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Dangerous Music Monitor ST/SR

Expandable Monitoring Controller
Published January 2007
By Hugh Robjohns

Dangerous Music Monitor ST/SR

This modular monitor controller system offers an easy upgrade path from stereo to surround capability, and transparent audio quality to boot.

Dangerous Music are an American company producing high-quality analogue equipment to help enhance the facilities and interfacing of computer DAW systems. Among the company's impressive product portfolio are the well regarded '2-Bus' analogue summing box, 'Monitor' monitor controller, 'Master' output section, 'S&M' sum and difference interface, and 'MQ' metering and headphone monitoring box. However, the subject of this review is the latest addition to the collection, the Dangerous Monitor system, comprising the ST and SR units, launched at the start of the year.

The ST unit is the core of the system and is a well-equipped stereo monitor controller, complete with talkback and headphone cue facilities. The optional SR unit expands the system's routing capabilities for full 5.1 surround monitoring duties. An elegant desktop wired remote control ships with the ST unit but is fully featured for 5.1 control from the outset, so there is no obsolescence or redundancy involved in upgrading, and hooking the SR into the ST takes only a few seconds.

Audio quality has always been very high on the priority list at Dangerous, and initial listening tests suggest that the ST/SR system achieves impressive levels of sonic transparency and neutrality. All input source, speaker selection, and mode switching is performed via sealed relays, as are the input level matching and volume control attenuators. This approach avoids the distortion issues of VCAs and their ilk, and also ensures very accurate tracking between channels — although all those relays switching in and out does produce quite a racket from the main control unit when you spin the volume knob! Surface-mount op-amps are used for signal buffering duties on a high-quality circuit board, and the device's construction is to a high standard.

ST Overview

As I've mentioned, the core of the system is the 1U rackmounting ST unit, which is powered by an external in-line universal supply accepting any mains voltage between 100 and 240V, 50 or 60Hz. The rear panel carries a pair of XLRs for a stereo auxiliary line-level inputs (of which more in a moment) plus a pair of 25-pin D-sub connectors, wired to the ubiquitous Tascam format. The first of these interfaces the four stereo, balanced, line-level monitor inputs, while the second provides three stereo speaker outputs and a stereo subwoofer feed. There is provision, when configuring the system, to introduce 12dB of gain for each input, to accommodate -10dBV sources, and to set level offsets between inputs in the form of a four-step attenuator, offering 1.5dB increments. In addition, the fourth input has a continuously variable input attenuator controlled from the front panel of the main unit. A similar level offset facility is available for the outputs, with four steps of 3dB.

The external power unit is connected via a five-pin DIN socket, while two male XLRs provide fixed line-level outputs for the talkback (slate) signal and a power amplifier output for the headphone cue feed. A three-pin female XLR is used for remote switching of the talkback mic (shorting pins two and three activates talkback), and an RJ45 connector provides the link to the remote-control panel. This is not an Ethernet network port — it just happens to use the same convenient form of connectivity.

Moving around to the front panel, there is a stereo headphone socket and volume control, followed by the built-in talkback mic, with an associated level control and a quarter-inch socket for an external mic input. The handbook warns that the input is designed for a high-impedance mic, and that if an ordinary mic is to be used, it should be connected via a 600Ω to 10kΩ matching transformer (not supplied). Although the built-in mic seems very sensitive, it's a shame that it's mounted on the rack unit rather than the remote panel, since this restricts where the ST unit can be placed, unless you use a separate talkback mic and go to the trouble of interfacing it appropriately.

The remaining ST facilities comprise four rotary controls to set various signal levels. The first determines how much of the control room's monitoring signal is routed to the headphone cue system. The next two set the level of the Aux input for the cue and monitoring sections, respectively, and the last sets the level of the fourth monitoring input, as previously mentioned. This instantly accessible level control makes it easy, for example, to match the perceived volume of a reference track off CD against a live mix.

The Aux input is a stereo input that can be fed to the control room (Aux to Main + Aux button on the remote) and/or to the cue feed (Aux to Cue). The Aux input can be used for a multitude of purposes, the most obvious being for latency-free monitoring during recording (by splitting the output from a mic preamp between DAW and monitor controller). You could also hook up the computer's soundcard output to hear warning beeps and so forth via the Aux input, and click tracks or other cue feeds could also be fed in here to the artist's headphone system. Another use might be to accept the output of a preamp handling a studio listen mic to allow duplex talkback with a studio.


