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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 1 response by erik_squires

erik_squires
16,591 posts
 
Hi Redfuneral,

That’s a complicated one! It’s also to do with the music you play. :) For your 10 Watt tube amp, check the rated input. I’m sure it’s probably closer to 50 watts. I’m not a tube guy, so I could be way off.

I can tell you my ICEPower 250 units idle around 7 watts each, and I estimate around 85% efficiency. So at 100 Watts output, figure 22 watts (7 + 15) of heat will be generated. Even after playing for an hour or more the little cases get at most slightly warm. There are no heat sinks, the wrap around aluminum case is all they have or need.  I use a flea powered 20W/ch lepai digital amplifier at my desk. You should get the biggest one you can, they are severely over-rated, but they run cold compared to the ICEPower monoblocks I use in the living room.

I’ve never heard of anyone noticing the heating effect of speakers themselves except in a professional setting. The worst that would happen in terms of pure heat is often tweeter padding resistors.

Best,


Erik
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