Using a 4 ohm with and 8 ohm cab

Discussion in 'Amps [BG]' started by mrmart72, Nov 29, 2012.


  1. mrmart72

    mrmart72

    Joined:
    Jun 27, 2012
    Hey all,

    I have a 4X10 4 ohm cabinet and have a line on a 1X15 8ohm cabinet. My amp, a Harke LH1000, has two separate outputs of 500 watts each. Can I put a 4 ohm and 8 ohm on amp or is that a bad idea?
  2. skychief

    skychief Gold Supporting Member

    Joined:
    Apr 27, 2011
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    You could do it (one cab into each output), but its a bad idea. The 410 would draw more power from the amp and therfore be the dominant cab (louder). Also there are other issues with mixing cab sizes, which has been beaten to death on this forum, so i wont labour on that.
  3. ThisBass

    ThisBass

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    Aug 29, 2012
    Location:
    Germany
    I don't suggest 410 4 Ohm with 15 8 Ohm cause the 410 probably howls down the 15.
  4. Jaco who?

    Jaco who?

    Joined:
    May 20, 2008
    The LH 1000 has a balance control. Each side of the amp can handle a 4Ω minimum load. Try before you buy, but you can turn the 4x10 down to match it's sensitivity to the 1x15. Contrary to the perfectionists on tb, the sun will still rise tomorrow if you do this.
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  6. basscooker

    basscooker

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    Owner, Chopshopamps.com
    yeah, both cabs will make sounds, but it probably won't be good for your amp, and might sound like poo. that 4x10+1X15 combination isn't ideal either. you stand a good chance of killing the 1x15, too.
  7. ntenny

    ntenny

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    Are you dead sure about this? All I did was google for specs, but I got the impression the outputs were wired in parallel, so with an 8-ohm and a 4-ohm cabinet the amp would see 2 2/3 ohms, which would probably result in Bad Things.

    -NT
  8. Kmonk

    Kmonk

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    If you use them together your load will be 2.67 Ohms. Not a good idea .
  9. ThisBass

    ThisBass

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    Aug 29, 2012
    Location:
    Germany
    That's like drinking different drinks of alcohols but a lot of folks do that but feel fine. :D

    even some 410 set ups do that.

    yeah and the earth is flat and there is a good chance to fall down beyound the edge.
  10. bass_lord_mutha

    bass_lord_mutha Supporting Member

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    Midland/Odessa, TX
    I love you lol.

    Yeah if each side will handle at least a 4 ohm load and you can balance the volume between each cab with the balance control, I don't see why this could possibly be a bad idea.

    P. S. It's only a bad idea to the other guys because it's not what THEY would do. These are the same guys that think there is a noticeable and earth-shattering difference in tone between pickups held up with metal springs or pickups held up with foam!! As long as you're running your rig within its limits and it sounds good to you, more power to you. I run a 2x10 and 1x15 now, but I used to run a 4x10 and 1x15, and it sounded spectacular :)
  11. gumtownbassman

    gumtownbassman Supporting Member

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    Location:
    New Zealand
    If you bother to look at the specs, it runs down to 2ohm for both of the two amplifiers.

    Dual Parallel Mode: 2 x 225 watts @ 8 ohms, 2 x 320 watts @ 4 ohms, 2 x 545 watts @ 2 ohms
    Bridge Mode: 1 x 750 watts @ 8 ohms, 1 x 1100 watts @ 4 ohms

    So your 4x10 will run at 320 watts and your 1x15 will run at 225 watts, just dial the amp balance to suit your levels between the two cabs (provided on cabs to separate amp outputs)
  12. tjh

    tjh Supporting Member

    Joined:
    Mar 22, 2006
    Location:
    Minnesota
    Actually, if you are going to mix a 410 and 115, this may be the amp to do it with ... generally the 115 will cook if you push it and split the power even with a 410, that is why I have suggested putting the 115 on top to those that mentioned this combination .. it would be easier to monitor on top if it wasn't liking what you were feeding it for dinner ...

    with the two power amp deal in the LH1000, you are putting 300+ into the 410, and 200+ into the 115, which might be about right, and especially with control of the volume to each ...

    .. with all that said, you mention that you 'have a line on a 115' ... any chance you can try before you buy ... also, if you stack them, try them individually also, and see if there is one that you prefer over the other ... then try them together ... does the sound resemble the one you preferred, or does it change, and for the better or for the worse ?? ... this would be what those that gave the negative feedback on your idea were referring to ... perhaps two 410's would sound better than your mix, or maybe two 115's ...

    .. in any case, decide for yourself taking everyones comments with you, but as considerations ... not dictating your actions ... JMHO
  13. gumtownbassman

    gumtownbassman Supporting Member

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    Location:
    New Zealand
    If the 4x10 is 4ohm and the 1x15 is 8ohm (both in parallel), the 4x10 will draw 2/3rds of the power, while the 1x15 draws 1/3rd (ohms law Watts =I2 x R).
  14. ThisBass

    ThisBass

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    Germany
    By the other hand there are impedance curves which make it impossible to predict any power consumption.
    Nominal Impedance is a good bet for estimate the power consumption but +/- 50% if you consider and calculate the whole frequency bandwith.
    By the other hand the AES2 recommendation does not spec a "Nominal Impedance" at all, nominal does not exist at the AES2.

    As long as you don't know cone excursion at the lows you can't predict nothing.
    ohms law Watts =I2 x R
    is not wrong but sometimes mistaken.
  15. gumtownbassman

    gumtownbassman Supporting Member

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    New Zealand
    I should have used Z instead of R, but it's in the general context of 'rule of thumb' (or approximately - keeping things general and simple) that a 4ohm cab will draw more power than a 8 ohm cab when both are in parallel to the same output.

    With the 'approximate' ratio of 2/3rds (4ohm) and 1/3rd(8ohm) as a ballpark figure.
    :bassist::)
  16. ThisBass

    ThisBass

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    that's right but I would never advice against due to a very simple 'approximate'
  17. ThisBass

    ThisBass

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    that was written due to power AND cone surface.
  18. tjh

    tjh Supporting Member

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    Mar 22, 2006
    Location:
    Minnesota
    thanks for the correction and keeping me accurate, but if you re-read my post that you quoted, it reads ...

    " generally the 115 will cook if you push it and split the power even with a 410,"

    note the word, IF ... such is not the case here because of the impedance differential the power is NOT split evenly between the two cabs ... but IF you split the power evenly ... was my inferrence ... hence my going on to say that it may not be a bad idea in this case... :)

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