Minimum Impedance? or Nominal?

Discussion in 'Audio Hardware' started by Katz, Feb 14, 2020.

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  1. Katz

    Katz Well-Known Member Thread Starter

    Location:
    Bucharest
    Hello there

    I own a pair of Triangle Genese Quartet - they are rated at nominal 8 ohm, minimum 3.5

    My amp is a Yamaha A-s2100, with 100 watts into 8 ohm and obviously more into less ohms

    My question is, which impedance matters? Nominal or Minimum?

    Or rather, if my amp specs say that they push 160 watts into 4 ohms, yet the minimum impedance on my speakers is 3.5 ohms...should I understand that the amp pushes north of 160 w into my speakers?

    I've no idea. As the great Michael Scott said, "explain it to my like I'm 5" please
     
    rischa likes this.
  2. chervokas

    chervokas Senior Member


    What really matters is the amp's ability to deliver current and the speaker's demand for current. You can't necessarily tell even by looking at the minimum impedance -- if that 3.5 ohm impedance is at 10kHz, it doesn't matter much at all, there's almost no musical energy up there and you're just trying to move a 1" tweeter. If the 3.5 ohm impedance stretched over two and half octaves in the upper bass and lower midrange, where there's lots of musical energy, and it's couples with a sharply capacitave phase angle, well, then the speaker is going to be a lot more demanding of the amp. Either way with 160 watts into 8 ohms, you're probably fine.
     
    head_unit likes this.
  3. Katz

    Katz Well-Known Member Thread Starter

    Location:
    Bucharest
    Thanks! It's actually 100w in 8ohm, 160 in 4
     
  4. head_unit

    head_unit Senior Member

    Location:
    Los Angeles CA USA
    It's just way more complicated than that. Sorry! Amplifiers are tested into resistors, where the current is in phase with the voltage and all is peaceful. That tells you very little about their power delivery into speakers.

    As @chervokas noted, speakers' impedance is rarely resistive, often being somewhat capacitive or inductive, and varying dynamically with power and frequency besides. That "4 ohm" or "8 ohm" is thus not very meaningful. So an amps' 4 ohm or even 2 ohm rating is most important, since it's a stronger indication of how much current the amp can deliver and so maybe what it can do into real-life speakers.
    --> the amp probably pushes maybe 200 watts on some peaks, but exactly how much power is not too important.

    Let me toss in a vaguely related standard thing I quote: "Head_Unit’s Rules Of Protection":
    1) If when things start to sound distorted or odd you TURN IT DOWN, you are unlikely to ever break anything.
    2) If you constantly "turn it up to 11" you will break something.
    NOTE: the size and power ratings of the speakers and amp do not affect rules 1 and 2. (Specs for amps are often not thorough since they are measured into resistors and speakers are not resistors. Speaker specifications are 92% meaningless (and I say that as a loudspeaker engineer)).
     
    Rick58 likes this.
  5. Rick58

    Rick58 Forum Resident

    Location:
    Eagle, ID, USA
    Not sure if Triangle speakers are as easy to drive as the 'used to be' ... my 2002 vintage Tituses are well known as being easy to drive and suitable for use with low powered tube amps (which I have). I have no issues at all with my mighty 8Wpc amps. Of course there's a limit to volume but it's well above anything I'd want to hear.

    Follow head_unit's advice and don't worry too much. Unless of course you need to turn things up to 11 all the time.

    Since your amp is rated at 100W into 8 and 160 into 4, it ... should ... be OK into the 3.5 ohm load. If the amp had specs like "100W into 8 ohms, 120W into 6 ohms, 4 ohm loads not recommended" then I'd worry.

    I would HOPE that modern amp manufacturers use something with a LITTLE reactance and not purely resistive loading for such tests.
     
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