A hundred years ago when I was in high school shopping for my first stereo, I was confused by amplifier power ratings. I was trying to compare receivers- starting with power as one of the most important categories.
In the late 60s the same amp could be rated at 30 watts, 22 watts per channel, or maybe even 70 watts IHF. The fact is, it was impossible to sort this out and compare apples to apples.
You would think this might have been sorted out over the years. But it hasn’t been. In fact, there is as much or more blatherskite going on today with amp ratings as ever. It’s downright devious.
What’s A Fair Playing Field?
There is a fair “standard” manufacturers should adhere to. Some do. They should rate power at:
*8 ohms
*20Hz to 20kHz
*Spec accurate distortion level at rated power
How tough is that? NAD, Bryston, Marantz and many others PLAY FAIR. Examples:
NAD C298, $2400: Power Amp
Rated 185×2
When tested by Stereophile mag, NAD exceeded claims
It actually did: 185×2, 20-20, .0005% THD.
It clipped, meaning it hit 1% THD at 275×2!
NAD M33, $6000: Integrated Amp
Rated 200×2
When tested by Stereophile mag, M33 exceeded claims.
It actually did 200×2, 20-20, .0002% THD
It clipped, meaning it hit 1% THD at 255×2!
Marantz Model 30, $3000: Integrated Amp
Rated 100×2
When tested by Stereophile mag, Model 30 exceeded claims
It actually did: 100×2, 20-20, .01% THD
It clipped, meaning it hit 1% THD at 165×2!
Bryston B135 Cubed, $7000: Integrated Amp
Rated 135×2
When tested by Stereophile mag, Bryston exceeded claims
It actually did: 135×2, 2020, .001 THD
It clipped, meaning it hit 1% THD at 155×2!
Now, how about some of the other guys? Step up to the plate fellas.
Benchmark AHB2 $3300: Power Amp
Rated 100×2
When tested by Stereophile mag, AHB2 reached claims, barely
It clipped, meaning it hit 1% THD at 108.
Parasound Halo $2500: Integrated Amp
Rated 160×2
When tested by Stereophile mag, Halo didn’t achieve claims
It only achieved its rated power of 160×2 when it went into clipping!
Cambridge CXA81 $1300: Integrated Amp
Rated 80×2
When tested by Stereophile mag, CXA81 didn’t achieve claims
It was above rated distortion at 80×2 and clipped at 89×2.
Further, how about some tube amps.
Jadis Orchestra Integrated Amp $5000
Rated 40×2
When tested by Stereophile mag, Orchestra didn’t achieve claims.
It clipped at 14×2!
Prima Luna ProLogue Integrated Amp $2500
Rated 35×2
When tested by Stereophile mag, Prima Luna didn’t achieve claims.
It clipped at 21×2!
Mastersound Compact 845 Integrated Amp $10,495
Rated 30×2
When tested by Stereophile mag, C845 didn’t achieve claims.
It clipped at 11.5 x2!
What Does This Mean?
Wattage is certainly not the only factor that we would consider in shopping for an amplifier.
But power IS an important starting point.
It isn’t kosher for a company to say it produces 160×2, but that power is only achieved at a high level of distortion = clipping. If you took that same 160×2 amp and re-rated it to where its power was .2% or whatever their claim is- the accurate power level would be closer to 100×2. You would view it in a different light at 100×2 vs 160×2.
NAD’s C298 is rated at 185×2 because NAD is very proud that its distortion level is still incredibly low at that rating. C298 clips at 275×2. If NAD played ball like many other companies,
they would list its power at 275×2. They would likely sell more amps if they said it had 275×2
instead of 185×2. But NAD is rating at a super conservative standard- not cheating!
If you bought a truck based on its towing capacity, you’d feel deceived if said truck couldn’t pull the boat you planned on. Even if there are other features of the truck you like, achieving stated
power is job number one.
The fact is, the vast majority of speakers out there LOVE POWER. All things being equal, power helps them start and stop faster. They’ll sound more clear and taut.
We can help you sort through the knuckle balls various advertising departments are throwing your way!