Dolby Laboratories CP65 manual Do not adjust, a. Setting Room Equalization, Action, Indication

5-14

B-Chain Alignment Procedures

a. Setting Room Equalization

Step	Action	Indication
No.

16

										dB
								+10
								+5
								0
										–5
										–10
						2.0		8.0
.05	.1	.2	.4	.8	1.6	3.15	6.3		12.5 kHz

17

✓ X X

					dB
					+10
					+5
					0
x
Do not adjust					–5
				2.0	–10
					8.0
.05 .1	.2	.4	.8	1.6 3.15	6.3 12.5 kHz

5-15

B-Chain Alignment Procedures

a. Setting Room Equalization

Notes

While observing the frequency response curve on the RTA, adjust the treble control on the Cat. No. 64 for a flat response as close as possible up to 2 kHz, followed by a 3 dB per octave roll-off above 2 kHz (the frequency response specified in ISO Standard 2969). Once you set this control, do not change the setting during the rest of the room equalization procedure.

The next step is to fine-tune the equalization by adjusting the third-octave controls on the Cat. No. 64 equalizer. There are certain rules to keep in mind:

•The object is to achieve the final adjustment of room equalization with all of the controls as close to the 12 o’clock position as is possible.

•All of the equalizer controls interact with each other so you should not start at the low end of the response curve and merely work your way to the high end. As each control is adjusted, the response obtained by adjustment of adjacent controls is affected.

•Start at the center frequency and attempt to achieve results with cut rather than with boost. The desired curve is a flat frequency response up to 2 kHz,falling at 3 dB per octave to 8 kHz (1dB per third-octave band). Do not change the position of the 50 Hz or 40 Hz band controls nor turn the controls for bands above 8 kHz unless you have modern loudspeakers. This protects the loudspeakers and power amplifiers from damage and prevents distortion of the reproduced sound.

•If modern woofer systems (vented-box direct radiator enclosures) are installed in the theatre , moderate bass equalization down to 40 Hz may be used.

•Once an adjustment seems OK, work on the frequencies to either side of it. You may find that a cut at one frequency is followed by a slight boost at adjacent frequencies.

•Control settings should not fall outside the band between the 9 o’clock and the 3 o’clock positions.

•Avoid diametrically opposed adjacent control settings.

Adjust for the response that is closest to the curve shown. The diagrams show a typical equalization procedure, from the response before equalization to the final equalization.