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How much power needed to drive 91db speakers?

Sonus Farber lists the sensitivity of my speakers at 91 db SPL@ 1 meter @4 ohms.  They also say I should use  50-450 watts of power. My PS Audio amps pump out 500 watts @4ohms, so the max isn’t a problem, but if I switched to something 15-50 class A watts, would that be more than enough power?  
 

Thanks in advance.

curiousjim

Showing 2 responses by toddalin

toddalin's avatar
toddalin
351 posts
 

Actually, no..., the difference between 1 watt and 100 watts would be less than 20 dB because the speakers will undergo power/thermal compression at higher power levels (especially sustained) and this reduces their dB output. The reduction could be substantial.

toddalin's avatar
toddalin
351 posts
 

"I would expect a speaker rated for 400 watts to be able to handle 100 watts with little to no compression. After all that is 6 db less than rated power."

You would be surprised!

I use JBL 2241H 18" woofers rated at 600 watts continuous.  These were redeveloped from the 2240 specifically to overcome the effects of power compression.

At 600 watts, they loose 4.3 dB.

At 300 watts, (i.e., -3 dB), they loose 2.6 dB.

At 60 watts (i.e., -10 dB), they loose 0.8 dB.

As I noted, these are 18" woofers with 4" vented voice coils specifically designed to mitigate power compression and I can imagine that a "lesser" woofer would undergo more compression that this.

https://jblpro.com/products/2241H

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