What Does Watts Per Channel Actual Mean?

Discussion in 'Audio Hardware' started by AcidPunk15, Aug 7, 2017.

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  1. Claude Benshaul

    Claude Benshaul Forum Resident

    This is true but we human are always seeking to put things on a scale and look for the one universal comparison metric. You will find the same phenomena with IQ, BMI, Cholesterol. MPG, DPI, basically every facet of our life has a metric that is known to all and practically useless when trying to derive meaningful conclusions. So it's not surprising that watts is the first thing people looks at when buying amplifiers.
     
  2. chervokas

    chervokas Forum Resident

    True but even a rough number is better than no number, otherwise we'd have 15 watt amps and 300 watt amps sitting out in the market and we'd be choosing blindly between very different amps as we consider our needs.
     
  3. RiCat

    RiCat Forum Resident

    Location:
    CT, USA
    Yes just as horsepower tells you the worth of a car. Yup bigger is better and the marketers have preyed upon the buyers willingness to believe that to sell just about any piece of crap imaginable. In this forum I have always thought we strive to present views and information that permit the derivation of meaningful conclusions.
     
  4. Thorensman

    Thorensman Forum Resident

    i truly think what matters is the correct matching between an amplifier and loudspeaker,
    Damping factor is another measurement which dictates how well the final sound quality bodes.
    The higher the figure the better .a high
    DF controls the bass cones.
    Too low a DF and the cones move
    In an uncontrolled manner resulting in poor bass perfirmance.
    KT 88 and others can probably explain better than i.
    What I am pointing out is that you don,t need that many watts if your speakers are well damped and efficient
    I run a 10 watt tube amp with 92db/w
    Speakers and the volume is awesome.
    Smaller speakers cannot in theory shift as much air as a bigger speaker so require more wattage.
    I believe in the 6o,s most speakers were
    Big as mono ruled for many.
    As stereo became more common and the need for an extra loudspeaker resulted smaller speakers . Smaller speakers started appearing as the long suffering wife
    Would not tolerate 2 large speakers .
    Now, to get more bass from a small loudspeaker ,You reduce its efficiency, and provide more wattage ( and hopefully CURRENT) and this gives the feel of greater bass response !
    Remember that transistors were becoming very popular as high power was easily obtained quite cheaply.
    Musical Fidelity i know this side of the water provide loads of current in there amplifiers .
    A good dealer ( maybe rare today ?) should be able to demonstrate this.
    Need for correct matching.
     
    Last edited: Aug 9, 2017
  5. head_unit

    head_unit Forum Resident

    Location:
    Los Angeles CA USA
    Heh, one school of thought holds that there is no such thing as RMS
    "What's a Watt (rms)?"
    AES E-Library » What's a Watt (rms)?
    but I have not read this in so long that I forget what the argument was. You could think of RMS (Root Mean Squared, a mathematical operation) as a way to try and equivalate sine wave power to DC power (particularly insofar as heating of wire by the passage of current is concerned). Reputable amps are specified as RMS because "peak" means nothing. Actual "RMS" is not a be-all and end-all, because amps are tested into resistors and real speakers are NOT resistors, not even close.
    You are almost correct-the RMS value of a sine wave is 1÷(square root of 2) ≈ 0.707 times the ZERO-to-peak value (not peak-to-peak)
     
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  6. head_unit

    head_unit Forum Resident

    Location:
    Los Angeles CA USA
    Manufacturers historically offer amps in power increments which equal the marketing department's need for particular price points. Seriously.

    And by the way, from a long series of conversations I had with the top amp engineer at a large consumer and OEM company, it is not really the wattage that costs. It is mostly the current output that costs. Transistors really push current, and the voltage is a byproduct. It's not so hard to get high voltage output, but it IS hard to get high current output. That is why for example long transmission lines run at very high voltage, to minimize the current...well, OK, it's not really quite the same thing but kinda sorta.

    In other words, a 1000 watt into 1 ohm amp will be considerably more expensive than a 1000 watt into 16 ohm amp.
    - Suppose your transistors can each output 1A of current. The 16 ohm amp needs 8 transistors. The 1 ohm amp needs 32. That is some of where the cost goes. The power supply is also a lot more expensive because again it is the current delivery that is expensive-you need much beefier parts to push more current into the amp section.
    Once upon a time Crown had an amp that could drive 1? 0.1? ohm (it was really for medical use). The power output was high, but not insanely so, however the price WAS steep, due to all that current output capability.
     
  7. chervokas

    chervokas Forum Resident

    I have to beg to differ with you about the meaningfulness of damping factor. Damping factor is just the nominal impedance of an imaginary speaker -- say, 8 ohms -- divided by the output impedance of the amp (and the resistance of some imaginary length and gauge of speaker wire). It's not a particular characteristic of the amp, it's just another way of turning the spec of output impedance into something that can be marketed. But since speakers aren't resistors and don't have fixed impedances -- they vary considerably with frequency -- and other factors, like the phase angle of the speaker, will also affect how much current the speaker might demand at low frequencies, and since we don't all use the same length and gauge of speaker wire, the spec sheet's damping factor isn't really that meaningful. Most solid state amps have very, very low output impedances and so have very, very impressive damping factor numbers. Most tube amps the opposite. The tube amps can still sound good, but they might be better served by shorter, thicker wires, and of course, care with respect to the speaker's impedance curve or yeah, sometimes the bass control can be sloppy.
     
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  8. chervokas

    chervokas Forum Resident

    It's not really a question of which is better or not, it's just a matter of being able to have some basic information about the products. I mean there is a difference between my brother's 400 horsepower muscle car and a 130 hp Camry. You wouldn't want no information about an amp's output power, even if you need to take specs with a grain of salt and all the measurements aren't taken the same way or reported fully.
     
  9. Thorensman

    Thorensman Forum Resident

    I
    i stand corrected. I kind of thought it might complete amp measurement.
    I read about DF and its effect on say a low power amp in relation to driving a loudspeaker.
    Despite using a few watts my amp/speaker produced decent bass
    Sometimes a certain
    Combination sounds good in spite of measurements.
     
  10. AcidPunk15

    AcidPunk15 Forum Resident Thread Starter

    Location:
    New Brunswick, NJ
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