We just got a SoundCraft Si Compact 32, but we can't figure out how to use the matrix. In the world of analog mixers, it's easy. You just choose what you want to mix in, and you're good to go.

Our SoundCraft mixer has a MTX button that makes the faders control the master fader of the four matrices: MTX 1, MTX 2, MTX 3 and MTX 4. If you press MTX 1, you get to change 14 of the faders. (We have 14 buses (aux outputs) too, if there is any relation there?) If you press it again, you get to change the three last faders.

Does anyone know how this works?

  • just purchased a si 3 expression does anyone know how to route the effects in the monitor mix or do you have to use external plz help thank you
    – user4132
    Commented May 29, 2013 at 4:24
  • @nellyp Neither the style of your question nor the way you post it is fitting the style of this website. Please write your question with a more formal language as a separate question. Of course, you should try searching for it on Google at least twenty minutes before you ask. Commented May 31, 2013 at 8:07

3 Answers 3


Further to the thread; the 2nd press of the MTX key that lights the last 3 faders allows sending mix L, R & Mono to your chosen matrix bus. This '2nd press' was required since on the smallest Si Compact control surface there are 16 faders and 17 sources (14 buses + L, R & M and the Matrix bus master to manage) so another system was required and to make the user guide and learning consistent across all Si Compact models we employ the same method of operation for all consoles; details of the matrix operation are included in the Quick Start Guide, Youtube videos and User Guide.

One point to make clear; Si Compact dispenses with the traditional 'group' bus as found in analogue, a group is no more than a post fade aux send with the channel send level set to unity gain so why not get rid of them and allow routing AND levels to be changed, now you can use the bus as a sub-group by routing it back to LR and MONO or as a post fade send to an external FX.

If you have further questions please use the Soundcraft web site Facebook pages or contact your distributor to make enquiries since Soundcraft do not actively participate and monitor any forums.

Regards Soundcraft-Studer Product Management Team

  • I tried contacting you, but I was sent to a local distributor who didn't know it.. How would you go about setting about something that works like VCA groups? I need it to be able to switch between compressed and uncompressed mixes easily and with only two faders. Commented May 10, 2012 at 17:11

I don't get any reputation for accepting my own answer, but I think that it is my responsibility to post an answer to this. Therefore, I will be more than pleased to accept your answer, if it is better!

The reason why there are 14 faders to control for each matrix, is that you are mixing in the 14 different buses (or aux'es/monitor mixes if you will). So you set up your monitor mix on Bus 4, and mix in fader 4 in MTX 1, and you get that in. I can't see how we didn't see that instantly.

On analog mixers, you mix the groups, not the sends. So, you have 14 buses, or monitor mixes. I just can't see why they would make a mixer with 14 buses and 4 matrices. (This is a question you can answer in the comments if you want. Because it has no fixed answer.) If you have 14 outputs where you have complete control over EVERY mic input, you can even make STEREO buses, why would you make 4 matrices instead of a subgroup or a VCA-group? (The mixer doesn't have any subgroups or VCA-groups.)


If by the term 'something that works like VCA groups?' you mean an audio sub-group route the source channels to a bus that you wish to use as the audio sub group and then route that audio sub group back to the main LR bus; the bus master is now your audio sub group level. Don't forget to un-route the source channels from the main LR bus to prevent the comb filtering caused by a single source routing to a single destination via two different length signal paths! There are examples of this setup in the user guide, quick-start guide and You tube videos.

For those interested... an audio sub group (or similar) is not a substitute for a VCA control group and vice-versa; an audio sub group is an audio processing path that controls the sum of the channels routed to it; in most digital consoles it is able to add processing like eq, and dynamics to the summed signal but it does not affect the levels in the source channels so turning an audio sub group ON/OFF or turning it up/down will not change the levels within the source channel. A VCA (sometimes called DCA) control group is a control/command system that ‘slaves’ source channel faders and ON/OFF functionality to the VCA masters to which it is assigned but it does not affect the processing of the audio in any other way therefore when actuating a VCA master you are effectively turning the source channels up/down ON/OFF which in turn affects the levels sent from the source channels. A way to get ‘the best of both worlds’ if you don’t have VCAs is to have NO sends from any source channels to anywhere else but the bus you’re going to use as the audio sub group then patch that audio sub group to an un-used input and use that to send to all the buses you need, now you can control the level of everything from the on your ‘audio sub group return input’

For more detail or other questions you can contact the product manager at Soundcraft directly [email protected] +44 1707 668059 or +44 7766 525971.

  • Are you there still? Commented May 15, 2012 at 11:51
  • I know this. The reason why I need VCA-groups is to use a similar technique to the one Dave Rat explains here: youtube.com/watch?v=MMMmR1u0CFk The mute groups on your mixer does in a way work as a VCA, only for the mute button. Is it possible for you to release a update where you can set a fader to be a VCA-group? Commented May 15, 2012 at 11:54

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