Very high-end monitor controllers like this new Dangerous unit are few and far between — most equivalent devices cost less than half as much, although few, if any, can match its sonic transparency, precision and versatility. The obvious first alternative for consideration is the Cranesong Avocet, which is extremely impressive. Of course, it is also more expensive than the Dangerous unit, especially in surround guise, but it does incorporate a reference grade D-A converter, which the Dangerous unit omits. Another strong contender comes from Audient in the form of the ASP510, which is a very well specified surround controller that costs roughly the same as the ST alone. Audient have also just introduced a stereo monitor controller called the Centro which looks similarly impressive, though this has no upgrade path from stereo to surround.

Moving down the price range brings in such options as the SPL stereo and surround controllers, or the Presonus Central Station, and the various passive controllers from the likes of Coleman. While highly cost-effective, and often with very clean signal paths, these units can't compete in the ultimate channel-matching accuracy and convenient input offset facilities of some of the more high-end products.

Remote Control Unit

The dedicated controller panel is curved in a very stylish way, but this also means that it occupies quite a large area of the desk (roughly 300 by 110mm). It links to the ST unit via a simple Cat 5 cable up to 100 feet long and terminated in standard RJ45 connectors. Again, while the control signals cannot be routed via a computer network switch or router, simple point-to-point Cat 5 cabling can be used.

The dominant feature of the panel is the large rotary switch on the right-hand side to set the monitoring level. The rest of the panel is covered with illuminated buttons, which are grouped logically and colour-coded blue, green, red and yellow to help identify their functions. The right-hand group of mainly red buttons next to the volume control is associated with the speaker mutes and solos, and sets out to serve a full 5.1 array. By default the buttons work as mutes, but if the Solo button is pressed they take on that function instead. Also in this group of nine are two yellow buttons, which engage Talkback and the monitor Dim mode (-20dB). The latter is normally activated automatically when the talkback button is pressed (to prevent potential howlrounds), but this function can be disabled if required. Strangely, if the talkback is activated via the rear-panel remote switch facility, the Dim function is not applied at all, and there is no configuration option to change this.

The elegant remote allows control of both units, which means that you don't need to upgrade the remote if you upgrade from stereo to surround.The elegant remote allows control of both units, which means that you don't need to upgrade the remote if you upgrade from stereo to surround.

The central group of 13 buttons is mainly concerned with selecting input sources and speakers. The bottom row of four buttons selects the required input source, while the row above has four more labelled 'Additional Switching'. Apparently, these will control the third component in the set, slated for release in mid-2007. This will be another 1U box with a two-card slot capacity and will give the user a choice of options including digital input with stereo and six channel D-A conversion, multi-format video switching, 5.1 stereo fold-down, and bass management for surround applications. There can be up to four units, allowing 16 additional function paths.

The top row of five buttons selects the loudspeaker arrays. These buttons provide for a main and two alternate speaker arrays, and activate the subwoofer output and an associated low-pass filter (-3dB at 57Hz, with an 18dB/octave slope).

The left-hand control section has six blue buttons concerned purely with configuring the unit, although one has a curious dual function. Labelled PPI (Producer Pacification Indicator), this button does nothing under normal operation other than toggle its light on and off. Dangerous suggest that this can be used to fool troublesome producers into believing you are changing something to make an already perfect mix sound just the way they want it... and I know from experience just how useful a function like this can be! When the control panel is in its configuration mode, the PPI button is used to reset everything to the factory defaults, or to exit the mode without saving any newly adjusted parameters.

Two yellow buttons in this group are used to enable the Aux input into the main monitoring, and to derive a mono sum (with 6dB attenuation). The arrangement of speaker mute buttons makes it easy to listen to mono as a phantom image or via a single speaker, which is very useful. Sadly, though, there is no button or facility for introducing a polarity inversion to one channel, which is disappointing on a unit that is so well specified in every other regard. Being able to flip the polarity of one channel is an immensely useful facility, not only for checking phase, but also for matching channel gains on stereo sources and mic arrays, and for auditioning the 'S' component of a stereo signal.

