when tr ying this, make sure the Preamp Clip LED is not activated. If this occurs, turn down your
Gain control until the LED does not light. The first preamp tube stage is NOT monitored by the pre-
amp clip circuit for this reason.
Active Input Jack
The Active input jack should be used with instruments having a built-in (on board) preamp or other sound
sources that will produce output levels greater than 1 volt RMS. The number of bass manufacturers has
increased significantly over the years, and it’s impossible to tr y and keep track of them all. Generally, if you
have ver y “hot” pickups and/or tone controls installed in your instrument, and you use them to boost the
level of your bass signal 10 dB or more, you may find the Active input more compatible. The best judge is
your own ears.
If you’re using a keyboard or bass pedal with the 750x, we have found the best choice to be the Active
input.
Note:
Using the Active input with passive basses (active instruments will always employ a batter y)
may result in a loss of high end transients. Players who roll off their high end star ting at about
2kHz, or prefer a “darker” sound, may find this input more to their liking.
If you hear some distor tion with your active bass and are using the Active Input, make sure the Preamp Clip
LED indicator is not lighting. If the preamp stage is not being driven into clipping, replace the batter y in your
instrument.
Gain Control
The Gain control adjusts the volume of the preamp section. Since the Gain control is similar to a “pad,” a
small amount of signal will be heard even with the Gain control rotated fully counter-clockwise (“MIN”) if the
Master Volume is up.
After all EQ settings and the Aural Enhancer are set, the Gain control should be raised until the Preamp Clip
LED barely flashes when your loudest note is struck. This will insure maximum signal to noise ratio and pre-
vent unwanted clipping of the preamp section.
Note:
The Gain can ser ve as an EFFECTS SEND LEVEL ADJUSTMENT. If your effect is being overdriv-
en, turn down the Gain control and readjust your Master Volume for overall loudness.
Preamp Clip LED
The Preamp Clip LED will light whenever the preamp, tone section or output buffer reach clipping (run out of
headroom). This function does NOT monitor the first tube stage of the Passive input. See that section for
more info.
In the event the clip indicator lights, turn down the Gain control. Since this circuit monitors the tone con-
trols, boosting any one of them can cause the Preamp Clip LED to activate. Once again, you may leave the
tone control at its desired level, but turn the Gain control down fur ther.
Note:
Even though the Preamp Clip LED lighting indicates that at some point the preamp is clipping,
no harm is being done to your amplifier. However, clipping of the power amp can cause damage to
your speakers and is not recommended.
Aural Enhancer
The Aural Enhancer is a feature that’s been on just about ever y SWR amplifier since the company’s incep-
tion in 1984, and is a trademark par t of the “SWR Sound” people have come to know and love. It was
developed to help bring out the fundamental low notes of the bass guitar, enhance the high-end transients,
and reduce cer tain frequencies that help “mask” the fundamentals. The ultimate result is:
1. A more transparent sound, especially noticeable when slapping and popping.
2. It can make a passive bass take on an “active” type of quality when set at positions of “2 o’clock” or
fur ther clockwise.
Let’s take a second to learn how the Aural Enhancer works. Think of it as a variable tone curve that changes
depending on where you set the Aural Enhancer control knob. As you raise the control clockwise from the
“MIN” position, you are elevating a whole range of sound (lows, mids, and highs) at a variety of frequency
points selected specifically because they’re different than those selected for the individual Tone Controls.
750x OWNER’S MANUAL • 5
