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 rec-
ommend 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/ 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. 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 mixing con-
sole.
XLR Ground/Lift Switch
Sometimes connecting to cer tain 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 factor y), ground is on Pin 1 of the Balanced Output jack as nor-
mal. When the switch is in the “in” position, the ground is lifted from Pin 1 of this output. If a persistent
hum exists after tr ying 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 dir ty 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 for th 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.
To use this feature, connect a shielded patch cord from the Tuner Out jack on your 750x to the input jack on
your tuner. Turn the amplifier on and you’re ready to go. If you do not wish to monitor your sound during the
tuning process, you may turn down the Master Volume or set the Speaker On/Off switch to “Off”.
Effects Loop (for external effects devices)
As mentioned previously in the “Effects Blend Control” section of the manual, the Effects Blend circuit in your
750x is similar to that used on recording consoles, with the effects loop on a “side chain” to the normal circuit.
Unless the Effects Blend control is set to the full “wet” position, you will always get the full sound of your instru-
ment AND get the diversity an external effects unit offers. Use of the effects loop will reduce the noise generat-
ed by external effects units (as compared to using the effect between your instrument and the input jack,
though many people use it in this fashion anyway). This is because the loop is after the preamp gain stages.
750x OWNER’S MANUAL • 11
