by BSS Audio Detailed product description 1 Introduction

Transcription

1 by Detailed product description 1 Introduction This document gives a detailed description of the Soundweb system. It gives much more technical information (and less sales information) than the Soundweb leaflet. However, to understand the system fully, there s no substitute for getting hold of a demonstration disk of the Soundweb Designer software, and trying it out for yourself. Soundweb is a set of audio processing units, which can be linked by a digital communications network. The units are completely flexible: you program the signal paths and block diagram of the processing using a PC, choosing the processing blocks from an extensive library. Soundweb units can contain microphone preamplifiers, so you can create almost any audio system, including all of the processing all the way from microphone to power amplifier. Section 2 DSP describes the DSP facilities, Section 6 Hardware product descriptions describes the individual Soundweb products. A single Soundweb unit can form a substantial audio processing system, but the real power of the product is that any number of Soundweb units can be connected together using the network. Each Soundweb unit comes with all the necessary network hardware already built in, so you can build a simple network simply by linking two units with a network cable, or build a very large audio system with hundreds of inputs and outputs. Section 3 The network describes the network. You design and control your Soundweb system from a software package called Soundweb Designer, which offers comprehensive facilities for producing and documenting system layouts, adjusting the audio processing, providing presets, security, on-line troubleshooting and many other features. Soundweb Designer is described in Section 7 Soundweb Designer software. When the system has been designed, you plug in your PC to any one of the units on a Soundweb network, whereupon you can download the system design, and adjust parameter settings and presets. When this has been done, you can leave the PC on line as a permanent control system, or disconnect it, leaving behind a variety of options for real time control. Section 4 Control options describes the control options available.

2 2 DSP Soundweb offers a library of DSP processing objects containing most commonly used audio processing functions: mixing, equalization, filtering, crossovers, delay, and dynamics processing, as well as utility functions such as tone generators and meters. BSS is committed to continuing development and enhancement of the library next to come are automatic mic mixing and levelling; more will follow. The layout of the processing is completely flexible. Processing objects are represented on the PC screen by boxes with connection points for their inputs and outputs: these are simply hooked up, using a CAD-like interface, to produce any layout that may be desired. The amount of DSP in the Soundweb 9088 and 9000 units is 160 MIPS. Here are some examples of what this means in practice: a single Soundweb 9088 can implement 13 channels of 12-band parametric EQ, or 15 channels with a compressor and gate in each, or a stereo 4-way crossover with limiters, delays and 12 bands of parametric EQ on each output and a stereo compressor on the input. The amount of processing available does depend on the circuit complexity: the numbers here simply give a rough idea of what is available. Soundweb s DSP runs at a fixed 48 khz sampling rate. Processing throughout is in 24 bit fixed point, giving an internal dynamic range of 144 db, with the exception of certain critical areas of the filters in which a technique called second order error feedback is used to enhance precision. 3 The network The Soundweb network is based on a proprietary custom chip (or ASIC ), for which patents are pending. The ASIC allows the transmission of 8 channels of 24 bit, 48 khz audio in each direction, and also provides around 3 Mbit/s of bandwidth for control packets: these are used to send parameter changes, meter data, and various other control items. The network uses standard category 5 cable: the same cable which is used for most present-day computer networks and advanced telephony installations. Connection is made via readily available RJ-45 telephone-jack like connectors, and a wide variety of off-the-shelf hardware items is available such as pre-made cables, patch bays and wall sockets. 3.1 A two unit network 3.2 Chaining several 9088s The simplest Soundweb network is formed by connecting one RJ-45 cable between two Soundweb 9088s. The cable can be up to 300 metres (1000 feet) long. This provides 8 channels of audio going each way between the two units, plus a control path. The existence of the control path means, for example, that a potentiometer connected to the control inputs on one unit (see section 4.1 Control ports) can be used to control the output gain of a mixer in the other unit, and it means that a PC plugged into either one of the units can reload programs and adjust parameters on both. Next up in complexity is a daisy chain of 9088s: the Out jack of the first 9088 is connected to the In jack of the second; the Out jack of the second is connected to the In jack of the third, and so on. When this is done, the 9088s form an audio ring: 8 channels travel round the ring from the first unit to the last and then back to the first. At each 9088, a channel can either be passed on from the previous unit in the ring, or replaced by an audio signal from one of the inputs or processing primitives. In this network, each network cable can be 300 metres long. The maximum size of the chain is a combination of total cable distance and number of units: under normal circumstances, a chain of at least 15 units should be possible. April 1998 Page 2

