A Quick Guide to Cables for Audio and Control

Originally published in Worship Musician, October 2023

It is likely that everyone reading this article can recall a time when something as simple as a bad cable put a damper on a live event they were attending or producing. YouTube is filled with videos of a heroic guitar tech switching out guitar cables or performing on-the-fly pedalboard repairs while the band tries to carry on sans guitarist. I know that my blood pressure still rises to this day when I think back to the days of large ‘homemade’ analog snakes and patch bays that seemed to have more channels taped over and marked ‘BAD!’ than channels that (hopefully?) were in working order. This quick guide borrows liberally from a reference document on the Allen & Heath website, feel free to check out the full version here.

Different protocols, different bandwidth

Allen & Heath's protocols—and many popular digital mixer protocols today—rely on standard Layer 2 Ethernet to transport audio between nodes. dSnake, ME, ACE, and DX links use 100BaseT Fast Ethernet, with 99.7% of bandwidth use. gigaACE uses 1000BaseT Gigabit Ethernet, with 93% bandwidth use. SLink ports auto-negotiate protocol and link speed, switching to dSnake, ME, DX, or gigACE mode depending on the connected device. With bandwidth use numbers well above the 90% range for most digital mixer audio transport protocols, it should be obvious that the quality and construction of the cables are of vital importance.

CAT cables and connectors

Use STP (shielded twisted pair) CAT5e or higher cables. Those with both foil and braided screens provide shielding from interference and are generally more rugged.

Although solid core types can perform better at longer distances, stranded core cables are less prone to damage when kinked or repeatedly coiled. If you use a solid core type for touring, check with the manufacturer that it is rated for the touring application. Solid core is preferable for permanent installation, whenever possible.

CCA vs Pure Copper

Copper Clad Aluminum (or ‘aluminium’ as the Brits would say) cables use an aluminum conductor that is coated with copper. The resistance of aluminum is much higher than copper, resulting in greater attenuation of the signal. This might result in packet losses, which often manifest as 'clicks' in the audio signal. The mechanical strain of aluminum against copper is much lower, resulting in a shorter lifespan of cables under stress.

Straight vs crossed?

In Allen & Heath land, all Network, ACE, gigaACE, DX, dSnake, and SLink ports are 'auto-switching' so both straight and cross-over CAT cables can be used for these connections. Check the specs and requirements for your audio gear as there may be instances where the odd device requires a specific cable configuration.

Connectors

For long-distance cables and those that are repeatedly plugged/unplugged, Neutrik EtherCon connectors are highly recommended. These have a shell that protects the connection and locks it in place when plugged into the mating EtherCon socket provided on many pro audio consoles and peripherals. Protective dust caps are also available for EtherCon connectors.

fibreACE

The Allen & Heath fibreACE card provides Neutrik OpticalCon sockets for the fiber (or ‘fibre’) link. OpticalCon uses a rugged housing around standard LC connections and is therefore backward compatible with LC. In a fixed installation, standard LC connectors can be used instead. Speaking of LC, it stands for Lucent Connector, Little Connector, or Local Connector, depending on whom you ask! Whatever the connector stands for, we recommend the use of OM3 or OM4 MultiMode optical cables up to 550m (1804 ft).

We’re in Control

Remember that every cable in the audio system matters—not just audio transport, but also control. Remote wall mount controllers in the foyer don’t pass audio signals, but they are just as important to creating a successful audio experience come Sunday morning.

The Allen & Heath IP range of controllers utilizes standard Layer 3 Ethernet. For cabling purposes, it can be addressed as any computer or node on a network. Standard CAT5e or higher can be used. When supplying PoE power, note that IP1 and IP6 use PoE IEEE 802.3af, whereas IP8 requires PoE+ IEEE 802.3at.s.

Dante

Dante is an Ethernet Layer 3-compliant audio networking solution created and developed by Audinate. As most Dante devices support Gigabit Ethernet, CAT5e or CAT6 cables are recommended. Please refer to the Audinate website for further information, they have a great resource area waiting for you and your IT team.

Good practices on Ethernet switches and network design can be found at https://www.audinate.com/learning/technical-documentation.

Waves SoundGrid

SoundGrid is an Audio-over-Ethernet networking and processing technology developed by Waves Audio. CAT6 STP cables are recommended for Waves SoundGrid systems. Information on cable types and cable lengths is available here:

https://www.waves.com/support/ethernet-cables-for-soundgrid-systems

Waves includes an important note about CAT7. If CAT6 is better than CAT5, CAT7 must be really awesome, right?! Important note: CAT7 is designed and wired for high – up to 10GB – bandwidth traffic. In a SoundGrid network, using CAT7 might accentuate the risk of impedance matching problems anywhere in the signal chain. In comparison, CAT5e/6/6a are designed for 1GB traffic and filter out overshoot/ringing occurring at connection points from appearing at the receiving ends. As such, Waves recommends using CAT5e/6 whenever possible. If your system works, don’t change cabling. If you are experiencing network/dropout issues using CAT7, consider switching to CAT5e/6.

MADI

MADI is an industry-standard multi-channel digital audio protocol specified by the Audio Engineering Society as AES10. A MADI option card is available for Allen & Heath consoles, providing a convenient interface for recording and integration with third-party systems.

Typically, two coaxial cables are required for each link, one for each direction. The MADI standard supports up to 50 meters (165 feet) but if audio is being transmitted from a third-party device to an Allen & Heath MADI card, with no audio being returned or being transmitted both ways between two A&H cards, then the cable length may be extended. For example, an RME MADI card transmitting audio to an Allen & Heath MADI card can work up to 150 meters (500 feet). Longer lengths may be achieved but this requires the use of a mains filter for each device if the link is to remain error-free during high-voltage mains interference.

Note that it is important that good quality BNC connectors are used and that they are correctly crimped to the cable. For this reason, it is best to buy pre-assembled cables rather than attempt to make your own. Note also that you should avoid kinking these cables or coiling them with tight loops as this may cause damage.

Final thoughts

So let’s jot down a ‘check audio and control cables!’ reminder in the calendar before the next service comes up and make sure to treat the IT team to a pizza lunch sometime soon. Remember that as church audio systems grow, they almost always grow closer and more tightly integrated with what used to be only IT and ‘facilities’ land. We’re going to need to be pals with IT for sure. Many of these cables will need to be installed professionally and maintained in collaboration with the facilities and tech teams. Let’s play nicely.

Good luck out there! //

Originally published in Worship Musician, October 2023

By Jeff Hawley

Jeff Hawley currently heads up the marketing for Allen & Heath USA. He is pursuing a PhD in philosophy at York St. John University . Jeff has a diverse background as a musician, engineer, and trendsetting industry executive. In addition to performing and producing everything from noise music to disco and Afro-Cuban jazz to avant-garde klezmer, Jeff has designed award-winning music industry products and accessories and directed the branding and marketing functions for several top musical instrument and pro audio brands. He enjoys eating peanuts, studying obscure logical positivist philosophical texts, and listening to George Jones on cassette tapes.

Connect with him at?www.dhirubhai.net/in/audiohawley