Loops In Theatres Are Causing A Buzz
And so they should.
Theatre Managers- Create the right buzz:
1. Imagine what it’s like to be a hard of hearing person
- Do you want to declare your disability, not enjoy your experience because you couldn’t hear, have a theatre pay lip service to you? No.
- 1 in 6 people in the UK have hearing problems. By creating a truly inclusive environment, more will visit with family and friends. And that’s good for business
2. Use only professional audio experts to install your loop
- An induction loop is like any other audio system. It needs designing and installing by experienced professional audio specialists.
- By working with experts you will be assured of a job well done, no compromise for users and no poor installations to rectify.
3. Be fully aware of all the costs of using a loop alternative
- FM and Infrared systems may appear to be an easy low cost alternative to an induction loop, but aside from poor performance and no anonymity for users, they do not offer long term value for money.
- Ongoing costs include managing, cleaning, charging, repairing, and replacing receivers.
Installers - Eliminate the Buzz with 5 simple steps
1. Prevent Ground Loops
- Only install equipment with balanced input/output connections
- Connect input signals to the loop amplifier using twisted pair screened cables.
- Connect the chassis of each piece of equipment to the same outlet supply ground point, keeping the conductors as short as possible using a star ground configuration.
2. If A Ground Loop Exists, Rectify It By:-
- Lifting the ‘ground lift’ switch on either the loop amplifier or the audio source equipment if fitted.
- Disconnecting the ground connection in the interconnecting signal lead at the input end to the induction loop amplifier.
- Using an isolation transformer on all inputs to the induction loop amplifier.
3. Avoid Cross Talk
- Do not run any signal cables parallel and in close proximity to the output (loop) cables.
- Use an SLS system; this has an average field strength of almost zero and is much more efficient than a standard perimeter loop reducing the magnetic field and risk of cross talk by 40 to 60dB within the looped area.
4. Prevent Acoustic/Inductive Feedback
- Do not use dynamic microphones or electric guitars within the looped area.
- Install a SuperLoopTM system with spill control to the stage and to the mixing console.
5. Set The Input Level Correctly
- Adjust the input sensitivity of the loop amplifier using actual signals in accordance with the manufacturer’s instructions. The higher the gain, the less stable the system may become
Not only are induction loop systems the preferred assistive listening technology of hard of hearing people, they also offer the best value for money, hassle free, no compromise solution for theatre managers and installers.
But sadly, it’s not the buzz of enjoyment that the hard of hearing person gets from using the system, the buzz of delight from simply switching their hearing aid to T and sensing the sounds so clearly they think they are in their head. The buzz of gratitude they have when they arrive at the theatre knowing they will not need to hunt down a receiver to hear, or the buzz they get out of using the assistive listening system without anyone else knowing.
It’s not even the buzz the theatre manager gets, delighted with the money and time saved from not having receivers to manage, clean, charge, repair and replace. And there’s certainly no buzz for the Installer, confident in the knowledge that he is getting it right, avoiding frustration from post installation problems, and delighting his customers.
No. It‘s the buzz, the hum and the screech that the installed loop system will, according to the theatre manager, inevitably cause. In fact, touring companies are so paranoid about the buzz from loop systems that they will insist they are turned off during performances, making them redundant and forcing the theatre to use a more discriminatory technology. Ordinarily, this would provoke a louder buzz of dissatisfied, excluded customers but, hard of hearing people are so used to a second rate service, they will rarely complain.
But it does not have to be like this. There are thousands of induction loop installations in theatres throughout the world working tirelessly to assist hard of hearing people without causing the slightest perturbation in the audio system. And it’s easy to achieve. Copenhagen Opera House, the Stockholm Concert Hall and the Danish broadcasting City are just a few examples.
Induction loops are no different to any other audio system. A well designed system, correctly installed will provide years of buzz free, hum free, screech-less service.
The same techniques used by professional audio technicians and equipment manufacturers to mitigate feedback, eliminate buzz and squash hum in an audio system apply to induction loop systems. Ground loops, feedback paths and cross signal coupling are well understood by sound technicians.
By using a common star ground, isolation transformers, balanced line feeds and a few other simple techniques they can cope with them all.
So why does it sometimes go wrong with induction loop installations?
Either professional audio technicians forget all they have learnt when installing loop systems or more likely, induction loop systems are being installed by well-meaning electricians and other contractors who do not understand the issues.