A ’˜Bit’ of an overview

DSP systems are becoming more and more commonplace in all levels of installation work, to the point where they are almost ubiquitous and you would need a good reason not to use one. Richard Northwood, lead consultant at COMS provides us with a run down of what’s available.

There are essentially two types of processor available which for the sake of this discussion can be defined as either freeform or defined. With a freeform device it is incumbent upon the user to stipulate what manipulation is done to the audio signal. This is typically done by dragging CAD type symbols on to a work area and then wiring them together (drawing lines between them) as if they were real items of equipment. The system is then downloaded to the DSP hardware and Bob's your uncle. In a defined system the manufacturer has already assembled the signal path for you and all you have to do is decide which elements you wish to use. Again, once you have completed this step a simple connection to the unit in question and all is happy.

Download connections were often serial in nature, RS-232 using multipin connectors, but are now almost all IP based. This ability to remotely load different configurations on to one hardware platform is also the basis for one of the main reasons for using a DSP system in an installation, remote control. Having installed and commissioned your audio system a remote control system such as AMX or Crestron could then easily send commands to the DSP box to initiate a whole host of different controls. This could take the form of manipulating individual controls, e.g. level in the bar, or could trigger a preset to load several settings, e.g. level and EQ in all areas for the evening sessions.

In the early days of audio DSP systems the user had to choose between the centralised approach with a large chunk of processing power communicating with outlying input/output boxes or with distributed processing with the processing power spread around the system, often with on-board inputs and outputs. As the market has matured it is now possible to take products and construct the architecture that best suits an individual project, often combining both approaches for increased system resilience.
Another strong point compared with the more traditional analogue approach is physical security. It is not possible for helpful souls to come and tweak your system if there are no physical knobs and buttons to play with. The following paragraphs provide a small taster of the offerings from the main players in the market.

Peavey

Peavey currently has essentially two different series of hardware, both coming under the MediaMatrix banner. There is the original ‘grey’ series of –Frames (X-Frame, MiniFrame, ManinFrame) which have been around since 1994 and there is the newer Nion series.
The old frame series can probably claim to be the original freeform DSP processors and are based on cards mounted in industrial PC chassis’ which are then connected to either BoBs (Break Out Boxes) via two CAT5 cables (D-9 cables originally) or to CABs (CobraNet Audio Bridge) which are, as the name suggests, connected over a network using CobraNet. The X-frame is the baby of the family with 8x8 audio onboard and the ability to connect up to two BoBs for a maximum of 24x24 in a system.
The newer Nion systems allow a choice of either distributed or centralised processing dependent upon your choice of system architecture.

BSS

There are two series of BSS processor, the original ‘green’ boxes (Sw9000 series) and the newer ‘blue’ boxes (SoundWeb London). The original series featured an eight channel bus to link units together. This is a proprietary bus but does have the advantage of being able to run up to 300m on standard CAT5 cable. Whilst no longer the flagship BSS processor it is still in production, with a range of ten different devices and accessories available. Not being the flagship product it is priced keenly and still has many adherents due to its familiarity and the 300m between boxes to get you out of trouble.
The SoundWeb London series has recently been expanded with the addition of four new models which take the abilities of the previous family members and include a local high speed 256 channel bus which can be run up to 100m on CAT5e. This greatly expands the potential system configurations which can be created as well as easing use in fault intolerant situations.

Rane

The Drag Net RPM processors are fixed I/O configuration units in 1-2U packages. Most configurations come with AES digital input and/or output to either get the most from your digital source or to allow digital expansion to other units. They do not have CobraNet or Ethersound I/O for network expansion however but do have a very flexible range of remote control panels.
Rane does have a couple of ancillary CobraNet devices though in the form of the NM1 network mic pre-amplifier which can form the heart of a networked paging station and the new Mongoose family. This is a 1U box which connects to a CobraNet network and is fed from up to eight analogue input and output panels linked to the Mongoose processor via the ever ubiquitous CAT5 cable.

