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Amp power to drive 4 ohm speakers?

Category: Speakers

Folks, I'm pretty new in the quality audio world, and started by buying the Cambridge 640A integrated amp. Now I'm considering some standmount speakers that are rated 4 ohms mostly because of the wealth of great consumer reviews for them. (Polk Audio Lsi9's)
The Cambridge is 65wpc @ 8 ohms, 100 wpc @ 4 ohms and I'm wondering if I can reasonably expect full performance from the speakers. 15 by 15 room, no headbanging volume.
I'd appreciate any input those more experienced can offer a novice. TIA.
Jeff
leadfeathers
2 responses Add your response
porziob
316 posts
 
The Cambridge will work fine with the Polks. Read the Stereophile review.
gregm
3,405 posts
 
Speaker impedance changes with frequency -- so it probably drops under 4ohm. Low impedance = more difficult load. This said, yr transistor Cambridge should have no electrical trouble making music to about +8-10db(spl) over whatever nominal sensitivity rating these Polks have. Mind you, this is just a rule-of-the-thumb estimate.
So, if the spkrs measure say, 85db spl nominal/W/1 metre you'd go to ~95W peaks w/out clipping and have some extra energy left in the Cambridge to spare... not very loud overall nor extended dynamic capability...

...I seem to remember these spkrs aren't very sensitive -- why not also consider other simpler loads. Many around. CHeers
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