Kingdom Hall Sound Systems
The picture shows a typical Kingdom Hall amplifier but with some key additions:
- Fully standards compliant Induction Loop system (two boxes bottom left) uses "Phased Array" technology. Enables you to comply with the law on disability in public places.
- TDS1SR - Single line Telephone Dialup System with answer capability.
- Internal graphic EQ fitted within amplifier.
- Frequency shifter disabled (gets rid of "trembling" or "warbling" effect).
Can this system be improved?
Yes it can. But first, why does it need improving? The system as shown represents possibly the best option for achieving a decent sound system at lowest cost. It works reliably and is easy to use for an experienced and skilled operator. In fact given someone like this, the congregation are rarely if ever going to even notice the sound system - the ultimate accolade.
Click to enlarge
However, most operators are not like this and will make many errors:
In fact, operating a sound system like this is hard work, tiring and very distracting for the operator who misses most of the meaning of what is said.
- Missing the first few words (forgetting to switch a microphone on) - Catastrophic for those "listening in"
- Failing to adjust the microphone volume levels properly so that everyone can hear
- Failing to switch off unused microphones - Leads to distractions and feedback
- "Gain riding" failing to keep just the microphone in use set to the correct volume whilst turning down others
- Reducing the volume on those that try to "eat" the microphone or shout
- Ensuring the music volume is loud enough to lead and encourage singing
- Evening out the difference in volume between shouters and whisperers
- Use an Automixer - The very best ones do all the hard work automatically. Selecting just the microphone(s) in use and fading out all others, yet being fast enough to catch the first word of a new speaker. This approach maximises gain before feedback and removes most of the workload from the operator.
- Use a compressor - Flattens out the dynamics of the spoken content. Prevents speech being too loud or too soft. A dynamic range of between 6-9dB is ideal for our application. Any more than this and some in the audience will start to miss words that are spoken quietly relative to the loudest speech. When this happens, intelligibility and hence meaning is lost. As a side issue, this causes the audience to tire more quickly as they concentrate harder to understand what is being said.
- Use an intelligent equaliser - Responds to changes in temperature, humidity and sound absorbtion (proportional to the number in attendance) to keep the tonal quality (hence intelligibility) consistent.
- Feedback suppression - Dynamically track and eliminate feedback frequencies.
- Fit high quality loudspeakers. Tannoy dual concentics are perfect as they have a wide and importantly, flat frequency response. New versions look good and can be angled precisely to form a pseudo LISCA array. With this configuration, sound is directed to all the right areas and critically, faces towards the ears of the audience - NOT pointing at their head or worse as with traditional ceiling speakers.
- Automatic talk timing - press to start and forget. Bell or buzzer operates automatically after the alloted time unless defeated.
- Radio Microphones - Double edged sword! Good for removing long cables and hence the associated trip hazard. BUT. You must buy top quality ones to avoid frequent problems. In particular, flat batteries are a nightmare, as are signal drop outs. Always buy top quality models working on the "true diversity" principle.
Equipment to Achieve this
Audio Technica ATM915 - This is a world class microphone. It is almost invisible and works very well. Specify the Microline capsule.
Tricky! Buy cheap or even medium priced kits at your peril. A good starting price is £400 per microphone (plus VAT). Always choose a true diversity model (avoids signal loss or drop out) with a top quality microphone capsule for flat frequency response. Be aware that cardioid capsules have a 'proximity' effect and will 'pop' if held too close to the mouth (over which you may have little control). Omni capsules won't pop and will pick up something even if pointed at the ear! However, beware of feedback and hence use the best quality capsule you can afford.
Given a typical operator, a well setup, totally automatic system is best. Soundweb are good as are Gestenter. The Soundweb in particular is hugely powerful and needs to be properly setup. Once setup, this box runs completely automatically and has all the compression, equalisation and gain funtions you could possibly need.
Induction Loop Systems
Few people know much about these systems. Do some proper research, buy Ampetronic products and don't waste your money.
Possibly the most critical component of all. A set of good quality speakers will allow much higher volumes before feedback and be much clearer. Tannoy are best.
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