Biamp

The Biamp range comprises two distinct sets of products with the Nexia and Audia brands. The Nexia devices are a range of five fixed I/O configurations available in a 1U package. The TC and VC variants have very good echo cancellation modules built-in and all the units can be linked with a proprietary NexLink bus for system expansion.
The Audia range starts with the baby AudiaSolo for fixed configurations without CobraNet. The Solo’s big brother the AudiaFlex then steps in with a modular chassis for input and output cards along with CobraNet expansion devices. The AudiaFlex can probably claim to be the first ‘all in one’ solution, just add sources and loudspeakers, as it has amplifier cards that can be mixed in a chassis along with microphone and line level cards.

Symetrix

Symetrix also follow the well worn path of having a range of fixed configuration boxes in the form of the Express series and then a more flexible offering of an 8x8 DSP box which can be expanded. This is done either using the SymLink bus for local expansion within a rack or CobraNet expansion across the project site.
Symetrix also have a wide range of wall panels for level and source control as well as input panels.

ElectroVoice

The ElectroVoice NetMax N8000 box takes the route of a 2U chassis with up to four local I/O cards. CobraNet is optional here to help reduce costs on smaller projects and they have the unique option of a DSP expansion card for those times when you want a little more grunt but can’t afford, or want, an additional box.
Working with their sister company Dynacord the N8000 incorporates a CAN bus interface to communicate directly with amplifiers and has several features built-in that are useful in building a fault tolerant voice alarm system.

Yamaha

The heart of the Yamaha DME system are the DME 64N and the DME 24N with varying amounts of onboard I/O coupled with the flexibility of the stand mini-YGDAI slot(s). The flexibility of the slots allows Yamaha to be the only system at present to directly support both the EtherSound and CobraNet standards allowing as much flexibility in installations as you need.
A range of external boxes permits interfacing to the analogue world as well as remote amplifier control. The Satellite series has some DSP processing capability onboard as well as analogue I/O.

Graphic Interfaces

Whichever hardware platform you choose it is reasonably certain that audio quality can be taken as read. The old marketing number battles over bit depth and sampling frequency were never great indicators of quality, and now seem largely irrelevant for all practical purposes on installations. What really sets the various products apart is the software used to implement systems and its ease of use. You have at present no choice over which software package to use, it must be the one designed by the hardware manufacturer for their products so this is the one item that is most likely to force your choice down one path or another.
Given the maturity of the different hardware platforms it is sad to see that much of the software supplied is still based upon old analogue principles with the concept of wiring up different processing blocks still universally prevalent. It would be great to see the processing power of modern computing platforms, be they PC or Mac, harnessed to actually make life easier for the humble system engineer. Surely it should be possible to work using task based wizards such that you can define how the system should operate by answering a few questions and not worry about block A being linked to block B with external control interface C. You could then delve in to the nitty gritty of how it happens only if you have a specialised requirement, or just plain enjoy tinkering.
The only small joy on the software front is that all manufacturers allow you to download their products and try before you buy. However it is still quite a complex task to perform on anything other than a simple meeting room and the only way to get the most out of any software package is to attend the manufacturers training course, which means a great deal of investment on your part in time and money. This one fact alone probably explains why there are many systems out there which are not appropriately equipped with DSP but they were familiar to the installer, programmer or consultant.

Transmission Protocols

No discussion of the different DSP systems available today can be separated for long from the issue of transport protocols. CobraNet and EtherSound still rule the roost at the moment and probably will do so for a while yet. Each has their own strengths and weaknesses and a large user base to champion them. Newer protocols appear to be just around the corner and almost ready for prime time usage. Whether this will create a new VHS-Betamax war or whether each will carve out its own niche remains to be seen.
Where do we go from here? There is now a large quantity of products that can be almost freely applied to whatever task you wish. This is healthy in that there does not appear to be any one dominant market force driving in a particular direction, leaving the way clear for innovation; however innovation is sorely needed as there are too many devices chasing the same market with the differentiation between them extremely subtle at times. It would refreshing to see a manufacturer reach outside the established audio industry to obtain some design experience from the wider world and actually examine what is done with their hardware. Here’s hoping!

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