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how can low watt tube amps drive speakers with higher power requirements

I am new to hifi and I am super confused about something. Most audio blogs out there ask newbies to stick to amps that output power within the recommended range of the speaker manufacturers. However, on forums, blogs and even some magazine articles, I find pros reviewing tube amps with much lower output power (even in some cases 10-30W below the speaker specs) and find no problems. How can these low power tube amp drive these speakers? For example, the LS 50 metas spec sheet says "Recommended amp power: 40W - 100W) but I have seen posts here and on other forums where people will hook these up to tube amps producing as low as 12W of power at 8 ohms. Am I missing something?
selekt86
pragmasi
212 posts
 
The answer is pretty much covered by the other responses here... the loudspeaker rating is how much power it will tolerate, the amplifier rating is how much power it is able to deliver. So you need an amplifier that can deliver the sound levels you want plus a bit of headroom to avoid excessive distortion / clipping.
One advantage of using a lower powered amplifier is that you don't need to attenuate the signal as much... potentiometers tend to perform progressively worse the more the volume is turned down, there's more information on that here if anyone's interested.
grinnell
1,077 posts
 
4 Watts drives my 92db Ref 3A de Capos just fine.  Not concert level but loud enough in a 12 x 20 room with openings on the side
twoleftears's avatar
twoleftears
5,313 posts
 
KEF doesn't know what kind of amp or quality of amp you're going to use.  The figures quoted are no doubt within a "safe" margin, and were probably determined as much by lawyers as by technical people.  Experiments are good, but always at your own risk.
kingharold
304 posts
 
An inadequate amplifier is easily driven into clipping and the clipped output of an amplifier includes excessive high frequency distortion energy.  It is the clipped output that is the tweeter killer.  For that reason low powered amps lacking soft clipping are more dangerous to speakers than are higher  power amps just idling along.
facten
2,784 posts
 
Aside from his stating the importance of speaker sensitivity Robert Harley states " Another electrical factor to consider is the loudspeaker's load impedance. ....The lower the loudspeaker's impedance, the more demand is placed on the power amp. If you choose low impedance speakers, be certain the power amp can drive them adequately."
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