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Amplifier Specification questions

I understand the differences between different classes of amplifiers. Most common amplifiers are Class A/B. Does this mean that all class A/B amplifiers operate in Class A to some point then switch over to Class B when they hit a predefined threshold by the design of the manufacturer. Do some so-called Class A/B amps only operate in Class B? My power amp is designed to operate up to 18 watts Class A before changing class of operation. I assume this number is in 8 ohms. My amp is rated at 150 watts into 8 ohms and 300 into 4 ohms. Does this mean that Class A rating will double to 36 watts in 4 ohms or will it stay at 18 watts regardless. What's funny is I was thinking I needed more power because my meters were always pretty well deflected but after looking closer, I realized the meters were on the 5-WATT scale instead of the 150-WATT scale. I can't believe I never noticed that before.

willywonka
swede58's avatar
swede58
108 posts
 

All amps. P=R*I^2=R*4*Iq^2

willywonka OP
191 posts
 

@swede58 I know Ohms law but it doesn't address all my questions. I am a retired electronic tech by trade. 

elliottbnewcombjr
5,234 posts
 

So, my Cayin A88T, (8 ohms: 22 wpc triode/45wpc ultra-linear), using the 16 ohm taps yields ____? Class A amps.

https://6moons.com/audioreviews/cayin/a88t.html

btw: Only model 1 has 16 ohm taps, later versions are still the same 8 ohm rating, only 4 or 8 taps provided.

thanks for any enlightenment

Elliott

ditusa's avatar
ditusa
1,745 posts
 

@willywonka Wrote:

 Most common amplifiers are Class A/B. Does this mean that all class A/B amplifiers operate in Class A to some point then switch over to Class B when they hit a predefined threshold by the design of the manufacturer.

Yes! See article below:

Mike

https://www.sound-au.com/class-a.htm

curiousjim's avatar
curiousjim
4,216 posts
 

And companies rate things differently. A for instance, I have a Hegel, class A/B amp. I’ve tried three times asking the company how many watts are class A and never got an answer!  The third time I asked, I was told that because of their design, it all sounds like class A!

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