Dynaudio pmn manual LFE Gain, Polarity, Phase

Air_US_rev_111.qxd 16-12-2004 14:17 Page 29

CALIBRATING THE SUBWOOFER - with the main monitors

LFE Gain

Range: 0 to +14dB

The LFE channel can be boosted up to 18dB using this parameter.

Polarity

Range: 0 or 180º

If the Subwoofer is correctly placed, setting the Polarity parameter at 180º should result in a full Phase cancellation at the set Cross -over frequency. If this is not the case - the Phase parameter described below should be adjusted.

Phase

Range: 0 to 180º

Phase Introduction

The integration of the AIR Base subwoofer with the AIR monitors requires on-location tuning. Apart from level calibration and choosing a Bass Management Crossover (X-over) frequency, the issue of phase alignment remains. For this purpose, the AIR Base has a 0-180 degree phase adjustment (in 5 degree steps) and a Phase Reverse function. The optimum setting of these will depend on several factors:

1.Room acoustics

2.Placement of monitors and listening position

3.Choice of X-over frequency

4.AIR Monitor type (6 or 15)

Phase settings are automatically saved and linked to the currently selected Cross-over frequency. Phase settings are Global settings and are therefore not saved with individual presets.

Initial setting

During calibration of the AIR Base's DSP software, we have come up with default settings that we found optimal in our listening room. If you're placing the AIR Base at the same distance from the listening position as your AIR Monitors, the default phase settings can be used as initial guidelines for setting the phase. If the distances are significantly different, these values are not likely to be optimal.

Adjustment

Now play repeatedly a low-frequency sweep signal that sweeps over the X-over frequency that you have chosen. Tracks 31-42 on the AIR Test CD may be used. Between each sweep, change the Phase Reverse setting. Note the difference. Ideally, with the right level calibration and phase setting, the sound should cancel out and virtually disappear at or near the X-over frequency, when the Phase Reverse control is in one position. Tune Phase Adjust to get the largest possible difference between the two Phase Reverse settings. Then leave it in the position where no cancellation occurs.

Iteration

You may need to iterate quite a bit, maybe readjust the level calibration a bit too. You may even want to reconsider your initial choice of X-over frequency and/or monitor placement and start the process over again. Be patient: The time spent getting this right is well spent.

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