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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 gs5556

gs5556
1,241 posts
 
The heat gain in your room will be affected by the amplifier since nearly 100% of power consumed by the speaker is converted to heat.

If you have two amplifiers, one being a 100 wpc Class A and the other a 100 wpc Class AB, both will pass through the same power to the same speakers. However, the Class A amplifier will consume about 1,000 watts of power at idle and at rated power and that will be converted into heat as long as the power is on. The Class AB amplifier will consume about 175 watts at idle and 400 watts at rated power. The heat transferred to your room will vary from 175 watts to 400 watts. Therefore the room heat gain will be a lot lower with the AB amplifier since the heat gain from the speakers will be the same with both amps (listening SPL and duration being equal).
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