The miniDSP DDRC-24 includes not only Dirac Live® but also a full set of crossover functions on its four output channels. One use of this is as a flexible tool for integrating subwoofers into your system along with Dirac Live. This app note shows you how.

This app note assumes that you have already installed the DDRC-24 utility and Dirac Live Calibration tool as per the User Manual.

Getting connected[Top]

Connect the system as shown in this diagram:

DDRC-24 subwoofer integration - system connections

The diagram assumes that you are using one subwoofer. If you are using two subwoofers, you can connect the second to output 4.

Configuring the plugin[Top]

Start the DDRC-24 plugin and click the Connect button. (See the User Manual for more information.) Set the Routing matrix like this (you can use the Outputs tab to change the displayed labels if you wish):

DDRC 24 sub routing

On the Outputs tab, click on the Xover button for channel 1. Here you will set a high pass filter, to remove low frequencies from the left speaker. Here is a typical example:

DDRC-24 subwoofer integration - high pass filter

Do the same for the right speaker (channel 2).

For the subwoofer (channel 3), set a low pass filter to remove high frequencies. Here is a typical example:

DDRC-24 subwoofer integration - low pass filter

Initial Measurement[Top]

Although not absolutely essential, it is recommended that you perform a measurement to check for initial integration between the subwoofer and the main speakers around the crossover frequency. While Dirac Live will correct for frequency response anomalies, it can't fully correct if you have a large "hole" in the frequency response at the crossover.

If you wish, you use Room EQ Wizard (REW) or a similar program to do this measurement. To use REW with the UMIK-1, please refer to our application section on acoustic measurements.

If you don't wish to learn how to use REW, you can simply use the Dirac Live Calibration Tool to perform this measurement. Save your configuration to a file and quit the DDRC-24 plugin first. Then follow the normal calibration procedure described in the User Manual, but only perform a single measurement (instead of the full set of nine) before proceeding to the Filter Design tab. The "before" measurement shows the combined responses of the subwoofer and speakers:

DDRC-24 subwoofer integration - measurement with DLCT

If there is a large "hole" in the response around the crossover, you will need to make some adjustments and remeasure. Quit DLCT before starting the DDRC-24 plugin again. Adding a delay to either the speakers or the subwoofer will change the response, as will inverting the subwoofer. You can also adjust the low pass and high pass crossover frequencies and change the slope. If the subwoofer is much higher or lower in level than the speakers, adjust the gain on the subwoofer.

See the User Manual for information on how to make these adjustments. After making adjustments, repeat the measurement.

Run Your Dirac Live Calibration[Top]

You can now proceed to run the full set of nine measurements for the Dirac Live calibration. Adjust the target curve to suit your preference. For example, this screenshot shows a target curve with an elevated bass level, which many people prefer, and the "after" response:

DDRC-24 subwoofer integration - after optimization

Wrapping up[Top]

If you haven't already, use the learning remote feature to set up remote control for volume, mute, preset selection, and Dirac Live filtering. Then sit back and enjoy some tunes!

That's it for this app note! Have fun, and please let us know how you go in our forum.