Hello Dj7675,
Since I own x8500 as well, I'm wondering if other amps inside the receiver would measure better (or worse). I'm using bi-amp configuration with front amps running the two five-inch woofers in my KEF R500 and hight2 amps are running the Uni-Q. I learned from you that I can now go to the custom setup and turn other amps off when I'm listening to two-channel music. I hope this would cut down on the heat that is generated by this receiver.
Also, I'm wondering what other engineers here have to say about Denon's take on the bi-amp configuration. Does this statement make any sense to audio engineers?
"Bi-amp connection is a method to connect separate amplifiers to the tweeter terminal and woofer terminal of a speaker that supports bi-amplification. This connection enables back EMF (power returned without being output) from the woofer to flow into the tweeter without affecting the sound quality, producing a higher sound quality."
All of the power amplifier boards in the X8500H and X6700H have the same design. Connections from the power amplifiers to the preamp outputs are the same. The power amplifiers share the power supply in parallel.
Differences in performance, if any, would be due to normal production tolerances, whatever they are in this case, and out-of-spec. production/parts. All of these causes of differences between power amplifier channels seem random among channels.
As a note; the amplifier boards may require some manual assembly. Higher labor content many drive production to a low cost country. The X4700H and X3700H amplifier boards are likely made in Vietnam along with the overall products since that is a low production cost country. It's possible that the X6700H and X8500H amplifier boards are made in the PRC, Vietnam or other low cost area by a third party.
Several X8500H and X6700H power amplifier boards have effectively been tested as part of the overall products. These power amplifier boards have tested a bit worse than the power amplifier channels in the X4700H and X3700H. They have also shown variability in results.
The design of the X4700H and X3700H power amplifiers is different from that is two higher priced units. If you are into Bode plots, looking at the distortion vs frequency vs. output chart for the power amplifiers in the ASR measurements it appears the two sets of AVR's would have different bode plots. Not better or worse, just different.
The separate power amplifier boards allow for more channels to be squeezed into an AVR. They also are good for marketing purposes. Much like higher prices, the separate boards seem to have a phycological effect, that is, more is better.
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