Information and Data

This page brings together our technical advice, installation guidance, product information and useful resources for public address systems, wireless microphones and related equipment.

All content is free to use and share, but please credit Sound Services where appropriate.

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A simple overview of the key differences between low impedance and 100v line sound systems, and where each is typically used.

Low impedance 8Ω sound systems are typically used for home audio, bands, live music, discos and other applications where the loudspeakers are fairly close to the amplifiers or where higher sound pressure levels are required.

Usually, a low impedance amplifier can have no more than two 8Ω loudspeakers connected to each output channel, resulting in a 4Ω load on the amplifier. Always refer to the amplifier manufacturer’s instructions and never connect more loudspeakers to the low impedance terminals than advised. The power handling of the loudspeakers should ideally be at least 50% higher than the amplifier output to help avoid damage. Cable should also be of a suitably high current rating so that maximum power is delivered to the loudspeakers. If you need more loudspeakers, you will usually need additional amplification.

Conversely, 100v line constant voltage sound systems allow much longer cable runs using thinner cable around a venue or site. Many loudspeakers with integral 100v line transformers can be wired in parallel without complication, provided the basic 90% wattage rule is followed.

100v line loudspeakers are rated in wattage rather than impedance. The total wattage of all loudspeakers on an amplifier output should not exceed 90% of the amplifier’s rated output. For example, a 120w 100v line amplifier could have a 20w loudspeaker, 4 x 10w loudspeakers and 3 x 6w loudspeakers connected and still have capacity for some future expansion.

Further guidance:

• Wiring and installing 100v line speakers and PA sound systems
• Wiring and installing low impedance speakers and sound systems

Practical guidance on wiring, installing and configuring public address systems and related equipment.

• Wiring and installing 100v line speakers and PA sound systems
• Wiring and installing low impedance speakers and sound systems
• Induction loop systems for the hard of hearing
• Circuits, wiring, connecting and terminology
• Stage sound and live PA systems

Information on wireless microphone systems, UK frequency regulations and general system selection.

• Wireless microphones frequencies, radiomics and In Ear Monitors in the UK
• Microphones and system selection
• AVSL guide to wireless audio

Key information on licensing, regulations and technical standards relevant to sound systems and installations.

• Wireless microphone licences
• Recorded, broadcast and live music licences
• British Standards – BSI
• IP ratings
• PAT testing
• Noise levels and decibels
• WEEE (waste electrical and electronic equipment)

Additional technical resources and manufacturer guides covering audio systems, power ratings and lighting control.

• AVSL guide to digital audio
• AVSL guide to power ratings
• DMX lighting
• DMX DIP switch utility

Access to a wide range of instruction manuals, circuit diagrams and technical data for both current and legacy equipment.

Sound Services holds a large selection of instruction manuals, circuit diagrams and technical data for Monacor, IMG Stageline, Adastra, QTX, Chord, Citronic, Eagle, NJS, SoundLab, Clever Acoustics, TOA, Carlsbro, Pulse and other leading PA sound and associated products.

We are continually expanding our library of public address and PA sound system handbooks and manuals for current and discontinued products. Please email us to enquire about user manuals for discontinued and legacy products, or see the relevant website listing which will usually include the user manual for currently available products.

Supporting documents and policies, including terms of trading, privacy information and environmental schemes.

• Sound Services Terms of Trading
• GDPR Personal Data Privacy Notice – General Data Protection Regulation, 25^th May 2018
• Useful Links
• Sound Services WEEE takeback scheme

PA sound hire in North Hampshire and Surrey border area

We offer PA sound system hire for small to medium-sized events in North East Hampshire and surrounding areas.

Please email us with your requirements.