27
18.0
Filters and Frequency Tables
The standard filter provided for the
FDS-360
is of the Linkwitz-Riley response
based on two second order Butterworth circuits in series. The response is a
24dB/OCT slope with a 'corner' frequency where the output of the filter if 6dB
down from its pass band level. The use of these filter realisations has been
well documented and provides the best possible phase and amplitude response
for driving large speaker systems.
Table 17.1 lists the component values for various frequencies and should be
used in conjunction with the drawing for the
FDS-360F
frequency card (
See
Figure 18.3
). Blank cards, or ready made cards can be provided by any BSS
dealer.
All resistors should be
¼
W metal film 2% tolerance or better. Capacitors
should be 5% tolerance or better.
Figure 18.1
shows how these components
relate to the separate filter blocks to assist in making mixed frequency cards
that might be needed for speaker systems that require gaps or overlaps in the
amplitude response of the filters. Other filter responses can also be realised
using these frequency cards, and your dealer will be able to supply these to
order.
18.1 Standard
Filters
Should the fourth band output be required to work as a full range buffered
output (
See section 14.1
), a full range frequency card is required to be inserted
into FC3 position. This card removes all filtering associated with the third
frequency point. The limiter setting capacitor C10 should be chosen to suit the
lowest frequency in the band, which would normally be 30Hz.
Figure 18.4
shows the frequency card modified for this result.
18.2 Full Range
Frequency Card
Filters and Frequency Tables
Fig 18.1 Frequency and
Component Function
Summary of Contents for FDS 360
Page 1: ...1 FDS 360 User Manual...
Page 51: ...51 User Notes...
Page 52: ...52 User Notes...
Page 53: ...53...
Page 54: ...54 User Notes...
