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Class A circuit?

I was just wondering when a manufacturer says thier product is all class A circuitry, does this mean that it really does meet some strict standard or this is just a subjective thing.


MisterBlue Sat, 12/13/2003 - 18:47

Class A is not a quality label (although it admittedly sounds like it). It's a specific electronic amplification circuitry.
You will also find "Class A/B", "Class D" and a number of other description that indicate to the electrical engineers amongst us how the circuits basically work.

Hope this helps,


Van_Hunter Sun, 12/14/2003 - 06:13

So a class D circuit with superior components could be better than a class A with inferior components? When you read the ads they always seem to lead off with "this Zoro Premic is all class A circuitry", which seems to imply that there is something better about class A.

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AudioGaff Sun, 12/14/2003 - 11:49

No, It doesn't work like that. A full explanation and background is beyoned the scope of a single posting and you should seek more detailed info from other places than in this forum. Class-D is a newer type and has to do with transister switching power. The Class and types come from the old days and are based on Vacuum-Tube amplifiers designs. Class-A designs among others, were used in all the older audio gear that all the great records were made with. Still to this day, some of the most popular and best sounding audio gear is usually Class-A in design. Some audio gear uses a Class-A output only, but is sold as a Class-A design. The marketing sharks have abused and exploited the term to be a catch-phrase to sell product.

A summary of what a Class-A amplifier is one where the operating point is chosen so that the output signal can swing equally in a positive or negative direction without exceeding the max collector dissipation.

macblack Sun, 12/14/2003 - 13:06

I believe that class-A has "better" distortion, meaning the distortion harmonics are more pleasant then class b or a/b.
I have a cranesong stc-8 which is class A and when I push it hard it sounds amazing (I use it as a mix bus comp).
If you are interested in high quality sound then class-A like the cranesong is what you want.
It totally changed my sound.


Johnson Cabasa Sun, 12/14/2003 - 19:00

class a just means taht the wave form is amplified as a complete wave form not split up. it doesn't say anything about headroom, it doesn't say anything about distortion, it doesn't say anything about phase.

sometimes it means something, sometimes its just hype

Van_Hunter Sun, 12/14/2003 - 21:59

Thank you for the replies. When I get a chance I will read up on the subject as I can see there is much more to it than I had anticipated, I believe my max collector has been distorted and exceeded,
Thanks again.