Rolls DU30b Mic Preamp with Automatic Audio Ducker

Rolls DU30b: Automatic Music Ducking So a Microphone Always Cuts Through

The Rolls DU30b is a microphone preamplifier with automatic audio ducking that lowers background music the moment someone speaks into the mic and restores it when they stop. It exists for the everyday paging problem in restaurants, shops, and venues: music is playing, an announcement needs to be heard, and no one wants to ride a fader by hand every time. The DU30b listens for the mic signal and automatically dips the music, so pages and announcements are always clear over the program. It combines a clean, quiet mic preamp with the ducking circuit in a compact box that runs on a small DC supply. For any space that plays music but occasionally has to talk over it, the DU30b automates that job completely.

Automatic Ducking That Runs Itself

The core of the DU30b is its automatic ducker, which senses when the microphone is active and turns the background music down by a set amount so the voice sits clearly on top. When the announcement ends, the music smoothly returns to its full level with no one touching a control. This is exactly the behavior a busy staff needs, because it means anyone can grab the mic and be heard without training or a trip to the mixer. The ducking is automatic and hands-free, which is what separates the DU30b from a plain mixer where someone has to lower the music manually every time. For unattended paging over music, that self-running duck is the whole reason the box exists.

Clean Mic Preamp and Simple I/O

The DU30b pairs its ducker with a clean, quiet microphone preamplifier feeding a balanced XLR mic input, plus RCA connections for the music input and output. The preamp presents 100k ohms unbalanced or 600 ohms balanced and delivers a wide 20 Hz to 40 kHz response with total harmonic distortion under about 0.03 percent and a noise floor near -78 dB. In plain terms, the mic sounds full and natural and the box stays quiet between announcements. The RCA music in and out let it sit inline between a music source and the amplifier with just two cables. For an install that needs both a good mic stage and automatic ducking, the DU30b combines them without adding noise to the program.

Compact Build and Low-Voltage Power

The DU30b is housed in a compact chassis about 4 by 4 by 1.5 inches and weighing roughly a pound, small enough to mount behind a counter or inside a rack. It runs on 12 to 16 VDC at only 50 mA through a center-negative DC jack, drawing very little power and staying cool in a closed cabinet. A front-panel power LED confirms at a glance that the unit is live. Its small, solid enclosure suits the permanent, out-of-the-way mounting that a paging system calls for. For an installer, that low-power, compact build makes the DU30b easy to place and forget once it is wired in.

Restaurant, Retail, and Gym Paging

The DU30b is aimed at commercial spaces that play music all day and need occasional clear announcements. A restaurant or bar can call names and specials over a playlist without a staff member ever touching the music level, and a retail floor can make store announcements that automatically cut through the background audio. A gym can page over workout music so instructions are heard without killing the energy of the room. Because the ducking is automatic, any employee can use the mic with no instruction. For any business built on background music and occasional paging, the DU30b handles both from one small box.

Worship and Installed-Sound Announcements

Beyond hospitality, the DU30b fits any installed system that needs a mic to override program audio automatically. A house of worship can duck pre-service music under a welcome or announcement, and a school or office can page over background audio in common areas. Because the box combines a proper mic preamp with automatic ducking, it drops into an existing system between the source and the amplifier without a full console. Its low power draw and compact size suit permanent rack or cabinet mounting. For installs where announcements must always win over music without an operator, the DU30b is the set-and-forget solution.