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Heat/Efficency of Speakers

What % of power sent to the speakers is turned to waste heat? That's the short version of my question.

I'm looking to minimize waste heat accross my stereo as my listening room is unforgiving come summer; no cooling and a computer system which cannot be relocated. I understand amplifier efficency & the classes as well as speaker efficency measured as W/db however the interplay eludes me.

Taking two hypothetical amplifiers: a Class A amplifier outputting 10W w/ 100W from the wall & a Class D outputting 200 w/ 220W draw I understand the D will be the cooler operator however this is where the discussion tends to end, D only wasting 20W vs the A amplifier's 90W. Considering appropriate speaker matches to each amp(as well as a standard HE speaker at say 95db/w), how do I determine the wattage converted sound and the watts spent as heat?

I'm asking because I was previously running a 10W tube amplifier in this room(4xel84 tubes) with 96db speakers. This was bearable in two hour doses this last summer. My friend assures me any Class D amplifier and many AB amps would have no such heating problems and says it's class not wattage that is my issue. Before I move to a different amplifier technology(and swap speakers, these voiced for SE tube partnering) I want to understand this issue fully. I'm unconcerned with power usage and only care about the heat.
redfuneral

Showing 3 responses by shadorne

shadorne's avatar
shadorne
7,477 posts
 
@cleeds

You are correct in your statements but you have twice misquoted me. You correct me but my statements more or less agree with yours just that I have stated things a little differently.

if I say a speaker churns out between 99% and 90% as heat then that equates to an efficiency of 1% to 10% in sound energy.

1% it typical for a high efficiency near full range speaker as you stated - it loses 99% of energy as heat (hot voice coils). 10% efficiency would represent the upper limit for a horn speaker - it loses 90% of energy as heat.


shadorne's avatar
shadorne
7,477 posts
 
@cleeds  

You might want to check your reading comprehension while I am checking my math!

 If 99% of energy is lost as heat as I stated then this makes a speaker very inefficient - a mere 1% being converted to acoustic energy - exactly what you concluded!
shadorne's avatar
shadorne
7,477 posts
 
Speakers typically churn out between 99% and 90% of energy as heat. Horns are the most efficient at 90% of power ending up as heat.
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