Rane THX Room EQ User Manual

Page 10

Home THX Equalization Manual Rev. 1.5

1.5)

Equalize:

The resulting spatial average will approximate the inverse of the correct EQ curve. As a starting

point, assume that a dip of -3 dB on the analyzer calls for an increase at the appropriate EQ frequency
of +3 dB. Remember the scale on the analyzer is 2 dB per division.

Since we will re-measure a number of times, any over correction or under correction will be

caught. When analyzing the averaged RTA curve, try to look for the mean SPL for all frequencies and
adjust the peaks and dips to that mean.

Remember that we are trying to achieve a response in the LCR channels of ±1 to 2 dB from 100

Hz to 1 kHZ without drastic EQ shifts. A boost of 6 dB places many demands on both amplifiers and
loudspeakers.

1.6)

Re-analyze:

After applying the corrections to the appropriate channel frequency centers, re-run the procedure

described in 1.4 to verify the corrections. You will find that you will have to measure and correct
several times to achieve a balanced and repeatable response.

NOTE: ABOVE 1 kHz, IN TYPICAL ROOM ENVIRONMENTS, THE SOUND FROM HOME THX LCR
SPEAKERS IS DIRECT FIELD DOMINATED AND THE FREQUENCY RESPONSE MAY BE POSI-
TION DEPENDENT. AVOID DRAMATIC EQ CHANGES ABOVE

1 kHz. SINCE WE ARE MORE

SENSITIVE TO FREQUENCY PEAKS THAN DIPS, USE THE CONTROLS AVAILABLE SPARINGLY
TO REDUCE HIGH FREQUENCY PEAKS, RATHER THAN TRYING FOR RULER FLAT RESPONSE

Avoid radical EQ beyond this point.

Typical Unequalized Room Response

Frequency Hz

SPL

100

160

250

400

630

1000

1600

2500

4000

6300

10000

16000

Fig 4