My protection kicked in.

@@andysummersthxcinemaandmyc7748 you're a real classy guy, do you talk that way around your mother ???

@@andysummersthxcinemaandmyc7748 Go play in your own goddamn sand box. Don't shit in ours. Go out to Fry's for your pitiful portable picknick player to play your fuzzy warbles on.

Don't feel alone mate! That was tough one

Ohm's law

It will get clearer over time. Consider that another name for voltage is ‘potential.’ With the volume knob at ‘0’ there should be no voltage at the output of the amplifier. As the volume is increased, the voltage at the output of the amplifier increases. (Be careful testing this, since some ancient amps must have a load, or they will self-destruct.) Now add a speaker to the output: without any intervention from the amplifier, two things will happen (1) part of the voltage will now drop across the speaker, (2) current will flow out on the ‘hot’ wire and back on the return or ‘common.’ In this situation power is now being consumed by the load (that is, the speaker), and the voltage ‘potential’ is now being realized. The power consumed is noted in Watts (Voltage x Current, V x I). But wait, there is more: since there is a ‘power’ amplifier in the circuit, and since there is a speaker also in the circuit, and music or other tones are being played two more things happen: (1) the speaker presents a varying load to the amplifier, and (2) the amplifier varies the amount of current delivered to the speaker terminals in order to maintain the voltage called for by the volume knob. [It does get a bit more involved in that the ‘gain’ and current levels may be a DC component setting the bias or average level which is more or less modulated by the AC signal waveform, but generally speaking the volume knob sets the voltage target the amp tries to achieve while the speaker load sets the current demand required to achieve it.] At any rate, if the amplifier is unable to supply the current required by the load to do its work, bad things start to happen: (1) the amplifier begins to clip, tops and bottoms of signal voltage are cut off because the amp is unable to produce enough current to achieve the peaks and valleys, the user hears distortion, if this situation continues long enough, things start to heat up and thermal protection circuits are triggered. If no corrective action is taken, and the situation continues, or gets worse (volume is increased further to ‘get past’ distortion, something is going to blow. The signal will start to resemble an elevated straight DC signal, the voice coil will heat up, and the amp’s fuses (if equipped) will blow, or the speaker fuses (if equipped (will blow). If neither the amp nor the speaker is equipped with fuses, the voice coil will weld itself to magnet, which will present a dead short to the output of the amplifier, where parts damage to the output stage could result before the fuse at the power supply inlet finally blows, if so equipped. Hope this explanation helps. It is really important to understand that a load will pull down a supply voltage. In weightlifting terms, most everyone can manage (has the potential) to lift 25 lbs.; not everyone can manage to lift 300 lbs., at least for very long, although it it probably true to say we could potentially do it, flow of adrenaline, etc. So, when you turn up the volume, especially into low-efficiency speakers, you are piling ever more weights on the bar; if the amp isn’t strong enough, something will buckle. With very efficient speakers, 25 Watts (or even 2) can be enough to achieve decent levels of loudness; with less efficient speakers, even 500 Watts May not be enough, or so they tell me.

You aren’t considering current in your equation. Watts = Power = Voltage x Current (V x I). The gain, as Paul explains, is set by voltage; but the Watts are determined more by the speaker load where V = Current x Resistance (V = I x R). So the resistance of the speaker has a great deal to do with the Voltage at the output of the amplifier. To make things more interesting, the resistance at the speaker varies with frequency, in fact, resistance to an AC waveform is called Impedance. (Impedance itself has two components, Capacitive and Inductive; Capacitive decreases with frequency, Inductive increases with frequency. Capacitive resistance [or reactance] current leads voltage [capacitors take time to charge]; Inductive resistance [or reactance] Voltage leads current [inductors take time to build the all important electro magnetic field]. The math to figure out AC signal characteristics is quite involved, and not easily measured, at least its component parts called out above, but its nature assured us that every speaker and amp design will be a bit different. Crossovers can be as much art as science and are peculiar to the drivers chosen. Getting back to your equations, more power will be required of different speakers presenting different loads to the amplifier. Generally speaking, highly efficient speakers present less of a load to the amplifier than less efficient speakers, but less efficient speakers seem to offer the speaker designer with more options in shaping the sound (judging by their preponderance in the market). Finally, as to power requirements vs ‘loudness.’ The relationship is not linear, as Paul mentioned at the top of his video, and I think he helped us all by eliminating from his discussion, but just as twice the voltage does not equal twice the power in practical terms (ideally this is true P=IV), twice the power does not equal twice the volume, due to the (relatively) sensitive nature of the human ear. Power increases along a logarithmic curve, such that: For a two-fold increase in electrical power, there is 3 dB increase in sound power, for a four-fold increase in electrical power, there is a 6-fold increase in sound power, and only when there is a ten-fold increase in power, do you get a corresponding ten-fold increase in sound power. As a Goggle search reminded me, decibel itself merely expresses a ratio of powers. Generally speaking, you need a lot more electrical power to gain a similar increase in sound power. So, while the values chosen for your example are valid, it wouldn’t work well unless you continued to add zeros (10 fold at a time). Anyway, I think you’re close to gaining an understanding, keep at it, and be careful. I’m not an engineer, either.

Because they talk about volts and gain is displayed in DB

tube life will be diminished, how fast depends on output or input tube and how the mfg. pushes the tubes with circuit design as some mfg.designs run the tubes less "hard" than others

I have a tube amp: I try to remember to turn it off if I will not be listening for a couple of hours or more.

Thanks for the two replies lady and gentleman. Very refreshing to hear from a woman audio enthusiast. Now let's see what uncle Paul says on the subject of tube life whether or not to lean on when not in use. Happy listening.

I'd say chose a loudspeaker that you prefer the sound of and then consider what amplification you need and want.

More watts and good old 85db bookshelf speakers

Both thanks

The man owes you *nothing* , douchebag.