Rane THX Room EQ - Manual (Page 12)

Home THX Equalization Manual Rev. 1.5
12
When equalizing the Subwoofer Channel, you should concentrate on reducing the serious peaks.
You may find that because of the depth of the room modes a ruler flat response is not within the range
of the equalizer. This not a major concern since a response within ± 3 or 4 dB is very acceptable.
One tip; a reduction of energy in the 20-30 Hz range will enable the subwoofer to play louder without
before encountering excursion problems.
1.9) Confirm the Subwoofer Splice: Center Channel
The next step is to activate the internal test signals present in your Home THX Controller and re-
adjust all SPL’s to their correct 75 dB C weighted levels. This will even out any level variations intro-
duced by equalization.
After level check, return to your “Wow!” Center Channel pink noise; Chapter 9. Observe on your
RTA the relative levels of the Subwoofer and the Center Channel. The overlap area is referred to as
the splice point. Follow the same averaging procedure you used in Section 1.4. In particular, look at
the crossover area between 80 Hz and 200 Hz. This area will usually appear uneven (Fig. 6).
Uneven Subwoofer Splice
Frequency Hz
dB
SPL
60
64
68
72
25 40 63 100 160 250 400 630 1000 1600 2500 4000 6300 10000 16000
Fig 6
The most common cause of an uneven Subwoofer splice is the relative difference in positions
between the LCR speakers and the Subwoofer(s). These position differences can cause frequencies
common to all the speakers to arrive at different times at the listening position, and partially cancel or
reinforce themselves. At this point use the Center Channel EQ to adjust the response at the
splice. DO NOT use the Subwoofer EQ .
1.10) Confirm Subwoofer Splice: Left and Right Channel
Next, in the Stereo or Bypass mode play both the Left and Right Pink Noise from “Wow!”; Chap-
ters 8 & 10. Measure and analyze as described in Section 1.4. Adjust both the Left and Right Chan-