This digitally controlled monitor controller boasts an impressive array of features.
Danish company 2400 Audio have been in business since 2013, producing passive monitoring controller systems of one sort or another, all with the underpinning premise of passing pure, unadulterated audio using an entirely passive, balanced signal path, but with digital control for versatility and the possibility of remote control. The Imperium product name has pervaded the company’s entire range, first with the Legend Imperium models, then with Legacy Imperium units, and now the latest ‘Next Generation’ Imperium NG versions. Pleasingly, the two previous Legacy Imperium models can, if desired, be upgraded to the latest Imperium NG standard, which speaks well for long‑term customer support. All units are hand‑built in Denmark and the company offer a variety of customisation options.
Two physical versions of the Imperium NG are available: a model with a fixed I/O capacity housed in a 1U rackmount case, and a larger 2U rackmount version which has more and expandable I/O. The core features of both systems are very similar though and, as mentioned above, there is a wealth of customisation and configuration options available for both models, which I’ll cover later. For this review I was supplied with the NG 1U unit fitted with the Mastering, Wi‑Fi, and USB options.
The core Imperium NG 1U is a rackmounting unit extending around 205mm behind the rack ears. Most of the rear‑panel audio I/O connectivity is via 10 XLRs which provide two stereo inputs and three stereo outputs — all analogue, balanced and line‑level. In addition, two pairs of quarter‑inch TRS sockets provide a stereo, balanced send and return loop for external signal processing, while a further pair of TRS sockets labelled as Hybrid I/O serve as a user‑configurable stereo input (default) or output. This last facility allows the unit to be configured with three stereo inputs (the standard condition) and three monitor speaker outputs, or two stereo inputs and four stereo outputs — whatever is required to suit a specific installation, and many will find that setup flexibility very useful.
Supplementary rear‑panel connections include a B‑type USB 2.0 (to host) socket, MIDI in and out on a pair of 5‑pin DINs (for remote control), an RJ45 socket, and a 12V DC coaxial power input (a 2A/12V wall‑wart PSU is included). However, all is not quite as it may appear since the RJ45 port is not compatible with standard Ethernet; it’s actually a customised ‘link port’ intended for the connection of future 2400 Audio products! Moreover, the USB socket only works if the optional USB card is installed. The wall‑wart power supply is only there for the digital control electronics — there is no active circuitry in the audio path at all — but, as the signal path is created entirely via relays, without the digital control you can’t connect an input to an output, let alone adjust the volume!
Since I’ve already mentioned configuration options, let’s look at those now. The NG 1U model can be enhanced with options named: Wi‑Fi, USB, Mastering, Trinnov, Barefoot MEME, and Custom Caps. The NG 2U model expands slightly on that list with additional stereo inputs (up to four) and outputs (up to eight).
The easiest option to explain is Custom Caps: a selection of individual button caps with alternative labelling to replace the standard front‑panel fitment — and owners can request their own personalised designs, too. By way of example, the review model was supplied with several alternative button caps including 'Shhh…', 'REAL LOUD', and even a ‘skull and crossbones’ graphic!
Predictably, the Wi‑Fi and USB options permit remote control of the Imperium NG from a computer or compatible mobile device like an iPad, using the multi‑platform TouchOSC app as the user interface. 2400 Audio provide convenient start‑up configurations for TouchOSC, but the system is totally user‑configurable if you want a custom setup. Of particular note, the computer USB option opens another useful possibility: the review unit was supplied with an Elgato StreamDeck USB control panel, which can be configured to provide one‑button access to any Imperium NG monitor‑control features and functions, extending those available via the unit’s own front‑panel controls.
As you might anticipate, the Trinnov and Barefoot MEME options allow direct interfacing with those particular manufacturers’ systems, controlling Trinnov’s ST2 room correction system’s preferences and Barefoot’s MEME monitor emulation modes, all via the same TouchOSC remote‑control system that controls the Imperium.
The review unit was supplied with an Elgato StreamDeck USB control panel, which can be configured to provide one‑button access to any Imperium NG monitor control features.
