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is there a problem with running two heads into one cab?

Discussion in 'Amps and Cabs [BG]' started by adamaarts, Jun 29, 2003.


  1. adamaarts

    adamaarts Supporting Member

    Apr 19, 2001
    Corona, CA
    Beta tester Source Audio, demos/reviews of many others
    my situation is this, i want to have three separate channels. one is clean , one with distortion and effects, and another for clean with effects.

    i have a Carvin R1000 head that will run the clean tone, and i want to a/b it with an ampeg V-9 (very old ampeg) and use another a/b for the distortion channel and clean channel of the amp, which i have already been sucsessful in doing. i will have my effects before the a/b for the ampeg so i can have both clean and distorted channels with effects or one separte clean channel, no effect.

    kind of like this:

    [​IMG]

    is htere a problem with running the two heads into a y splitter then into one 8x10 cab? it only has one input, and thats for all 8 speakers. will the amps be fighting eachother for the cab? are there circutry problems with this. im not going to try it until im sure it wont hurt anything. sometimes i will be using both amps (for a wet/dry mixed signal)

    thankjs for any help. this just seems risky and i thought id ask.
     
  2. HeavyDuty

    HeavyDuty Supporting Curmudgeon Staff Member Gold Supporting Member

    Jun 26, 2000
    Suburban Chicago, IL
    I wouldn't do it!
     
  3. Trevorus

    Trevorus

    Oct 18, 2002
    Urbana, IL
    what will happen is when one head is operating, and one is idle, the idle head will get slammed with all the speaker power from the active one. DO NOT DO THIS! you will kill one or both of your amps.
     
  4. Phat Ham

    Phat Ham

    Feb 13, 2000
    DC
    As has been stated you will destroy one or both of your amps if you run your rig the way you described. What you need is an a/b box between the two amps and the speaker cab. So each amp will go into one of the inputs on the a/b box and the output from the box will go to the speaker cab. You need a special a/b box made to handle the high power; if you use a normal a/b box it will cause problems.
     
  5. adamaarts

    adamaarts Supporting Member

    Apr 19, 2001
    Corona, CA
    Beta tester Source Audio, demos/reviews of many others
    thats what i thought...

    well i had another plan. to add two inputs on the back of the cab, one each for four drivers that will give 2 8 ohm loads, but can be switched to a 4 ohm load with a switch. is that possible. im sure it is.

    but im really lazy, and poor, so i may not go that route. what would i need, just a new back plate and some wire and a little speaker knowhow?

    doesnt seem too hard, but is that worth the trouble? thats what im actually asking myself, but you can help if you want.
     
  6. Scott D

    Scott D

    Apr 21, 2003
    Minneapolis, MN
    dude, the Ampeg V-9 is a 9x10 man, not an 8x10
     
  7. PICK

    PICK

    Jan 27, 2002
    Sydney, Australia
    I think he means the V-9 amp.
     
  8. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH

    That's not possible either. You can't add a switch to a cab to alter the impedance under a different wiring scheme.

    You yourself state that you're "lazy and poor", so why the need for such an elaborate scheme?
     
  9. adamaarts

    adamaarts Supporting Member

    Apr 19, 2001
    Corona, CA
    Beta tester Source Audio, demos/reviews of many others
    ok clearing two things up

    1. the v-9 i mentioned is the amp, not the cab

    2. the wiring i mentioned was meant to be 2 8 ohm loads, like two separate cabs, two sets of four speakers, but make it so i can daisy chain (instead of a switch) the two cabs to make one" load"



    i dont know, any other ideas?
     
  10. geshel

    geshel

    Oct 2, 2001
    Seattle
    That will work. It'll be up to you though to make sure that you never have two amps hooked up to it when it's not in "split" mode.

    You could also sell the speaker and get two 4x10s.
     
  11. I'm no expert on this subject but have you thought about plugging the two heads into the cab through another A/B switch ?
     
  12. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    You can't use a standard A/B switch for speaker-level output. They are designed for instrument/line level.
     
  13. The V9 is a tube head. Run it at all without a load and you'll destroy it. Get two cabs and forget this switching crap; all you're going to do is end up trashing your amps and your speaker cab. Theoretically, what you're asking CAN be done, but for practicality and safety, don't try it. None of the previously proposed solutions in this thread are workable without extensive alterations to your cab. Besides, that V9 needs a 4 ohm load. Running it at 8 ohms risks damage to it even without a messy switching system. Bottom line: is it safe? No. Don't do it. V9's are rare enough without the few that are left getting fried.
     
  14. FretNoMore

    FretNoMore * Cooking with GAS *

    Jan 25, 2002
    The frozen north
    Get a second cab and your scheme will work.
     
  15. adamaarts

    adamaarts Supporting Member

    Apr 19, 2001
    Corona, CA
    Beta tester Source Audio, demos/reviews of many others
    i do have a 1x15 cab, thats 4 ohms, but its a carvin so needless to say, i cant really use it, unless it runs really quiet, which in some situations isnt possible.

    and running a tube ampe without a cab is bad, but with out an instrument is fine. i didnt take the tube amp into consideration when i thought of this. i guess ill just have to get some other way of making this happen.

    thanks to TBers for helping me, and saving me from two bad amps.