Firstly, let me just say I've nothing against Rotel whatsoever, I just find their specification misleading compared to those of some other manufacturers.
The specifications clearly state FTC for the power rating. This means continuous power, all channels driven, at the bandwidth, load, and THD specified (in this case 20hz-20khz, 8 ohms, <0.03%THD).
Ok, FTC (Federal Trade Commission) was something I wasn't familiar with. For the benefit of anyone else who may be interested and didn't already know: it is an independent agency of the US Government for the protection of consumers.
According to the relevant section (432.3 for power amplifier output claims):
(e) Rated power shall be obtainable at all frequencies within the rated power band without exceeding the rated maximum percentage of total harmonic distortion after input signals at said frequencies have been continuously applied at full rated power for not less than five (5) minutes at the amplifier's auxiliary input, or if not provided, at the phono input.
In Rotel's specification it does not actually state a "rated power band". Neither is there any frequency range next to the power figures. It does state a frequency response (10 - 40 kHz ±3dB), but this is definitely not the same thing as a "power band" or "power frequency response". That wasn't my original point though.
Power consumption, by FTC and EIA standards, refers to the long-term consumption while outputting 1/8th of the power rating. Due to the very high peak-to-average ratio of musical content, this represents the output at which a typical amplifier occasionally clips on transients. (Good amps don't, hence the resurgence and importance of additional specifications based on concepts of dynamic/peak power...at least from a few manufacturers). Consumption can also be stated at a specified output (eg idle, 1/3 power, full power, specific power).
Where in this Rotel specification for power consumption does it state FTC or EIA standards? It doesn't!
Quite often two power levels are stated for electrical equipment and sometimes they use three. If three are stated they are usually for stand-by, idling and the maximum power (or current) the equipment could possibly draw from the supply. This maximum figure is required fo electrical safety and supply considerations. Are you suggesting dingwall that the 600 watt power consumption figure quoted in this specification is not the maximum power this amplifier can draw from the supply?
The signal voltage even at a massive 600W into 8 ohms is only 70V, so an amplifier can in theory output many multiples of the fuse current rating without using power reserves. However in practice to achieve high power, you do need the big transformers and capacitors to supply the current needed. (Current delivery is difficult and a limiting factor linked to dynamic power. You can say that continuous power rating alone does not predict or correlate with transient/shortbust power, but the peak current does. Impedance dips in the speaker load also need less voltage and more current at the same power. Hence the importance given to this specification...at least from a few manufacturers.)
On any amplifier high continuous power output relies on a large transformer and the maximum current output (peak power output) relies on the size of the output capacitors. With regard to
"an amplifier can in theory output many multiples of the fuse current rating without using power reserves" yes, a great many amplifiers can output more current than the fuse current rating, but that's nothing to do with my original concern with the specification. What I'm saying is that you cannot input a certain maximum power (watts) and get a
continuous power out to the speakers which is a higher figure than the maximum power consumption figure.
If this 600 watt power consumption figure is not a maximum figure then I don't know what use it is. If it is a maximum power consumption figure then this amplifier cannot output a continuous 1000watts.
I think Rotel are owed an apology!
Not yet, I still think Rotel's specifications are misleading!
