User manual

miniDSP Ltd, Hong Kong / www.minidsp.com / Features and speci fications subject to change wi thout pri or noti ce 42
6.3 OPTIMIZING GAIN STRUCTURE
If the acoustic output level of different channels shows substantial differences (greater than 6 dB), then there
may be room to improve the gain structure of your system. Follow the procedure below carefully. Note that:
 You must not adjust the Channel volume sliders away from the maximum at any point in this procedure.
 It is not necessary to get all test meter readings at exactly the target level. The aim of the procedure is simply
to reduce gain differences between channels, not to eliminate them.
 In step 6, there is a judgment call on which channels should have increased gain and which should have
reduced gain.
 It is possible that you will get to step 7 and realize that there is nothing you can do to improve the gain
structure of your system.
Changing the connection type or gain structure settings of individual channels will invalidate all of
your existing Dirac Live projects. You will need to discard all existing projects and filter sets after
completing this procedure, and redo your Dirac Live calibration.
6.3.1 Procedure for optimizing output gain
1. If your amplifiers have gain controls, set them all to maximum (including the subwoofer).
2. Quit and restart Dirac Live Calibration Tool.
3. On the Output & Levels tab, set all Channel volume sliders to maximum. Do not move them again while
performing this procedure.
4. Set the Output volume low and turn on the test signal for channel 1. Adjust Output volume and Input
gain so the meter reads in the middle of the green area i.e. −12 dB.
5. Turn on the test signal for the remaining channels and note the level of the test signal on the meter (for
example, −6 dB, −15 dB, etc).
6. Determine the target level for each channel:
a. The speaker channels should all have the same target level.
b. If the Custom System configuration is used, the subwoofer target is the same as the speakers.
c. If the 5.1 or 7.1 configuration is used, the subwoofer target is 6 dB higher than the speakers. For
example, if the speaker target is −12 dB, the subwoofer target is then −6 dB.
7. Using the tables on the next page, decide on the best method to change the gains of each channe l to get
closer to the target values.
8. Power off the power amplifiers and the DDRC-88A, and make the changes.
9. Power on the DDRC-88A and the power amplifiers, restart Dirac Live Calibration Tool, and re-run the
levels check on the Output & Levels tab.