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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
grinnell
1,074 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
2,726 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."
tuberist's avatar
tuberist
951 posts
 
I agree with the Miller on the choice Of loudspeakers since then you have many, many amplifier options. . If you start with a low powered amplifier then you are going to be limited in your loudspeaker choices. Generally speaking, lower efficiency speakers may have better bass and higher efficiency speakers are more difficult to design for good bass impact. Another thing to be aware of is the nominal impedance of a loudspeaker. Low impedances are going to require a lot more power, as a general rule of thumb. The loudspeakers I use are 99db efficient at eight ohms nominal. I have used these loudspeakers with as little as eight watts  per channel to play very loudly.
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