MC3™ Using and Applications

This short guide is written for those who are experienced with pro-audio monitors, mixers and interfaces. Complete details about the many features built into the Radial MC3 monitor controller and information on connecting it to your system can be found in the user guide (PDF download).

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Top studio engineers tend to work in rooms they are familiar with. They know how these rooms sound and instinctively know how their mixes will translate to other playback systems. Switching speakers helps you develop this instinctive sense by allowing you to compare how your mix translates from one set of monitors to another.

The MC3 Monitor Control is typically connected to the output of your mixing console, digital audio interface or laptop computer represented as a reel-to-reel machine in the diagram. The outputs of the MC3 connect two pairs of stereo monitors, a subwoofer and up to four pairs of headphones.


Power cable clamp.

Setting up the MC3

Before making any connections, always ensure levels are turned down or equipment is turned off. This will help avoid turn-on transients that could harm more sensitive components like tweeters. It is also good practice to test signal flow at a low volume before turning things up.

There is no power switch on the MC3. As soon as you plug in the power supply, it will turn on. Next to the power jack there is a handy cable clamp that can be used to prevent accidental disconnection. To use, unscrew the clamp, pass the power cable through and tighten.

The MC3 will automatically configure to operate in balanced or unbalanced mode depending on what type of input you connect to it. If using unbalanced (TS) cables to connect to the MC3, the outputs will also be unbalanced.

Most mixers, workstations and near-field monitors can be used in either mode, so this should not pose a problem when used with the proper interface cables. The diagram below shows various types of balanced and unbalanced audio cables.


Connecting the MC3

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  1. Connect included power supply.
  2. Connect the stereo output of your recording system to the ¼" SOURCE INPUT connectors on the MC3.
  3. Connect the stereo OUT-A to your main monitors and OUT-B to your second set of monitors.
  4. Turn the A and B outputs on or off using the front panel selectors. The LED indicators will illuminate when the output is active.
  5. Cue up your track and test the system at a low volume. Check for proper stereo orientation by panning the source track full left and full right.


Setting the trim controls

The MC3 top panel is configured with a series of recessed trim controls. These set & forget controls are used to fine tune the output level going to each component so that when you switch from one set of monitors to the other, they play back at relatively similar levels. Besides the stereo monitors, there are level adjustment trim controls for the subwoofer output and preset DIM level.

Trims controls for main monitors, subwoofer and preset DIM level

Although most active monitors are equipped with level controls, getting to them while listening is difficult. You have to reach around the back to make the adjustments, go back to the engineer’s seat, listen and then fine tune again which can take forever. With the MC3, you adjust the level while sitting in your chair! Easy and efficient!

Locate the MON-A and MON-B level controls to finish setting up your stereo monitor pairs. Set the recessed LEVEL ADJUSTMENT controls on the MC3 top panel to the full-clockwise position using a screwdriver or guitar pick. Hit play on your recording system. Slowly increase the MASTER level on the MC3. You should hear sound from monitors-A. Try going back and forth between monitor-A and B a few times to hear the relative volume between the two sets. Set the trim controls to balance the level between your monitor pairs.


Setup a subwoofer

You can also connect a subwoofer to the MC3. The SUB output on the MC3 is actively summed to mono so that the stereo input from your recorder sends both the left and right bass channels to the subwoofer. You would of course adjust the sub's crossover frequency to suit.

Connecting from the MC3 to your subwoofer is done using an unbalanced ¼" cable. This will not affect the balanced monitor-A and B connections. Turning on the subwoofer is done by depressing the SUB toggle switch on the front panel. The output level may be adjusted using the top mounted SUBWOOFER trim control. Again, you should set the relative level so that it sounds balanced when played with your monitors.

Subwoofer controls

On the top panel and next to the SUBWOOFER LEVEL control is a PHASE switch. This changes the electrical polarity and inverts the signal going to the subwoofer. Depending on where you are sitting in the room, this can have a very dramatic effect on what is known as room modes. Room modes are basically places in the room where two sound waves collide. When the two waves are at the same frequency and in-phase, they will amplify each other. This can form hot spots where certain bass frequencies are louder than others. When two out-of-phase sound waves collide, they will cancel each other out and create a null spot in the room. This can leave the bass sounding thin.

Try moving your subwoofer around the room following the manufacturer’s recommendation and then try reversing the phase of the SUB output to see how it affects the sound. You will quickly come to realize that speaker placement is an imperfect science and that once you find a comfortable balance you will likely leave the monitors alone. Getting used to how your mixes translate to other playback systems takes some time. This is normal.


Using the DIM control

DIM level trim

A cool feature built into the MC3 is the DIM control. This lets you reduce the level going to your monitors and subs without affecting the MASTER level settings. So for instance, if you are working on a mix and someone comes in to the studio to discuss something or your cell phone starts ringing, you can temporarily lower the volume of the monitors and then instantly go back to the settings you had before the interruption.

As with the monitors and sub outputs, you can set the DIM attenuation level using the set & forget DIM LEVEL ADJUSTMENT control on the top panel. The attenuated level is usually set quite low so that you can easily communicate over the playback volume. The DIM is sometimes used by engineers who like to mix at low levels to reduce ear fatigue. Being able to precisely set the DIM volume makes it easy to go back to familiar listening levels with a push of a button.


Headphones section

The MC3 is also equipped with a built-in stereo headphone amplifier. The headphone amplifier taps the feed after the MASTER level control and sends it to the front panel headphone jacks and the rear panel ¼" AUX output. There are two standard ¼” TRS stereo headphone outputs for studio headphones and a 3.5mm (⅛") TRS stereo out for ear buds.

The headphone amp also drives the rear panel AUX output. This active output is an unbalanced stereo ¼" TRS output that is set using the headphone level control. The AUX output can be used to drive a fourth set of headphones or as a line-level output to feed additional equipment.

Be Careful: the output of the headphone amp is very powerful. Always ensure the headphone level is turned down (fully counter-clockwise) before auditioning music through headphones. This will not only save your ears, but save the ears of your client! Slowly increase the headphone volume control until you reach a comfortable listening level.