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  1. #1
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    Default Amp wiring question

    This is probably a dumb question but here goes. If my amp is rated at 100W per channel at 2 ohms and I wire two 4 ohm speakers in parallel to one channel so that the amp sees a 2 ohm load, does each speaker receive 100W or 50W?

    Thx,

    Al
    Al

    2006 Mobius LSV

  2. #2
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    Al, I believe it would be 100w but here's and article that goes through the calaculation

    http://www.termpro.com/articles/spkrz.html

    correction 50 w each speaker ( i was using the 8 ohm Speaker load)
    Last edited by jmvotto; 10-16-2009 at 11:35 AM.
    A Day at the Lake...Priceless
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  3. #3
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    Default

    If you have a 4 ohm speaker wired to one channel of the amp, positive to positive and negetive to negetive then the amp sees 4 ohms. So in this case you will only be putting out 50w.
    Now if you add a second 4 ohm speaker to that channel, with both positives of each speaker to the positive post on the amp and the same with negetives, then your amp would see a 2 ohm load.
    The only way to change that up is to have 2 ohm speakers.

    Here is a good online reference.
    http://www.colomar.com/Shavano/spkr_wiring.html


    PWI as usual...

  4. #4
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    newty, question? ( excuse my ignorance)

    how are most tower double ups wired for the tower, series or paralle and what do most people run them from 2 channelsat 2 ohms or 4 channel amps at 4 ohms?

    also, how are the cabin speakers wired from the factory series or parallel?

    I don't see too many speakers besides subs that handle 2 ohm loads?
    A Day at the Lake...Priceless
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    Joe V
    2012 Möbius XLV~ Loaded & Exiled
    2007 Outback V ~ sold

  5. #5
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    Default

    the questions you pose above depend on the speakers and amps. there are not many 2ohm door speakers, but they do come in 3, 4, 6 and 8ohm variants. how you wire them depends on how many speakers you plan to run and what the amp you are using can be configured for. I am planning on running the hollow points wired in parallel and a 2ch amp stable to 2ohms stereo. you could also run a 4ch amp and run it bridged, but most 4ch are not 2ohm stable bridged unless you spend some coin, and you would not get the same bang for the buck in series for an 8ohm load bridged.
    not sure how the tower speakers are wired currently, but it's not hard to tell if you pull one side out. my in-boat speakers were wired with the bow on 2 channels and the 4 in the main lounge wired in parallel to the other 2 channels. presents a 4ohm load for the fronts and a 2ohm load for the main cabin on the 4ch amp(assuming they are 4ohm speakers, which I believe they are). my guess is this is how most of the boats are wired.
    '06 Supra Launch 20SSV-gone but never forgotten

  6. #6
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    and if you really want to get cute, some of the old school "cheater" amps are stable to .5 and .25 ohm loads. you can run an entire boat off one orion hcca225. rated at 25x2, but realistically more like 3-400x2. you start getting into runnning full range speakers in stereo and run the subs mixed mono across both channels. impedence gets real tricky then
    '06 Supra Launch 20SSV-gone but never forgotten

  7. #7
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    Default

    Quote Originally Posted by newty View Post
    If you have a 4 ohm speaker wired to one channel of the amp, positive to positive and negetive to negetive then the amp sees 4 ohms. So in this case you will only be putting out 50w.
    Now if you add a second 4 ohm speaker to that channel, with both positives of each speaker to the positive post on the amp and the same with negetives, then your amp would see a 2 ohm load.
    The only way to change that up is to have 2 ohm speakers.

    Here is a good online reference.
    http://www.colomar.com/Shavano/spkr_wiring.html
    newty,

    Thanks for the reply, but I think you misunderstood my question. I know that the amp is seeing a 2 ohm load in this configuration. What I am asking is how many watts is being applied to each speaker?

    Quote Originally Posted by jmvotto View Post
    Al, I believe it would be 100w but here's and article that goes through the calaculation

    http://www.termpro.com/articles/spkrz.html

    correction 50 w each speaker ( i was using the 8 ohm Speaker load)
    Thanks for that link JM. That answered my question - each speaker is getting 50W as you also concluded.

    Quote Originally Posted by jmvotto View Post
    newty, question? ( excuse my ignorance)

    how are most tower double ups wired for the tower, series or paralle and what do most people run them from 2 channelsat 2 ohms or 4 channel amps at 4 ohms?

    also, how are the cabin speakers wired from the factory series or parallel?

    I don't see too many speakers besides subs that handle 2 ohm loads?
    jm,

    In the last sentence of your question above, the issue is how much impedance the amp sees, not how many the speakers can handle. So if you wire two 4 ohm speakers in parralel, the amp will see a 2 ohm load but the speakers are still 4 ohm speakers. From the speaker's perspective, we want to make sure it can handle the amount of watts the amp is feeding it.
    Al

    2006 Mobius LSV

  8. #8
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    thanks,
    got it . I just got two more aerial tower cans and i thought this thread through me for a loop on how i wanted to wire the 4 tower pods from two channels( 3& 4)

    I had a brain F$%T, all is good now.
    A Day at the Lake...Priceless
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    Joe V
    2012 Möbius XLV~ Loaded & Exiled
    2007 Outback V ~ sold

  9. #9
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    oh I see that now Cab.
    The amp will putout 100w @ 2 ohms, but will the speakers see 100w or do they spilt the load essentially getting 50w each?
    Good question, I'm not really sure. I think because each speaker acts as a resister they each will (provided they are the same ohm load) each draw half the power.


    PWI as usual...

  10. #10
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    Default

    Jm,

    No worries. So are you running the 4 tower speakers in parallel with channels 3&4, the 4 rear cabin speakers in parallel with channels 1&2, the sub off channels 5&6 bridged, and the bow speakers off the head unit?
    Al

    2006 Mobius LSV

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