wrote:



OK - a few basics on speakers - at least as they were sold in the
US under FTC regulations (sit on your fingers, Phil!):


** The are simply no FTC rules for published speaker power ratings. The rules you seem to be alluding to are for *amplifers* used in home entertainment.


c) Low cost, low-wattage amplifiers are much more likely to cause speaker damage than large amplifiers.


** Depends a lot who is using the amplifer - but in general the risk of speaker damage goes up with more amp power.


What can happen with some solid-state designs is that when the
amplifier clips (called to produce more power than it can),
it may send straight DC into the speaker

** Absurd.

Clipping does not cause DC, the main effect is to compress the dynamic range of the music so there is more average power going to the speaker - which eventually overheats the voice coil.


This issue is far less so from a tube amp - the simplistic explanation is that it is harder for a transformer to pass DC,


** Impossible in fact, but clipping wave peaks is just what tube guitar amps do most of all the time and blown speakers are very common - due again to high average power levels.


.... Phil