Announcement

Collapse
No announcement yet.

Testing Wattage?

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Testing Wattage?

    How can I see how much wattage I am putting out? Can I hook up a multimeter set it on AC and put it on the l and r while playing? I heard I might have to add a resistor as well from another audiophile? Is this correct?
    On the cheap diy. That is my motto - www.hifiposse.com

  • #2
    Are you measuring amplifier power? Ohm's Law basically. Voltage squared, divided by the resistance.
    ​A complex signal and a complex load complicate the results. You could use a Wattmeter but a Voltmeter and a pure test tone of 1KHz will usually suffice in lieu of more sophisticated techniques.

    Comment


    • #3
      So I see sites says there speakers are 1W @ 1 meter. Just wondering how they are checking that. I get the pure tone test. But a Watt meter is a good idea.
      On the cheap diy. That is my motto - www.hifiposse.com

      Comment


      • #4
        The 1W @ 1 meter is a way to measure the sensitivity of a given speaker ( this can be thought of as how efficient a speaker is but this is not really correct) Basically don"t worry about watts, it"s mostly marketing hype. Most music listening is well under 10 watts, often under 1 watt. There are exceptions such as headroom and subwoofers.

        Comment


        • #5
          Measuring watts is like herding cats. It varies so much so fast that you can't get an accurate reading.
          www.billfitzmaurice.com
          www.billfitzmaurice.info/forum

          Comment


          • #6
            input 60 cycles and set the voltage to 2.83V with a voltmeter on AC setting.
            R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio

            Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51


            95% of Climate Models Agree: The Observations Must be Wrong
            Gravity is an overrated force on the cosmic scale. Physicists are missing the bigger picture. They fell into a black hole and were never seen advancing the understanding of the cosmos again.

            Comment


            • #7
              Most all watt ratings you read from mfg.'s are based on a sine wave - amp power out, speaker power capability, etc. It's the only repeatable way to rate systems because the variables in music are endless. So if you an apples to apples comparison of your system vis-a-vis other systems' ratings, all you need is a sine wave signal and a good AC voltmeter (DVM) at the speaker inputs. W rms = (rms volts)2 / Speaker ohms.

              Sine wave signals are easy to generate on a PC, tablet etc. Here's a MS-Windows app for sine wave generation:

              https://drive.google.com/file/d/0B04...ew?usp=sharing

              Comment


              • #8
                Originally posted by Pete Schumacher View Post
                input 60 cycles and set the voltage to 2.83V with a voltmeter on AC setting.
                That's fine if he wants to measure a 60Hz sine, and if he knows the speaker impedance at 60Hz, but that's not what the original post says.
                www.billfitzmaurice.com
                www.billfitzmaurice.info/forum

                Comment


                • #9
                  Speaker sensitivity is rated at 2.83V (1W @ 8 Ohm), and most DVMs work well at 60Hz for a reason.
                  R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio

                  Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51


                  95% of Climate Models Agree: The Observations Must be Wrong
                  Gravity is an overrated force on the cosmic scale. Physicists are missing the bigger picture. They fell into a black hole and were never seen advancing the understanding of the cosmos again.

                  Comment


                  • #10
                    Originally posted by Pete Schumacher View Post
                    input 60 cycles and set the voltage to 2.83V with a voltmeter on AC setting.
                    ​1KHz seems to be the industry standard. I would measure at 100Hz, 1000Hz and 10,000Hz. Also, he should use a True RMS meter if he has one.

                    Comment


                    • #11
                      Originally posted by billfitzmaurice View Post

                      That's fine if he wants to measure a 60Hz sine, and if he knows the speaker impedance at 60Hz, but that's not what the original post says.
                      "but that's not what the original post says." Read that twice, still unsure what you mean.

                      "and if he knows the speaker impedance at 60Hz" Not relevant. Mfg.'s don't test and rate using a particular driver. All you need is the rms voltage and the "nominal" load impedance (e.g., 8 or 4 ohms). That will give you an equivalent rating.

                      "That's fine if he wants to measure a 60Hz sine" Agreed, for a cheap meter. A Fluke DVM will measure rms at all freq. - within its capabilities.

                      Comment


                      • #12
                        Originally posted by Millstonemike View Post
                        "but that's not what the original post says." Read that twice, still unsure what you mean.
                        As I understand it he wants to know how much power is being delivered when listening to typical music program. Considering that the delivered power will depend on the voltage output, which is never steady with music program, and the speaker impedance, which varies with frequency, the herding cats analogy applies, and every one of those cats is owned by Schrodinger. Without gear that the average user wouldn't have the best you can arrive at is a very rough approximation.

                        www.billfitzmaurice.com
                        www.billfitzmaurice.info/forum

                        Comment


                        • #13
                          Measuring the power of an amplifier is, at its basis, a trivial task. You would use a resistor so that you have a stable reference against which you can make repeatable measurements. You can expect reasonably good results by connecting an oscilloscope to the output and adjusting the amplifier output while watching for "sine clipping" (Google all these terms).

                          With a digital multimeter (DMM) you can measure the output directly at a fixed frequency. Most DMM I have tested are accurate to at least 100Hz but it's a good idea to check the bandwidth of the meter because trying to measure at a frequency beyond what it is designed to operate will give erroneous results.
                          The meter will measure a voltage. Even if the amplifier is clipping it will measure AC Volts - not DC. There is a popular myth that a clipping amplifier outputs DC voltage.
                          Simply square your result and divide by the resistor value. So if you measure 10V, it's 10^2 / R. For an 8 ohm resistor that's 12.5 Watts.

                          And that's it. There is no magic to determining power. The advanced users, such as myself, have distortion meters to quantify results, but the average person that just wants to know "how much power" doesn't need all that.

                          Comment


                          • #14
                            Originally posted by hobbyhands View Post
                            So I see sites says there speakers are 1W @ 1 meter. Just wondering how they are checking that. I get the pure tone test. But a Watt meter is a good idea.
                            To be clear - you are looking for calibration? or real time analysis while playing Music?
                            "Not a Speaker Designer - Not even on the Internet"
                            "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

                            Comment


                            • #15
                              So I have 2 goals. Perhaps I'm over thinking this. I would like to monitor the wattage live so as not to go past the suggest wattage of the drivers so I don't bust them.
                              On the cheap diy. That is my motto - www.hifiposse.com

                              Comment

                              Working...
                              X