The View from 2005: The rules of the game haven’t changed much, except that we are all mostly using powered speakers, so we can’t reasonably compare amplifiers. My experience has been that powered speakers usually have barely adequate power at best. Be forewarned.

Bricks

In studio-land, power amps are big lumps of circuitry that live at the bottom of racks, under consoles, in closets, and other dark moist places. They are used to multiply the voltage and current of the audio signal you would like to actually hear with your ears, to amplitudes appropriate to drive your particular set of loudspeakers.

You set ‘em and forget ‘em, mostly, until some unfortunate soul mis-patches a power guitar channel direct out into an inadvertently assigned, wide-open reverb return and the resulting noise alerts NORAD that the end of the world is nigh and then pops the circuit protection in the amp. After that, you spend five minutes trembling from adrenaline overdose, crawling around among the dark moist dust bunnies that have accumulated and praying that the big lump still has circuitry that can be reset.

Such devices are subject to a certain mystique. First among their mythical virtues is that they must be utterly indestructible. Second is that no matter how boneheaded you and your associates might become (“Let’s see if we can make a bass sound that they can hear in Ireland. Bob, call your friend in Dublin while I retune the bass . . .), the power amp shall not permit the speaker to become shredded, nor the speaker cable melted, nor the power amp converted to a cinder, yea, all shall be saved no-matter-what. Third is that they must sound really good (whatever that means), with huge power reserves, incredible damping, unbelievably fast slew rate, and microscule distortion. Manufacturers make ‘em big, heavy, black, and often with no controls at all, just some jacks and binding posts: the Ultimate Baaad Black Box! Often they have handles on the front so that Arnold Schwarzenegger, when he’s visiting, can easily lift the mother up and slide it into the rack (the rest of us use two people, one on each side, just to avoid having our hands snapped off at the wrists). Such virtues don’t come cheap. Bricks like these can cost a kilobuck and up.

The question is: do you really need a big one? How much power do you really need? Does the latest HyperWatt 7325 with its big Titanium Interspace Transient Switching® circuits really sound better than your old no-longer-beloved Realistic 60 or Silvertone Sonata? Hell, can you even hear a difference?

Our Story Up To Now

Faithful and alert readers will recall that I’ve been trying to figure out how various audio items sound to real humans (as in “sounds totally awesome” or “sounds like a dead cucumber being run over by a Peterbilt”), as an informational service for y’all.

A couple of months ago, I ventured to test vocal microphones by asking folks to rate them, in comparative tests, on a scale between awful and sublime (er, zero to ten). Well, since nobody’s been sued over that, we decided to do some listening tests for amps. But, instead of a product comparison, we decided to simply try to answer the question: can you hear differences between power amplifiers? At different loudness levels? Using different speakers? And if we can hear differences, what are the physical causes of those differences?

Some good questions.