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Dangerous Music D-Box+

Summing Mixer, Monitor Controller & D-A Converter
By Hugh Robjohns

Dangerous Music D-Box+

Technology has moved on in the 10 years since the original D‑Box was released — but the concept seems stronger than ever.

I reviewed Dangerous Music's D‑Box, which combined the roles of active monitor controller and analogue summing mixer, in SOS March 2009 ( It has since won several well-deserved awards and proved enduringly popular. But technology moves on, so Dangerous decided it was time to reinvent the D‑Box to raise the quality, increase its flexibility, and take advantage of the smartphones and tablets we now all take for granted. The result is called the D‑Box+ — but that modest plus sign doesn't really do this redesign justice...

More Of Everything!

The D‑Box+ adds USB and Bluetooth to the original's three input sources, and offers separate source selection for the control room and artist headphones, and switching for three speaker sets rather than two. There's also a new summing mixer design, new D-A converters, new digital connectivity, and a new Bluetooth remote control app (iOS, Android, Mac OS and Windows). Other new features include an assignable line out, duplicated rear-panel headphone sockets, individual speaker trims, summing-bus output trim, automatic mono, and subwoofer associations with one of the speaker outs.

The build quality is exemplary. A substantial 1U rackmount powder-coated steel chassis contains a large main PCB populated with surface-mount components, plus a daughter–board carrying the USB and Bluetooth interfaces. It's still recognisably a D‑Box, but one that has very obviously been extensively enhanced and updated.

The rear panel is packed with even more connectivity than the original D‑Box, with new additions including a  USB input and a  Bluetooth receiver for audio streaming and remote control.The rear panel is packed with even more connectivity than the original D‑Box, with new additions including a USB input and a Bluetooth receiver for audio streaming and remote control.

The rear panel is crammed with connectivity. Next to the universal IEC mains inlet and power switch is a pair of quarter-inch headphone outputs, which are parallel-wired duplicates of the artist and control-room headphone sockets on the front. Three pairs of balanced speaker line outputs on quarter-inch TRS sockets cater for three sets of stereo monitors, or two sets plus one or two subwoofers. One stereo balanced line output, again quarter-inch TRS, can be switched between the control room or headphone source selectors, and a second is a dedicated output from the internal summing bus, whose eight balanced inputs enter via an AES59 (Tascam) standard 25-pin D-sub. A pair of 'combi' XLRs accepts the main analogue stereo monitoring input, while a set of male/female XLRs takes in an AES3 or S/PDIF digital audio signal (up to 192kHz) and provides a link (thru) output. A USB 2.0 Type B socket accepts audio (again, up to 192kHz) from a computer; it's class-compliant with Mac OS and there's an ASIO driver for Windows. Finally, there's a rotatable Bluetooth antenna.


Most front-panel operations are obvious and straightforward but, as with many Dangerous products, some buttons have secondary modes. Starting on the left, the phones and control–room quarter-inch headphone outputs each have a rotary volume control. The phones output is intended for artists, while the control–room output is notionally for the engineer. The two powerful (3W) headphone amps can drive loads down to 4Ω, so passive splitting to feed multiple headphones is possible, even with 32Ω models. Dangerous tell me that, depending on the impedance, each amp can drive as many as eight sets of headphones, for a total of 16 (note that they should all have the same impedance to ensure equal volume).

The talkback section has a volume control, built-in electret mic, and a button to activate talkback. There's no provision to connect a conventional external mic but, conveniently, the app allows you to use your smartphone's mic instead. The talkback button's bright red LED lights when talkback (which goes to the artist/phones outputs) is active, and it features 'momentoggle' operation: press and hold for a momentary action that deactivates when released, or press briefly to latch it on/off.

Source selection for the phones and, separately, the control–room headphone outputs comes next, using two arrays of five buttons, all with integrated LEDs. The source options are the output of the summing bus and the analogue, AES3, USB and Bluetooth inputs. The first four source buttons have green LEDs but the last, naturally, has a blue one. The default mode selects sources individually and exclusively, but the phones and control–room sections can each be set to mix multiple sources. To toggle their mix modes on/off you put the unit into Setup mode (press and hold the control room USB and AES source buttons until their lights blink), then press the Sum source button in the phones and/or control–room section(s). Orange brackets around these buttons act as an aide memoir for their secondary functions. On the subject of configuration tweaks, it's worth noting that the analogue input can be set to +4dBu or -10dBV sensitivity.

Moving right, four buttons control the speaker outputs. The top two select speaker sets 1 and 2. Speaker set 3, labelled Sub(woofer), can be used as a third stereo monitor set, or for an independently mutable subwoofer. The fourth button sums the selected stereo outs to mono. Two screwdriver trimmers in the summing section allow the levels of speaker outputs 2 and 3 to be adjusted relative to that of speaker 1 for volume balancing. Usefully, this allows you to choose to match the levels of different speaker sets (for honest comparisons, not skewed by loudness differences), or set them differently (such as for a bigger, louder set of speakers to impress clients!).

The facilities and functions are well thought-out and easy to control, and the sound quality is sublime, even from the digital sources.

Again, the default is that the three speaker outputs are selected individually, but there's also a mode that allows the D‑Box+ to drive multiple speaker systems simultaneously (for separate control-room and studio monitor speakers, for example). It's also possible to link the speaker 3 (Sub) output to speaker 1 or 2, so that selecting one set of speakers feeds an associated sub. Yet another useful option is to link the mono-sum function to a specific speaker (1 or 2) output, so that selecting one speaker output automatically engages the mono sum (useful, for example, when working a single Auratone).

The next section has a button to feed the line outs from the phones or the control–room source (at a fixed level, independent of the volume control), so you could, for instance, send it to a remote video feed, or to the live room for an artist to control from their phone. Another button enables/disables the Bluetooth connection.

The monitor volume control, on the right, is a rotary encoder with a press–switch action. A ring of green LEDs indicates the current level setting, and pressing the knob activates dim (indicated by a yellow LED below the knob, which can be difficult to see if the unit is below the eye line!). The amount of attenuation applied when dim is engaged can be changed in Setup mode, as can the default behaviour of activating dim during talkback. It's important to establish a fixed acoustic reference volume level in the studio to prevent your decisions being skewed by loudness, and the D‑Box+ caters for that. Once established, a simple double-press of the volume knob instantly recalls that setting. Finally, there's a full factory reset option to cancel any user-programmed configurations.

The only controls I've skipped over so far are associated with the eight-input summing bus. This section features an all-new circuit design, but the only user controls are eight LEDs, which glow increasingly brightly to register the levels of their input signals, and a level attenuator. At maximum this provides unity gain, while the one o'clock position gives around 6dB of attenuation and fully counter-clockwise provides full attenuation. The eight summing inputs are hard-panned left–right in their odd/even pairs, but inputs 7–8 can be summed to mono by pressing the associated button — useful when, for example, mixing stems with the kick and snare on seven and eight.

Published August 2019