Looking at the physical hardware unit, a power on/off switch sits at the left of the front panel, although this only controls the internal DC supply; the wall‑wart PSU obviously remains powered while plugged into a live mains socket. Moving right, the lower row of three buttons selects one of the three available inputs (there’s no mixing facility), while the upper row selects various monitoring conditions. In the standard unit these buttons access a Parallel Output function (assigning the monitored signal to two output destinations simultaneously, for example to feed a subwoofer along with the main stereo monitors), activate the insert loop, and bypass the volume control attenuation (with suitable protective interlocks!)
In the review unit, which was fitted with the Mastering option, these default button functions were repurposed to provide direct access to features more commonly required in mastering. However, none of the standard unit’s facilities are lost in this rearrangement as they can all still be accessed via the TouchOSC interface. So, on the review unit the Parallel Output and Insert functions were replaced with dedicated Cut‑Left and Cut‑Right buttons, while the Level Bypass mode was replaced with a Swap L‑R option. (The original button caps were included with the unit.)
Monitor controllers typically use a rotary volume control, of course, but the Imperium NG doesn’t. Instead, spread across the centre of the front panel is an array of eight numbered, programmable buttons, which allow instant access to various user‑defined and instantly repeatable listening levels. The company argue that this approach provides a much better workflow than the traditional rotary volume controls: since most of us use only a few reference listening levels it makes good, practical sense in offering those as guaranteed, easily repeatable button presets. Also, in most monitor controllers the volume control is performed by a dual potentiometer, which inevitably suffers stereo mis‑tracking, particularly at the quiet end of the range. The Imperium NG implements volume control using combinations of relays switching closely matched resistors, giving 256 discrete attenuation levels with perfect stereo imaging at all levels. One rather nice feature for multi‑user installations is that the Imperium NG allows up to eight different ‘Level Profiles’ to be stored, so different engineers can recall their own personalised volume button preferences, if required.
Over on the right‑hand side of the front panel is another group of six buttons, with the lower bank selecting the output destinations (again, only one at a time unless the Parallel Output option is activated). If an extra output destination is required the Hybrid I/O facility can be configured accordingly, in which case the default Input 3 becomes the new Output 4 (and a different button cap can be fitted for identification, obviously).
The upper row of buttons normally activate a left‑channel polarity inversion, and select mono and cut (mute) modes. Sensibly, pressing the Polarity and Mono buttons together auditions the stereo difference or Sides signal (left minus right), but that task is made easier with the Mastering option installed, as the Polarity button is replaced with a dedicated Stereo‑Difference (DIFF) function, giving a more convenient single‑button press. Usefully, the Mono button can be programmed to activate automatically when a specific output destination is selected, if required, so feeding a mono‑check speaker is easy to set up.
Although the core functions of the Imperium NG can be controlled directly from the front panel, 2400 Audio actually designed the unit with remote control very much in mind, primarily using the TouchOSC app. (This must be purchased separately, but a voucher is included for a 15% discount on the Mac OS/Widows version.)
Hexler’s TouchOSC app provides full cross‑platform compatibility (Mac OS, Windows, Linux, iOS and Android) and is completely user‑configurable — although a standard TouchOSC control layout is downloadable to make it easy to get up and running with the Imperium NG. More importantly, TouchOSC provides a very simple, effective and low‑cost way to access and control considerably more features than would ever be practical to control from 1U rackmount hardware.
As already mentioned, the link between the Imperium and whatever is hosting the TouchOSC app can be via the built‑in MIDI I/O using a MIDI‑USB interface (although control information is passed as SysEx data and apparently not all USB MIDI interfaces accommodate it correctly). Alternatively, either the USB or Wi‑fi connections can be used if one (or both) of those options is/are installed. Controlling the NG directly from an iPad or smartphone is a unique feature which might appeal to users who move around the studio a lot.
The default TouchOSC layout presents a ‘Monitor Console’ tab displaying all of the Imperium’s functions in a straightforward way as visual buttons, and clicking or pressing on them activates the corresponding function. Input sources are arrayed on the left, output destinations on the right, and the various auditioning modes are spread across the centre, duplicating and extending the functions of the hardware unit. The eight preset volume buttons are presented at the bottom of the GUI along with a virtual slider acting as a variable volume control (while also displaying the current attenuation level in decibels).
