BSS Audio FDS 360 Bedienungsanleitung
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FDS 360
User Manual
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This equipment has been tested and found to comply with the following European Standards for
Electromagnetic Compatibility:
Emission Specification: EN55013 (1990) (Associated equipment)
Immunity Specification: EN50082/1 (1992) (RF Immunity, Fast Transients and ESD)
Mains Disturbance: EN61000/3/2 (1995)
For continued compliance ensure that all input and output cables are wired with cable screen connected to Pin
1 of the XLR. The input XLR Pin 1 on BSS equipment is generally connected to chassis via a capacitor to
prevent ground loops whilst ensuring good EMC compatibility.
V3.0 JMK 14October1996
We have written this manual with the aim of helping installers, sound engineers and consultants alike get to
grips with the FDS-360 and obtain its maximum capability.
If you are new to BSS products, we recommend that you begin at the start of the manual. If, however, you are
already familiar with the intended application, and just want to get the unit installed without delay, then
follow the highlighted sections.
We welcome any comments or questions regarding the FDS-360 or other BSS products, and you may contact us
at the address or World Wide Web site given in the warranty section.
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Contents
Contents
1.0 What is a Crossover? 5
2.0 The difference between Active and
Passive Crossovers 6
3.0 Other advantages 7
4.0 The Linkwitz-Riley advantage 8
5.0 What is special about BSS
Crossovers? 9
6.0 Unpacking 9
7.0 Mechanical Installation 12
8.0 Mains Power Connection 13
9.0 Input Connections 14
9.1 XLR Plugs. 14
10.0 Output Connections 14
10.1 XLR Plugs 14
11.0 Controls 16
11.1 Mode Switch 16
11.2 Level Control 16
11.3 Mute Switch 16
11.4 Polarity Switch 17
11.5 Mono Low Switch 17
11.6 Phase Control 17
11.7 Limiter Threshold Switch 18
11.8 Signal LEDs 18
12.0 Frequency Cards 19
Card Location for Four Way System 19
Card Location for Three Way System 19
Card Location for Stereo Two Way System 19
13.0 Rear Barrier Strip 20
13.1 Limiter Cancel 20
13.2 Auto Mute Cancel 20
13.3 Limiter Threshold Reference 20
13.4 Band Insertion Points 20
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Contents
14.0 Modes of Operation 21
14.1 Mono Three Way with Extra Full Range
Buffered Output 21
14.2 Operating a Sub-Woofer system from an
Effects Send 21
14.3 Mono Low between separate units 21
15.0 Limiter Adjustment 22
Adjustment for A 22
Adjustment for B 22
16.0 Phase Adjustment 24
17.0 System Diagrams and Descriptions25
17.1 Full unit 25
17.2 15Hz Subsonic Filter Change 25
18.0 Filters and Frequency Tables 27
18.1 Standard Filters 27
18.2 Full Range Frequency Card 27
19.0 BSS Supported Options 30
19.1 Output Balancing 30
19.2 Security Cover 30
20.0 FDS-360 Equalisation Options 31
20.1 Introduction 31
20.2 FDS-360D Installation 31
20.3 Circuit Description 31
20.4 Filter Design 33
20.5 Application Notes 35
20.6 Application of the FDS-360D to a system 36
20.7 FDS-360 E Installation 38
21.0 Electronic/Chassis Earth Link 39
22.0 Transient Suppressor Replacement 39
23.0 Troubleshooting 40
24.0 Glossary 41
25.0 Specifications 44
26.0 Warranty Information 45
Index 49
User Notes 51
Spare Parts Information
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1.0 What is a Crossover?
Crossovers
Crossovers are a necessary part of sound reinforcement systems because the
loudspeaker drive-unit which can produce clear reliable high SPL (sound
level) over the full audio bandwidth has yet to be invented. All real-world
drive units work best when they are driven over a limited band of frequencies,
for example: Low, Mid and High.
Any crossover aims to provide the division of the audio band necessary, so
each drive unit receives only the frequencies it is designed to handle. In a
high power, high performance sound system, the crossover should also reject
unsuitable frequencies to avoid damage and poor quality sound.
Fig 1.1 Stereo 2-way
Crossover setup
Fig 1.2 Mono 3-way
Crossover setup
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2.0 The difference between Active and
Passive Crossovers
Passive crossovers divide the frequency spectrum after the signal has been
raised to a high power level. They are generally heavy, bulky and inefficient.
Active crossovers utilise ICs and transistors, and divide the frequency
spectrum at line levels, immediately ahead of the amplifiers (See Figure 2.1).
An active crossover does the same job as a passive crossover, but with more
precision, flexibility, efficiency, and quality.
Fig 2.1
Active and Passive Crossovers
• Crossover frequencies can be more readily altered to suit different driver-
horncombinations.
• The level balance between the 2 or 3 frequency bands (brought on by
differences in driver and amplifier sensitivity) can be readily trimmed.
