Mesa/Boogie Mark 5, Owner'S Manual, Page: 47 / 70

SPEAKERS:
Two 4 Ohm and two 8 Ohm jacks are provided for speaker interfacing. The
MARK V
is not very sensitive to speaker
mismatches and will not be damaged by them, except that very low ohmage loads will cause the power tubes to wear faster. A single
twelve-inch 8 Ohm speaker should generally be connected to an 8 Ohm output. When using two 8 Ohm speakers,
connect them both to the 4 Ohm outputs provided (because the total load is 4 Ohms in that case.) Check out the
information further back in this manual regarding speaker impedance and possible speaker hook-up schemes.
4x12 cabinets may be 4, 8 or 16 Ohms. If you are not sure of the impedance of your cabinet, you may need to remove
the Rear Panel in order to verify the impedance rating of the individual speaker or speakers.
MESA
4x12 and 4x10
cabinets come standard wired to 8 Ohms, and are wired in series-parallel. Some Non-
MESA
4x12 cabinets are wired 16 Ohms using
four 16 Ohm speakers. By wiring all four speakers in parallel, you can reduce the cabinet to an impedance load of 4 Ohms (assuming
the speakers are 16 Ohms each.) No matter how unusual your speaker setup, it is always possible to get good performance.
TUNER OUT:
This jack located above the SLAVE jack is a Tuner Output and allows for silent tuning in live stage or studio environ-
ments where it is essential to tune your instrument without sound. When a Tuner is connected to this jack, tap MUTE on the Foot
Controller and the signal to the speakers will be muted. The signal will remain muted until you tap MUTE again to bring
the signal back.
NOTE: The EFX LOOP switch must be set to LOOP ACTIVE for the MUTE function of the Foot Controller to work properly.
SLAVE:
This 1/4” jack and control provide a signal derived from the speaker jack. Perfect for using either the
MARK V
head version
or combo as a master pre-amp and additional power amps for more power when needed. Some players use the SLAVE to derive an
EFX Send Signal and go to other amps for their wet sound.
NOTE:
Once a signal is taken from the
SLAVE, it can not be inserted back into the EFX Loop Return jack or a
feedback loop will occur. Much like holding a microphone into a PA system’s cabinets...a loud high pitched squeal
will be the result.
BIAS SELECT:
This mini toggle allows for proper biasing when swapping to EL34 type power tubes for a brighter harmonic laden response.
It selects a different set of bias resistors and insures that these extremely different power tubes will sound better and work much more reliably.
The adjacent LED indicator alerts you that the bias has been set to accommodate the EL34’s.
NOTE: It is extremely important that the BIAS SWITCH setting match the type of tubes in use. Failure to comply will
result in damage to your amplifier. Always check the BIAS SWITCH whenever swapping tubes!
Regardless of the type of power tube you choose, we strongly suggest keeping at least one spare set of tubes and a bag of
extra fuses with you at all times should a power tube fail when performing. A little preparation wil save you a lot of frustration.
NOTE: Using the AC POWER switch set to VARIAC POWER will reduce the strain on EL34 tubes (and 6L6 as well). If you prefer the sound of
this setting, you will reduce the likelihood of tube problems and greatly extend their toneful life, as they are basically coasting.
rear panel: f
eatureS
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