Lions And Tigers And Snakes

How many of us remember the days when tube amplifiers were slowly being replaced by transistor-powered amps? The sound was tinny in comparison, distortion was sharp and irritating, and that warm wonderful sound was gone. The forces of technological change however are irrefutable and unstoppable, and today some of the best-sounding guitar amplifiers bear little resemblance to their ancestors.

We've witnessed this same (almost) inevitable analog-to-digital "conversion" in just about every other product category. The benefits in most cases far outweigh the perceived or real limitations of digitizing electronic signals. Specifiers, installers and users no longer hesitate to use products featuring digital technology. There is less talk about lack of reliability, signal loss, degraded frequency response, or poor sonic quality when considering digital. We don't give it a second thought.

At InfoComm in June, it became evident that this digital transition is taking greater hold in an area once wholly dominated by analog solutions. At the show, RSS (Roland System Solutions) added its new S-4000 to the growing number of digital snake products on the market. These digital snakes are produced by such illustrious names as Whirlwind, ProCo, Aviom, LightViper and Optocore, and there's even a prototype from a Silicon Valley startup from outside our industry called Network Solutions.

Snakes are not the most obvious part of the audio chain when we think about converting a system from analog to digital. We usually imagine that the mixing and processing functions are the most likely parts of the signal chain to benefit the most from the digital world. Distribution and routing of the signals in a sound system are one of the "backwaters" of the audio world left to analog.

Analog snakes have been around for over 40 years, and embody some of the best and most reliable technology our industry has to offer. However digital snakes offer one distinct advantage: less physical bulk, cutting weight down from 200 pounds or more for the typical 48 x 16 analog snake to less than 10 pounds for the comparable digital snake using Cat-5 cable.

It is safe to say that the analog snakes offered today are the best we've ever seen in performance and reliability. However, over time internal splices and cuts are caused by coiling and uncoiling for hundreds of shows, connectors degrade, and internal parts become loose.

For analog snakes, the main disadvantages are not only the size and bulk of the cable but just as importantly the inherent losses of signal strength and purity over long lengths of cable and the vulnerability to outside noises and interference. The bulk or size of copper cable becomes a problem for the installer when he has to pull the cable through conduit from the stage to the mix position. Finding a viable path, installing (and paying for) the necessary conduit, and making sure that the cable's route does not cross paths with any source of induced hum or noise can be very difficult.

It is also expensive. The labor and material costs of pulling a 48-channel copper snake usually exceed the cost of the snake itself. As a result, most contractors do not install pre-assembled snakes inside runs of conduit, but rather pull individual cable for each input and output being routed between the stage and the various mix positions. Even so, the amount of copper cable that must be installed (one separate strand for each run, sometimes twisted pair, shielded, unshielded, etc.) means that the cost including labor for secure distribution of the audio signal is far greater than the cost of a standard snake. In fact, often the labor and material cost for installing the conduit and pulling the wire is greater than the cost of even a digital snake, which is considerably more expensive than its analog equivalent because of the A-D and D-A converters, the internal electronics and the software. Two Cat-5 cables can carry up to 80 channels of audio, and today, installation of Cat-5 is a standard building requirement, making the installation of a digital snake much easier than the analog equivalent.

Another primary function of a snake is to provide signal splits. The standard method in an analog snake is to use a transformer-isolated split at the microphone source. These splitters are bulky and expensive, and they require insertion of devices that also contribute to signal loss and degradation. When troubleshooting a problem in the distribution and routing of the signal, the engineer must be very careful to isolate each component, one at a time, without affecting other components, and to correctly and unambiguously identify the problem.

In spite of these challenges, the analog snake has a place alongside wired microphones, non-line-array speakers, and other legacy products.

The Advantages Of A Digital Snake

Digital snakes offer many advantages over traditional analog signal distribution schemes. The small weight and size of Cat-5e cable makes it very easy to install, and, of course, rental setups are more portable as a result and faster to set up. Furthermore, they are immune to induced hums and buzzes, and have none of the transmission losses inherent in analog snakes in long runs.

Another less obvious, but probably more important advantage is that a digital snake puts the microphone preamp on stage right near the microphone. This reduces the length of the run of low-level audio. Since a digital snake will accept both mic- and line-level audio, it also eliminates the expense of direct boxes for non-mic-level sources.

Having the mic preamp on stage requires that the digital snake offers some kind of remote control of the preamp. A few digital snakes offer this feature, which really is essential for any live sound environment. It's important to be able to quickly and easily back off the preamp trim when the lead singer "eats" the mic as the concert gets louder and louder. Remote control of preamp gain can be from a computer, or more conveniently, some systems offer a hardware remote that can always be right at hand for fast adjustments to any channel.

Digital snakes also offer memory presets for preamp settings. Memory is one of the great advantages of anything digital in audio. It not only allows for fast setup from event to event, but also affords the installation engineer the comfort that when an inexperienced user messes up the gain structure for an installation, the engineer doesn't need to make a site visit. The user can recall the default preset and immediately restore the ideal settings for that installation.

Remember also how easy it is to have a "lossless" copy of the digital audio found on a CD? It is similarly easy to copy or split the audio in a digital snake. In today's houses of worship and other live sound venues, a split for the monitor console is required, as well as additional splits for the recording rig and the broadcast room, and other remote locations. A digital snake system can split the source audio, saving money usually spent on traditional analog splitters.

Another advantage in the use of a digital snake is redundancy. Analog snakes are often plagued by the loss of a channel or two over time. Digital snakes like the RSS S-4000 have a built-in redundant Cat-5 port and will switch automatically and seamlessly to the secondary cable if tragedy strikes the main cable. The RSS S-4000 will also alert the user that the primary cable was cut or disconnected.

Another major advantage of a digital snake is future-proofing an installed system. With an analog snake installation, the installer must add extra channels (in blocks of 24 or 48) at the time of installation "just in case." This is a large, up-front expense for the client. With a digital snake, a couple of extra Cat-5 cables can be pulled for virtually no additional cost. This then allows for 40 or 80 or more extra channels whenever needed. Modular systems also allow for expansion of the input or return channel count in small blocks of 4 or 8.

Going digital in the audio world has now been extended into the routing and distribution components of the sound system with some powerful benefits for designers, installers, engineers and users.