Detailed Parameters
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Section 6
The Fletcher-Munson Equal-Loudness curves show that the perception of low frequency signals decreases
quickly with decreasing volume. The DriveRack 4800 and 4820 offer the AutoWarmth®Insert module on
each output (Insert 1) to compensate for this perceived loss in low frequencies. AutoWarmth is a patent
pending process that compensates for the naturally occurring perceived loss of low frequency at low signal
levels. The result of using AutoWarmth is warm and balanced signal even at low signal levels.

AutoWarmth On/Off switch

This parameter turns the AutoWarmth function on and off.

Threshold fader

The Threshold sets the level at which AutoWarmth begins to work. Signals below the Threshold are
processed to increase the Bass response in proportion to the overall volume of the signal. Above the
Threshold there is no processing. The Threshold meter will light green when the threshold has been crossed
and AutoWarmth is active. The Threshold range is between -60 and 0 dBFS. To set the Threshold, turn
AutoWarmth off and adjust the Master Gain to the desired listening level. Turn AutoWarmth on and adjust
the Threshold until the Threshold Meter is toggling on and off. Now as the volume decreases below the
Threshold, the bass will gradually increase. Be careful when using AutoWarmth followed by an AGC. The
AGC can add gain when the signal is below the AutoWarmth threshold resulting in overcompensated Bass.

Amount fader

The Amount parameter controls how much bass is added. A setting of 1.00:1 compensates for the per-
ceived loss of bass by inversely matching the Fletcher-Munson Equal Loudness curves. Higher settings
(greater that 1.00) cause more bass compensation; lower settings result is less bass compensation. The
Amount parameter is adjustable between 0.25:1 and 4.00:1.
6.13 - AutoWarmth®Insert
DriveRack
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DriveRack®4800/4820 User Manual
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