Discussion in 'Amps and Cabs [BG]' started by Jumping_Bomb_Angel, Mar 31, 2002.

  1. Howdy Pilgrims.

    I have a combo that runs on 8 ohms, and a cabinet that runs on 16 - are they compatible? Will I damage anything? Please help.
  2. ldiezman


    Jul 11, 2001
    16 ohms? I've never heard of a cab that was 16 ohms.. Guess i just don't get out enough

    It is my understanding that you can always go up.. I mean that if your amp is 4 ohms, you can run it into a cab that is 8 ohms..

    I also have a question about ohms so i figured i'd post here.. What are the advantages/ Dissadvantages of having a 4 ohm or 8 ohm cab? Is their an advantage?
  3. rockindoc

    rockindoc Daily Lama

    Jan 26, 2002
    Bonham, Tx
    Good question! Hope you get a better response than I did.
  4. If yours is a solid state amp there's no problem. If it's a tube amp then there's a problem. Tube amps have a matching tranformer on the output stage designed to match the amp and the impedance of the cab. Unless the matching transformer is designed to deal with a 16 ohm load you may be asking for trouble.
  5. SRSiegel

    SRSiegel Guest

    Sep 17, 2001
    Ann Arbor, Michigan
    ok, an answer to your original question... if your combo is normally run at 8 ohms... and you want to ADD another cab that is 16 ohms... you will be running at a resultant resistance of 5.33333 ohms. if your combo is only rated at 8 ohms, then yes you will overheat the poweramp inside and possibly burn something up. bad idea. if however, the combo is rated down to 4 ohms, then you should be good to go. you can check to see what its minumum impedance (resistance) rating is on the back of the amp, or the owners manual if you have it. if all else fails, email the manufacturer.

    if however, you are just switching speakers... from the 8 ohm to the 16, then what mudbass says is completely true. no prob for a solid state, possible conflicts with a tube amp. however i wouldnt reccomend switching to a 16 ohm speaker from an 8 on that combo. if you do this the power deivered to the speaker by the amp will fall dramatically. bassically cutting your headroom in half... this is a bad thing.

    the advantages of 8 or 4 ohm cabinets are as follows. none whatsoever sound quality wise. if you could suply the same power to an 8 ohm versus a 4 ohm cabinet.. they would sound exactly the same. but you cant (unless you have a tube amp) and example:

    a head is rated at 600 watts, at 8 ohms bridged. in order to get the full power from this amp, it is best to have an 8 ohm cabinet. a 4 ohm cab will overheat the head. if the amp were rated as 600 watts at 4 ohms (like mine) then a 4 ohm cab will allow you the most power. if you have an 8 ohm cab and the head is rated at 4 ohms, you will not get the maximum power, but a reduced value. for example, my head only bridges to 500 watts at 8 ohms.

    so the advantage is only which impedance works best with your head to allow the maximum power without overheating. nearly all amps have the minumum ohm load somewhere on the back or in the owners manual. dont go below it. to get the most power from your head, use a combination of cabinets that will net you the minimum ohm load.

    some quick combinations:

    8 ohms + 8 ohms (standard parallel setup) = 4 ohms
    4 ohms + 8 ohms (parallel) = 2.67 ohms
    4 ohms + 4 ohms (parallel) = 2 ohms

    8 ohms + 8 ohms (series) = 16 ohms
    8 ohms + 4 ohms (series) = 12 ohms
    4 ohms + 4 ohms (series) = 8 ohms
    4 ohms + 2 ohms (series) = 6 ohms
    2 ohms + 2 ohms (series) = 4 ohms

    every time you use the jacks on the back of your amp, or daisy chain cabinets together, you are running in parallel. series requires a special cable setup, which i am too lazy to explain now.

    heres the formulas i used:

    resistors (speakers) in series
    R1 + R2 + R3 + ...... = R(equivalent)

    resistors (speakers) in parallel

    1/(R1) + 1/(R2) + 1/(R3) + .... = 1/(Requivalent)

    i hope that helps everyone, ive seen a lot of questions about ohms lately. and this stuff has been drilled into my thanks to my physics lecture.
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