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  3. 162022-139155

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

I have an Atoll IN200 integrated amp (earlier version of this: https://www.atoll-electronique.com/en/products/integrated/integrated-in200sig/)

Having read a lot of praise about class A power, I’m wondering how to tell from specs when my integrated likely needs to switch from class A to class B?

The reason I’m curious is that I’m still wondering how my speakers might sound with a pure class A amplifier (such as Pass, etc.) but perhaps the integrated I have is already demonstrating much of that if there is a long enough delivery of class A power from it already? My speakers are 8 ohms, 87 db sensitivity, standmounts.

I apologize if this question is too simple; I hope I’ve posed it clearly.

P.S. This is not about dissatisfaction with my integrated or other gear (I have tubes, too). It's really just part of a longer term attempt to understand how different power sources change the character of a system, particularly the speakers.
128x128hilde45
georgehifi's avatar
georgehifi
10,312 posts
 
It seems proved as BS. What I’m amazed at is that I confronted them via email with the evidence it couldn’t be true and they just repeated the BS.
If your 100% sure they said "The IN200 works in Class A up to about 40W under 8 Ohm" Ask them to come on here and prove it, and they'll get a new one ripped. 

But if they said
"The heat dissipation of all the heatsinks is 40w" this is probably correct. But this is a very different thing and has nothing to do about how high the Class-A ability is you’ll get into 8ohms.

Cheers George
hilde45's avatar
hilde45 OP
4,974 posts
 
George, I’ve quoted them verbatim. They claimed it twice. 
I like their product. That’s not in question. 
georgehifi's avatar
georgehifi
10,312 posts
 
I like their product. That’s not in question.
I not saying that it sounds bad, may sound good for all I know.

Just that there’s so much of this going on to catch out the gullible, it’s got to be pulled up, just like the "boutique" $150> snake oil ac fuses con that goes on.

Cheers George
hilde45's avatar
hilde45 OP
4,974 posts
 
We’re in complete agreement, George, and thank you!
rockrider
181 posts
 

Hi @hilde45,


Maybe you’ve already read this interesting article about class A by Nelson Pass:  https://positive-feedback.com/audio-discourse/leaving-class-a-2019-redux-a-biased-opinion-from-nelson-pass/


So, if you know the idle power draw of your Atoll IN200, you could infer somewhat where the class A bias is set. 


(Idle power draw is with the amp fully powered up and ready to play music, NOT “standby” power which might only be enough circuitry to receive a remote power-on command.)


For example, the Luxman L-590AXII is rated at 30 WPC class A, and burns 260 watts at idle. Assuming 40 watts of the 260 is the PreAmp section, that leaves 220 watts idling to drive 60 watts for 2 channels of class A. In this case the power amp idle draw is about 3.7 x the class A power rating. 


Since Atoll does not appear to publish their idle power draw, you could use something like an inexpensive Kill-a-Watt power meter to get you in the ballpark. If it only draws 30 watts at idle then you probably have trivial class A after accounting for the PreAmp. 


I built a little Pass designed Amp Camp Amp, but found it wasn’t up to the sound quality I’m after, and I would not recommend judging any other class A amps based on this small amp’s performance. But it was fun to make, and I’ll probably never sell it.


I find this stuff interesting. Happy holidays!

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