Home Theatre surround speaker SPL requirements

[voodooless]

This is a question that comes up a lot: how loud must those surround speakers go compared to the fronts?

While it's very tempting to just have all speakers of the same model, it is often impractical and economically undesirable. So what gives? What can you get away with?

Instinctively, my impression was that in general, the surround speakers are much less loud on average than the LRC's. But is that true?

Well, science is to the rescue I guess . I found this paper that looked precisely into this question among other things.

They analyzed 4 soundtracks and concluded the following:

The material studied demonstrates that the surround channels are operating at about 5...10 dB lower maximum level than the front monitor triplet. Most likely this also applies to the height output channels in immersive audio presentation systems, too, due to the tendency to concentrate a lot of the action in the front at the screen in cinema mixes

Well, 4 soundtracks aren't very much, but at least it's a start. All of these show lower SPL for the surround channels.

Another interesting thing is the center channel, which shows you should have a much bigger one, than R and L.

So, what do you guys think?

 

[DVDdoug]

If I'm reading the graphs correctly A has some 0dB (or near 0dB) peaks in all channels.

 

[voodooless]

If I'm reading the graphs correctly A has some 0dB (or near 0dB) peaks in all channels.

They do, but the time spend there is infinitesimal.

Remember that maxSPL is not really a statistic number. As long as your amp can handle it, and your speakers are high-passed properly, so they cannot bottom out, they will handle a bit more power for short periods just fine. Genelec even specs 3 maximum SPL numbers with different properties.

 

[abdo123]

The data show barely any trends, but then, 4 soundtracks is nothing lol.

 

[Blumlein 88]

Somewhere here this was discussed. A few different sources showed average +6db for center vs right and left up front. And a bit more variance in the surround data, but yes -6 to -10 db less.

I've been pondering how to get a louder center since then. It is a problem because I use a projector and those sideways centers have some issues. Probably more economical to get an acoustically transparent screen and just put a big floorstanding center behind it.

I am using LSR 308's for center and surrounds. F208s for right and left. The center is the only one that gets strained in use even with big blockbuster sound tracks.