Is class A better than class A/B for power amps?

[A. Vivaldi]

<font color='#000000'>I've noticed that class A amps are rare and expensive. I've read some articles on them but have never heard one. Does anyone here have one or think they sound better? What advantages or disadvantages are there in having one?</font>

 

[Rip Van Woofer]

<font color='#000000'>Theoretically, Class A amps have an advantage in that they are not subject to &quot;crossover distortion&quot; caused by the switching action between two output transistors (Class B operation), since a true Class A amp uses only one per channel. But only theoretically. In real world terms, engineers long ago solved that little problem. In fact, the class AB amp (think of it as a &quot;hybrid&quot; between pure Class A and Class B operation) is the solution they came up with. There is no performance difference between a competently designed class AB amp and a class A. I'll leave it to more knowledgeable people here to get into the technical details. I &quot;kinda sorta&quot; understand them but...

Class A amps are extremely ineffecient and use lots of power. They look at your AC outlet the way Anna Nicole looks at a large triple-thick shake. You will qualify for &quot;preferred customer&quot; status with your electric company for owning one!

Finally, I've read that many amps advertised as Class A ain't necessarily so.

Bottom line: it's more high-end audiophile mythology.</font>

 

[A. Vivaldi]

<font color='#000000'>Leave it up to ole' Rip to lay it on the line and tell it like it is! Thanks. I have heard though that class A amps were better for listening at lower volumes, like late at night in a small apartment as in my situation. There are a few good makers of low watt class A integrateds, but I'd be better off investing in some good headphone gear though.</font>

 

[Guest]

<font color='#000000'>I have a different experience to tell. I bought my first class a integrated in 1976, a Kenwood KA 7100 and although it has noisy switches and no remote it smoked MF 3.2 and Arcam FMJ A32 integrateds. Rated 55/ch (julian hirsch, hope i spelled that right god bless him, tested it at around 80) &nbsp;the KA handled my NHT 2.9's with clarity and power the newer a/b designs had problems with despite being rated at 115 level. Compared to BAT VK300 SE(150w@8 ohms and 300w@4 ohms) it wasn't as powerful but sound quality was closer and preference is more a matter of taste. Class A is better as a general rule. Some amps are A,A/B ; this means the amp runs as class A for the first few to 25/35 watts then switches to class A/B when more power is needed. Ideal for moderate or late night listening and much less heat, money and weight than for pure class A. If class a/b was as good as class a noone would bother to make A,A/B design amps. Some say the popularity of tubes is class a. The difference in sound is A sounds like analog (vinyl) and A/B sounds like digital (CD) not surprising since A/B chops the sound into small pieces and tries to reaasemble them so fast you don't notice. A/B is defiinitely cheaper and probably offers better sound at a given price point.</font>

 

[Guest]

<font color='#000000'>Addressing an earlier post &quot;true class a uses only one device...&quot; &nbsp;I don't ever recall anyone making that claim before and it is contrary to what I've seen inside all class a solid states that I've seen the insides of.&quot; No diff between class a and a/b &quot; again not much to support that one ;maybe try &quot;no difference between class b and class a/b&quot; now I can support that as builders trying to pull the wool over our eyes. Class a/b are class a wannabees and are trying to make you think you getting class a. &quot; A;A/B&quot; is different and honest a true hybrid if you will. &nbsp;Unless an amp is &quot;digital&quot; (Linn &amp; Bel Canto come to mind) it is class a or class b PERIOD , all the other letters are advertising BS , despite my reservations about their advertising some of these other classes are very good and often have some technological merit that the class &quot;xyz&quot; nomenclature is trying to highlight. I hope this helps.</font>