SUPPRESSING AC POWER HUM
Sometimes low-frequency hum caused by AC power, poorly grounded pickups, or a multitude of other
reasons creeps into your system. (In the U.S., this is at 60 Hz, but elsewhere in the world it may be at 50
Hz.) If you can't eliminate the hum by using ground lifts, switching polarity, or any of the other means
recommended by the manufacturer of your electrical equipment, then try this:
If your instrument's pickup is introducing low hum, then plug it into the Dual Parametric D.I. and the Dual
Parametric D.I. into your mixer, amp, etc. Turn one Band off and set the other's boost/cut to its 9 o'clock
position and its Octave knob to .015. Set the Frequency Multiplier Switch to its leftmost position, "X 1."
Turn the Frequency knob fully counterclockwise. While listening to your amp, P.A., or monitors, turn the
Frequency knob clockwise until the hum disappears. Turn the boost/cut knob clockwise until you hear the
hum again. Now turn it counterclockwise until it disappears. Don't cut any more signal than necessary,
since some instruments (particularly basses and cellos) produce useful sound in the same range as
electricity-caused hum.
You can also connect the Dual Parametric D.I. in line between signal processors to suppress
AC power hum. Follow the same directions outlined above-and make sure that your levels are
set properly!
“SCOOPING OUT” A BASS GUITAR’S TONE
Some bassists like to slap and pop on their instruments, and to emphasize that tone it's often desirable
to boost the bottom and top end and cut the midrange frequencies a bit. This "scooping out" is easy to
do with the Dual Parametric D.I.:
Use one Band, and set the Frequency knob to its midpoint, its multiplier to "X 10," the Octave knob to 1,
and the boost/cut knob to -25dB. Slap your bass, and turn the Frequency knob back and forth until the
right zone is scooped out. A setting of -25dB may be too deep a cut, so experiment with less severe set-
tings; experiment with different Octave settings, too, since you may want a wider or narrower band affect-
ed by the Dual Parametric D.I. If you want to add more "bite" when you snap strings, turn on the second
Band and pump up some highs.
SUPER HONK WAH-WAH FOR ELECTRIC GUITAR
Many guitarists like the nasal sound that a wah-wah pedal gives a guitar, without rocking the wah-wah
back and forth. You can duplicate the sound with the Dual Parametric D.I. by setting Band One's controls
like this: Frequency at about 1.3kHz, the Octave control midway between .5 and 1 at about .75, and
boost at +15. This provides a very nasal tone. For a deeper effect, duplicate the settings on Band Two. If
you want to add brightness rather than deepen the "honk" sound, widen Band Two's Octave setting to 1.5
octaves and select a Frequency center of around 3.5kHz. This adds a bit of an edge, and brings out the
pick's sound.
DUAL PARAMETRIC D.I.
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