A second tab accesses the eight programmable Level Profiles mentioned earlier, and with the Mastering option installed different profiles can be assigned to the different outputs, too, which is helpful in level‑matching different speaker systems. A third tab opens three sub‑pages: Scenes, Assign Table, and Advanced. The Scenes page allows preset combinations of all Imperium settings to be stored, facilitating fast A/B comparisons of different setups, while the Assign Table page allows additional functions to be associated with the Input and Output buttons, such as automatically selecting mono or a specific level profile to particular outputs.
The Advanced tab contains several more sub‑pages to configure various set‑once‑and‑forget features to suit specific installations. These include how the insert connections work: conventionally, or bypassing the attenuation to allow external volume control, or as a permanent live send — perhaps to feed an external meter display, for example. There’s also an option to decide whether the listening level jumps or ramps up/down to the new volume (ramping is only available with the Mastering option installed). The reallocation of front‑panel button functions is also determined here. With the Trinnov or Barefoot options installed, additional sub‑pages configure the remote‑control capabilities for those devices and, finally, a full factory reset can also be initiated from the Advanced tab.
The Imperium NG is a well‑designed and impressively versatile passive monitor controller, made all the more flexible thanks to its elegant digital control paradigm and the use of third‑party controllers like TouchOSC and StreamDeck.
Arguments rage on social media as to the pros and cons of passive and active monitor controllers, but the truth is that it’s all about the design and implementation, and there are good and bad examples of both formats. In the case of the Imperium NG, the sound quality is as good as it gets; there’s literally nothing between the source and destination apart from a few sealed relays and some precision resistors. And for anyone who dislikes chattering relays, the ones used here just chirp quietly rather than click noisily! With an entirely passive signal path there is no underlying mains hum, no headroom limitation, and no amplification artefacts of any kind, while the precision‑matched relay attenuator ensures perfect channel matching at all listening levels and precisely repeatable volume settings.
However, it also means that frills and extra functions are absent. There’s no digital input D‑A, and no headphone monitoring or built‑in talkback functions, for example. There’s also no output buffering, which means that routing a signal to multiple outputs inevitably results in a slight level loss to all destinations. There is no level correction when summing to mono, either... but do these things matter to most users? Probably not.
As a straightforward studio monitor controller, the Imperium NG has a lot going for it, especially in terms of its innate sound quality and flexible controllability. The Mastering option adds a couple of features which improve its suitability in that environment, too, although one function I consider essential in a mastering application, but which is currently missing, is the ability to trim input levels to allow level‑matched A‑B comparisons. There is a workaround using the Scenes facility, but it’s a rather slow and clumsy workflow.
However, 2400 Audio could address this shortfall quite easily in a future firmware update simply by allowing the user to store (temporarily) a level offset value for a selected input, such that switching inputs also adjusts the attenuator setting appropriately. The Mastering option already implements exactly that capability to level match different outputs (through the level profiles function), so it’s not much of a stretch — and having raised this with 2400 Audio I’m told it’s already under consideration for a future update. Indeed, the company have a history of introducing useful updates to expand functionality quite regularly.
Price‑wise, the Imperium NG offers an attractive solution in comparison to other high‑end monitor controllers, but with very versatile remote‑control options which give it a unique advantage over more traditional designs. I was impressed with the quality, capability and versatility of the Imperium NG and it’s certainly worthy of adding to any shortlist if seeking a high‑end monitor controller.
The Coleman Audio M3PMkIII is another passive monitor controller, broadly comparable in features and price. An active alternative at a similar price is the Dangerous Music Source.
- Very high‑quality digitally controlled passive signal path with precision relay‑switched attenuator.
- Unique multi‑platform remote‑control capabilities.
- Configurable with a range of useful options.
- Mastering option adds application‑specific extra features.
- None of any practical relevance to most users.
This very high‑quality passive monitor controller has a relay‑switched volume attenuator and, making it unique, is remote‑controllable from computers or mobile devices.
2400 Imperium 1U NG base unit £950. Mastering Option £399. USB Option £149. Wi‑Fi Option £175. TouchOSC under £20. Prices include VAT.
SX Pro +44 (0)1462 414 196.