3 3.3 Hubs and complex networks To produce more complex networks, the Soundweb 9000 hub is used. Each hub has six network jacks; each jack can generate the full 8 channels of audio in each direction. It is possible to hook a chain of 9088s to each hub jack, so that the hub forms the interlock point between the audio rings. Multiple hubs can be connected together, and multiple connections can be made between hubs to increase the number of channels available. By continuing to do this, a web of processing devices is built up (which is what gives the product its name). 4 Control options Real time control of a Soundweb system is provided by one of several different means. The first means of control, and the one invariably used for initial system setup, is via the Soundweb Designer software. Soundweb Designer allows the user to create a variety of control panels, and to provide password protection for them see sections 7.2 Control panels and 7.4 Security for details. Coming soon is the second means of control the Soundweb 9010 remote control panel: see section 6.3 Coming soon: 9010 Remote Control Panel for details. 4.1 Control ports The remainder of this section describes the control connector, and the interface to AMX systems. The Soundweb 9088 and 9000 boxes both provide a control connector, which has eight control inputs, eight logic outputs and a special optically isolated watchdog output. The control inputs can be used as contact closure sensors: the switch can be used to operate any binary functions in the unit such as mute controls or preset activations. It is also possible to connect a simple potentiometer to a control input: this can be used to adjust any continuous variable in the Soundweb system such as a gain or compressor threshold. Finally, a resistor ladder and a multipole switch can be used to operate a multi-way control such as a source selector. The logic outputs can be used to provide an indicator for any binary output function such as a gate open light, or to provide a tally for a switch. Using the control inputs and logic outputs, it is possible to provide a custom hardware control panel for the facility. This can be built from readily available off the shelf components, and can be made to whatever cosmetic styling is wanted an engraved brass plate for a hotel reception would be an example. In addition to the eight logic outputs, an opto-isolator output is provided for watchdog purposes. The opto-isolator conducts as long as power is applied to the unit and the software has not crashed. Any power failure or crash in the software will cause the opto-isolator to cease conducting: this can be used as a trigger for a secondary alarm system. 4.2 AMX The serial port connector on the back of a Soundweb 9088 or 9000 can be used to interface to an external control system. In particular, software support is provided for the AXCESS system made by AMX corporation. Any parameters of the Soundweb system can be made available to the AMX system; the user can export a header file suitable for inclusion within the AMX program. BSS provide a suitable library file to support the AXCESS compiler. April 1998 Page 3

4 5 Flash EPROM storage All Soundweb units use flash EPROM as their non-volatile storage medium. The flash EPROM contains the firmware which operates the unit, allowing upgrade of the firmware from a PC without the need to open up the unit and replace EPROM chips. The flash EPROM is also used to hold the configuration data of the unit. If a Soundweb unit should lose contact with the rest of the network (perhaps because of a cable fault or power failure), it will continue operating according to its current audio settings. If power is removed and reapplied, it will recover the settings which were in force at the time that power failed. 6 Hardware product descriptions Networked Signal Processor The 9088 Networked Signal Processor forms the heart of the Soundweb system. In a single rack space unit, it offers 8 analogue audio inputs, 8 analogue audio outputs, 160 MIPS of digital signal processing, a pair of network jacks, and a variety of control options. The front panel of the 9088 has a number of LEDs to allow a quick view of activity on the audio inputs and on the network. It also has a mini-din connector for an RS-232 serial port: this is normally used to connect a PC for system setup and control. The rear panel contains the audio inputs and outputs and the network jacks. It also contains a second RS-232 port, which is normally used for control from an external controller such as AMX. Finally, it contains a control connector: see section 4 Control options for a description of how this is used. Both control i/o and analogue i/o connections are made via Phoenix style two-part screw terminals; the female connectors are shipped with the Soundweb unit, so installation can be made with no soldering and no extra connectors to buy. The 9088 contains two preamplifier cards for the analogue inputs: each card handles four of the inputs. Two types of card are available: the line card and the mic/line card. The line card gives a choice of two gain settings: 0 db and 12 db (intended as a pro/consumer switch). The mic/line card provides a range of gain settings from 0 db to 72 db, together with phantom power and phase reverse. In all cases, each input can be switched individually. The analogue outputs are equipped with analogue attenuation after the DAC stage. If the unit is used at anything lower than its full output level, it makes sense to apply the final gain reduction in the analogue domain: in this way, the DAC noise is also attenuated and the signal to noise ratio is kept at a maximum. The core of the 9088 contains two Motorola DSP chips, running at 80MHz each and thus providing a total of 160 MIPS of DSP. There is also a block of dynamic RAM allowing a total of 11 seconds of audio delay. The main control processor is a Motorola series CPU, which runs a real-time multi-tasking operating system; this CPU takes care of system operation and interfacing and performs all the necessary housekeeping functions. Finally, the core contains a flash EPROM (see section 5 Flash EPROM storage), in which is stored all of the software to run the unit, and also the unit s configuration. April 1998 Page 4

