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<blockquote data-quote="helotaxi" data-source="post: 4100044" data-attributes="member: 550915">If the efficiency is bad at an impedance into which the amp is designed to be run, then there is a problem with the design of the amp.&nbsp; Class D amps are going to be more efficient in real world use across the board compared to a Class A/B design regardless of impedance.&nbsp; A Class A/B amp is most efficient at full power and even then the efficiency of a really good design well executed is going to be around 70%.&nbsp; At less than full power (where you operate an amp 100% of the time when playing music) the efficiency suffers horribly dropping onto the 30% range.&nbsp; Compare this with a Class D amp that is within a few percentage points of its maximum efficiency regardless of power output.&nbsp; Not that big a deal when talking about smaller amps that are only putting out an average of 30W with music but when you start talking about larger sub amps that are doing a few hundred watts on music, the difference in efficiency is pretty important.You also have to account for amp footprint unless space is of no concern.&nbsp; I have a very large Class A/B amp from the mid 90&#039;s and it is roughly 3x the size of my modern Class D sub amp.&nbsp; Puts out less power, too.I&#039;ve run similar setups with mixed results depending on the type of music I was listening to.&nbsp; Rock, country jazz etc. the stock electrical was usually more than adequate.&nbsp; Throw in the bass tracks or heavy classical and the headlights looked like strobes even with an alt 2x the size of the stock one and two batteries.&nbsp; Just because your setup works out OK, the same can&#039;t necessarily be said about his.Agreed.</blockquote>

[QUOTE="helotaxi, post: 4100044, member: 550915"] If the efficiency is bad at an impedance into which the amp is designed to be run, then there is a problem with the design of the amp. Class D amps are going to be more efficient in real world use across the board compared to a Class A/B design regardless of impedance. A Class A/B amp is most efficient at full power and even then the efficiency of a really good design well executed is going to be around 70%. At less than full power (where you operate an amp 100% of the time when playing music) the efficiency suffers horribly dropping onto the 30% range. Compare this with a Class D amp that is within a few percentage points of its maximum efficiency regardless of power output. Not that big a deal when talking about smaller amps that are only putting out an average of 30W with music but when you start talking about larger sub amps that are doing a few hundred watts on music, the difference in efficiency is pretty important. You also have to account for amp footprint unless space is of no concern. I have a very large Class A/B amp from the mid 90's and it is roughly 3x the size of my modern Class D sub amp. Puts out less power, too. I've run similar setups with mixed results depending on the type of music I was listening to. Rock, country jazz etc. the stock electrical was usually more than adequate. Throw in the bass tracks or heavy classical and the headlights looked like strobes even with an alt 2x the size of the stock one and two batteries. Just because your setup works out OK, the same can't necessarily be said about his. Agreed. [/QUOTE]

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