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Using 200w amp with 300w rms speaker

I have a McIntosh MC202. I currently have a pair of B&W CM9 S2s. I was looking at the 804 D2s but heard the 702 S2s and 804 D3s today and the 702 S2s sounded MUCH better than the 804 D3s. This makes me want to upgrade to the CM10 S2s instead of the 804 D2s instead. However the CM10 S2 have an rms of 300w whereas the 804 D2s have an rms in 200w. My layout will not allow me to upgrade my amp so I’m stuck at 200w. My question is if you think 200w is enough for the CM10 S2s. I’d also seen a pair of Focal 1028 Bes on USAudioMart so was interested in those too but again they are 300w rms. Love to hear some thoughts on this...
128x128jnelso61
kijanki's avatar
kijanki
4,442 posts
 
The power recommendation is for MAXIMUM safe power.
Yes, but it is maximum average power, not maximum peak power.  
Average power is equivalent to dissipated heat.
Pavg = Vrms*Irms    Peak power for sinewave is twice larger than average power.  RMS of power would be about 20% higher than average for sinewave, but it doesn't represent anything useful.  It is incorrect term.   Just stating power in watts means it is average.

300W will be about 12% louder than 200W

knotscott's avatar
knotscott
1,065 posts
 
Buy what you like the sound of.  You have excellent amps capable of driving a speaker well. At the level of equipment you have, unless you're doing some really silly things with the system, I wouldn’t even give those specs a thought.  
kijanki's avatar
kijanki
4,442 posts
 
+1 knotscott

Sensitivity: 90dB/W/m
It means that 1W from 1m will produce 90dB.  The fact that you have two speakers adds 3dB.  Because it is not open space, reflections in the room will likely add another 3dB.  So, your speakers driven by 1W power will produce 96dB from the distance of 1m, 90dB from 2m and 84dB from distance of 4m.   Assuming 4m distance it will be 84dB from 1W, 94dB (twice as loud) from 10W, 104dB from 100W and 107dB from 200W.  It should be plenty loud for you (and your neighbors).

(Sensitivity: 90dB/W/m - it should be called Efficiency.  Sensitivity is rated at 2.83V at 1m.   at 8ohm Efficiency = Sensitivity)

mattmiller's avatar
mattmiller
1,515 posts
 
Hey just because there rated at 300w dosent mean you cant drive them with 450w! My Dynaudio speakers are rated at 200w and I drive them with a 350w per channel amp no problem they sound fantastic and I love the extra power (so do the speakers). Sure your 200w will drive the more power hungry speakers but if you listen fairly loudly then you will be seeing your amps power guard lights glow a lot! Not the best situation.

Matt M
millercarbon's avatar
millercarbon
12,531 posts
 
Sensitivity is correct because we are measuring how sensitive the speaker output volume is to the input signal. This is not the same as efficiency, which relates to how efficient the speaker is at doing work vs heat. The same driver has the same efficiency no matter where it is. In one speaker its used as a horn driver, in another its ported, while in a third its sealed. Same driver, same efficiency, different sensitivity in each case.
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