5 Active Hub 6.3 Coming soon: 9010 Remote Control Panel The 9000 active hub shares the same DSP core as the 9088, and the same control i/o connector. However, the audio i/o is quite different. The 9000 has no analogue inputs or outputs; instead, it has six network jacks. See Section 3.3 Hubs and complex networks for a description of how the hubs are used to make complex networks. The 9010 remote control panel connects to the Soundweb network via the usual category five cable although direct cable termination is used in place of the RJ-45 connectors. The unit provides a graphic LCD display, six programmable soft keys, a programmable parameter wheel, and two inputs for paging microphones. It fits into a three-gang wall box. 7 Soundweb Designer software 7.1 System design and documentation 7.2 Control panels Soundweb Designer is a software package which runs on a PC under Windows 95 or Windows NT. You use Soundweb Designer to lay out the set of Soundweb units that will be used for a particular design, and to define the network connections between them. Within each unit, you define the audio processing objects that will be present in your system, and their interconnection. Soundweb Designer has several facilities to assist in system documentation: you can annotate your designs with text and graphics, and print a list of the Soundweb equipment needed for the system, together with a wiring list for the network. Your designs can also be exported to Windows metafiles for inclusion in other documents. Soundweb Designer provides default control panels to allow the adjustment of each audio processing object. As well as using these, you are allowed to build your own custom control panels. The software allows a great deal of customisation of the panel layouts, including the use of colour or images as backgrounds, and control over the shape, size, colour and edge styles of particular control items such as faders or buttons. 7.3 Presets and configurations Soundweb Designer allows you to specify presets, which are complete records of the state of your system. These can be stored or recalled as necessary. Also available are mini-presets, which allow you to store and recall the state of a particular group of parameters, without affecting the whole system. Most commonly, presets are used to recall different sets of parameter adjustments. However, they can do more than this. Each Soundweb unit can store up to 12 totally different DSP layouts (these are called configurations ); if a preset being recalled requires a different configuration from that currently active, the unit will mute its outputs and reload the DSP with the appropriate program before continuing. April 1998 Page 5

6 7.4 Security 7.5 Macros Soundweb Designer allows you to specify multi-level password protection for your system. You can define different users, assign security levels to each user, and then demand that certain features of the system require a particular security level in order to allow them to be operated. You can also specify that a particular user should be forced into a particular control panel at startup, thus ensuring that personnel get just the control screens that you have in mind for them. Macros allow you to group together frequently used collections of processing objects, complete with their usual settings. Once defined, a macro looks to the user exactly like any other processing object. Macros can be used as a way of protecting a consultant s intellectual property. Details of the macro definition are not available to the end user, who only sees the form of the macro: what are its inputs and outputs, and what parameters are available for adjustment. 8 Coming soon BSS will continue to develop the Soundweb system, both by adding new hardware devices and by upgrading the software. We will add different types of audio processing, and also enhance facilities for operating the processing that exists. DSP objects coming soon are a gain-sharing automatic mixer and a leveller; other DSP objects will follow. Also in the pipeline are support for modem operation, software upgrades over the network and a variety of other enhancements. April 1998 Page 6

7 9 Performance specifications 9.1 General 9.2 Line input card 9.3 Mic/line input card 9.4 Control ports Frequency response (±0.5 db): 15 Hz to 20 khz THD (20 Hz to 20 khz, +10dBu output): <0.01% Dynamic range (22 Hz to 22 khz unweighted): 100 db typical Maximum output level: +20 dbu Inter-channel crosstalk: <-75 db Input Impedance: 10 kω Maximum input level: +20 dbu (+8 dbu with 12 db gain) Gain range: 0 or 12dB Input impedance: 4 kω Maximum input level: +20 dbu Gain range: 0 to 70dB CMRR >75dB at 1 khz Equivalent Input Noise (EIN): <-127 dbu with 150 Ω source Phantom power: 48 V nominal Logic output voltage: 0 or +5 V Logic output impedance: 440 Ω Opto output series impedance: 220 Ω (isolated) Control input voltage: 0 to 4.5 V Control input impedance: 47 kω (log) to +5 V All information in this document is correct to the best of our ability. However, reserve the right to modify any product description or specifications without notice. For further information contact: or USA Linkside House 1449 Donelson Pike Summit Road Nashville, Potters Bar TN Herts EN6 3JB United Kingdom USA Tel: +44 (0) Tel: (615) Fax: +44(0) Fax: (615) info@bss.co.uk pfreuden@harman.com April 1998 Page 7