SWR Sound 750x - Manual (Page 15)

Preamp Out
This jack provides another audio output, but it is located later in the signal chain than the Ef fects Send
jack. This signal is post-EQ AND post-effects loop, but still before (pre) the Master Volume control. You
should use this jack when using an effects device in the effects loop and wish to achieve:
1. A line level output for use in conjunction with an additional (slave) power amp—such as SWR’s Power
750.
2. An unbalanced output suitable for recording or live mixing board purposes.
Effects Activator Footswitch Jacks
Your 750x comes equipped with the capability for hands-free control of the onboard Overdrive and
SubWave™ effects. To achieve this function, locate the dual footswitch included in your 750x packaging.
Connect the end with the two 1/4" color-coded phone plugs to the corresponding input jacks on the rear of
your 750x as follows:
Red = Overdrive
Blue = Subwave
Note: In some cases, the color code on the Overdrive plug is gray, and the Subwave plug is orange.
Turn the effects on and off by stepping on the desired switch or switches. As you do so, the illuminated
switches above the Overdrive and Subwave™ controls on the front panel should alternate on and off, and
the chosen effect(s) should engage and disengage accordingly. (Just so you know, we left the footswitch
jacks independent of each other just in case you want to use your own separate footswitches and locate
them in different positions on your custom pedalboard.)
Note: The type of switches contained inside the footswitch chassis are both momentar y, normally
open. Also, if you connect the footswitch to the unit while the unit is on, the effects may engage.
This is normal.
Cooling Fan & Fan Mode Switch
The power amp in your 750x is cooled by two methods: a) an (internal) extruded aluminum heatsink; b) a
fan. Be sure to leave at least a 1/2" clearance between the vent on the top of your 750x and anything you
wish to put on top of it. This will allow for the heat generated by internal components to escape.
You have complete operational control of the fan via the Fan Mode Switch. Setting the Fan Mode Switch to
the “On” position activates the internal cooling fan. Setting the switch to the “Off” position deactivates the
cooling fan, regardless of the internal temperature of the unit. For this reason, it is recommended that the
Fan Mode Switch be set to the “On” position for the majority of the time that the amplifier is in operation.
Note: It is normal for the cooling fan to be audible at low levels. We recommend deactivating the
fan only in situations where the noise floor is so low that normal fan noise might be noticeable or
distracting, such as recording situations where a microphone is used in close proximity to the unit.
750x – SPEAKER OUTPUT SECTION
This section of the manual will deal with the proper connection of speaker cabinets to the power amplifier in
the 750x. Some of this ground has already been covered in the “Getting Star ted—Connecting Your Speaker
Cabinets” section in the beginning of the manual. This is meant to supplement that section and provide
information in greater detail, as power amplifiers, impedance and speaker cabinets are all crucial in deter-
mining how best to operate your new 750x.
How Impedance Affects Power Ratings
People often have questions about impedance. What is it? The root of the word “impedance” is the verb
“impede,” which means to block or resist. That’s what impedance is—resistance to power.
Solid-state power amps do not have a pre-determined impedance. They deliver power at whatever imped-
ance the speaker cabinet tells it to. That’s why you hear the term “slave amp”—amplifiers only do what
they’re told. So if someone tells you that they have a “4 ohm power amp,” their terminology and under-
standing of the concept is way off the mark.
750x OWNER’S MANUAL • 13