"Rich Andrews" wrote in message
.44
(Bruce J. Richman) wrote in
:

Art wrote:


"Rich Andrews" wrote in message
.44...
Matt Zach wrote in
:

I am looking at my first tube amp. It delivers 40 wpc class A. I
own an inefficient pair of A/D/S 810 speakers.
Will I have problems with this amp driving these speakers ?
Thanks,
Matt



What do you mean by inefficient? 85db watt/meter? 80db
watt/meter? What would be efficient to you? 90db 2.83v/meter?


And furthermore, how big is the room?




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All important variables. As is the listener's customary volume
level with which he feels comfortable. In short, the question he
poses probably can't be answered by simply looking at amplifier
power ratings or speaker effriciency statistics.



Bruce J. Richman





Well, the questions posed to the original poster certainly won't
answer the question of if he will be having difficulty driving the
speakers, it is a start. I think that trying to determine if the amp
is even adequate for the SPL expected is a good first step. If the
speakers are very inefeccient and he expects 118db, then yes, his amp
will had difficulty driving the load to his satisfaction.

Letsee 40 watts is 16 dBw. Your typical home audio speaker runs 90 dB/w.
That means that this 40 watt peanut whistle can't muster 118 dB a meter from
the speaker, let alone create any kind of serious sound field in a typical
listening room. If you consider typical low efficency speakers with 83 dBw
sensitivity, now 1 meter SPL is down to 109 dB. It's really hopeless trying
to do a quality stereo with average or low efficiency speakers and a peanut
whistle for an amplifier.