IK Multimedia ARC System
It's not always practical to solve room problems with acoustic treatment. Enter IK's updated monitor correction system...
Although it handles analysis and correction in software, the ARC 2 package includes an omni microphone to take the necessary measurements.
The right way to sort out monitoring problems starts with fixing any room acoustic problems that are fixable. In a typical home studio, as we see in many Studio SOS articles, that might mean installing some mid/high absorbers and finding the best position for your monitors. This can result in a huge improvement, but it is rarely a complete solution, and in particular, does little to address any serious low-frequency concerns. Many rooms are simply too small to fit effective bass trapping, and even in larger studios, some form of monitor equalisation may be required to achieve a subjectively flat response. At one time this was done by ear using graphic equalisers, but the room resonances aren't always considerate enough to fall exactly on the frequencies your graphic EQ offers, and even if they do, a third-octave graphic equaliser can still be too blunt a tool to do the job with adequate precision.
Simple monitor equalisation is a compromise solution: resonances are time-domain effects, whereas equalisation is a frequency-domain solution, so although you can pull down the level of the monitoring at frequencies that coincide with resonant peaks in the room response, those resonances will still exist and can still cause overhang on notes hitting those resonant frequencies. Where the room has been acoustically treated, well-considered equalisation can nevertheless make a valuable contribution to monitoring accuracy, but in my view it isn't a substitute for room treatment. In other words you can't expect EQ to turn a cave into a mastering studio.
The process of measuring your room and speakers is made very simple by helpful prompts from the ARC software.
IK's ARC 2 system is a more sophisticated solution, combining equalisation with time-domain manipulation to get around some of the phase issues caused by basic EQ. Although the literature seems to suggest that you can then forget all about acoustic treatment, I would still be inclined to treat the room as effectively as possible before handing over to ARC 2!
ARC stands for Advanced Room Correction, and ARC 2 is an updated version of the original ARC system reviewed in March 2008 (/sos/mar08/articles/ikmultimediaarc.htm). The box includes a measurement microphone, measurement software and a plug-in to provide the necessary monitoring correction. Based on patented Audyssey MultEQ XT32 technology, ARC is intended for use with nearfield monitoring systems, countering the way in which the room skews the frequency distribution and phase of reflected sound. To paraphrase the official explanation of how this room correction technology works: "MultEQ XT32 looks at patterns in the time-domain responses and classifies them into clusters based on the similarities in those patterns, typically in three to five groups. A representative response is created from each cluster and a final response is then created by grouping them.” ARC 2 is backwards-compatible with measurements made using previous ARC system versions as far back as v1.3, though some of the newer features of ARC 2 are not used when these older files are loaded.
The 64-bit native plug-in that performs the EQ and time-domain manipulation includes support for the AAX plug-in format as well as the usual Windows and Mac OS suspects, and is be authorised online. The user interface has been redesigned since the first incarnation of ARC, the resolution in the super-low 10-40 Hz region is said to be four times greater than that of the original for more precise correction. Recognising that different engineers have different ideas on how monitors should sound, there are now also user tweaks to adjust the final response to taste. Also new in this version is a Virtual Monitoring feature that is similar in concept to Focusrite's VRM box, emulating the sound of various playback devices such as car audio systems and domestic music players. A newly designed monitor control panel provides a level knob and an adjustable level dim switch, and like some larger hardware monitor controllers, makes it possible to monitor Stereo, Mono or Sides signals.
The manual is very detailed and easy to follow, with most of the prompts also being repeated in the software. The included flat-response omni mic is first used to measure the response of the room in various positions while a test signal plays back over your monitors. This must be done with the mic aimed towards the ceiling, not towards the speakers. Prompts help you set up your audio interface, which must support 48kHz operation for this part of the procedure, and check your meters to ensure you have a suitable level of test signal hitting the mic. Any direct source monitoring must be turned off. Only once the monitor level and mic amp gain puts the signal level within the accepted range are you allowed to move on to the next stage, which starts with putting the mic where your head normally resides while mixing. When you start the measurement process, you get a short countdown followed by a few seconds of sweep tones from each speaker: then you're ready to reposition the mic and move on to the next position. Additional measurements should be taken around the listening position in symmetrical pairs — for example, slightly to each side of where you normally sit, and perhaps either side of a spot further back and further forward. If two of you generally sit behind the desk, you can widen the mic spacings to cover the area where you both sit. After seven measurements you get the option to finish, or you can carry on making additional measurements up to a maximum of 16.
Multiple sets of measurements can be taken, named and stored. This is useful if you have more than one set of monitors, in which case you can assign them speaker icons with graphics to match most monitor types. You might also want to create setups for different listening positions in the room, or to have separate setups for a single person monitoring from dead centre and for two people sitting either side of centre.
With the hard work over, you can load the ARC 2 plug-in inside your DAW and get mixing. Both the measurement curve and the correction curve are visible in the plug-in window. The former provides the option to select which monitor you're working with if you have more than one stored setup, while the latter gives you a choice of a flat response or a number of preset 'tailored' voicings, including various Virtual Monitoring emulations.The ARC 2 plug-in lets you select from multiple measured curves — if, for instance, you have several sets of monitors — and apply either a flat response or, as here, a Virtual Monitoring speaker emulation. A couple of well-known smaller studio speakers are simulated along with laptop speakers, small desktop speakers, car audio, iPod docks and so on. These are very useful in telling you how well your mix might hold up in imperfect listening environments. At the bottom of the plug-in window, along with the Correction On button, you'll find a Gain Trim knob and a large PPM meter. Trim is an important feature when choosing correction voicings, as unless you adjust the gain to match, you'll nearly always assume the loudest one is best.