Maybe I can help translate the author's EE work into "HN speak" in that what the author did with this amp design is similar to how programmers do "turing tarpit

Maybe I can help translate the author's EE work into "HN speak" in that what the author did with this amp design is similar to how programmers do "turing tarpit" language challenges. The game rules are usually picked based on how much the player wants to put up with. His spec for low freq 3dB down is weirdly low to me because I don't own drivers that run that low (LOL) although the spec for 1dB down is probably more "audiophile relevant". I suppose as a design goal if a recording has a 5 hz signal I'd want it to be properly amplified for the speakers to turn into heat instead of sound, rather than clipping and making noisy harmonics every 5 or 10 hz up the band, so there is that justification, but, why not input filter instead of just making heat in the speaker crossover? In this story, the game rules were use as little post-1970 components as possible while maxing out various specs to beyond human hearing. A good analogy for programmers would be writing a quicksort in BF or intercal. You don't do that because you need production code, you do that on a dare or to see if its possible or for the sheer heck of it. Personally if I needed 50 or so watts I'd use a TI TPA3116 and call it good. There's kits available on ebay and elsewhere, its a stereotypical more than a couple watts less than a hundred watts modern class D amp. Simple design one chip no need for heatsink at lower power out. Does need 24V power and a heatsink for full power out. The chip costs about a buck. But that breaks the rules of the game because those didn't ship till maybe two or three years ago, not 1965.