MixBuss Installation and Setup Guide

Incorporating the MixBuss into your existing studio is a fairly simple operation.  In essence you connect the outputs from each of your DAW interface directly into the inputs on the MixBuss so that all of the summing for the mix is done through the MixBuss itself instead of being bounced down digitally to a stereo track inside the DAW.  This installation guide uses Cakewalk's Sonar application with a Focusrite Saffire 26io firewire interface as an example of how to properly interface the MixBuss into a computer-based DAW environment.

Connecting The Outputs

In this setup, each output pair from the Saffire is routed to a pair of inputs on the MixBuss.  Starting with the analog outputs, Line 1/2 is connected to inputs 1 and 2, Line 3/4 to inputs 3 and 4, etc.  Since the Saffire supports 2 ADAT lightpipe connections for up to 16 additional outputs, we will only be using the first ADAT output for this example.  Therefore, the ADAT 1 outputs will be set to inputs 9 through 16 on the MixBuss.  The image below shows how the outputs are assigned in Sonar.  Please note that all of the output faders for the interface are set to 0dB for unity gain.

Click here to enlarge photo.

Calibrating The MixBuss

Now that we have the outputs connected, we need to ensure that the level coming out of the MixBuss is the same as the level going in.  This requires us to set the Mix Level output so that the incoming signal level is the same as the output level that feeds your DAW inputs.  You will need a stereo -3db test tone signal which can be found here.  Import the calibration tone into a stereo track in your DAW and assign it to the 1/2 outputs on your interface.  This will set the -3dB signal out to both the channel 1 channel 2 outputs on the DAW interface.

First we will check the input signal of channels 1 and 2.  Set the MixBuss channel 1-2 selector to "Stereo" so that the channel 1 input signal is now panned full left and the channel 2 input selector is panned full right.  This ensures that the test tone signal is panned to full stereo exactly as it was output from the DAW.  In order to set the output Mix Level, we need to assign the MixBuss outputs to a stereo pair of inputs on the interface.  For this example, we will use inputs 1/2 on the Saffire.  Create an audio track for the mix and set it to record enable so that you can monitor the incoming signal level.  The image below shows an example of an armed input track for recording the MixBuss output signal.

You will notice that the output assignment for this track is set to none so that the incoming signal is not routed to any outputs on the interface.  This will avoid a nasty feedback loop that could overload the circuits on your interface, possibly damaging them in the process.  With the track now set to record enable, play back the test tone.  As the tone is being played back, turn the Mix Level volume knob until the input meters in the record track read -3dB.  Once your meters read -3dB, you can disengage playback, and the unit is now calibrated for unity gain. 

Mixing With The MixBuss

Now that you have unity gain going from the DAW through the MixBuss and back into the DAW, you can start mixing with the unit.  The easiest way to integrate without requiring a lot of changes to your workflow and mix methodology is to create what are called stems.  A stem is essentially a stereo submix of components in your mix, like overheads for drums, a stereo mix of toms, stereo guitars, room mics, a drum submix, etc.  Basically anything you create within the DAW that can be assigned to stereo tracks or groups for mixdown can become a stem for summing.  If you do everything in the box, each stem will be assigned to the master output where everything is mixed down to a single stereo pair.  When summing externally, you assign each stem to a pair of inputs on the summing buss.  Once you have all the stems assigned, you then arm a stereo track for recording in your DAW and assign the outputs from the summing buss to your DAW inputs.  Now you can press record, and it will record the summed output from the MixBuss as the song plays back in realtime.  Below is an image of individual track assignments to stem outputs in Sonar.

Click here to enlarge photo.

The images below show the stem group assignments to individual interface outputs.  These outputs are in turn connected to the MixBuss inputs and provide the basis for the externally summed mix.

Click here to enlarge photo.

Click here to enlarge photo.

You can also take advantage of the mono selections on the MixBuss for interface outputs that are panned center.  For example, if you have a snare top, snare bottom, kick drum and vocal tracks, you can assign each of these tracks to a single interface output and tie those outputs to either the 1-2 or 3-4 inputs on the MixBuss with "Mono" signal routing selected.  This ensures that the signal from the DAW goes through no internal summing calculations for panning before it is sent to the outputs and can lead to a more up front sound for those tracks in the mix.  For those tracks that will be panned mono, you need to assign the track output to a single side of the stereo output pair on your interface.  For example, if the kick and snare are assigned to the interface outputs 3/4, then the kick would be panned hard left and the snare panned hard right so that the kick is assigned to interface 3 output only, and the snare is assigned to interface 4 output only.
Then on the MixBuss channels 3-4 are set to "Mono" with the selector switch.
The image below shows a mono output configuration in Sonar.

Finalizing The Mix

What you'll notice when mixing with the MixBuss is that your mixes will improve in clarity and will probably require you to tweak the mix for the MixBuss summing. You may need to adjust your stems outputs as a result, and this is quite common if the mix has already been established for bouncing "in the box".  The best way to use the MixBuss is to do the mixes with all of your outputs assigned so that you're always monitoring off the MixBuss outputs.  If you set your mix up in the box and get it to the point where everything is "right" and then do your assignments to mix externally, you may notice that the result is much different than what you hear from the in the box summing.  This is quite normal and is part of the reason external summing is so popular.  It actually improves your mixes because it brings out elements that get lost during the internal summing.  So as long as you keep this in mind and expect to do some minor tweaking when translating the in the box mix to an externally summed mix, everything will be fine.  However, the best approach is to always have your outputs connected to the MixBuss so that you're always monitoring the output of the externally summed mix.  If you keep it connected in this way, then you'll always be hearing exactly what is summed from the Mixbuss, and no further tweaking will be required.

One final note.  If you tend to run your stems fairly hot to ensure the highest signal-to-noise ratio on output of the DAC converters from your interface, you may run the risk of overloading your inputs when recording your externally summed mix.  Not to worry.  All you need to do is adjust the Mix Level output so that the inputs are no longer overloading when recording.  This gives you the advantage of being able to tweak the output signal without affecting the unity gain relationship you established when calibrating the unit, thus ensuring optimal signal processing while operating the unit.