🚀 go-pugleaf

In article <1993Jan27.000515.19195@parc.xerox.com> tapscott@parc.xerox.com (Peter Tapscott) writes:
>
>
>Using the equation P = V^2/R to estimate power is OK if
>the correct V is used. 
>
>I assume that the actual DC voltage is higher than 12, say 14.5
>volts, but that the 2.5 volts is needed to boas the output transistors
>of the amp, so I will use 12V to be consistant with Lennard.
>
>A sine wave must be produced to measure RMS, so its max peak-to-peak
>voltage is 12 volts. Its peak voltage is half that, 6V. The RMS voltage
>is (SQRT 2)/2 times that, or about 4.2 VRMS. I will use 4VRMS for
>simplicity. Then,
>
>P = 16/R for a 12 volt DC supply. For an 8 ohm speaker, the max
>output is only about 2 watts. Figure 4 watts for a 4 ohm speaker.
>

  This calculation seems to be correct, does this mean that all deck makers are
lying ? Since almost all decks have a rated power of about 4 - 12 rms. Some of
the so called high-power decks even boast of 25rms such as many Pioneer decks 
nowadays. I seen the insides of some of these decks, and they dont seem to have
any switching supply along with a current power step-up transformer. Also if you
look at any transitor,IC catalog such as ECG or NTE etc, there are IC's along
with the specs listed. These are the same IC's used in low power applications,
they are usually rated at about 8-12 watts using 12V directly. WOuld someone
care to further clarify this issue ?