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BSS Audio FDS 360 User Manual

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FDS 360
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  • Page 1 FDS 360 User Manual...
  • Page 2 V3.0 14 October 1996 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.

  • Page 3: Table Of Contents

    Contents Contents What is a Crossover? The difference between Active and Passive Crossovers Other advantages The Linkwitz-Riley advantage What is special about BSS Crossovers? Unpacking Mechanical Installation Mains Power Connection Input Connections XLR Plugs. 10.0 Output Connections 10.1 XLR Plugs 11.0 Controls 11.1...
  • Page 4 Contents 14.0 Modes of Operation 14.1 Mono Three Way with Extra Full Range Buffered Output 14.2 Operating a Sub-Woofer system from an Effects Send 14.3 Mono Low between separate units 15.0 Limiter Adjustment Adjustment for A Adjustment for B 16.0 Phase Adjustment 17.0 System Diagrams and Descriptions 25...

  • Page 5: What Is A Crossover

    Crossovers What is a Crossover? 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.

  • Page 6: The Difference Between Active And Passive Crossovers

    Active and Passive Crossovers 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).

  • Page 7: Other Advantages

    Crossover advantages 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.

  • Page 8: The Linkwitz-Riley Advantage

    Linkwitz-Riley Alignment 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 4.1 Linkwitz-Riley filters Zero Phase difference at crossover: The phase difference between drivers operating in adjacent frequency bands is close to zero degrees at the crossover frequency.

  • Page 9: What Is Special About Bss Crossovers

    BSS Crossovers Unpacking 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.
  • Page 10 Getting to know the FDS-360 11.2 11.8 Fig 6.1 Front Panel 11.5 11.4 Fig 6.2 Rear Panel 10.0 5x20mm FUSE 11.1...
  • Page 11 11.6 11.3 11.7 13.0 8 dB 8 dB WATS560B WATS560B 8 dB 8 dB WATS560B WATS560B All numbers in bubbles refer to Section numbers.

  • Page 12: Mechanical Installation

    Installation Mechanical Installation A vertical rack space of 1U (1¾" / 10½mm) deep is required. Ventilation gaps are unnecessary (See Figure 7.1). If the FDS-360 is likely to undergo extreme vibration through extensive road trucking and touring, it is advisable to support the unit at the rear and/or sides to lessen the stress on the front mounting flange.

  • Page 13: Mains Power Connection

    Connecting to Power Mains Power Connection Voltage: The FDS-360 operates on supply voltages between 95 and 125V AC. It must not be plugged into 220, 230 and 240V AC outlets. If the unit is accidentally connected to an AC supply giving in excess of 132V AC, refer to section 23, (See Figure 8.1).

  • Page 14: Input Connections

    Input Connections Input Connections 9.1 XLR Plugs. The two input signals are 10k ohm active balanced on a standard 3 pin 'female' XLR which will accept levels up to +20dBv. The wiring convention is as follows: (See Figure 9.1a): Pin 1: No connection (the shield of the drain wire can be terminated here if desired).
  • Page 15 Output Connections Technicians note: As with a traditional transformer balanced output, either output phase (+ or -, hot or cold) can be linked to ground to 'unbalance the line' without upsetting the operation of the unit. As with a transformer, output level remains the same in the unbalanced mode.

  • Page 16: Controls

    Controls 11.0 Controls 11.1 Mode Switch The mode switch is located at the rear of the unit and sets the internal architecture for either the stereo 2-way, the mono 3-way, or mono 4-way mode. In the mono modes, the channel 1 input connector is used. Refer to section 14 for other possibilities.

  • Page 17: Polarity Switch

    11.4 Polarity Switch These four latching switched allow 180 degree phase reversal of the signal output for each band individually. Refer to section 16 for more information. 11.5 Mono Low Switch When operating the FDS-360 in the stereo 2-way mode, this switch will sum together the signal information in bands 1 and 3 so that the outputs of these bands are equal, regardless of input stereo image.

  • Page 18: Limiter Threshold Switch

    Controls 11.7 Limiter 8 dB 8 dB Threshold Switch WATS560B WATS560B 8 dB 8 dB WATS560B WATS560B These four switch blocks on the rear panel allow the individual band limiter thresholds to be set. With all switches in the 'out' position, the threshold will be either +10dBv or +4dBv depending on the barrier strip link.

  • Page 19: Frequency Cards

    Frequency Cards 12.0 Frequency Cards The frequency programming cards for the FDS-360 are located underneath the small panel on the top cover of the unit. Access to them is obtained by loosening the captive screw and then removing the cover. Each frequency card contains the components required for one low pass filter, one high pass filter, the limiter dynamics setting and phase control setting.

