Reference levels?

[danger boy]

Lots of people mention "reference levels" and I'd kind of like to know how reference levels are measured, and what makes a home theater a reference level system? Does the SPL matter? Are we talking 95db or 115db or more here? Anyone can please explain it in laymans terms. thanks

[mantis]

I'll try,
reference level .......ok,
when you test tone your system,you need to use a SPL in order to setup the level all the way around.75db all the way around is industry standard.Basically it's 10db lower as test tones are loud.
Once set at this level,without dynamic range and just voice and common background sound in a film will generally play around 85db at reference.When Dynamic range kicks in it can get into the 100db range and slightly behond.
Most receivers will play at reference at 0db.Not all use this type of readout,like some Yamaha's are at -30db range,Rotel is like 72db,it depends where/how they set up there volume control display.
Reference level is generally to loud for most home theater's.If you have a room lets say 15x26,you might beable to withstand reference volume setting.It's really loud.
I'm not sure if thats laymans terms, its as simple as I think I can put it.
Reference is used alot and I see why It can be confusing.Hell I don't understand "reference" all the time.

[Dr. Spec]

I like Mantis' explanation. I've seen several references (pardon the pun) to this term explained exactly as he describes.

I've also seen "reference" levels referred to as how loud Dolby Digital and DTS specify the sound systems need to go in actual movie theaters, particularly with respect to bass output. Most numbers I've read refer to 105 dB "steady" and 115 dB "peak" output, all the way down to 20 Hz.

115 dB at the frequencies we normally talk and hear (500Hz-8kHz) is extremely loud - too loud for comfort in any listening situation. However, the human ear is much less sensitive to bass frequencies, and we can take them very loud without audible discomfort - in fact many of us CRAVE room shaking, vision blurring, pants waffling bass output.

I've seen many HT posters asking "can my sub hit 'reference' levels in my XYZ-sized room?" It takes a TWO mighty good subs to hit a clean 115 dB peak at 20 Hz at the listening position in a reasonably sized (2000 ft3) HT room and it can't be done in a large (3000 ft3) HT room unless you want to spend huge dollars.

Just another take on "reference", which indeed is not a universally defined term.

Doc

[DaMonk]

reference levels are the levels that the movie makers use for
theatre applications (85db)which is usually too loud for most home theatres recommended is (75db) which is a compromise
level as to not rob to much from the film makers intent. But the bottom line is as long as the levels are even set at whatever
sounds good to you.Run It! confused, me too!