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Guenter Villnow
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Guenter Villnow
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This app note demonstrates how to use the DDRC-24 for subwoofer control and correction. While the DDRC-24 is a stereo unit, the flexibility that we build into every miniDSP allows it to easily be adapted for this purpose. How?... read on!

Note: if you haven't already, please take some time to download and read over the DDRC-24 User Manual and the miniDSP Dirac Live User Manual, as you will need to refer to them. Before proceeding, install all the necessary software.

1. Getting connected [Top]

Figure 1 shows a typical system setup with a DDRC-24 and one subwoofer.

Example system for DDRC-24 subwoofer control with Dirac Live

Figure 1. Typical system setup with DDRC-24 and one subwoofer

The audio connections are simple:

  1. Connect input channel 1 of the DDRC-24 to the Sub output of your A/V receiver or processor.
  2. Connect output channel 1 of the DDRC-24 to the input of your subwoofer (or subwoofer amplifier if using a separate amp). If you have more subs, connect them to additional outputs of the DDRC-24.

In other words, you are inserting the DDRC-24 in the signal path between the AVR/AVP and the sub(s). Note: if you have two subwoofer outputs on your AVR/AVP, there is no need to use both – set your AVR/AVP for a single output and connect as shown.

You will also need to connect your computer up for measurement:

  1. Connect a USB cable from the computer to the DDRC-24.
  2. Connect a USB cable from the computer to the UMIK-1 or UMIK-2.

2. Configure the plugin [Top]

In the DDRC-24 plugin, click on Restore to Defaults to make sure that all settings are in a known state. Then set the routing matrix so both Dirac channels go to output channel 1:

Routing matrix for Dirac Live measurement with single subwoofer

If you have more than one sub, turn on the additional channel(s) as needed. For example, for three subs:

Routing matrix for Dirac Live measurement with three subwoofers

That's the only setup that you need to do. Click on the Start Dirac Live Software button to start the DiracLive app.

3. Run Dirac Live calibration [Top]

In the DiracLive app, run your calibration. (Refer to the miniDSP Dirac Live User Manual if you haven't done this before.) There will probably be a lot of variation between microphone locations, which you can see by clicking on the "Spread" button. Here is the sub in our test system with 9 measurements:

Dirac Live measurement with a single subwoofer

Then go to the Filter Export tab and load the Dirac Live filters into the DDRC-24. Before quitting DiracLive, go back to the Volume Calibration tab and set Master Output volume to 0 dB.

If you decide to use Room EQ Wizard to measure the effect of Dirac Live calibration, remember that Dirac Live uses nine (or more) measurements, so the individual measurements won't be completely flat. For example, here is our measurement of the sub after calibration with the mic in the center of the listening area (blue), one seat to the left (orange) and one seat to the right (green):

Subwoofer measurements in three seats after Dirac Live

If you want less variation across seats, you can try placing the subwoofer in a different location. However, much better results can be obtained by using multiple subwoofers. See our app note Tuning multiple subwoofers with miniDSP. (Do the multisub tuning first, then run Dirac Live afterwords.)

4. Integration [Top]

You have a few more steps to get everything set up:

  1. If you haven't already set Master Volume to 0 dB, start the DDRC-24 plugin and click Connect. Set Master Volume to 0 dB. (You will control volume in the AVR/AVP.)

  2. Add additional delay to the speakers. This is needed because the DDRC-24 adds 13 ms of delay to the subwoofer, which is equivalent to 4.5 meters or 14 feet 8 inches. Add this amount of delay to all speakers.

  3. Adjust subwoofer trim. The Dirac Live correction may have changed the level of the subwoofer, so check and adjust this in your AVR/AVP.

  4. Check integration. The simple way is to play some movies to confirm that the subwoofer sounds good. For more accurate results, use REW and feed the test signal through the AVR/AVP over HDMI. See Using the UMIK-1 or UMIK-2 and REW with HDMI output - Windows or Using the UMIK-1 or UMIK-2 and REW with HDMI output - Mac.

Wrapping up [Top]

And that's it! Have fun, and let us know how you go in our forum.

Related products - DDRC-24