Used in commercial audio installations for decades due to its outstanding convenience and low cost, the 100V line system is still the best option for a great many audio systems in both business and residential settings.

The 100V line product range is vast, with many different types of amplifiers and speakers available, that have been specially designed for easy installation and zero maintenance over a long working life.

Using standard speaker cable and simple wiring principles helps to massively reduce the costs involved with even the largest installation, with modern 100V line amplifiers capable of supplying multiple speakers with no problem.


In a standard (low impedance) audio system, say a home hifi for example, the amplifier and speakers operate on a fairly low voltage, but high current capacity design. So a 100 watt amplifier will be able to produce say 30V at its speaker terminals at maximum output.

This output is connected to suitable low impedance speakers which are usually 4 or 8 Ohms, and the speakers and amplifier work in a push/pull relationship, with higher volumes, and especially bass signal reproduction, requiring higher current.

Which is fine. For PA speakers, hifi systems and stand alone audio systems, the full frequency and dynamic power delivery of a low impedance system is desirable, allowing for superb bass response and clear top end, even at high volume.

The issue comes when you want more than 2 speakers connected, as is this case in an installation. The electrical properties of low impedance speakers mean that adding speakers in a line either halves (Parallel), or doubles (Series) the load that’s presented to the amplifier.

So for example, a stereo setup. An amplifier with 2 speakers that are 8 Ohm each. Add another pair of speakers and the amplifier is now pushing against either a 4 ohm load or a 16 ohm load, and so on. These numbers alter for every additional speaker, and the amplifier will eventually be caused permanent damage.


100V to the rescue! Designed especially for long cable runs and to allow multiple speaker connections from a single amplifier, the 100V line speaker system is perfect for installation audio.

Also known as high impedance or high voltage audio systems, a 100V line system works by taking any typical line level audio input signal and outputting it as a steady 100 Volts RMS to the speaker terminals.
The 100V line speakers feature a step-down transformer which serves two functions. It will convert the arriving 100V signal to a low impedance one that the speaker can use, and secondly it isolates the speaker coils low impedance load from the amplifier.

The other benefit of this design is that the transformer can offer selectable wattage tappings, and independent volume control per speaker


So, what this means in an installation system is that you can for example have a 100V line amplifier with 100 Watt output. If you selected a 1 Watt tapping on the speaker, you can connect 100 speakers, or 50 speakers tapped at 2 Watts etc.

These are normally in a Parallel or ‘daisy-chain’ wiring configuration, and the simple maths involved with 100V line systems makes them so much simpler to work with then their low impedance versions.

Of all the 100V line speakers available, the ceiling speaker is by far the most commonly used for commercial audio installations. Its low cost, coupled with easy fitment into dropped ceilings and the fact it does not require brackets or other fixtures makes it perfect for a large site.

Ceiling Speakers also blend in extremely well with their surroundings, as most designs feature a thin, flush mount grille in white, which just vanish into a white painted ceiling, making them desirable in offices, restaurants and shops.


A ceiling speaker, due to its placement and open back design, is limited for certain frequency response and performance. It will specifically struggle to produce lower midrange and bass with any real zest.

For the parts of an install that require a more focussed output, such as a hall or busy social area, a 100V line wall speaker can provide that much needed push in performance that a ceiling speaker simply cannot provide.

A favourite of us at Audio Installations, a wall speaker such as the Amate B6/T will bring you serious sound quality and volume, with its selectable power tappings ranging from a background level 5W, right up to 40W output.


A standard 100V line amplifier offers a range of audio inputs from standard line level sources, and many will actually include FM/DAB radios and USB/Mp3 audio file playback as built in features.

With modern Bluetooth connectivity on most of our models, you have many options for music playback, and microphone announcements through dedicated mic inputs.

The output will be single channel on lower cost models, allowing a simple daisy chain speaker system to be connected, and giving you control of volume and tonal adjustments.

Installation audio is always single channel (Mono) as a stereo effect to the output is only desirable in hifi or home cinema where the listener is equal distance from all speakers in the system.

For the addition of extra audio zones, an amplifier will include independently controllable outputs which allows for designated areas to be turned on or off, or have their volume affected. They will however, only play the same source audio signal.


For playback of different music in several areas at the same time, a more complicated amplifier with what’s known as a matrix mixer must be used to power the system.

These units will feature multiple audio inputs, and the internal switching circuitry allows any input to be assigned to any of the outputs. They of course can also play the same source to all areas too.

Often found in commercial buildings, shopping centres, sports centres and places like hospitals, these matrix systems often feature more power than standard 100V line amplifiers, and can operate significantly large numbers of speakers in an installation.

This allows an fantastic amount of control from a single device and location, with volumes for each zone, and handy features such as system wide microphone talkover with automatic muting of whatever is playing.


  • You can connect many speakers to a single suitable amplifier without issues.
  • Individual transformer power tappings on each speaker.
  • Economical wiring using long runs of low cost speaker cabling.
  • Simple load calculations for large systems making for easy installation.
  • System can allow for easy addition of further speakers (amplifier power dependant)
  • Low purchase cost of equipment compared to low impedance systems.
  • Easy operation for customers.
  • Multiple audio zones controllable from a single amplifier.