• Inside an active crossover unit, line-driving, signal summing, driver
equalisation, system muting and polarity ('phase') reversal facilities can all be
incorporated at small extra cost.
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Crossover advantages
3.0 Other advantages
The drive-units in sound reinforcement systems utilising active crossovers
benefit because:
• Steep rolloffs are readily attainable. The -24dB/OCT rolloff in the BSS FDS-
360 active crossover rapidly discharges out-of-band energy. At one octave
below the crossover point power received by the driver has dropped to less
than ½% (or 1/200th) of full power. The result: Bad sound resulting from out-
of-band resonances are effectively masked immediately beyond the crossover
frequency (See Figure 3.1). This contrasts markedly with passive crossovers,
where slopes in excess of -12dB/OCT are rarely achieved, and power rolloff is
4 times less rapid, per octave.
Fig 3.1 Crossover
Terminology
• If one frequency range is driven into clip, drive-units and horns in other
frequency ranges are protected from damage, and distortion is kept to a
minimum.
• Direct connection of drive-units to the power amplifier cuts out loss of
damping factor, normally inevitable thanks to the appreciable resistance of
the inductors in passive crossovers.
Amplifiers benefit too from the use of active crossovers. Because they do not
handle a full-range signal, clipping produces far less harmonic and
intermodulation distortion. The results: Momentary overdrive sounds less
harsh. Also the amplifiers' dynamic headroom is generally higher, and
heatsink temperatures can run lower.
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Linkwitz-Riley Alignment
4.0 The Linkwitz-Riley advantage
There is an additional set of advantages exclusive to active crossovers made
by BSS, and other manufactures using the Linkwitz-Riley alignment (See
Figure 4.1).
Fig 4.2 Radiation
Pattern Frequency
showing excellent on-
axis symmetry
Zero Phase difference at crossover: The phase difference between drivers
operating in adjacent frequency bands is close to zero degrees at the
crossover frequency.
'Phase alignment' in this manner prevents interactive effects (i.e.: High and
Low drivers 'fighting' each other), over the narrow band of frequencies around
the crossover point; this is where the units from two adjacent frequency ranges
are contributing near equal amounts of sound pressure.
More predictable sound dispersion: By providing in-phase summation at the
crossover point(s), the Linkwitz-Riley alignment provides for more cogent
sound dispersion - it provides on-axis symmetrical radiation patterns. (See
Figure 4.2).
'Invisible' slopes: The absence of electrical phase difference close to the
crossover frequency helps to make the steep -24dB/OCT slope effectively
inaudible,. Response peaks and dips are negligible and inaudible given the
correct polarity ('phasing') of the speaker connections. The same is not true of
the shallower (-6, -12 or -18dB/OCT) rates or rolloff, in other crossovers.
Fig 4.1 Linkwitz-Riley
filters
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BSS Crossovers
5.0 What is special about BSS Crossovers?
The FDS-360 is an electronic crossover system, and incorporates all the latest
technology and facilities that are required for todays high powered
loudspeaker systems. This frequency dividing system (FDS) is substantially
more than a basic crossover, combining a high degree of sophistication which
enables accurate control of loudspeaker power, dispersion and acoustical
summation around the critical crossover region.
The FDS-360 features the following:
• Stereo two-way mode, or switchable three/four way mono mode.
• Separate frequency band limiters matched to the precise band of
frequencies controlled.
• Separate polarity switching for each band.
• LED signal level monitoring.
• Band insertion points for interfacing external equalisation and time delay
units.
• Band-edge phase adjustment allowing 360 degrees of control.
• Crossover filter programming via plug-in frequency cards allowing any
frequency, choice of 12/18/24dB/OCT slopes and filter responses to be
specified. 24dB/OCT Linkwitz-Riley responses are supplied as standard.
• Internal equalisation option.
Every FDS-360 is manufactured to the highest professional standards with a
robust steel case, high quality circuit boards and ICs, and high quality
components to provide reliable performance under the most demanding
conditions of the global sound-reinforcement environment. In common with
all other BSS equipment, the FDS-360 is subject to stringent quality control
procedures throughout the manufacturing process. Components are tested
against demanding acceptance criteria. Every completed unit is tested both
by measurement and in a listening test carried out by trained audio
professionals. To positively ensure reliability, all units are burnt-in for fifty
hours, before being tested.
Unpacking
As part of BSS' system of quality control, this product is carefully inspected
before packing to ensure flawless appearance.
After unpacking the unit, please inspect for any physical damage and retain
the shipping carton and ALL relevant packing materials for use should the unit
need returning.
In the event that damage has occurred, please notify your dealer
immediately, so that a written claim to cover the damages can be initiated.
See Section 26.
6.0 Unpacking
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Getting to know the FDS-360
11.2
11.411.5
11.8
Fig 6.1 Front Panel
Fig 6.2 Rear Panel
FUSE
5x20mm
240
.5 1
ON
OFF W
A
.5 1
ON
OFF W
A
10.0
8.0 11.1
Inhaltsverzeichnis
Andere BSS Audio Crossover Handbücher
