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In Reply to: RE: 20-30Watts Class A nominations apart from Aleph for pure sound posted by bare on April 10, 2017 at 19:50:48
NO Pass class A does Not get hot. Certainly Not his Firstwatt designs Only the earliest designs got HOT. Nelson is constantly developing new topologies... each version an improvement on it's predecessor.
By their very nature Class A amps run HOT relative to other designs. There's nothing Nelson can do about that. All one needs to do is look at the idle power consumption spec relative to the amp's output power. That idle power consumption is a direct indicator of heat dissipation. The smaller 10 - 25w Firstwatt amps dissipate anywhere from about 150-watts to 250-watts in heat. That's HUGE for the small amount of audio power they actually produce, which is typical of Class A. Nelson isn't going to change the laws of physics to change the relationship of Class A to heat dissipation.
Model / Audio Ouput / Heat Dissipation
F7 20w / 170w
F6 25w / 180w
SIT1 10w / 200w
SIT2 10w / 200w
J2 30w / 200w
M2 25w / 160w
F5 25w / 180w
F4 25w / 180w
F3 15w / 200w
F2 5w / 150w
F1 10w / 200w
Aleph J 25w / 200w
Aleph 30 30w/200w
Aleph 3 30w / 250w
XS150 150w / 700w
XS300 300w / 900w
Edits: 04/11/17Follow Ups:
Obviously, Class A creates more heat by design, but how the heat is dissipated makes a difference. My X250 was A/B but it was never hot to the touch even with heavy use. It was well ventilated as well, which makes a difference in how hot the chassis may seem.
I hope there's more than beauty involved in all that Pass metal, LOL
I understand what you are saying....
But "hot to the touch" is not the issue. It's the total amount of heat dissipated by the amp. And Class A amps put out a lot of heat for the small amount of audio power they produce.
An amp that is dissipating 250watts in heat across large massive heat sinks may not feel "hot to the touch" in any particular spot but it is still dissipating 250watts.
That same amp design with a much smaller heat sink will feel hotter "to the touch" but that doesn't mean it's putting out more heat. It's still 250watts in this example.
I agree the watts are generating heat, but I'm thinking if the heat is neutralized, if you will,at the heat sycns, then less effect of room temperature.
No matter how we slice it Class A is not efficient and that energy has to be dissipated. I was just thinking an amp that didn't radiate the heat into the room may be more of an advantage if you lived in an area with a hot summer. Which is almost everywhere now, LOL
Nirvana Electronic Works (N.E.W) A-20 - a nice little amp you can sometimes find at reasonable prices.
Original Monarchy SM-70 - the ORIGINAL SM-70 is biased pretty far into class A, runs in class A down to maybe 2~3 ohms load. Gives you about 25 watts a channel @ 8 ohms. (Don't confuse the "SM-70 Pro" models for class A, they are high-bias class A/B, not class A. I've owned both. The "original" SM-70 sounds better IMHO.) A pair of them, each driven with balanced input in mono, makes a really great amplifier of about 100 watts a side for under $1,000. Because they have no global feedback, their harmonic output is rich in second-order and low in higher-order harmonics, giving these amps a somewhat tube-like character.
Forte 4a, 50 watts @ 8 ohms, 100 watts @ 4 ohms, class- A. With the Soderburg mods, these amps sound WONDERFUL.
I own all the above and can vouch for their sound and reliability.
I do not own but have read that the Pioneer M-22 amplifier- 22 watts / channel @ 8 ohms, class A- is a very good amplifier.
ANd then there are a number of current and vintage Luxman class-A products which have their following.
I have owned some vintage Yamaha "silver" integrated amps which can be switched into low-power class-A mode. I was not terribly impressed with these.
I know tubes run hot,but I would look at the Atmasphere s-30 OTL.Single driver with relatively stable 6-8 ohm load.Might be heaven.
I have never tried an Atmasphere in my system but have heard them elsewhere and they sound very good. I've always wanted one.
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