Krell Industries Evolution 505 - Manual (Page 26)

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Using the Filter Button or Key (17)
Four filters make subtle changes to the high frequencies at ultrasonic levels, alter-
ing the sonic presentation from your loudspeakers. Once a filter setting has been
selected, it is held in memory even if the Evolution 505 is turned off and then
returned to operational status.
Filter 1, 2, 3, and 4 are available in any SACD format. Only Filters 1 and 2 are
available in the conventional CD format. All filters have a different output gain,
higher bandwidth, and a more gradual rolloff in the SACD format, compared to
Filter 1 and 2 in the CD format.
Filter 1 and 2 are designed to eliminate aliasing artifacts that are the result of the
D/A re-construction process.
Conventional Compact Disc Format Filters
Filter 1 operates flat from 20 Hz to 20 kHz, with a very steep roll-off characteristic
above 20 kHz (21.5 kHz, -3 dB).
Filter 2 operates up to 20 kHz (-3 dB) with a more gradual roll-off characteristic
when compared to Filter 1.
SACD Format Filters
Filter 1 in the SACD format, has the same relative output gain as Filter 1 and 2 in
the CD format, and it has the highest bandwidth of the four SACD filters. Filters 2,
3 and 4 in the SACD format, operate at reduced bandwidth with steeper slope fil-
tering and different output gain.
Filter 1 operates up to 180 kHz (highest bandwidth) and has the slowest roll-off
characteristic with no change in output gain.
Filter 2 operates up to 75 kHz and has the steepest roll-off characteristic. It has a
+0.5 dB increase in output gain over the entire audio pass band compared to
Filter 1.
Filter 3 operates up to 80 kHz and has the 2nd steepest roll-off characteristic. It
has a +5.5 dB increase in output gain over the entire audio pass band compared
to Filter 1.
Filter 4 operates up to 90 kHz and has the 3rd steepest roll-off characteristic. It
has a +3.5 dB increase in output gain over the entire audio pass band compared
to Filter 1.
(SECTION FIVE: Evolution 505 Operation continued)