SWR Sound 750x - Manual (Page 6)

Important: The minimum total impedance when operating the 750x is 2.6 ohms. This means you can safely
use:
a) A single 8 ohm cabinet
b) A single 4 ohm cabinet
c) Two 8 ohm cabinets (total: 4 ohms)
d) One 8 ohm cabinet and one 4 ohm cabinet (total: 2.6 ohms) **
e) Three 8 ohm cabinets (total: 2.6 ohms) **
**Running the amplifier constantly at 2.6 ohms, while technically acceptable, will cause the amp to run hot-
ter than usual, and will cause heat-related wear on components sooner than normal.
Turning The Unit On
Remove the AC cable from the accessor y pack and connect it from the amplifier to a standard wall outlet.
Make sure that the both the Gain and Master Volume controls are set to the minimum position. Locate the
Power switch on the right side of the front panel and turn the amplifier on. The Power switch should then illu-
minate in red. Upon powering up, don’t be surprised if you hear a small pop. This is absolutely normal.
(Eliminating this “power on transient” would require a component called a relay. SWR chose not to incorpo-
rate this type of component due to the fact that relays degrade signal quality and often fail, causing the unit
to have no output and requiring a trip to a local ser vice center. The noise can be eliminated by setting the
speaker on/off switch to the “off” position upon powering up, after which point you can set the switch to
“on” for operation.)
Getting Sound Out Of The 750x
Plug your instrument into the desired input jack (please refer to “Front Panel Features” for more detail). Turn
your instrument’s volume up to at least 75% of maximum and slowly adjust up the Gain control. Keep play-
ing and turning the Gain control up until you see the Preamp Clip LED turn red. Then back off the Gain
Control about one large hash mark on the dial. Now turn up the Master Volume control to an equal level.
You should now hear the sound of your instrument amplified through the 750x into your speaker cabinet(s).
Eventually you may want to reset the Gain Control in conjunction with your desired settings for the Overdrive
effect, but we’ll get to that later on in the manual.
750x – FRONT PANEL FEATURES
Input Jacks
Both input jacks accept a standard 1/4" phone plug and both inputs can be used at the same time. Since
the two inputs are totally independent, no loss in volume or tone will occur by using two instruments simul-
taneously. However, the main applicational use for the two separate input jacks is their dif ference in level,
as the Passive/Active input has five times more gain than the Active input. In other words, it’s not necessar-
ily intended as a “submixer” for two instruments, but no harm will come from having two instruments
plugged in at once. Please read below for more details.
Passive/Active Input Jack
This input jack is designed to accommodate both “passive” instruments and most “active” instruments. A
passive instrument has no built-in preamp and does not use a batter y, while an active bass utilizes a bat-
ter y-operated preamp for gain, tone controls, or both. The Passive/Active Input will work with all instruments
having a maximum output of less than 1 volt RMS. Some active pickups such as EMG, Bar tolini, etc., use
batteries for operation and will work per fectly using this input. Instruments made by MTD, Sadowsky,
Modulus, etc., have active electronics that are suited for use in the Passive/Active input.
Generally speaking, tr y this input first. If you hear a small amount of distor tion and the Preamp Clip LED is
not activated, tr y using the Active input jack. If the Active input does not correct any audible distor tion,
check the batter y in your bass.
Note: If you would like to overdrive the first TUBE stage, this can be accomplished by using an
external preamp between your instrument and the Passive/Active input. To obtain optimum sound
4 • 750x OWNER’S MANUAL