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  1. #1
    Romeo Delight
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    11.07.13 @ 11:34 AM
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    Amps...watts...ohms...volts...??

    Can anyone please help me on my learning curve of amps. I mean, other than just playing guitar, I've never before understood amps and their details. Now I have a better appreciation and want to understand as much as I can. If anyone has any links that can help me out, that would be great too.

    What does the "watts" represent? What's the difference between 120 watts and 60 watts?

    What are ohms and what to they represent?

    What about volts?

  2. #2
    Romeo Delight
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    08.13.09 @ 01:54 PM
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    let's see...

    voltage is measured in volts
    current is measured in amps
    resistance is measured in ohms

    the basic equation to measure most electrical performance is ohm's law. it is, v=ir, or voltage is equal to current x resistance.

    here's an analogy...think of water rushing through a garden hose. if you crimp the hose, you slow the water down. the crimping of the hose is you increasing the resistance. so the diameter of the hose determines how fast (amps) and how powerful (volts) the water is travelling through the hose.

    then there's power. it is measured in watts. power is equal to voltage x current (p=vi).

    good luck.

  3. #3
    Good Enough
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    03.30.13 @ 09:28 AM
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    Quote Originally Posted by the insider
    let's see...

    voltage is measured in volts
    current is measured in amps
    resistance is measured in ohms

    the basic equation to measure most electrical performance is ohm's law. it is, v=ir, or voltage is equal to current x resistance.

    here's an analogy...think of water rushing through a garden hose. if you crimp the hose, you slow the water down. the crimping of the hose is you increasing the resistance. so the diameter of the hose determines how fast (amps) and how powerful (volts) the water is travelling through the hose.

    then there's power. it is measured in watts. power is equal to voltage x current (p=vi).

    good luck.
    That's nice. I'm sure that explained it all and left no question whatsoever in Flet's mind.

    Flet, if your "tube amp" is set to put out 60 watts that's very loud and will keep up with just about anything going on around you on stage. If it's set to deliver an output volume of 120 watts and it's cranked through a 4x12 speaker cabinet you'd better glue your fillings down before you stand in front of it.
    I said tube amp because solid state amps (no tubes) will not be as loud at the same rated wattages, which means on the average a 60 watt solid state amp will be as loud as a 20 to 30 watt tube amp. They may appear louder but will get muddier as the volume increases while a good tube amp will keep a tighter, more focused sound to cut through the mix better.
    If you're going to get a solid state amp for the stage I'd think about something along the lines of 100 watts.

    The ohms on the back represent what the output transformer of the head or amp wants to see to work efficently. The ohms on the back of the speaker are it's resistance to an electrical current. A speaker or speaker combination is rated at 4, 8, or 16 ohms to match what the output transformer wants to see.
    The transformer has wires, or "taps" in it attached to the outside speaker plugs, that are set to match the ratings of your speakers. If the ratings don't match you'll change the tone, power, and in some case ability of the transformer to disipate heat from itself. In a worst case scenario with no speaker load attached, the very high voltages inside an amp will cause those voltages to arc across the output tubes and burn out all kinds of things, usually resulting in big wads of cash to replace, and in some cases with improper amp grounding you won't have to worry about cash because all your worldly worries will be over.
    In other words, if your amp says 8 ohms at the back make sure the speaker load is 8 ohms. There are exceptions but this is probably confusing enough.

    There are all kinds of other things that make up an amp's ability to deliver tone as opposed to volume, but volume and speaker load were all you asked about.

  4. #4
    Little Dreamer Floyd the Barber's Avatar
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    02.22.05 @ 02:30 PM
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    there's a switch on the back of my amp head that selects 40, 80, and 160 and found out eventually,by calling techs is this.

    160= 1 cab
    80= 2 cabs
    40= more than 2

  5. #5
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    02.18.11 @ 08:09 PM
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    Default building my own amps ...

    hey just curious, what sorts of electronics courses would one haveto to take to start building your own amps?

    obviously it's a very dangerous hobby, but sounds like a great deal of fun.

  6. #6
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    12.19.16 @ 05:15 PM
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    Don't let those wattage ratings on the back of the amp fool ya. If it is near the AC cord it is power CONSUMED. I've had many people tell me their little peavey amp had 240 watts knowing full-well it only put out 60 watts. That other 180 watts is expended as heat.
    To further expand on Ohm's law, Power=Current X Voltage, or P=IV, power expressed as watts, current as amperes, and volts as, well, you know.
    All the variables in the two formulae, P=IV and V=IR are interchangeable giving you a plethora of options to calculate the four quantities, such as P=IČR or I=√(R/P).

    But that's DC. AC gets way more intense. Resistance becomes impedance. And to think Edison wanted to make our power plants DC. Anyone care to expand on why that is a very stupid idea?

    Next week: Light bulbs and how I blew my interview with Bell Labs. Can you say positive temperature coefficient?

  7. #7
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    hehehe!

    love that.


    good info.

 

 

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