# HK AVR247 vs. HK AVR645



## azgreenb (Nov 19, 2007)

I own the HK AVR645 but I keep seeing the Best Buy ad claiming that the AVR247 has:

"595W: 85 watts x 7, THD <0.07%, @1kHz into 8ohms"
&
"350W: 50 watts x 7 (All channels operating at full-rated power)"

While my AVR645 states:

"75 Watts per channel @ <0.07% THD, 20Hz – 20kHz into 8 ohms"

I believe that my AVR645 is more powerful than the AVR247, but what is the difference bewteen the two ratings? 

It seems deceptive of BB to use the 595W spec when in actuality the 350W is the more realistic.


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## brent_s (Feb 26, 2007)

BB is just repeating what H/K has spec'd for the 247. 

There is no FTC standard for rating the power of multi-channel amps, only stereo. Most stand alone amp makers still spec the all channels full frequency range power and H/K usually does that with their receivers as well. However, with the 247 it looks like they've chosen to also play the specsmanship game that other receiver manufacturers have been using for a number of years. The 247 will produce 85 watts as specified into any given channel, maybe even a pair simultaneously and that's enough to settle any legal issue. Take a look at any bench measurement of a receiver where the reviewer did an all channels power measurement. Very few will even come close to their advertised power rating when driving all channels at once. For instance, the Yamaha RX-V1800 is rated at 130x7, but only produced 55x7 @ 1Khz on the Bench. Chalk one up for THX certification...HomeTheaterMag just measured the Onkyo 805 to hit 120x7/160x5 (no frequency range given) with a 130x7 spec.

The good news is, so far, no one has found 5/7 channel full power content in real world usage. 

-Brent


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