Configuring The ST

The system can be customised in various ways to suit different applications and requirements, by holding down the blue Setup button at the top of the left hand group to enter the configuration mode. Pressing the button for an input or loudspeaker channel then allows level offsets to be introduced, switched with the Up and Down buttons as necessary, with the setting being indicated on a row of four LEDs above the buttons. To accommodate nominally -10dBV sources, 12dB of additional gain can be invoked for the selected input by pressing the blue Gain button, and if you're working in surround sound, each source button can be configured to route 5.1 channel inputs instead of the default stereo inputs, by pressing the blue 5.1 button. In a similar way, the subwoofer output can be enabled for a selected loudspeaker feed, with or without the low-pass filtering.

As mentioned earlier, the monitor Dim is activated automatically whenever the Talkback button is pressed, but this can be disabled by holding the Talkback button down and then pressing the Dim button. Likewise, pressing the Aux button while holding the Talkback button configures the system to activate the Aux input automatically whenever the talkback button is pressed, the idea being to allow live two way conversations via a studio-listen mic input brought back into the system through the Aux channel. This probably all sounds far more complicated than it really is! Configuration changes can be made 'live' without nasty pops or bangs, which is handy if you need to adjust input level offsets on the fly.

Surround Mode

The SR unit is another 1U rackmount box, powered by an identical in-line universal power supply module to the ST unit. Essentially, the SR box simply extends the ST's input and output signal switching, and expands the volume control attenuator to cope with the additional channels. Upgrading the system for surround sound monitoring is as simple as plugging in a pair of short ribbon cables to cross-patch the D-sub connectors on the ST unit with a corresponding pair on the SR unit, and then replugging the Cat 5 cable from the remote control panel to the SR unit, while a supplied short link cable is used to link the control signals back into the ST unit.

The two rack units link to each other via D-sub connectors, wired to the Tascam standard, while the remote links to the units via the same RJ45 connectors used for Ethernet.The two rack units link to each other via D-sub connectors, wired to the Tascam standard, while the remote links to the units via the same RJ45 connectors used for Ethernet.

In this configuration, all I/O is now connected to the SR unit via more Tascam format D-sub connectors. Each of the four input sources is provided with its own D-sub socket (although only the first six channels are used in each connector), and three more provide the outputs to each speaker array. The first two speaker sockets provide full 5.1 outputs (Main and Alt 1 arrays), while the third is restricted to stereo monitoring for Alt 2 (left and right front channels only; there is no inbuilt downmixing). The additional channels in this connector are used to provide three subwoofer outputs (mono, left and right). To facilitate sharing a subwoofer with both stereo and 5.1 speaker setups, the LFE feed is routed to both the LFE out and the sub outs when a surround input source is selected. An eighth D-sub connector provides a buffered feed for an external multi-channel metering system, which is a useful extra facility. The only controls on the front panel of the SR unit are four recessed trimmers to balance the volume of the left and right surround, centre and LFE channels against the main stereo pair. However, these adjustments apply to both 5.1 speaker array outputs.

In Use

The Dangerous ST/SR system works very well indeed and sounds completely clean and transparent, and when patching the system in and out of my monitoring chain, I couldn't hear any change in quality at all. The signal paths are very clean and noise free, with masses of headroom, and the headphone driver is seriously powerful! The volume switching technology and level offset options are similar to those employed in the excellent Cranesong Avocet monitor controller, which is my current favourite. The Dangerous ST/SR system offers a very similar approach but at a rather more attractive price, especially for the surround version. However, the ST/SR system only provides four analogue inputs and currently there are no digital inputs (unlike the Avocet and many other high-end monitor controllers). This is something that needs to be taken into account when you're making comparisons and budgeting.

This Dangerous unit provides virtually all the facilities required of a decent monitor controller. It is controlled through an elegant interface and there is an easy upgrade path for surround sound. The inclusion of talkback and a cue headphone feed is very useful, and the Aux inputs provide some welcome flexibility and functionality too. I find the absence of a polarity inversion feature disappointing, but maybe that reflects my BBC upbringing more than a real-world requirement. I also think that not being able to activate the Dim mode with the external talkback remote switch restricts the possible applications a little too much as well, which is a shame. But to be fair, I am yet to find my perfect monitor controller commercially. This Dangerous Audio ST/SR model comes a lot closer than many and it is well worth auditioning if you are in the market for a very serious monitor controller. 

Published January 2007