3.SETUP MENU continued …

Highlighting ‘g. ROOM RESONANCE FILTER’ in menu 2 and then pressing SELECT displays this menu:

ROOM RESONANCE

RESONANCE FILTER

RESULT

2g. ROOM RESONANCE FILTER

a.TEST TONE : Off

b.TEST TONE LEVEL : +0.0 dB

c.TEST TONE FREQ : 21 Hz

d.APPLY FILTER : No

e.FLTR CENTER FREQ : 60 Hz

f.FILTER DEPTH : 1 dB

g.FILTER WIDTH : 20 Hz

h.THX ULTRA2 SUB : No

i.THX BG COMPENSATION : NA

Center Frequency

Filter Depth

Filter Width

Rooms often have a single prominent resonance peak which can make bass sound boomy, even with the finest subwoofer. The AVM 50 has a proprietary set of low frequency test tones that allow you to find and easily remove that resonance peak.

The Room Resonance Filter is a notch filter – it is not designed to boost weaker bass frequencies. While running the test tones, if you discover that instead of a prominent peak, there is a prominent dip in response, the best way to fill it is through a subtle repositioning of the subwoofer and/or listening position. Using electronics alone to accomplish this is often met with frustration, for example, a 10 dB boost would require the amplifier to work ten times harder, as well as speakers that can handle that much more power.

Test Tone and Test Tone Level:

Test tones sweep from 18 Hz up to the XOVER FREQ (or the SUB/LFE XOVER frequency) that you have set in menu 2a. or 2b., whichever is higher. You can vary the level to obtain a comfortable playback volume.

Filter Center Frequency:

The frequency that is reduced the most when the filter is applied is called the Center Frequency. Set this to the frequency that sounds the loudest or most boomy when the built-in test tones are played. If you’re using a sound pressure level meter, set it to ‘Flat’ or ‘C-weighting’.

Filter Depth:

This is the amount of center frequency ‘cut’, or reduction in volume, in the subwoofer channel. Frequencies just above and just below the center frequency are also reduced, but not as much. Range is from 1 to 20 dB. Adjust to bring the level of the resonant peak down to the same level as the other frequencies.

Filter Width:

This adjustment varies the range and sharpness of the filter. For example, if Filter Width is set to 3 Hz, the Room Resonance Filter cuts a very narrow range at the filter center frequency. If Filter Width is changed to 18 Hz, a broader range is reduced. Adjust so that resulting frequency response is as flat as it can be made.

Changing Center Frequency and Depth settings affects the available range of Width and causes it to automatically decrease if required.

THX Boundary Gain Compensation:

If your listening room layout results in the subwoofer and/or listeners being too close to a wall, an excessive bass effect can result. With a subwoofer that extends to 20 Hz, including all THX Ultra2 certified subwoofers, Boundary Gain Compensation can improve bass balance. To enable, set THX ULTRA 2 SUB to ‘Yes’ and then THX BG COMPENSATION to ‘On’.

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