M/S Proc review – compact mid-side processing app for iOS from ART Teknika

Download from iTunes App StoreMC proc logo 1I posted a review of ART Teknika’s first iOS music app release – the convolution reverb app iConvolver – earlier this week. I was suitably impressed with the app and, while it obviously faces some well-established competition (for example, in AltiSpace), it does a good job and the user-interface is simple to use. It is also currently available of a 50% off launch pricing of just UK£2.99/US$3.99. Really? A convolution reverb for the price of a large, high-street, coffee? No, I don’t understand the App Store pricing model for music apps either….

Anyway, this week saw ART Teknika release their second iOS music app. In this case we have M/S Proc which is something perhaps just a bit more specialised; the app offers mid-side processing with level and EQ controls.

Mid-side processing is something that has only really become popular for home/project studio owners in the last few years. Yes, we have had ‘stereo widening’ software for some time but much of it has been a bit ‘black box’ and nobody (other than the designers) really knew what was going on inside. However, the option to apply mid-side processing is now much more widely available. That includes under iOS where apps such as Stereo Designer (a personal favourite of mine) and AUM (another one!) both provide some M/S processing options and mastering apps such as Final Touch and Audio Mastering also allow you to tweak the stereo imaging of your mixes using this approach.

M/C Proc - mid-side processing made easy for iOS.

M/S Proc – mid-side processing made easy for iOS.

What is M/S processing? Well, we are very used to processing in stereo where the left and right channels are treated separately….   with M/S processing, the audio is instead split into two different channels – the ‘mid’ channel (everything panned towards the centre) and the ‘side’ channel (everything panned towards the left and right edges of the stereo image) and those two channels are processed independently.

The obvious application here is to emphasise the sides and therefore enhance the sense of ‘stereo’ but this is also technology that can allow you to lower the level of the centre, which is often where the lead vocals sit, to generate a rough and ready karaoke mix…. amongst, of course, all sorts of other possibilities.

So, what you need is a stereo sound source to start with – a full mix or a stereo drum sub-mix, for example – and a desire to make adjustments to its ‘stereo-ness’ in some way… and that’s where an app like M/S Proc can lend a hand….

A bit on the side

M/S Proc is a universal app, requires iOS7.0 or later to run and is an 7MB download. It also has a special launch price of UK£2.29/US$3.49 for a limited time only. This is 50% off what will become the standard price.

The app can be used stand-alone (you can load a file from your iTunes library for processing, for example) but includes both Audiobus and IAA support from the off so, for recording duties, you could easily use it within your usual iOS music making workflow as, for example, an insert or send effect in your DAW/sequencer.

The Settings page - set and forget :-)

The Settings page – set and forget :-)

There is a Settings page where you can configure the app’s key global parameters and a Files page where you go to either load/save presets or to load/import audio files if you want to use the app in stand-alone mode. The settings include a Buffer Size option but, if running the app within a host (for example, as I did within Cubasis for most of my testing) then, most likely, the host will control this anyway.

More KISS software

Like iConvolver, M/S Proc is – in UI terms at least – another example of the KISS approach to software design. All the key controls are housed in a single screen. In the top half, you can switch between ‘device’ or ‘file’ mode (the latter is used when you wish to load a pre-recorded stereo audio file into the app) while the File button allows you to access the presets/file import options mentioned above. You also have an ‘On’ button, a bypass button and a Settings button on the right.

The upper-centre is dominated by visual information in terms of input and output meters while the bulk of the display shows the EQ curves being applied to the mid and side channels once you start tweaking any of the rest of the controls.

MC Proc can be used to playback standard stereo audio files as shown here.

M/S Proc can be used to playback standard stereo audio files as shown here.

he bottom half of the display contains 13 faders split into three groups. You get a three-band EQ for each channel – low and high shelves plus a parametric mid band – and, on the right, the three green faders allow you to adjust the balance between the mid and side channels plus the overall output level. All this is really pretty straightforward in operation – functionally at least – and the concepts easy enough to grasp without the need for spending hours inside a PDF manual. The EQ controls provide just enough flexibility to generate some useful tonal tweaks but without getting bogged down in too many options.

