-level gear and mixing
consoles. (Because the signal is electrically unbalanced, you can use an unbalanced-to-balanced output trans-
former to connect to equipment requiring a balanced input.)
Before you connect a signal processor to your amp, either turn the amp off or to standby.
Use high-quality shielded cords between the amp and processor. Never use a speaker cord.
Setting Effects Loop levels
1. After you connect the amp’s Send and Return with the signal processor’s input and output, set the amp’s
Send Level and Return Level between 1 and 2.
2. Plug in your guitar, turn the signal processor on, and then turn on the amp (or flip the standby switch).
3. Set the amp’s Effects Loop Send Level and the signal processor’s input level so that you don’t overload the
processor. Keep your ears open for unwanted distortion from the signal processor (you’ll know it by its
crackly, unmusical sound). Whack a few chords on your guitar to check that your settings are correct.
4. Now turn up the Effects Loop Return knob until the proper volume and overdrive are dialed in. You’ll
probably have to experiment with the signal processor’s output level until you get the best sound and low-
est amount of noise.
5. Make sure that you set your straight/effects blend at the signal processor, since all of your preamp’s signal is
passed through the Effects Loop. Do not use an effects-only output to return from the processor to the
amp. Always use the “mix” output, if the unit has one.
The Effects Loop Send is configured so that it is always active, so you can use it as a variable output. Note
that if you use the Send to drive slave amps, etc., and have nothing plugged into the Return jack, the signal
still passes from the preamp to the power amp.
Speakers
The speakers in your Hundred Duo Twelve are specially designed Celestion 12" G12T-85 models with a 85-
watt power-handling capacity. They were selected for their classic tone and ability to deliver lots of volume.
To protect them, keep the grille on your amp at all times, and don’t use the back of the amp for storing any
sharp objects.
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Channel 2
Channel 1
Hundred
Duo Twelve
PULL
SELECT
PULL
BOOST
STANDBY
POWER
LOW
GAIN
HIGH
GAIN
VOLUME
BASS
MIDDLE
TREBLE
MASTER
VOLUME
TREBLE
MIDDLE
BASS
MASTER
REVERB
PRESENCE
HANDCRAFTED BY RIVERA RESEARCH & DEVELOPMENT
SUN VALLEY, CA USA
INPUTS
PULL
BRIGHT
PULL
NOTCH
PULL
NINJA
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DE. REFER SERVICING TO QUALIFIED PERSONNEL.
RETURN
LEVEL
SEND
LEVEL
SEND
Z
IN
250K
Ω
Z
OUT
560
Ω
RETURN
EFFECTS LOOP
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