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Class A into Class AB

What is the goal of a designer who makes intergrated amps that have class A for x amount of watts before it goes into class AB? Are there any examples of this being implemented well? I get this feeling that it’s kind of just a marketing thing...where people think they are getting some quality class A without the very high price tag. I was particularly looking at the CODA CSiB amps where you have three choices of how much of your first watts are class A. I have since found a few other respectable brands that implement this as well. I have yet to come across anyone who has heard much of difference between AB amps and one’s that’s state "first X amount of watts..." Class A/AB. Anyone have any experience with these kind of integrated amplifiers? Just looking for a little bit of understanding as I’m trying to upgrade my amplifier.
tmac1700
jjss49's avatar
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jjss49
6,612 posts
 
What is the goal of a designer who makes intergrated amps that have class A for x amount of watts before it goes into class AB?

to provide a balance between purity of sound for most of the listening experience, versus heat, cost (of the unit and energy use), volume headroom, weight/size of the unit

Are there any examples of this being implemented well?

yes there are many
tennisdoc56
128 posts
 
My stereo experience began during the watt wars in the late 70’s and early 80s.  30 to 50 watts with horn midrange and 12 inch woofers made wood filling sound and no damage to speakers during peaks.  Watts became cheaper d speaker designers were free to experiment with smaller woofers and inefficient crossovers.  I had an power meter from realistic and measure the output from from a 100 wpc nakamichi stasis amplifier into my Polk sda 2 speakers.  The meter had a high and low setting 0 to 1 watt and 1 to 100. Even in a large living room most of the listening was under 1 watt and momentarily reached 5 during peak symphony or rock drum/bass combinations. 
henry53's avatar
henry53
280 posts
 
I use a Vincent Audio pre power SA 31 MK / SP 331 MK, first 10 watts are Class A. Calculations imply that would be 99% plus of my listening time. 
larryro2
137 posts
 
Why are you not using Class D?
hz79hc's avatar
hz79hc
24 posts
 
I found the real sweet spot.  I bought a 1970s vintage Yamaha CA-800.  A very nice class AB 55 or 60w into 8ohms ...with a wonderful *twist* above & beyond its classic look.

It has an operating mode switch whose purpose is to keep the amp operating solely in Class A mode (rated at 10w in Class A, I think)
-or- to operate normally in AB behavior and the stated power rating.  

Now, be -very- jealous!!  ;-)
I am not aware how many Yammie models had that nor do I know over what time period such a control was available.  Whether other manufacturers of that or any other era have offered such a control--I don't know...
Warren
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