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<blockquote data-quote="squeak9798" data-source="post: 3684993" data-attributes="member: 555320">They had some that were labeled &quot;class A&quot;, but it was simply a class A/B amplifier.&nbsp; For example, the 50 II is labeled in their literature as being a &quot;pure class A&quot;.....but it&#039;s idle current draw is only 1.5A.&nbsp; On 14.4V with that current draw, and assuming the maximum efficiency class A operation can have of 25%....that means it&#039;s limited to a maximum [under ideal conditions] &quot;class A&quot; power output of 5.4w (total, so 2.7w per channel).&nbsp; Anything above and beyond that (it&#039;s rated 25w x 2 @ 4ohm) is class B.To my knowledge, the ONLY pure class A amplifier for car audio is the HSS Fidelity tube amplifier.&nbsp; Only a class A output stage.Every other car audio amplifier labeled as &quot;class A&quot; has been a class A/B amplifier, some with a higher bias (such as the Tru A class amplifier).....but all of them at a certain power level will switch to class &quot;B&quot; operation.&nbsp; Monolithics included.</blockquote>

[QUOTE="squeak9798, post: 3684993, member: 555320"] They had some that were labeled "class A", but it was simply a class A/B amplifier. For example, the 50 II is labeled in their literature as being a "pure class A".....but it's idle current draw is only 1.5A. On 14.4V with that current draw, and assuming the maximum efficiency class A operation can have of 25%....that means it's limited to a maximum [under ideal conditions] "class A" power output of 5.4w (total, so 2.7w per channel). Anything above and beyond that (it's rated 25w x 2 @ 4ohm) is class B. To my knowledge, the ONLY pure class A amplifier for car audio is the HSS Fidelity tube amplifier. Only a class A output stage. Every other car audio amplifier labeled as "class A" has been a class A/B amplifier, some with a higher bias (such as the Tru A class amplifier).....but all of them at a certain power level will switch to class "B" operation. Monolithics included. [/QUOTE]

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