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TENET was a real burner. We had complaints from our neighbours every night we played it.
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I wish I could find that analysis of the JBL driver - I think it was the 2242 - which showed power compression after a few milliseconds, definitely not minutes. The JBL sheet says 5 minutes - that does not mean the power compression does not happen before then.
My assumption - based on the document I have in mind - is that compression happens pretty soon on a driver. If I am mistaken and it only happens after 5 minutes, then the whole power compression thing is non-relevant to cinema (maybe just for Nolan's movies!
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Still, let me make a point here: as it's been said, the fact that a driver is rated x Watts, does not mean that it's comfortable running at x Watts. Power compression (maybe), distortion and also linearity all go down the drain at rated power - the worse the driver the more of course.
If I were designing my own screening room, I'd still want to make sure none of my drivers ever get pushed to rated power (which is, let's not forget, the power the driver can handle BEFORE PHYSICAL DAMAGE HAPPEN). Even on LFE, I want those brief moment to be clear and powerful. If my driver loses linearity and 20-30hz disappear (aka: do not reproduce at the intended level) during a brief, loud moment, then what's the point...Comment
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The 5 minute mark would be how far the power has been compressed in that amount of time (sort of like an RT-60...how far does it decay over a set time window). Who is running their subwoofers, in a designed system, right up to destruction. Note to, 800W pink noise for 2-hours is hardly a driver on the verge of destruction. I believe that is x-max.Comment
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My understanding is that the amount of power compressions stated inf he data sheet happens after milliseconds - then you can check after 5 or 50 minutes and it won’t get any worse - or not much.
Well if you go over Xmax the driver will likely damage. I had those drivers at home, I could hear the distortion when I was pushing them hard. And that was just home theatre! ?
so, feel free to push them to the maximum and even more. They’re good drivers and they won’t fail easily. But if JBL says 800W, there’s a good reason for that!Comment
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If you want, you can measure and graph the compression of individual drivers so that each user can make their own choice.
I like to use this data when designing speakers (a hobby of mine for over 40 years).
As Stefan already said, the coupling to the room in the bass is a special challenge. That's why we use two large horns as LFE and two large TL subwoofers for the surrounds in our 800m³ hall. This works really well.
There is a very nice basic article on measuring compression on one of my favorite sites on the web that describes it very clearly (in German).
https://hifi-selbstbau.de/grundlagen...ression-ntlich
If a manufacturer stuck such a graphic next to the nameplate, one could separate the wheat from the chaff for this parameter at a glance.Comment
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interesting link thanks. Google translate seems to work ok with that BTW!
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