Dismiss Notice

Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

ohmage question

Discussion in 'Amps and Cabs [BG]' started by sloppysubs, Aug 13, 2003.


  1. sloppysubs

    sloppysubs

    Nov 24, 2002
    Swansboro, NC
    if i have a 4 ohm amp, can i run two 8 ohm cabs? whats the deal, i just really dont get it.
     
  2. Yep that'll work just fine. Go amp-cab-cab that'll make it 4 ohm. You can use just one cab also. It is probably 4 ohm minimum which means it can be anthing above 4 ohm just not under like 2 ohms.
     
  3. sloppysubs

    sloppysubs

    Nov 24, 2002
    Swansboro, NC
    ok so 4 ohm will run 2 8 ohm or a single 4 ohm
    8 ohm will run one 8 ohm? and i didnt knwo that had 2 ohms...or at least not exclusively.
     
  4. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    Let's try this in layman's terms:

    One 8 ohm cab hooked to your amp = 8 ohms.
    Two 8 ohm cabs hooked to your amp = 4 ohms (two of them make it half, get it?)

    One 4 ohm cab hooked to your amp = 4 ohms.
    Two 4 ohm cabs hooked to your amp = 2 ohms (again, two of them make it half).

    One 8 ohm cab plus one 4 ohm cab hooked to your cab makes it 2.6666 ohms, and the 4 ohm cab will sound louder than the 8 ohm cab, the sound level will NOT be balanced between them, assuming all other things the same. If your amp is rated for a 4 ohm minimum load, running a 2.666 ohm load will stress the amp out, probably resulting in shutdown and/or damage to its components.

    There's really no such word as "ohmage", the proper term is "impedance", use it and it will impress your friends and neighbors.

    Rule of thumb is to NEVER, EVER run a lower impedance than what your amp is rated for. Most amps can handle 4 ohms as their minimum, some higher power, more expensive amps can operate under a 2 ohm load, but it stresses them more.

    Hope this helps!
     
  5. tommer

    tommer

    Aug 11, 2003
    New York City
    Say you have an amp head (350 watts @ 4 ohms and 200 watts @ 8 ohms) with 2 speaker jacks on the back and hook up two 8 ohm cabinets (one in each speaker jack). Is this running the amp at 4 ohms?

    and

    Does that work the same as hooking the cabiets up daisey-chain (head to cabinet to cabinet) style?

    Thanks.

    Tommy
    www.napalmstars.com
     
  6. MJ5150

    MJ5150 Terrific Twister

    Apr 12, 2001
    Lacey, WA
    tommer asks........."Say you have an amp head (350 watts @ 4 ohms and 200 watts @ 8 ohms) with 2 speaker jacks on the back and hook up two 8 ohm cabinets (one in each speaker jack). Is this running the amp at 4 ohms?"

    Yes. When you play, the amp will be putting out 350 watts at 4ohms.

    I am not familiar with daisy chaining cabs, so I will leave that question to the professionals.


    -Mike
     
  7. tommer

    tommer

    Aug 11, 2003
    New York City
    Daisy-chaining cabinets is when you have a cord going from your amp head to your 1st cabinet and another cord from your 1st cabinet to your second cabinet (not from your amp head to your 2nd cabinet)....I think.

    Tommy
    www.napalmstars.com
     
  8. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    You will be running the SAME impedance regardless of whether the two cabs are independently plugged into the back of the amp via two cables, or if the speakers are connected to each other, with one cord heading to the amp.

    You can INCREASE the impedance to 16 ohms with two 8 ohm speakers by using a special cable which would "Y" the positive lead from the amp to both speakers simultaneously, but there's no way to do this without a special cable. Its called a series connection, as opposed to parallel described above.
     
  9. boobinga

    boobinga

    Feb 9, 2001
    Pacific NW
    I pay homage to ohmage. Always.
     
  10. i have an 8 ohm and a 4ohm cab, but my head cant run both at the same time cause of the load. i dont have a power amp but i do have another head. what would i need to use them both at the same time to produce one signal? i hope i phrased this correctly
    :bassist:
     
  11. to do that you would have to use both heads, but you still won't have a balanced sound. You'll have to get cabs that match impedence or a head that will take 2 ohms, and no 2.6 ohms will not hurt it.
     
  12. Thor

    Thor Moderator Staff Member Gold Supporting Member

    Here is a list of TB resources you may find helpful.

    Understanding impedance is really key to making amplification work for you. Every serious electrically enhanced musician should undertake some study of this critical topic.

    Some impedance definitions:

    http://www.talkbass.com/forum/showthread.php?s=&threadid=74898&highlight=ohms

    Icez [Gunnar Þór] has a good synopsis of the fundamentals:

    http://www.talkbass.com/forum/showthread.php?s=&threadid=79484&highlight=ohms

    Here are some SEARCH results you may find useful/

    http://www.talkbass.com/forum/searc...d=653172&sortby=lastpost&sortorder=descending

    Hope that helps you.

    Thor
     
  13. i understand that much, but what im trying to figuer out is how or what ports(pre amp out on one/pre amp in on the other) would i use to bridge one amp to the other so that i can use the power source from both to run each cab but still get only one signal
    (my guitar, into two heads, making one sound, how, why)
    :bassist: