You are here

Soundcraft Si Expression

Digital Mixing Console By Mike Crofts
Published October 2013

Soundcraft Si Expression

The new Si Expression range aims to combine the flexibility of digital mixing with 'analogue' ease of use. Is it time you made the switch?

The Si Expression range follows on from Soundcraft's successful Si Compact series of digital mixers. The new models are very similar in appearance and basic functionality to their predecessors, but with various technical developments including a new colour scheme and, perhaps most significantly, lower prices. I reviewed the Si Compact back in SOS March 2012 (, and as the two ranges have a lot of features in common, this review will focus on the practical aspects of using the Si Expression live, rather than describing all the technical functionality, which is available on the manufacturer's web site should you need it.

There are three models in the Si Expression range, designated simply 1, 2 and 3. The numerals represent different 'frame sizes', with different numbers of analogue inputs and faders. In ascending order, the options provide 16, 24 or 32 analogue inputs on the back of the mixer; however, the total number of processing channels is the same for all three versions, and by using an input option card, a total of 66 inputs is available to each model throughout the range. Each version also has exactly the same number of mix buses and channel processing, plus four Lexicon effects engines.

For this review, Soundcraft's UK distributors, Sound Technology, sent me an Si Expression 2, a MADI expansion card and a digital Mini Stagebox. As it had been a while since I'd used the old Si Compact desk, I was really starting from scratch once more!

Getting Started

Soundcraft have designed the Si Expression 2 very much with live sound in mind, and have also tried to give it as much of an analogue 'feel' as possible, in the sense that the LCD screen deliberately has not been placed at the heart of everything that happens — you have to use the knobs. As a result, setting up and operating the Si Expression is very straightforward, and there's not a great deal you have to know in order to be up and running with a basic mix. The factory default setting assigns the inputs and buses to the fader banks in a logical way, but there's a good deal of customisation available to the user. One major plus point here for anyone looking to make the move from analogue to digital mixing is that the Si Expression has a generous complement of physical inputs and outputs on the rear panel, and can therefore replace an existing analogue mixer without necessarily changing any other part of a sound system, either mobile or installed.

To try to describe the Si Expression 2 in basic terms is a challenge, but in essence, it has 24 mic preamps with the aforementioned total of 66 inputs available to the mix, four extra balanced TRS line inputs, 14 mix buses plus the main stereo and mono output buses, comprehensive on-board EQ and dynamics processing, and the four effects engines mentioned earlier. For live-sound work, a huge attraction is the Mini Stagebox digital snake system, which makes life so much easier for mobile use, and is available in 16-in/8-out or 32-in/16-out formats, both connecting to the desk via a single Cat5 cable.

Channel Strip

All consoles in the Si Expression range have a healthy number of local analogue inputs and outputs, and so can serve as 'drop-in' replacements for most analogue mixers.All consoles in the Si Expression range have a healthy number of local analogue inputs and outputs, and so can serve as 'drop-in' replacements for most analogue mixers.

I often hear people say — usually when I'm showing off my moving faders and flashy displays — that they would consider a digital mixer if only it was as easy to operate as an analogue one, and I must say the functional layout of the Si Expression makes it one of the most obvious and easy-to-follow digital boards you're likely to find.

The controls you'd normally find on each analogue channel strip are all grouped within a nicely laid-out section referred to as the 'Assignable Channel Strip' or ACS, but of course there are more facilities in here than you'd expect on a traditional mixer. As well as an input section, with good metering, phantom power, polarity inversion, trim and a sweepable high-pass filter, there's a four-band EQ, plus a gate, compressor and an 'output control' area, which includes pan, Left/Right/Mono output routing, and a delay line. All of the ACS functions are available on every mono channel, and the internal processing is always on, so there's no effect on overall performance no matter how much of this available processing power you use.

Many of the ACS functions can be used with the Si Expression's 'Interrogate' facility, where pressing and holding a function key lights up the Select button on every channel with that feature switched on. For example, if you press and hold the '48V' button, every channel with phantom power activated will have its Select button lit up. You can then use the Select buttons to toggle this function on and off for any channel you like. It's really quick and really handy.

When not in Interrogate mode, pressing the Select button on any channel will link the ACS controls to that channel or bus if appropriate. The physical controls in the ACS are all rotary encoders with nice bright rings of LEDs around them, so a quick glance at the panel area provides an instant visual snapshot of where everything is set. If more detail is required, the Si Expression has a clever trick up its sleeve: every time you move one of these controls, a more detailed graphic pops up on the main LCD, showing not only the rotary control's position but also its current setting in numbers, so you know exactly where you are. It's a neat feature, although I found that in order to make this display appear, I had to actually adjust one of the encoders; I couldn't simply check the settings without changing them slightly.

The functions within the ACS are easy to use and there is a good range of control available. There are no factory presets here, such as 'female vocal' or 'snare', so you do need a basic understanding of the dynamics and EQ controls in order to use them effectively. Luckily all the functions are clearly labelled and the panel layout is clear and easy to read, and an hour spent playing around with the channel functions should be enough to get the hang of things.

Hands On

The channel strip section of the control surface provides easy access to the selected channel's most commonly used features, including EQ, dynamics and preamp controls.The channel strip section of the control surface provides easy access to the selected channel's most commonly used features, including EQ, dynamics and preamp controls.

The first thing I want to do when preparing to use a digital mixer is to set up the input and output patching and fader assignments so that I can control things according to my preferred layout — which includes having control of all the most frequently used mix elements on a single fader layer if possible. In its factory default state the Si Expression assigns the console's 24 mic inputs to processing channels 1-24, using faders 1-22 on layer A and faders 1 and 2 on layer B. The line inputs and effects returns are also on layer B, while layers C and D are for mix-bus masters and matrix-bus masters, respectively. There's no dedicated user layer, because all the layers are flexible and you can put pretty much whatever you want wherever you want it.

I took the Si Expression along on two outdoor events, both involving multiple band line-ups, which is a great way to get acquainted with a new console! The first event had limited setup time, and by the time the stage had been handed over to our crew we only had just under an hour to get everything up and running. We were running our JBL PRX active main speakers, so the stage end of things was quickly in place and ready to go. I installed the Soundcraft Mini Stagebox, ran out the Cat5 cable and a power line back to the 'mix tent', and about 15 minutes later I had the Si Expression in place and powered up, and we were ready to start line-checking our inputs from the stage.

At that stage I hadn't properly configured the input patching, although I had checked that the MADI card in the expansion slot was being seen by the mixer, so I assigned all the Mini Stagebox inputs to the corresponding mixer channels (replacing the default console mic inputs on layer A), with the exception of my local CD input which was connected to the first pair of line inputs on the console itself. As I wanted the background music to be controlled from the 'top' fader layer, I assigned the stereo line inputs (by default controlled by faders 17+18 on layer B) to faders 21+22 on layer A, which obligingly turned a nice magenta colour to tell me that they were controlling local line inputs.

Patching and setting up fader layers on the Si Expression is logical and easy, and the combination of touchscreen and physical panel controls minimises the risk of making mistakes. It's a straightforward and secure process that can be done during setting up at the venue, and the 'auto complete' facility can speed things up even more if you want to patch multiple consecutive inputs in one go. I like the way the Si Expression displays touchscreen icons, and although the LCD is fairly small I didn't find any difficulty operating the touch functions.

For setting up my live mix, I pressed the Inputs button, and the settings for the currently selected channel were displayed as a neat table of information. From here I was able to change the name of the channel from 'CH 01' to 'Kick' using the handy QWERTY keyboard, which pops up on screen and is infinitely more practical and less annoying than having to use a rotary dial to select characters one at a time, then press Enter — which is still how some digital mixers work. In addition to the input patching, this menu also allows direct-output options to be set, and it's possible to override the pre-fader/post-fader settings for each mix bus individually — all in all, a good degree of user control.

Bus Lanes

As soon as a control on the desk is moved, the colour touchscreen will show what parameter is being adjusted, along with its value.As soon as a control on the desk is moved, the colour touchscreen will show what parameter is being adjusted, along with its value.

I was running four stage-monitor mixes, and I was going to need some basic reverb on vocals and acoustic guitars. This is where the 'TOTEM' keys came into play. TOTEM stands for 'The One-touch Easy Mix', and manifests itself as a row of buttons that access all the Si Expression's mix buses, apart from the main output. There are plenty of these buses available, and no matter which model of Si Expression you buy, you still get the same number of output buses and mix functionality. There are 14 assignable aux buses, four effects buses and four matrix buses, which should be more than enough for the kind of work the Si Expression would be asked to do. There is no facility to set up DCA groups, which at first is a bit of an eyebrow-raiser, but subgroups can be easily created in the traditional way, by setting up a post-fader aux mix containing a group of input channels that are routed only to that particular aux bus, and not assigned to the main stereo bus.

