Question For The Ever Helpful John Phillips

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by dumb donnie, Aug 17, 2005.


  1. dumb donnie

    dumb donnie Member

    Messages:
    214
    Joined:
    Jan 12, 2004
    Location:
    Marietta, Ga
    This is an easy one, but I figured I would ask. I have a tube combo with two speaker outs and a switch for 4/8/16 ohm operation. I have two 16 ohm speakers I would like to use, but since the speaker outs require a 1/4" jack I need a special cable. Unfortunately I haven't been able to locate a speaker cable that will allow you to wire a combo in parallel.

    Anyways, my plan is to get two of the standard combo speaker cables (1/4" phono to +/- speaker wire) and connect each of the two 16 ohm speakers into a different jack. This way I end up with two 16 ohm loads into two separate speaker jacks. My question is, what setting do I set the impedence switch at? Did that make any sense?

    My guess is going to be 8 ohms, but I wanted to check in here before I did anything. Since this is such a commonly asked question (or at least a variation of a commonly asked question) I will delete it after it's answered to prevent clutter.
     
  2. calieng

    calieng Member

    Messages:
    646
    Joined:
    Nov 21, 2003
    Location:
    San Diego, CA
    If the combo jacks are simply an internal 'Y' connection then you just plug in each 16 ohm speaker using both jacks and set to 8 ohm operation.

    You can also buy a 'Y' adapter from Radio Shack if you ever need to plug two cabs into a single output. Divide the impedance of one cab to get the resulting impedance with two cabs in parallel. You should make sure the adapter is decent quality because a short in it would be bad. I actually would make my own from some speaker wire and good quality jacks.
     
  3. dumb donnie

    dumb donnie Member

    Messages:
    214
    Joined:
    Jan 12, 2004
    Location:
    Marietta, Ga
    The speakers aren't in cabs, they are in the 2x12 combo (or will be I should say).
     
  4. calieng

    calieng Member

    Messages:
    646
    Joined:
    Nov 21, 2003
    Location:
    San Diego, CA
    duh! sorry.

    Very simple.

    [​IMG]

    Connect one speaker to a cable with a 1/4" plug and connect to the main speaker input on the amp. Set to 8 ohms.

    Connect the second speaker to the first speaker with speaker wire. + connects to + and - connects to -
     
  5. Blue Strat

    Blue Strat Member

    Messages:
    29,990
    Joined:
    Aug 2, 2002
    Location:
    Sterling, VA (not far from Washington DC)
    8 ohms is correct. I'm not sure what type of wiring you've got, but you should find someone with a soldering iron to wire the 2 speakers in parallel and run a single pair to a 1/4" plug to plug into the back of the amp.
     
  6. dumb donnie

    dumb donnie Member

    Messages:
    214
    Joined:
    Jan 12, 2004
    Location:
    Marietta, Ga
    Doesn't that put the speakers in series giving me a 32 ohm load?


    Are you saying that i shoul hook a wire up to the + and - of each speaker and then solder the two +'s together and then solder the two -'s together, and then connect the doubled connections to a 1/4" plug?
     
  7. calieng

    calieng Member

    Messages:
    646
    Joined:
    Nov 21, 2003
    Location:
    San Diego, CA
    Read this and then wire them in parallel.

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

    Step by Step.

    You have two speakers. Let's call them A and B.

    1. Connect the speaker cable to speaker A just as if you only have one speaker in the amp. One wire to + and the other wire to -

    2. Take a single piece of wire and conect one end to + terminal on speaker A and the other end to + terminal on speaker B

    3. Take another piece of wire and connect one end to - terminal on speaker A and the other end to - terminal on speaker B.

    That's it ... do nothing else. You are done. Just make sure the speaker cable is plugged in to the amp and the impedance is set to 8 ohms.
     
  8. dumb donnie

    dumb donnie Member

    Messages:
    214
    Joined:
    Jan 12, 2004
    Location:
    Marietta, Ga
    Ok, now I gotcha, thanks!
     

Share This Page