XD20 Installation and Operating Guide
Version 1.1
Document # 9301H264001.1
56
1.
Confirm that all amplifiers are on, mute is off, and masking and curtains are opened.
2.
Before setting levels, confirm that SPL settings are completed on the cinema processor according
to their recommendations. When setting levels, the cinema processor should be set to calibration
level. In most cases, this is with the fader set to “7”.
3.
Using a high-quality, calibrated SPL meter set the SPL levels according to the chart below. Note
that SPL readings for screen and surroundings should be measured un-weighted, or C-weighted,
with the meter set to slow. The proper level setting of the subwoofer should be calibrated with an
RTA.
Table 10: SPL levels
Channel Description SPL
1 Left
85
dB
2 Right
85
dB
3 Center
85
dB
4
Sub bass
91 dB*
5
Left Surround
82 dB
6
Right Surround
82 dB
7
Left Center
85 dB
8
Right Center
85 dB
* Subwoofer should be set to 10 dB of in-band gain (see SMPTE RP-200), which equates to
approximately 91 dBC (slow).
Note
: Any change made with either Reference Tone or Pink Noise will affect the other. For
example, if you change the level of Reference Tone to +1.0 on Ch1, when you select Ch1 in
the Pink Noise test section, it, will also be at +1.0.
5.4.3. A Note about DTS Subwoofer Output
The XD20 subwoofer output level ranges from 20 Hz to 80 Hz and 20 Hz to 120 Hz (Coherent Acoustics
format), up to 27 dB above reference (85 dB).
Caution
: Check your subwoofer’s specifications to avoid damage to the speaker.
If a subwoofer is driven below its low frequency cutoff, its driver(s) may become unloaded. When
unloaded, the voice coil can travel outside of the magnet’s gap, overheating and/or causing mechanical
damage to the speaker. Contact your speaker manufacturer for more information.
5.4.3.1. Subwoofer Signal in the Surround Channels
The subwoofer signal is derived by filtering the surround signals from 80 Hz and below, and then routing
this signal to its own “subwoofer” output on the XD20.
You can verify this while performing a B-chain alignment of a theater as follows:
1.
Play the internal pink noise generator Subwoofer test. (Refer to Section 7.2.2, Audio Tests, in
Chapter 7, Setup Menus, in this guide.)
2.
Turn off the subwoofer speaker and look at the pattern on the RTA.
You’ll see a dramatic roll-off at 80Hz. It is normal to see DTS subwoofer pink noise, above
80Hz, in the surround speakers..