  • Page 20: Rear Barrier Strip

    Rear Barrier Strip 13.0 Rear Barrier Strip The barrier strip located on the rear of the FDS-360 provides for a number of facilities specific to the BSS FDS-360, to give the operator greater flexibility. 13.1 Limiter Cancel By adding a wire link between the two marked terminals all four limiters can be cancelled and taken out of circuit.

  • Page 21: Modes Of Operation

    Modes of Operation 14.0 Modes of Operation The FDS-360 can be configured as either a stereo 2-way, or mono three/four- way electronic crossover. Further possibilities within this framework can be utilised to allow more flexibility. For applications where only a three way system is used, the fourth way or 14.1 Mono Three band will not be directly used.

  • Page 22: Limiter Adjustment

    Limiter Adjustment 15.0 Limiter Adjustment The FDS-360 is provided with separate limiters, each of which are carefully designed to provide the maximum possible protection to the speaker system by dynamically controlling the maximum power made available to the power amplifier, and hence the loudspeakers. The frequency card has components that optimise its response to suit the frequencies that are being controlled.
  • Page 23 Fig 15.1 Limiter Switch Settings 4dBv RMS Volts Threshold Settings Link 2.47 1.95 1.56 1.24 0.98 0.78 0.62 0.49 0.39 0.31 0.25 0.21 -11.5 The 1 and 0.5dB switch positions should be used to set for intermediate settings. The grey box indicates that the switch is ON. A blank box indicates that the switch is OFF.

  • Page 24: Phase Adjustment

    Phase Adjustment 16.0 Phase Adjustment One of the characteristics of the Linkwitz-Riley filter response is that at the 'corner' frequency between two adjacent bands the phase of the signal from each band is the same. i.e. the two output signals are in phase. (Some small departure from this occurs in band-pass outputs due to residual effects from the opposite 'corner' frequencies).

  • Page 25: System Diagrams And Descriptions

    System Diagram/Description 17.0 System Diagrams and Descriptions The input section of the FDS-360 contains the input signal de-balancing, 17.1 Full unit subsonic and ultrasonic filtering. From here the signal is fed into four parallel paths for filtering and limiting. These four paths are essentially similar, apart from the number and types of filters required.

  • Page 27: Filters And Frequency Tables

    Filters and Frequency Tables 18.0 Filters and Frequency Tables The standard filter provided for the FDS-360 is of the Linkwitz-Riley response 18.1 Standard based on two second order Butterworth circuits in series. The response is a Filters 24dB/OCT slope with a 'corner' frequency where the output of the filter if 6dB down from its pass band level.
  • Page 28 Filters and Frequency Tables Fig 18.2 Component Values for Frequency Cards type FDS-360/1 FDS-360 FREQUENCY CARD COMPONENT SELECTION - 24dB/Octave Freq. 100k 100nF 330nF 150nF 100nF 330nF 150nF 150k 100nF 330nF 150nF 180k 100nF 330nF 150nF 220k 100k 100nF 220nF 100nF 330k 100nF...
  • Page 29 FDS-360 FREQUENCY CARD COMPONENT SELECTION - 24dB/Octave See Notes at bottom for full component ID. Freq. 3n3F 10nF 3n3F 3n3F 10nF 3n3F 3n3F 10nF 3n3F 3n3F 6n8F 2n2F 3n3F 6n8F 2n2F 330k 3n3F 6n8F 2n2F 120k 100k 3n3F 6n8F 2n2F 1n0F 6n8F 2n2F...

  • Page 30: Bss Supported Options

    Supported Options 19.0 BSS Supported Options 19.1 Output The FDS-360 has unbalanced output as standard. Should output balancing be required, then the BSS AR204 line balancing unit should be used. This unit Balancing provides four input/output circuits, each isolated by a transformer. It utilises a custom designed high quality toroidal transformer carefully developed to accommodate high line level signals down to 15Hz.

  • Page 31: Fds-360 Equalisation Options

    Equalisation Options 20.0 FDS-360 Equalisation Options 20.1 Introduction In certain areas of application, it is necessary to have within a loudspeaker system some form of fixed equalisation to enable a particular type of sound to be reproduced. This can be to overcome problems of room resonances or individual loudspeaker frequency responses.
  • Page 32 Equalisation Options Fig 20.1 Schematic for one filter block Fig 20.2 Bell Response curve for filter block Fig 20.3 HF/LF Response curve for filter block...

  • Page 33: Filter Design

    20.4 Filter Design Reference should be made to Figure 20.1. Section A: First Order Low Pass Filter. This can be used in conjunction with that of section B, and an example plot is shown in Figure 20.4. The equation for the -3dB frequency point of this circuit is: 1/(6.28 x R2 x Cx), where R is in ohms, C is in Farads,...
  • Page 34 Equalisation Options First Order Response Cf = 15nF, Fc (-3dB) = 1kHz Fig 20.4 First Order Sample Response 10dB Frequency (Hz) Section B: Parametric Equaliser Filter. This is a fully adjustable bell shape equaliser for which control is given over: •...

