# How to interpret SPL specifications?



## Chris_E (Feb 2, 2010)

After noticing the high spl claims on many pro components (versus home audio where nothing is said) I'm getting curious and thought I'd better ask the ones that might know. 
So, what conclusions is it possible to draw from the following spec's? 

*Genelec about their 1038B*
Max short term sin wave acoustic output on axis in half space, averaged from 100Hz to 3kHz. at 1m >= 120dB SPL
Max long term RMS acoustic output in same conditions with IEC-weighted noise (limited by driver unit protection circuit) at 1m >= 116dB SPL
Max peak acoustic output per pair from the engineer with music material at 2m >= 124dB

*Dynaudio on the AIR-25*
Peak SPL pair (IEC Short Term) at 1m 134dB
Max SPL (IEC Long Term) at 1m 107dB RMS

*Adam Audio on the S5X-H*
Long term output >= 121dB
Short term sine wave acoustic output 100Hz - 3kHz at 1m >= 121 dB
Max peak acoustic output per pair with music material at 1m >= 131dB


I find it particulary interesting that the 1038 is rated lowest for peak spl but highest for long term and the Air 25 beeing the opposite. Is it a reasonable conclusion that the 1038 will go louder than the Air on highly compressed music material (as pressed cd's) but the Air possibly beeing a better choice for studio work?

And that the S5X is a notch above both with respect to spl?

Chris


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## Zeitgeist (Apr 4, 2009)

I think of Genelec as pretty much industry standard.

I'm not sure that max levels are a good comparison when looking for a studio monitor.

Mixing at levels as high as 100-120db just sounds insane to me.

Max SPL doesn't equal flat frequency response or quality.


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## AudiocRaver (Jun 6, 2012)

There is so little detail given that can be used for real direct comparison that most the numbers given don't mean much, other than to say, "They go REALLY LOUD."

Long-term RMS numbers are probably the most meaningful when thinking about maximum speaker volume levels, all other factors being the same. The headroom, or peak, capabilities of speakers are difficult to determine and specify, and there are a lot of ways to skin that cat, thus the wide range of "apparent" headroom differences.

In practical terms in a recording studio, assuming non-powered speakers, monitors will be vastly over-powered so that power amp clipping will simply never be an issue, and then when the speakers start to "break up" and distort at high levels, well, that's too loud, and that's when you dial them back. Fried drivers are not terribly unusual in studios that work at high volume levels.

You're fairly safe to stick with the long-term RMS numbers for max volume assessment. Safe except for the ears, of course, as previously noted. Also, as previously noted, high volume does not equate to good sound, although the brands mentioned have reputations for sounding pretty nice as well.


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## Chris_E (Feb 2, 2010)

Thanks. I totally agree on spl not beeing any indication on sound quality as well as the possibilities of inflating max spl by choosing a test method that will result in high numbers. 
Still, powerful sound it is one of several qualities that might be considered. Think I'll have to send an email to respective manufacturer and ask for clarification. Will be interesting to see if I get any answers.


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