Music Technology
Super Class A 30W amplifier
SuperclassA-Amp_1a.jpg
SuperclassA-Amp_2b.jpg

I love ogling these crazed homebrewed audio power amps that people build. This one is based on Jean Hiraga’s 20W Class-A Amplifier, but it’s been tricked out further to become the “Super Class A 30W Amplifier.” Check out those monster caps. Those are six 220000 uF capacitors (1.2 Farads!) and (in the center) that’s a 500VA potted toroid transformer for the power supply. Even with that significant heat sinking in the back, the sink’s still a scorcher, at over 100-degress above room temp.

Construction of a Class-A Amplifier

20 thoughts on “Super Class A 30W amplifier

  1. You have to admire audiophiles who go against all the trends and listen to vinyl and build class A amps! Real independent people!

    In my younger, more foolish days, this sort of thing would have appealed to me…

  2. What a waste of power.
    I bet you didn’t even do the math right, 1.2F of cap and a 500VA tranny? and 4 of those TO264 FETs? all for a lousy 30W audio output?

    Class D FTW.

  3. Come over and check out my T-amps. 15 watt power drain when driving my 90db/W Canton towers at clean musical orchestra levels.

  4. That reminds me of a “discussion” I attempted to have with someone over a low-end amplifier that was claiming to have over 800 watts of output. I looked at the heatsink and immediately declared that you’d be lucky to get 10 watts of good sound out of it before the distortion since there was no way there was 800 watts of Class-A amplifier in that box(it was 1/2 the size of a standard VCR) and if there was it was going to blow because they didn’t have near enough heat sink for it. They just couldn’t grasp that 800 watts of power meant at least 800 watts of heat as well.

  5. Class-A amps are theoretically only 50% efficient maximum — i.e. you need a 100W power supply to output 50W of audio.

    In reality, because home speakers are not designed to pass DC current, the practical class-A design is only 25% efficient. Pretty wasteful.

  6. @jimmy
    Please refrain from the profanity (which I’ve removed) and personal insults or you’ll be removed from the discussion. Thanks.

  7. Jimmy is talking nonsense about a subject he does not fully understand – generally amplifiers don’t generate as much heat as they produce in sound output and that is the rule that he is working from.

    Class A amplifiers, however, do. At the very least. 800W of load output generates at the very least 800W of heat. That’s why your iPod doesn’t need several Farads of capacitance and a heatsink that’s larger than the components – it doesn’t use this design.

    They’re specifically used as medium output, low efficiency and high heat disapation.

  8. As has already been stated, a Class-A amplifier means that if you have 800 watts of output you also have at least 800 watts dissipated as heat. Fact. Why didn’t you know that?

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Gareth Branwyn is a freelance writer and the former Editorial Director of Maker Media. He is the author or editor of over a dozen books on technology, DIY, and geek culture. He is currently a contributor to Boing Boing, Wink Books, and Wink Fun. And he has a new best-of writing collection and “lazy man’s memoir,” called Borg Like Me.

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