  • Page 35: Application Notes

    20.5 Application 100Hz Notch to reduce mains related interference Notes The design specification for this would be: = 100Hz = Maximum possible dB cut= Maximum possible Using the Fc equation given earlier, and selecting Cf = 220nF gives a value for Rf = 7.23k ohms.

  • Page 36: Application Of The Fds-360D To A System

    Equalisation Options HF Shelf RQ = 0, Fc = 16kHz Fig 20.8 Sample HF Shelving Response Curves Frequency (Hz) 20.6 Application of A target response should be arrived at by either inspection from a set of frequency response curves, or by adjustment of an external equaliser the FDS-360D to a connected into the system.
  • Page 37 Fig 20.10 Design Curves for RdB R Boost/Cut vs dB Boost/Cut R Boost/Cut (k ) dB Boost/Cut...
  • Page 38 FDS 360 D-Card Connection of the filter blocks into the FDS360 frequency bands is arranged by the wire link strapping between the various connection areas: Filter I.P : Are the inputs to the filter blocks. Filter O.P : Are the outputs of the filter blocks. O.P : Are the band insert returns, and are connected to the Filter O.P.
  • Page 39 Fig 20.12 FDS360 EQ 'D' card Schematic...

  • Page 40: Fds-360 E Installation

    FDS 360 E-Card 20.7 FDS-360 E The 360E board filters 3 and 4 are shelf type filters which can be configured as High or Low pass cut or boost. Filters 1 and 2 remain the same as the Installation parametric EQ filters on the 360D board (See section 20.4 for further details). The design idea for filters 3 and 4 is to provide gentle slopes which will enhance or cut low or high frequencies.
  • Page 41 Fig 20.14 FDS-360 EQ 'E' Card Schematic...

  • Page 42: Electronic/Chassis Earth Link

    Chassis Earth Link Transient Suppressor Replacement 21.0 Electronic/Chassis Earth Link In some installations it may be necessary to separate the electronic 0V from the chassis and mains power earth to help in avoiding earth loops around the unbalanced output connections. Should this become necessary, it is easily achieved by removing a wire link inside the FDS-360.

  • Page 43: Troubleshooting

    Troubleshooting 23.0 Troubleshooting Problem: No output Is the MUTE switch depressed? Solution: Is the mains power on? (See section 8.0) Check the connections. See Fuse failure (below). Do you have an input signal? Is the SIGNAL LED on? Check the input and output connections (See sections 9.0 & 10.0). Are the power amplifiers switched on? Problem: Excessive Hum, Intermittent sound First check the connections on your input and output plugs (See sections 9.0 &...

  • Page 44: Glossary

    Glossary 24.0 Glossary Active Active electronic circuits are those which are capable of voltage and power gain by using transistors and integrated circuits. Passive circuits are those which use only capacitors, resistors, transformers, etc. Amplitude Refers to the voltage level or intensity of a signal, and is usually measured in voltage or decibels.
  • Page 45 Distortion Any modification of a signal which produces new frequency components not presents in the original. Harmonic distortion refers to added frequencies that are overtones to the fundamental frequency. Intermodulation distortion refers to added frequencies that are sum and difference values derived from the beating together of two frequencies.
  • Page 46 Glossary Transient A sudden burst of energy in an audio signal which only lasts for a small period of time relative to the rest of the signal. The level of a transient can often reach 10 times or so the normal operating level of the audio equipment, and may cause distortion.

  • Page 47: Specifications

    Specifications 25.0 Specifications Gain: 0dB standard. Optional +10dB to order. Noise: 85dBm 20Hz to 20kHz unweighted. Distortion: <0.5% THD up to +20dBm output, limiter cancelled. Typically 0.0005% THD +6dBm output. Filters: 24dB/OCT Linkwitz-Riley as standard. Options include any 12, 18, 24dB/OCT filter type with user specified frequencies preset by plug-cards.

  • Page 48: Warranty Information

    26.0 Warranty Information This unit is warranted by BSS Audio to the original end user purchaser against defects in workmanship and the materials used in its manufacture for a period of one year from the date of shipment to the end user.

  • Page 49: Index

    Index 15Hz Subsonic Filter Limiter Threshold Reference. See Index Rear Barrier Strip Limiter Threshold Switch. See Con- trols Auto Mute Cancel. See Rear Barrier Limiters Strip Linkwitz-Riley Band Insertion Points. See Rear Mains Connection Barrier Strip Mains interference Bass shelving Manual Version No.
  • Page 50 Index Voltage. See Mains Connection Warranty Wiring convention. See Inputs WWW address Zero Phase difference...

  • Page 51: User Notes

    User Notes...
  • Page 52 User Notes...
  • Page 54 User Notes...

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