Speaker Outputs; Level Controls - Mesa/Boogie 50/50 STEREO TUBE Operating Manual

Thank you for your purchase of the "Fifty/Fifty Stereo" Power Amplifier! Inside this clean,
compact, two rack-space unit is a true guitar amp that's unabashedly aggressive! Looking for
raw punch? Guitar tone coloration? Power tube overdrive at manageable volume levels?
You'll find it here. And to help you get down to it, here is a brief description of it's functions
and features.
INPUTS
Located on the rear panel, these two 1/4" jacks are the Channel A and Channel B inputs for
the Fifty/Fifty. They are primarily designed to handle the "line-level" signals from a preamp or
an effects rack; but they are also sensitive enough to permit direct connection of an
instrument for test purposes, if needed. The amplifier is stereo, offering two separate
channels of amplification. If you wish to use only one of its channels, it is necessary to: 1)
Make sure a speaker (or load resistor) remains connected to a speaker jack on both
channels, including the unused one; or 2) Turn the Level control of the unused channel to
zero. (This is necessary because an amplifier channel receiving any amount of signal at its
input will require a "load" at its output - or else damage will most likely result.)

SPEAKER OUTPUTS

The Fifty/Fifty provides one 8-ohm and two 4-ohm speaker outputs for each channel. When
using a single 8-ohm speaker or 8-ohm cabinet on a channel, connect the speaker or cabinet
to the 8-ohm jack. If using two 8-ohm speakers (assuming they are wired in parallel) or
cabinets on a channel, plug them both into the 4-ohm jacks. (The logic here is that two 8-ohm
loads connected in parallel add up to a 4-ohm total load). Mismatching of speaker
impedance will not cause damage or severe loss of power. (Extreme mismatches will
decrease tube life, however). If you opt to use only one channel of the Fifty/Fifty with speakers
connected to only one channel's output(s), you must turn the unused channel's Level control
to zero! Otherwise the channel will be operating without a load, and damage to the tubes
and/or the transformer will result.
POWER AND STANDBY SWITCHES
AC Power is turned on via the Power switch and indicated by the pilot lamp. Before switching
on the power, place the Standby switch into its "STANDBY" position and allow 20-30
seconds of warmup time before switching the Standby "ON". This helps extend tube life by
preventing a high-voltage turn-on surge. (However, all of our amplifiers are tested to
withstand this extra stress, just in case this procedure is neglected by the user). "Standby"
mode should also be used to keep the tubes warm during set breaks.

LEVEL CONTROLS

Each channel of the Fifty/Fifty has its own Level control. If the amplifier is being fed by signals
from a typical preamp, try a setting of "2" as a starting point. If the amp is being fed by lower-
level signals such as those from "minus 20db"- type effects units, etc., you may need to raise
the Levels as high as "8".
Remember to turn the Level to "zero" on any channel not connected to a speaker or load
resistor!
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