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How hot is pure Class A solid state vs. SET?

Generally speaking, would a Class A solid state amp generate a lot more or similar heat as a single ended tube amp? Not surface temp, but the air around it. Tubes get hot, but their surface area is usually very small compared to big heat sinks on a SS Class A amp.

I am thinking about going from an AB SS amp to a Pass Aleph 30, but I am concerned about the heat. I have an Almarro A205A 5 WPC EL84/12AX7 SEP amp that is fine for me in this regard.
eugene81
meiwan
399 posts
 
I'm running a 30 watt class A all tube integrated amp. It gets hot to the touch, but won't keep me warm in the winter.
rodge827's avatar
rodge827
625 posts
 
I just went from a 300b SET integrated amp to a SS Class A integrated and the heat is about the same.
Hope this helps.
eugene81 OP
270 posts
 
Thanks for the responses. Two 100W light bulbs: that puts it into perspective (although an idle Class A SS amp is not as efficient as a light bulb <- sad). Too hot to touch, but not putting out a significant amount of heat into a decent sized living room.

Almarro states power consumption of its 18 WPC A318B 300b SET at 260W, so assuming the same efficiency my A205A is drawing about 70W at the wall -- roughly 1/3 of 200W just like you said, Al.

Anyway, I guess the numbers from Pass and Almarro gives us an idea...

Pass: 30W/200W = 15%
Almarro: 18W/260W = 6.9%

Class A SS wins on efficiency in this case.
zmanastronomy's avatar
zmanastronomy
738 posts
 
My Almarro A318B draws 250w and it put out enough heat to warm a house:)
It seems a lot hotter than two 125w light bulbs.
almarg's avatar
almarg
9,670 posts
 
It looks like the A318B uses a pair of 6C33C's, which is an extremely hot-running tube. Its filaments alone consume in the rough vicinity of 40 watts per tube, assuming both filaments in each tube are used. So your EL84-based amp figures to be considerably more efficient.

Also, just to be sure the light bulb reference is clear, nothing on the Pass amp will come close to being as hot as the surface of the bulbs, since in the case of the amp the heat will be radiated from a much larger total surface area (the Aleph 30 manual indicates that the heat sink temperature will be between 120 and 130 degF). But the total amount of heat radiated into the room by the amp will be about the same as if two 100W incandescent bulbs were positioned at the same location (slightly more than that, actually, as my understanding is that an incandescent bulb will convert about 10% of the power going into it into light, the other 90% being converted into heat).

Best regards,
-- Al
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