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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
itsjustme
682 posts
 
another agreement with @tom6897. **Pure** class A is tons of money, heat for what amounts to very little benefit. High bias Class AB works great.  There are way better places to spend money and get more sound improvement.

And i design these things.
The idea of subtle nuance while the amp is running at 100% of power is a contradiction.  The room is shaking.
yyzsantabarbara
4,941 posts
 
I find the Class A amps that I have owned smoother sounding than AB amp that I have owned. The CODA CSiB is a good integrated amp. I had Version 1 with the most Class A watts. I still own the KRELL K-300i integrated which does not put out a lot of heat and has the first 90 watts in Class A. I liked it more than the CODA CSB so Is sold the CSiB and kept the KRELL.

I also have the CDDA 07x and CODA #8 (Version 1). I like that combo more than the CSiB. Last week I heard the CODA #16 with the CODA 07x and it was easily better sounding than my #8. The #16 has the first 100 watts in Class A. It sounded smoother than the #8 and with more clarity. The CODA #16 was not that hot. Maybe I needed to play it for a few hours at loud volumes?

I have also had 3 Class D amps recently. Which were enjoyable but sold mainly because I liked the CODA gear a bit more.
jjss49's avatar
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jjss49
6,612 posts
 
@larry5729 

maybe arcam has made some sweet sounding amps in their history, but after owning 3-4 arcams over the years, for various purposes, i have yet to experience one
erikt
269 posts
 
The Luxman L-509X is biased to be pure Class A for the first 6 watts.

I've got mine paired to Audio Note AN-K SPx/SE at 90db efficiency.

I do practically all of my listening in Class A - if you believe those seductive dancing meters :-)
holmz's avatar
holmz
2,328 posts
 
I do practically all of my listening in Class A - if you believe those seductive dancing meters :-)
I believe you and the others, including myself, that in an RMS sense… it is mostly Class-A.

Just the crest factor of a lot of music can be ~13dB. So that often jumps the peaks up to Class-AB.
Maybe at 60-65dB it is under/within Class-A.
But at 75-80dB those peaks will be above the meager level where the bias disappears it being qualified as “Class-A like” operation...”
And it has historically been in the louder sections of music where I have heard the grainy’ness, so maybe that was cross over distortion from Class-AB?
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