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D28boy

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This is something that's bothering me but I can't seem to find an answer on the interweby and I know we have a few tecchy types on here.....

 

Does a 100 watt amp use the same amount of electricity as a 100 watt light bulb ? If not why ? [blush]

 

I´m absolutely no expert but i think the amp needs more energy to produce the same effect, heat loss is higher in an amp i believe, but i´m sure someone gonna shoot me down [biggrin][rolleyes]

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Hey, finally someone who realizes "watts" is a measurement of power consumption, not volume level. So... you're not stupid, in fact you're WAY ahead of the game.

 

The power consumption of your amp is not the "output" rating, but SHOULD be listed on the SN plate, or printed on the chassis with the amp specs.

 

The name plated on one of my old Music Man amps list the specs as follows:

 

Input: 120v, 60hz, 1.6 amps

Output: 65 watts R.M.S.

 

1.6 amps is the draw out of the electrical outlet. To me "amps" is a much more useful thing to know than "watts", for line voltage and hertz are a given constant. As electrical circuits are protected by circuit breakers sized by "amps", knowing your amp draw, and adding them together for the various equipment on the circuit, gives you your operational and safety calculations.

 

As for "watts", stated above (with formula), 1.6A at 120v = 192w.

 

To easily go from watts to amps without the fancy math, just figure 1A per 100w draw. This simple conversion automatically gives you a little headroom and safety factor.

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An amp with 100 watts output uses more than 100 watts input because it uses up a lot of juice inside the amp making the signal go from the input to the output.

 

Like Larry said, his amp "uses" 192 watts and "puts out" 65 watts. That's when the amp is turned all the way up and all the bells and whistles are on. The rest is used up internally and ends up as heat and light energy.

 

The rated input is the amount of wattage going through the wires from the AC plug to the amp. The rated output is the amount of wattage that's going through the wires from the amp to the speaker. [thumbup]

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I have a 40 watt all tube Egnater Tweaker and I put a clamp on amp meter on the input power cord and I was shocked. At a nice volume and that was loud but not deafening I was only reading .6 to .7 amp AC. With the Gain at max and the volume at max it was about 1.75 amps AC I also did with my 100 watt solid state B100 Acoustic Bass amp and the current was lower. At a nice volume with the gain at about 1/3 and the volume at 1/2 it was only about .5 amps AC.

 

And what is the name plate listed input ratings on the above amps?

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I have a 40 watt all tube Egnater Tweaker and I put a clamp on amp meter on the input power cord and I was shocked. At a nice volume and that was loud but not deafening I was only reading .6 to .7 amp AC. With the Gain at max and the volume at max it was about 1.75 amps AC I also did with my 100 watt solid state B100 Acoustic Bass amp and the current was lower. At a nice volume with the gain at about 1/3 and the volume at 1/2 it was only about .5 amps AC.

You forgot to switch on the Turbo! [thumbup]

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The name plated on one of my old Music Man amps list the specs as follows:

 

Input: 120v, 60hz, 1.6 amps

Output: 65 watts R.M.S.

...

 

As for "watts", stated above (with formula), 1.6A at 120v = 192w...

Just for fun I checked the plate on my own old (1977) M-M 212 65 and it reads;

 

Input: 220v, 50Hz, .9 amps.

Output: 65 watts R.M.S.

 

Being a U.K. version it has the higher voltage but using the same wattage calculation we get pretty much the same result;

0.9A @ 220v = 198watts.

 

"Ye Canna' Change the Laws o' Physics!" as Scotty used to say.

 

P.

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The upper physical limits at full output power are 78.5% in class B operation, and 6.25% in class A operation. When about valve/tube amps, the power consumption of the heaters will also come into account.

 

In general, valve tube amps dissipate typically more than 75%, BJT class AB circuits more than 30%, MOSFET amps more than 40%. Without output signal, they all make just heat out of 100% the input power but will consume significantly less, too.

 

As for the light bulb, filament lamps effect around 12...16%, halogen bulbs up to 22%, all the rest will also be heat.

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