When does my class Atoll IN200 A/B integrated switch from class A to class B?

Quick follow up. I discovered this comment about their more advanced amp and I sent it to Atoll:

What I found said,

“The high bias allows the IN400SE to operate in a Class A for the first ten watts before going into Class AB operation."
http://www.theabsolutesound.com/articles/atoll-electronique-in400se-integrated-amplifier/

And I asked Atoll if they were claiming the my IN200SE operates to 40w in class A while a later and more expensive model only operates in Class A for the first 10 watts? If that is true, why did you not employ this technology in the later amp?""

They replied: "The IN400se use almost the same technology as the IN200se so both work in class A up to the third of the maximum power."

So, they're in contradiction. Is it Class A up to 10w or to 40w? They seem to say both but insist (to me) that it's 40w in Class A. Despite the lack of heat, fins, etc.

They're just jerking me around at this point, right?

I think they are jerking you around. Eliminating the electrical insulating material between the transistor and heatsink will reduce the thermal impedance, allowing a bit more of the transistors heat to be transferred to the heatsink, but this doesn't change the laws of thermodynamics. The heat still has to go somewhere. 

This would allow the heatsinks to run a little hotter without risk of damaging the transistors - say 60 or 65 degrees C. But even so, heatsinks this small would not allow nearly enough heat to be dissipated for 40W class A operation. And your case would be so hot that you wouldn't be able to touch it for more than a second or two.

Take a look at the Pass Int-60. This is rated at only 60w/ch into 8 ohm (although that's pretty conservative) and has rail voltages considerably less than your amp, which means the transistors need to dissipate less power at the same idle current. The Int-60 will do class A up to 30w/ch. Now take a look at the size of the heatsinks on this amp. 

Yes.  10W sounds exactly right for the '400 model.

Coda is an interesting company in that it has models with different flavors, i.e. with different levels of class A operation.  Unfortunately this isn't a switch on the face plate; you choose which version when ordering.

Coda uses three different taps on the transformer to achieve their versions. I have the CSiB integrated in V1 which is 150 watts into 8 ohms but with class A up to 18 watts, the V3 is 400 watts into 8 ohms and class A to 8 watt. So a unit can be adjusted to one of three versions, the correct transformer tap soldered in place and the bias set, all performed at the factory, not a user adjustment. 

I also have a Pass INT-60 which is class A to 30 watts, both wonderful units. Weighs in at 90 + lbs.

I agree with what most have said that your unit is likely class A to 10 watts or less.

The most important thing is how it sounds to you!

hilde45
When does my class Atoll IN200 A/B integrated switch from class A to class B?

Looking at the size of the heat sinks https://ibb.co/1LXDhKt and the rail volts needed for Class-B 120w output, your lucky to have a couple of watts of Class-A

Because of the high rail volts needed for 120w of class-B, the heat dissipation of Class-A goes up exponentially as the rails volts rise for Class-B.

Think this way, if you have a 10w Class-A "only" amp (no B) the heat is X
If that same amp is still 10w Class-A ((but 120w of B) then the heat is far far higher.

Like I said your lucky to have a couple of watts of Class-A (sorry probably not what you wanted to hear) 

Cheers George