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What will Cabs powerating become when using 2 cabs?

Discussion in 'Amps and Cabs [BG]' started by semborg, Jun 28, 2005.

  1. Okay so I am gonna buy GK 115 SBX cab.
    (With my Yamaha bbt500h 2x10 cab)
    The 15 cab is rated 400watts at 8ohm.
    The 2x10 cab is rated 250 watt 4ohm.

    What will happen with the cabs when I run them together? (In paralell)

    Will this result bad or something?
    Can I run this setup?
  2. will the cabs powerratings change?
  3. Happy MurphDay

    Happy MurphDay

    Mar 9, 2004
    the power ratings won't change, however, your amp must be able to handle a 2ohm load or you'll cook the amp

    the 8 ohm cab will receive 1/3 of the power
    while the 4 ohm cab will receive the rest of the power,
    but the cabs will be able to handle the same ammount of watts
  4. A cab's power rating cannot change. It is an indication of how much power it can handle. It does not indicate how loud it will be.
  5. The 15 cab will only be getting 125 watts when the 2x10 cab is at its thermal limit of 250.

    Adding the 15 still helps a little, with music vs test tones you can pump more than 250 into the 2x10 without destroying it, maybe even 500W for peaks. Even then you'd only be putting 250 into the 400W 15. You'll surely blow the 2x10 by the time you're working the 15 near its limits.

    You'd be way better off with them reversed, a 250W 8 ohm cab with the higher capacity 400W 4 ohm cab. Then they'd be overloading at roughly the same point.

    Or 2 8 ohm cabs with similar power ratings.

  6. But I already got the 2x10 4 ohm cab...
  7. But my amp cannot put more than 250watt to each cab?
  8. oldfclefer

    oldfclefer low ended

    May 5, 2005
    Southern Ohio
    As long as you don't go below your amp's lowest ohm rating you'll be fine adding a cab. Speaker efficiency is very underrated as far as loudness is concerned. Adding a cab will give you much more punch. As to the power ratings, they don't change, but your amp's output will increase so you'll have to be aware of what it's ouput is at the ohm rating you're running. If the amp's output is higher than your lowest rated cab, don't push it. Chances are you won't need to. If you like the sound, you might consider getting into a matched setup with a better power rating. With your current setup you should be able to run a 400watt amp with relatively little concern.
  9. IvanMike

    IvanMike Player Characters fear me... Supporting Member

    Nov 10, 2002
    Middletown CT, USA

    check out the Ohms FAQ thread linked in the FAQ sticky at the top of amps. That should answer most of your questions, or put you to sleep. :p
  10. Hmm, I don't get it.
    Right now I am only using 1 cab. rated at 250watts.
    And my amp cannot push more than 250 watts.
    But at 2 ohm the amp will put 500 watts.

    All the time I thought it would put 250 watt to the first cab.
    And 250 to the other. (totally 500)
    But can it for example give 400 watts to the first one, and 100 to the other one?

    Maybe it is better to buy a 4 ohm cab instead if this is the case?

    Thanks for great help
  11. The power each cab gets is opposite of the proportion of its ohms.

    Combine a 4 and an 8 ohm cab, the 8 gets 1/2 the power of the 4.

    If they're both same ohms, they split the power equally.

    It depends on the ohm rating of the cab, not the power rating.

    And solid state amps put out more power into lower ohm loads. So 250W at 8 ohm amps put out around 400w at 4 ohm loads. Like hooking up 2 100W light bulbs, you get 200 watts of light out of the same outlet.

    amps don't work the same way, you don't quite get double the wattage output with 4 vs 8 ohm speakers.

    How confusing is that? Wow...

    Speakers: power divides precisely between speakers based on ohm values. 300W from amp = 100w for 8 ohm speaker adn 200 W for 4 ohm speaker when used together.

    AMPS: max output power tends toward the same ratio but usually falls quite short. 200W amp wth 8 ohm speaker puts out less than 400 w into a 4 ohm speaker. More like 300-350

  12. It sounds UNSAFE to go a 8 ohm 15". Should I rather go 4 ohm 4x10" or 4 ohm 1x15"?
  13. The short answer is that it is fine to add an 8ohm 1x15 or any other 8 ohm cab to your rig. In fact that gives you the option of adding another 8 ohm cab later.

    Forget the mumbo jumbo.............Go get your cab! :hyper:
  14. Get them the same ohms and the power will divide equally between them. If you have one cab already, just get the same ohm rating for the 2nd one.

    Buying both at once?
    If your amp will go to 2 ohm loads you can get both cabs in 4 ohms apiece. You'll get a little more power from the amp with 2 4 ohm cabs.

    Or both cabs in 8 ohms apiece is fine too. You won't lose significant power with 2 8's.

  15. Ok, thank you. But I already got the 2x10 4 ohm.
    And I cannot find any 1x15" at 4 ohms that I want. (Only found 1 from EBS and PEAVEY)
    (P.S I live in sweden)

    So you mean that there's no chance to destroy the 2x10 when push it to hard?
    The amp can never give more than 250watts to it?

    Thank you alot for great help. What should I do without TB? :smug:
  16. Adding another cab will not increase the power into your 2x10. You will still get 250watts into your 2x10 and about 150watts into an 8 ohm cab.
  17. ahh cool, then there is no risks at all running this setup
    wohoo :hyper:
  18. Actually, it *is* possible for an amp rated at 250 W into a particular load to put out more than 250 W into that load--if you push it really hard. So you can't really say it's absolutely impossible to hurt the 210. The rating are for maximum power delivered under certain specified conditions, usually meaning low distortion. If you push the amp into heavy distortion, it can put out considerably more than its rated power.

    But if you use the gear sensibly, you should be fine. It worries me a little that you're thinking there are "no risks at all." Don't let that encourage you to use your gear in an excessive way.
  19. But when do I know I push it to hard?
    When It starts to distort?

    (I have Output limiter switch on the head, should it be ON?)
  20. You can't get a guarantee. You can only try to be sensible.

    If you get more than occasional very brief and light distortion, you may be pushing it too hard. Even better would be no audible distortion. I don't know your amp, but if the output limiter does what it sounds as if it does, it might help.

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