The Si Expression's method of controlling aux and effects sends from input channels is a 'sends on faders' arrangement. On a traditional analogue mixer, you create auxiliary mixes for monitors or effects using rotary aux send controls located within each channel strip. Digital mixers that have a single assignable channel strip often use this to provide the same functionality: you select the channel, select the aux feed you want to control, and adjust the send level from that channel. However, there is a more convenient and faster method of controlling aux mixes, which is descriptively referred to as 'sends on faders'. In this paradigm, an aux mix bus is selected and all the faders jump into 'aux' mode, where they are used to adjust the amount of signal sent to the selected aux bus from each channel. In other words, you mix all the aux buses using the channel faders in exactly the same way as the main mix. The Si Expression operates only in this mode: to send anything to an aux bus, all you do is press one of the 14 Mix buttons, whereupon all the faders instantly switch to control that particular mix. The same applies to the effects and matrix sends. It's fast, easy and you can see the 'shape' or overall content of any mix just by looking at the faders — you just have to remember that you are in 'sends on faders' mode, and that moving any channel faders will only control the selected aux mix, and will have no effect on what's going to front of house.

As with all other functions on the Si Expression, any controls which are not associated with whatever mode the desk is in are inoperable and are not illuminated. For example, the global Mode encoders will be unlit when a mix bus is selected, as will the ACS panel. One feature I really like about the aux mixing arrangement is the fader slot colours, which make it extremely easy to see which channels are set pre-fader (yellow) and post-fader (green). I also very much like the one-button-per-aux-bus design — there's nothing to dial up or select from a menu, and you don't have to cycle through the buses by pressing something a number of times. You just press Mix 9 and you're working on mix nine. So, back to the gig...

Gig Time

Soundcraft Si Expression

All the line checks worked out, and all monitor mixes were appearing in all the right places, so I started tuning the channels using the ACS controls. These are each dedicated to a particular function, so there is no layering or function selection going on here. Soundcraft have aimed for an 'analogue' feel and I think they have succeeded. All the controls function smoothly and are appropriately geared so that there is a good degree of fine control available.

In practice the ACS is utterly benign and all parameter adjustment is smooth and sweet; the rate of parameter change doesn't always seem to exactly track the rate at which you turn the controls, which worked fine for me once I got used to the feel of these controls. The lack of 'get me started' presets (apart from within the effects engines) means you will need at least a basic appreciation of how compression and EQ work in order to get best results, and a library of channel presets might be attractive to potential users who are not confident about some of the facilities.

After those two live concerts the Si Expression was fast becoming my new best friend. I found it to be a very easy desk to set up and use, with or without the digital snake, and I appreciated the clean layout and intuitive way the various functions are accessed and parameters adjusted. The channel EQ has 'only' four bands, but despite the outer bands being shelving only, the inner bands overlap almost the entire low- and high-frequency areas so you can use a bell curve across much of the frequency range if you really need to — I liked the EQ and didn't have any issue with the setup.

About the only thing I found difficult in practice with was the illumination of the surface keys. The encoders, screen and fader slots are all nice and bright, but when I used it outdoors in the sunlight, I'd have liked to turn up the wick on the buttons a bit more.

Express Yourself

My lasting impression of the Si Expression is one of functionality and simplicity. It doesn't do everything, but it certainly does enough, and it does it very nicely. There's a truckload of features that I haven't covered in this report, and I'd recommend a read through the information on the web site — downloading the user guide is a good start, getting your hands on the product is even better.

If you're considering a first step into the world of digital mixing, I think the Si Expression is one of the most practical digital mixers you'll find, and also one of the easiest to use. I really like the feature set, and I like the overall product quality in terms of sound, feel and build. There is a great level of control, quiet running, smooth and fast faders, and decent metering — but what really endears me to this desk is its sheer user-friendliness and flexibility, attributes which I'm glad Soundcraft haven't lost sight of in coming up with this affordable little gem. This compact mixer has a very big appeal, and since it's been in my workshop, I really have wanted to take it out on every single job I've worked on. Unfortunately I have to give it back any day now, but it's definitely going to remain on my shopping radar — I've even started looking at the price of flightcases...  


Similarly priced alternatives include the Presonus StudioLive 24-4-2, the Behringer X32, Tascam D3200 and Yamaha 01V96i.


The Soundcraft Si Compact range comes in three different sizes, of which the smallest, with 16 local mic inputs, is the Si Expression 1, priced at £2299$2499. The Expression 2, reviewed here, is £2799$2999, while the larger Expression 3, which has 32 mic inputs, costs £3399$3499.

Also available are two digital snakes: the Stagebox Mini 16 (16 inputs, four returns) and the Stagebox Mini 32 (32 inputs, 16 returns). These are priced at £999$999 and £1999$1999, respectively, and are supplied with a MADI Cat5 expansion card. All prices include VAT.


  • Great capability in a very practical package.
  • Easy to understand and operate.
  • Flexible and configurable.


  • Buttons could be brighter for daylight working.
  • Wish it came in dark grey or black, but then I am old-fashioned!


A powerful yet easy-to-use console that should be attractive to anyone considering making the move to digital mixing.


See 'Pricing' box.

Sound Technology +44 (0)1462 480000.

See 'Pricing' box.

Harman US +1 818 920 3212.