What is PoE ?
Power over Ethernet describes the distribution of electrical power over network infrastructures, equipments and cables.
The Institute of Electrical and Electronics Engineers (IEEE) has implemented specifications for various PoE standards : 802.3af (2003), 802.3at (2009) and 802.3bt (2018).
PSE = Power Sourcing Equipment
PD= Powered Device
Why is PoE new in audio ?
Power over Ethernet is a major technological evolution in the AV industry.e.
While security or telecommunications have used PoE since its birth, there was no major benefit for the loudspeaker manufacturers to embed Type 1 or Type 2 PoE amplifiers in their products.
Today, increasing available network power is attracting more and more interest amoung professional audio manufacturers, and can be deployed in a wider range of audio applications.
The ubiquity of networked audio is another advantage of using high-power PoE.
Is this sufficient power ?
Right. For those familiar with power amplifiers and big sound systems, the PoE figures may not seem impressive. Chest-moving subwoofers, concert and club systems play at very high levels and are powered with 2000, 5000 and even 10000W amplifiers !
But a lot of sound systems installed in vairous venues do not need extrem power.
To be more precise, commercial audio, or fixed installation audio, rely on small A vrai dire, la plupart des systèmes audio sur le marché de l’audio commercial, ou audio d’installation, sont de petite taille. They play music, voice or informative messages in restaurants, hotels, meeting rooms, offices, retails, schools, transportation hubs, etc.
Now we can try to match the power of certain types of PoE sources to the specifications of typical loudspeakers, and the resulting sound levels.
Here we compare the size, the power and the sensitivity of a variety of drivers used in the field of commercial audio, as well as the lowest frequency of their usable range.
The mentioned values are averages taken amoung a set of up to 40 drivers.
The resulting SPL values are simple calculations of the SPL level that can be expected when driving the loudspeakers at the PoE stated power.
While loudspeakers bigger than 3inch will not have enough power from a standard PoE amplifier device, it seems clear the PoE++ devices allow many more applications.
The SPL levels reach 110dB (@1m) and the usable frequency ranges begin to be acceptable for background music, and totally suitable for vocal contents.
Ok, so how much sound is that and where to use PoE audio ?
Commercial architectures and facilities require the installation of permanent AV equipments such as digital signage, microphones, screens, and loudspeakers.
The use of networks and digital data is spread throughout all the establishments mentioned, and the AV devices, softwares and tools have adapted to this new « connected » environment.
So yes, PoE powered audio systems are destined to be prescribed in an growing number of audiovisual projects.
If we take the SPL levels a loudspeaker can achieve with the different types of PoE networks, and take into account the decay of sound over a distance, we can identify the industry sectors in wihch the PoE+ and PoE++ offer new possibilities.
Sound decay over distance (for ponctual source and linear sources) and matching PoE powers.
Conclusion
It’s no surprise the PoE increasing powers will benefit the distributed audio solutions based on relatively small size loudspeakers of 3, 4, 5 and 6 inches.
The latest PoE++ standard (802.3bt) opens up a wider market where connectivity and network use is fully taken into account by the project planners from the outset. Any cabinet equipped with bigger transducers, and installed in more SPL demanding facilities, will suffer from a lack of power, and in the end, a price to quality ratio issue.
Notes :
– Quality or price are not taken in consideration in the comparison of loudspeaker specifications.rs.
– It is possible that some loudspeaker and transducer designs cover wider frequency ranges and higher specifications than mentioned averages.
– The sound levels required for mentioned applications are subjective and given from experience.
