• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Peak Power from tube amps

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RMS was defined before there were amplifiers. Root Mean Squared, a pure math concept.
And, it was not confined just to sine waves.
After that, RMS was utilized as a measurement for AC Power (Edison or Tesla anyone?). It was defined as Sine Wave Voltage that had would heat a resistor, just the same as if the voltage was DC.

By the way, DC is as average as it gets.

Example:
120VDC into a 120 Ohm resistor will have 1 Amp current. The heating power is:
120VDC x 1 Amp = 120 Watts.

For a 120VAC pure sine wave, it will have exactly the same heating effect on the 120 Ohm resistor as the 120VDC above (120 Watts).

It turns out that for a pure sine wave, the Crest (peak) of the sine wave Voltage is Root(2) x the RMS Voltage. Root(2) is approximately 1.414.

Notice that if you square Root(2), you get 2.

Power is also defined as (E squared)/R
For DC (E squared)/R
For a pure sine wave: (1.414 x Vrms squared)/R = 2/R

Therefore, the peak power of a pure sine wave into a non reactive resistor is exactly 2 times the RMS power.

The amplifier industry has had many "wonderful" marketing terms, and "ways" to present
amplifier performance.

Decades ago, marketing had a power measurement that was 1 dB higher, or some such nonsense.

Then there was the marketing ways to present frequency response:
1. +/- 1 dB from 20Hz to 20kHz looks OK, right?
2. +0, -2 dB from 20Hz to 20kHz looks worse, right?
Both amps have a 2 dB difference of the highest amplitude to the lowest amplitude.
Yes, you can argue that one 'seems' to have a better smoother, flatter frequency response, but those 2 specs do NOT prove it.

And, +/1 dB numbers are smaller than 2 dB . . . yeah, right.
If the amp is $299.99, it is cheaper than a $300.00 amp, but not significantly so,
only psychologically so.

For a really confusing concept, how about the 'Peak RMS power' of a Radar Magnetron?
 
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