Automatically ducks music under announcements
- Perfect for restaurants and small clubs
- Clean, Quiet Mic Preamp
The DU30b is a microphone preamp and background
music preamp. When an announcement is made into
the microphone, the music is automatically “ducked”
under the announcement. Then the music is brought
back to it’s previous level.
Frequency Response 20 Hz - 40 kHz
THD + Noise <0.03% typical
Input/Output jacks XLR balanced output
RCA unbalanced input and output
5 x 1.2 mm DC Jack - Center Negative
Thank you for your purchase of the Rolls DU30b Mic Preamp Audio
Ducker. This device temporarily and automatically mutes or “ducks” a
background music signal under a paging microphone or other auxil-
iary signal. After the announcement, the music level is automatically
returned to it’s previous level.
MIC IN: Female XLR jack for con-
nection to a dynamic or condens-
PHTM PWR: Jumper for engag-
ing the +12 volt phantom power to
the microphone input - configured
AUX IN: Stereo RCA jacks for
connecting to a source different
from the Mic In as the master
LINE IN: Stereo RCA jack for
connection to the stereo signal
source to be “ducked” such as
a tuner, CD player or cassette
OUTPUT: Stereo RCA jacks for
connection to the system’s ampli-
12 VDC: Power input. Connect
to the enclosed Rolls PS27 AC
MIC/LINE: When pressed in, the
gain of the XLR Mic In is reduced
RELEASE TIME: Adjusts the
amount of time for the “ducked”
signal to return to its normal level.
Counterclockwise; slow - Clock-
MIC LEVEL: Adjusts the amount of gain in the Mic In circuit.
DUCK SENSITIVITY: The Threshold at which “ducking” begins.
When the microphone level reaches the threshold, the signal pres-
ent at the Line In jacks is reduced until the announcement is over,
then the Line In signal returns to its previous level
A NOTE ON THE DU30b THRESHOLD SETTING, WITH THE SENSI-
TIVITY CONTROL FULLY CLOCKWISE: If the control (paging) signal is on
the XLR input, then ducking begins (the threshold is) at -40 dB when the
Mic/Line switch is set to “Mic”, and 0 dB when the switch is set to “Line”. If
the control signal is on the RCA input, ducking begins at -40 dB.
Adjusts the amount of background signal (or Line
fully counter clockwise the signal is reduced 6 dB,
ckwise the signal is reduced 70 dB.
If you are using a condenser microphone, carefully connect the two
Phantom Power jumper pins together. Set the level of the music
signal (Line In) for a comfortable level. Speak into the microphone
and adjust the Mic Level for a comfortable level, then adjust the
Sensitivity so that the music is muted when speaking with a normal
voice. Set the Release Time control for the amount of time you wish
for the Aux In signal to return to normal. Set the Duck Depth control
for the amount of Aux In signal reduction you want when the Mic or
Alternate signal is present.
For information on the Rolls One Year Limited Warranty, and
to register this product, visit our website at
