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effects present at the Balanced Output.
Note: You can still use the Overdrive and SubWave™ Level controls to set the amount of effects present at
the Balanced Output when in the DIRECT + EFX mode; however, that will also affect the level present at
the speaker outputs. Also, though the Gain control will not affect the level of the "clean" bass signal pres-
ent at the Balanced Output when in DIRECT + EFX mode, it WILL affect the level of sub-octave present.
This is normal, and occurs because the SubWave™ circuit is located after the first stage of the preamp
tube and is blended back into the signal specifically for this special mode of the three-position switch. We
recommend that you set the Gain and Effects Level Controls in accordance with previously mentioned
instructions, and the gain structure should fall into place fairly automatically.
Wiring for the XLR jack at the Balanced Output is as follows:
Pin 1 = ground, Pin 2 = + (plus), Pin 3 = – (minus) (American Standard)
Note: Turn off transients appear at the Balanced Output when the amplifier is shut down. We recommend
that equipment being used in conjunction with the Balanced Output be turned down, off, or disconnected
BEFORE the 750x is turned off.
XLR Mode Switch (Line/Direct/Direct + EFX)
This three-position switch determines the signal present at the Balanced (XLR) Output jack as described in
the section directly above. In simple terms:
1. Direct = pre-EQ and onboard effects, post-first tube stage
2. Line = post-EQ and onboard effects
3. Direct + EFX = pre-EQ/post-first tube stage blended with onboard effects
Make sure the switch is set either to full left, full right or center to avoid an intermittent condition.
XLR Pad Control
This control sets the level present at the Balanced (XLR) Output. Turning the control counter-clockwise
reduces the overall level, while turning the control clockwise boosts the overall level. It should be noted
that turning the control fully counter-clockwise to "MIN" does not fully defeat the signal. This is normal,
as the XLR Pad is designed to provide a range of usable levels to be sent to a front-of-house or studio mix-
ing console.
XLR Ground/Lift Switch
Sometimes connecting to certain mixing boards or studio consoles with non-standard XLR wiring can cause
a ground loop. Your 750x has a push-button switch for lifting the ground on the Balanced (XLR) Output. (It
affects no other outputs.) Pushing on the switch will change the mode of operation. When the switch is in
the "out" position (default setting from the factory), ground is on Pin 1 of the Balanced Output jack as
normal. When the switch is in the "in" position, the ground is lifted from Pin 1 of this output. If a persist-
ent hum exists after trying both positions of the ground lift, there is probably:
1. A bad cable or connection somewhere between your Balanced Output jack and the snake leading
to the mixing console
2. A dirty or miswired A/C socket
3. Miswired or poorly wired A/C in the building
4. Fluorescent lighting directly above you or in close proximity (especially when using single-coil
pickups)
5. A cell phone in your right pocket that's interacting with the electronics in your bass (don't laugh,
this actually happens!)
But, in the case of a true ground loop, this switch can often times solve the problem.
Tuner Out
The Tuner Out function allows the user to plug their instrument tuner into this jack and "tune up" without
having to unplug and go back and forth from amp to tuner. This feature is totally isolated from the rest of
the preamp and will function regardless of the settings on the front panel. Being isolated on a side chain
avoids loading down of the instrument, which can cause a loss in dynamic range.
750x OWNER'S MANUAL • 11
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