I’m deep into audio power amplifiers because they remind me of race car engines. Both power sources are wildly inefficient, converting only a small percentage of their stored energy into work while dissipating the rest as heat and vibration. Mainly though, I love how race car engines sound. How they shake the air. Just like amps and speakers.
Audio-frequency power amplifiers take a small input signal-usually less than 1V-apply it to an input impedance of (typically) no less than 10k ohms, and make this tiny eyeblink of power (0.0001 W) into a waveform that's many times more powerful, capable in some cases of doing hundreds of watts of speaker-moving work. To grasp the magnitude of this chore, and what I am about to describe, it might be useful to imagine power amplifiers as energy adders.
The majority of audio amplifiers I've encountered were built-in closed metal boxes (with power cords), and every high school grad knows that energy is conserved: neither gained or lost. Therefore, if we want more energy at the output-if we want the amplifier to amplify-then we need to import energy from an outside source like our household AC line) and store it in something-capacitors-that's engineered to hold and release a rapidly varying stream of energy.
Audio frequency amplifiers are notoriously inefficient. Therefore, amplifiers of the highest fidelity must not only store (by necessity limited) volumes of stable standing energy in their capacitors; they must also have effortless access to a flow of fresh energy through their power cords (to fill and refill those capacitors) and, equally important, a direct, low-impedance path to an infinite source of free electrons from our good and gracious Mother Earth.
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Denne historien er fra February 2022-utgaven av Stereophile.
Start din 7-dagers gratis prøveperiode på Magzter GOLD for å få tilgang til tusenvis av utvalgte premiumhistorier og 9000+ magasiner og aviser.
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My last Far East trip
First comes the anticipation, that initial jet of warm water, that miraculous searching, finding the sweet spot, then heaven on earth as it cleans and caresses.
Riding the Common Wave
In the e-commerce era, brick-and-mortar dealerships must give customers compelling reasons to stop by. Los Angeles hi-fi dealership Common Wave's owner Wesley Katzir keeps customers coming through the door with a simple idea: that music matters in our everyday lives and that what he enjoys, other people will enjoy, too.
Mind Games to the bottom of the rabbit hole
After a wild decade in the biggest pop music group ever, John Lennon's post-Beatles years were spent in protest, in various kinds of therapy, in immigration court, and in search of a new musical identity.
Trane meets the Motor City
Detroit became a destination for migrating African Americans early, starting with the Underground Railroad; the city's proximity to Canada was convenient for those seeking to escape Southern slavery.
Vital art never rests
At this late date, it seems impossible that there could still be \"lost\" albums lingering in the vaults by musicians as important and successful as Johnny Cash and Paul McCartney.
DUKE IN 10
TO COMMEMORATE THE 50TH ANNIVERSARY OF DUKE'S DEATH, ROBERT BAIRD SELECTS A DOUBLE HANDFUL OF EXEMPLARY TRACKS FROM PERHAPS AMERICA'S GREATEST MUSICAL GENIUS.
Piega Coax Gen2 811
It's funny how we discover some music in unexpected, twisting ways.
Pass Laboratories XP-27
One of the pleasures of reviewing-and also using-products from Pass Laboratories is an encounter with Nelson Pass's writing, which can usually be found in the owner's manual and is always competent, insightful, and sometimes funny.
EMT 928 II
Modern turntables are a paradox.
Dynaudio Contour 30i
Ah, Denmark. Land of the Vikings and blue-eyed, blond-haired folk with faces sculpted just so.
