Coleman SR5.1 MkII

If you're in the market for a good-quality, no-frills surround monitor controller, this may be just what you're looking for.

With the ubiquitous DAW the centrepiece of most recording studios these days, the functionality of the traditional console is increasingly being shared between stand-alone mic preamps and monitor controllers. Stereo monitoring controllers are easily available across all price points, but surround monitoring is still less common, and there are considerably fewer surround monitoring controllers to choose from.

American manufacturers Coleman Audio produce an interesting range of products, including various stereo and surround monitoring controllers. I have reviewed a stereo unit (the M3PH) in these pages before, as well as the versatile A/B 5.1 switcher, which I actually ended up buying.

For simple surround monitoring, Coleman have produced the SR5.1, which extends the company's familiar philosophy of switched volume controls and a straightforward signal path to the world of surround sound.

Overview

This is a very simple unit which provides all the basic and essential facilities in a simple-to-use format, with the emphasis on quality rather than bells and whistles. The unit is housed in a standard 1U rackmounting case, with all the connectors on the rear panel and a few push buttons on the front, with easily accessed level trimmers for system calibration.

The main differences between the original and the current MkII version is that the level trimmers have been moved to the front panel for easier access (they were hidden inside), and two fold-down options have been added. However, some confusion might arise here, as the current production model differs slightly from what is shown in most of the brochure and on-line pictures... but I'll explain that later.

An on-off mains rocker switch occupies the right-hand side of the front panel, with a large rotary switched attenuator placed almost centrally to control the volume of all six channels with a claimed 0.05dB accuracy. Sadly, there are no level markings around the control, just a series of blobs, which isn't ideal for resetting the monitoring volume for reference listening levels.

To the left of the volume control is a row of six white push buttons which are labelled as 'speaker mutes', but actually appear to be input mutes. This difference becomes significant in the context of the fold-down options I'll come on to shortly. The order of the buttons reflects the AES recommended channel allocation (L, R, C, LFE, LS, RS).

To the left of these buttons are six holes to access multi-turn level trimmers mounted just behind the front panel. These span a wide range with unity gain as the maximum setting, and I had no trouble aligning a variety of active monitors and amp/speaker combinations in three different control room settings.

Moving further left, there are two more push buttons to select one of two fold-down modes: fold-down to stereo and fold-down to mono (an earlier version, which is still shown on-line and in many of the Coleman brochures, provided fold-down modes to LRC and stereo). Each mode has a set of trimmers to adjust the balance as necessary, but although the speaker output level trims are accessible from the front, the centre and surround channel contribution levels are only available internally, requiring the lid to be removed for initial calibration.

Photo: Mike Cameron

The rear panel is festooned with XLR combi-jacks for the six balanced inputs, allowing TRS or XLR connections to be made. The balanced outputs are also provided on XLRs. Electronic buffering is provided across all six channel inputs and outputs, but that is the only active electronics in the signal path (apart from the fold-down mixing stages).

There are no facilities for alternative input sources or additional monitoring outputs. Coleman recommend using the A/B 5.1 switcher to provide that functionality if required.

In Use

The SR5.1 MkII couldn't be any easier to use. Plug in a 5.1 source, plug in a 5.1 monitoring system. Calibrate levels. Job done. The 'speaker mute' buttons allow you to quickly kill the rears, the fronts, centre or whatever when you need to check on localisation of sounds, track down unexpected noises and so on.

The sound quality is very clean, transparent and dynamic — significantly more so than many budget controllers, and the image stability is excellent at all volume settings. Although the SR5.1 MkII is a very simple surround controller, I can't fault it in its basic operation or sound quality, other than the lack of calibration marks on the volume knob, which is hardly a make-or-break issue.

Where I am a little less convinced is when it comes to the provision of the fold-down options. The fold-down to stereo works well enough, with the centre channel being split equally to left and right, each surround signal feeding its corresponding front channel, and the LFE absent completely. The relative levels of Centre and Surrounds are adjustable (the handbook suggests 3dB down on the left and right channel levels) via internal trim pots.

However, when working with a 5.1 monitoring system, I expect a mono down-mix to come from the centre channel only, but the Coleman box provides it via the left and right channels equally. Of course, this may not bother some users, but I found it rather distracting. Furthermore, you can't mute, say, the right-hand channel, to hear the mono mix on a single speaker. This is because the 'speaker mute' buttons don't actually mute the speaker outputs at all, they mute the channel inputs instead. So all that happens when you press the Mute Right button is that the right channel's contribution to the mix disappears, but the rest of it still comes out of both left and right speakers. In the right context this input mute facility is actually quite handy, it's just that it doesn't help to provide single speaker monitoring in the case of wanting a mono check.

That said, this is a small niggle that probably won't matter to most users and, at the end of the day, this is a very fine surround monitor controller that does what it needs to do accurately, with good sonics, and at a price that reflects both its simplicity and build quality. If you are thinking of moving into mixing for surround sound, this product provides an effective and practical solution to the problem of controlling the levels of six channels at the same time, with transparency and precision.