Reference Levels in a Home Cinema - September 18th, 2008
A good home cinema room should be able to play at theatrical levels effortlessly. That would mean 105db at the listener’s position from every speaker and 115db from the LFE channel.
This is an issue that would need to be addressed when purchasing the electronics for any home cinema project. If the client wants a system able to play at reference levels, we’d have to do some basic calculations for their particular cinema room.
Let’s give a simple example. We’d assume the speaker is in a free field and that the inverse square law is operating. Let’s choose a speaker that has an efficiency rating of 90db and can handle 200W maximum. We have a beefy power amp of 250W per channel, and the listener in that cinema room is located four meters away from that speaker.
Choosing this combination of electronics for this home cinema installation would give us the following results: the speaker can handle 200W, so it will give us 113db at 1 meter. The question is what would happen at the listener’s position?
The listener would only get 100.9db, at four meters. This is below the reference level of 105db. Correct selection of electronics is essential in a home cinema installation, when theatrical reference levels are desired.