Inside, outside

From a technical perspective, I had no problems with M/S Proc in use. Used stand-alone, I was able to import files from my iTunes library and subject them to a bit of mid-side processing. This was actually quite revealing and worth experimenting with… some commercial tracks can stand this kind of processing much better than others and, if you are not too careful, you can easily turn a solid mix into a rather horrible mess of audio artefacts. I don’t think this is M/S Proc’s problem; manipulating stereo imagery in audio files is something that is perfectly possible to abuse to the point of damage rather than enhancement whatever tools you use to do it….

Used as an insert effect of the main stereo output within Cubasis, M/C proc could act as part of a DIY mastering signal chain.

Used as an insert effect of the main stereo output within Cubasis, M/S Proc could act as part of a DIY mastering signal chain.

I did most of my own testing, however, by using M/S Proc as an IAA plugin within Cubasis (and, just for a quick test, inside AUM). In this case, I applied it in a couple of obvious ways; on a stereo drum track to tweak the stereo width and as an insert effect on my master stereo output channel to experiment with the overall stereo image of my mix. In both cases, I started by leaving the EQ flat and just changing the balance of the mid and side levels. Even with just these two sliders, it was possible to create a dramatic change in the feel of the stereo image…. from pretty much mono through to super-wide…. but, as ever with these kinds of processing options, subtle is generally the best way to go and, in that role, M/S Proc does a very nice turn.

Adding in some experimentation with the EQ made things more interesting. For example, you could give your stereo image a bit of extra sparkle by applying a little bit of high-end just to the sides. Equally, you could make the bass and kick feel even more locked to the centre of the image by boosting the low end on the centre channel. For a more experimental/advanced approach, boosting/cutting different mid-range frequencies in the centre and side channels – so that they each emphasised different frequency ranges – also enhanced the stereo imaging in a pleasing way. Again, perhaps the best starting point is to dial in something until it is obvious… and then back off a bit…. but M/S Proc can do subtle or not-so-subtle; the choice is yours.

The app's Files page provides access to the presets and any stereo audio files you might have imported.

The app’s Files page provides access to the presets and any stereo audio files you might have imported.

Oh, and while karaoke is not really my thing, with a combination of the EQ and mid-side levels, you can duck a lead vocal reasonably well. It does, of course, depend upon how the original vocal has been mixed (and what stereo processing has been applied to it) but M/S Proc can play that role if required and providing you don’t expect miracles (that is, to remove a lead vocal completely).

Side by side

I did run M/S Proc side-by-side with the mid-side processing available in AUM and Stereo Designer. Compared to both, M/S Proc does a good job – it is certainly not outclassed in terms of performance – but each does a somewhat different job and, as a consequence, produces somewhat different results. Given just how dependent mid-side processing is on the nature of the source materials, I think this is actually a case where having a choice of different processors is a real advantage; there will be cases when each of them is the ‘right’ processor for the task and another the ‘wrong’ choice.

Installed within AUM, M/C proc made for an interesting comparison with other mid-side processing options.

Installed within AUM, M/S Proc made for an interesting comparison with other mid-side processing options.

And, at the launch price of just UK£2.29/US$3.49, and with Stereo Designer priced at UK£3.99/US$4.99, it really isn’t too much of a stretch to own both. They do somewhat different jobs and offer somewhat different control sets. Both are capable of some excellent fine-tuning of your stereo image, whether on an individual instrument or a stereo mix….. but to use both with caution; super-wide sounding stereo is an addictive effect until, of course, you play your mix back on a mono playback system and discover that you mix is now way off….   use with caution :-)

In summary

As with iConvolver, I think ART Teknika have got a very iOS-friendly balance here between the features offered and a relatively straightforward user interface. The controls themselves take no time to learn and you can, therefore, focus very quickly on learning about the best way to use them.

Whether you need mid-side processing in your iOS audio processing arsenal is another matter. This is perhaps more of a niche processing option than for example, a straight EQ, compressor or even a convolution reverb. That said, M/C Proc is not going to break anyone’s bank. It performed solidly for me in testing and, within that somewhat more specialised processing field, offers some useful options. Here’s hoping ART Teknika continue to pursue this budding collection of iOS audio processing options; iConvolver and M/S Proc are a great start and I’m looking forward to what might come next….

M/S Proc – Mid/Side Level & EQ


iConvolver – Impulse Response Reverb


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