What does 2-ohm impedance with wire to make 4 ohm impedance mean?

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What does 2-ohm impedance with wire to make 4 ohm impedance mean?

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This is on my Infinity speakers: "True Four Ohm Impedance technology: speaker's 2-ohm impedance combines with speaker wire impedance for a 4-ohm load."

So when looking for an amp do I look at the RMS Power Output (Watts x Channels) or Power at 2 Ohms (Watts x Channels) to figure out to power the RMS power range of th e speakers?

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  • Those speakers are closer to 3 ohm impedance. I would look at the 4 ohm specs when choosing an amp.

    GLH Geeked

  • kevint1022

    GLH is right on.  they are about 3 ohms.  it's not exactly correct, but you can just take the average RMS for 2 ohm and 4 ohm loads and you'll be pretty close.  meaning if the amp is rated say... 60 watts at 4 ohm and 90 watts at 2 ohm, you'd be getting about 75 watts to a 3 ohm load.

  • I've been wondering this exact same thing while researching which amp to buy. I've got a pair of 4032cf's up front and 6032cf's in back and when checked with my Fluke they come up between 1.9 and 2.1 ohms. It also got me researching speaker wire impedance which lead me to this site and this site and after reading those and a few other it would have me believe that for even a 15' run, which should more than double enough to get to both sets of speakers with my amp in the middle of the car, of 14 gauge will only add 0.0885 ohms, which would be well under that "True Four Ohm Impedance Technology" stuff I've been reading.

    So I guess the real question would be where are they getting this 2-ohm speaker wire impedance measurement from?

    [edited by: oldhome7 at 2:04 AM (GMT -5) on Mon, May 28 2012]
  • Noooooo...... Please not another Infinity/JBL/Polk speakers impedance marketing ploy thread !!!

    (Are you sure they measured THAT low ? I've got anywhere between 2.6 and 3.4 ohms when I've measured them)  

    GLH Geeked

  • Yea, I'll try and snap a pic of my reading tomorrow, it'll just have to be with my cheap RS meter as my Fluke is on loan right now for some scoping.

  • What is RS ? Your Fluke has O-scope function ?

    GLH Geeked

  • I'm an Auto Mechanic by trade so a scope is helpful, probably not the kind of scope you are thinking of though. And RS=Radioshack, just an older one I had before I became a mechanic, great for basic stuff.

    Edit: Here's a snap with my phone, sorry for the crappy quality.

    Edit 2: Didn't realize it would post so small the first time.

    [edited by: oldhome7 at 7:01 AM (GMT -5) on Mon, May 28 2012]
  • If you have the red lead on the + terminal and the black lead on the - terminal, (don't think it matters) then I can't argue with the meter. 18-16 gauge speaker wire is not going to matter much, I agree. In the case of 2 of my 4 channel amps, they are rated to make 50 watts at a 4 ohm load and 75 watts at a 2 ohm load, each channel. You could get by with a pretty small 4 channel amp as long as it is 2 ohm stable stereo output, most are.

    My pick among these would be the Kicker Class D, it does 50 watts RMS x 4 into 2 ohms. You would need to turn the front channels down, i.e., limit the AC voltage output by using a DMM. -


    GLH Geeked

  • Yea the leads are correct haha. I've got spools of 14-gauge laying around so that's what piqued my interest in the matter.

    Before all this, I was looking at the Kenwood 8405 which does 60 x 4 into 4 ohms, the 6032cf's are rated at that, and I didn't know if they were really gonna show up as a 4 ohm load or not. Now that things are cleared I know if I ever get around to upgrading to the component set that amp is rated at 90 watts at 2 ohms and has a higher SNR than the 2404S that I was looking at as well.

  • From Harmon-Kardon -

    "All of the speakers in the Infinity Reference line feature a 2 ohm voice coil. However, when you factor in the small OEM speaker wire of most vehicles and the heating in the voice coil during use, the impedance actually seen by the amplifier will increase."

    GLH Geeked

  • And you won't get anywhere NEAR 2-ohms of wire resistance unless you are running 32-gauge or smaller wire.

    Perhaps some of the speakers use a 2-ohm voice coil, but for the most part, Infinity was making 3-ohm speakers.  Pulled a bit more power from the amp/head unit than 4-ohm speakers, but they wanted to market them as 2-ohm speakers.  But most HU's were not stable below 4-ohms, so they had to come up with a way to say they were safe for a 4-ohm supply.

    Naturally when the voice coil heats up, the impedance seen by the amp will increase and this is also accounted for by the amp manufacturer's that claim the amp is 2-ohm or 4-ohm stable - they really mean you can run 2-ohm or 4-ohm speakers with them.

    Hope This Helps!!!

    Anyone else have suggestions?

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • Sweet, glad all this is cleared up. Now I can really look into 2-ohm 4 channel amps.