Originally Posted by happy hopping
Rated Output Power (1kHz, 1ch driven) 115W (8ohms, 0.9% THD)
Rated Output Power (20Hz-20kHz, 2ch driven) 80W (8ohms, 0.09% THD)
what exactly does it mean by 1 channel driven vs. 2 channel driven? What does that mean in plain english?
I use Klipsch 5.1, 100W / chnl.
AVRs generally share the same power supply among all of their 5-11 power amplifiers which is a good idea. Every power supply has a tendency for its output voltage to do down when the current draw goes up. The more concurrent channels you operate at high levels and with a speaker load, the greater the current drain and the lower the power supply voltage becomes. As the power supply sags, the maximum possible undistorted power from any channel decreases.
It is a mistake to think of the power ratings of speakers and the power output of power amplifiers as being closely matched. One reason for this is that the power ratings of speakers are actually far more complex than the single numbers that you see on spec sheets. For example the undistorted power handling capability of speakers drops precipitiously in the bass range.
For example, this is the maximum power handling capability of a theoretically perfect SOTA 6 1/2" speaker (real speakers are even more limited than is shown here):
Freq,Hz Max SPL, DB Displacement Limited Max power, Watts
20 81 0.1
30 88 1
40 93 2
50 97 5
60 100 11
70 103 20
80 105 34
90 107 54
100 109 83
130 114 236*
* The speaker is thermally limited to 100 watts so it really can only put out about 110 dB SPL
On the spec sheet this speaker may be rated at 100 watts, but as you can see at 60 Hz (which is really a pretty high bass frequency) this speaker can only take 11 watts before it begins distorting pretty seriously. Rrunning out of Xmax or displacement capacity is the speaker equivalent of clipping.
I don't want you to get too engaged with my model as disturbing as it may seem. I want you to understand that saying a loudspeaker can handle so many watts is like saying that a full 2 gallon pail weighs so many pounds. In reality the weight of the pail varies depending on whether you fill it with foam beads, oil, water, sand, or lead shot. Think of bass as being the lead shot of audio.
Stepping back to the power amplifiers in your AVR the big disconnnect between specs and real life usage relates to the difference between running amplifiers with pure tones on a test bench with a resistive dummy load, and playing music into a normal speaker load. Audiophiles have long thought that speaker loads and pure test tones are easy and that speakers and music were hard. Reality is very different as I first discovered when I started testing amplifiers with loudspeaker loads and music more than a decade ago.
Test tones and resistors have been the standard for testing amplifiers because for one thing it is easier to do and easier to analyze the results. About a decade ago I decided to take advantage of some more sophisticated knowledge about signals and systems analysis that could only really bear fruit if you used computers for testing audio gear. I had a good friend of mine who had about a dozen well-known (Bryston, Crown, Parasound, etc.) audiophile amplifiers sitting around to a 1 day long amplifier testing binge. Basically I hooked each amplifier up to resistive and loudspeaker loads and ran approximate 2 minute recordings that contained a mixture of test tones and music. I captured the results with a computer and did the actual analysis later on.
The actual equipment tests showed some pretty dramatic differences that were audible and visble. When we ran the test tones into standard load resistors we stressed the local infrastructure which included dedicated 30 amp power circuits. line voltage stabilizers that weighed about 100 points, and banks of forced-air-cooled high precision temperature insensitive load resistors. Cables got warm, equipment hummed, and the room picked up a dozen degrees. When we ran music everything acted like it was tea time. When we ran into speaker loads, everything acted like it was on vacation.
If you have a subwoofer and are playing music and movies, it is likely that the bench test results for a single channel are a good estimate of how your AVR is challenged in actual use.