thanx: RE: [sdiy] ot: please recommend a low power pentode power amp circuit

[Peter Grenader]

James Patchell wrote:

>> Also, recall speaker efficiency.  I think (no PhD here, only a BS...) that
>> a smaller speaker (i.e., headphone) will be easier to drive than a 10",
>> 12", or 15" speaker.


There are many things that contribute to a speaker driver's efficiency.
Size of the cone is one part of it, but so is the material the cone is made
of as well as the cabinet its mounted in, the biggest misconception in that
being that ported cabinets are more efficient than if sealed.

As far as driver itself though, boils down to the mass and tension of its
diaphragm in relation to the signal driving the transducer, and the use of a
ferrofluid lubricant or not.

But there are 15 inch drivers out there that are a hell of a lot more
efficient than headphone speakers. Remember, while a smaller cone will react
to less energy,  a larger cone moves a lot more air  - and this contributes
to a drivers efficiency.