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running both sides of a power amp?

Discussion in 'Amps and Cabs [BG]' started by wotnwhy, Sep 9, 2003.

  1. i have a Tech 21 sansamp pre amp and a gemini power amp.

    can i get a cable splitter to run from the 1/4" out of the pre amp to both the setreo inputs of the power amp?

    the reason i ask is 'cos if it is possible then, if i got 2 cabs, i wouldn't have to worry about the combined impedence, and i could controll the volume of each cab seperatly.

  2. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Perfectly OK to do! Some power amps have a switch on the back to allow you to connect the inputs without an extra cable.
  3. Yep, what Billy said. I used to do this with pa gear.
  4. jerry

    jerry Doesn't know BDO Gold Supporting Member

    Dec 13, 1999
    I would check to see if your poweramp has a parallel switch first.
  5. ok, i checked it all out, and i have the parallel switch so i can do that, i still havent got the cabs (probably glock), but before i do i just wanna make sure this is ok.

    say i got the glockenklang 2x12 and 1x15. the 2x12 would be @ 4ohm and the 1x15 would be @ 8ohm. because i'm running the power amp in stereo thats ok right? it's not gonna feck up the amp or cabs at all?

  6. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    So you want to load one channel to 4 ohms, and the other to 8 ohms. Should be no problem as long as your amp can handle a 4 ohm load.
  7. As long as both cabs are full range you'll be fine using the parallel switch. I'm doing this now. If you prefer to bi-amp and have a seperate crossover, then I believe you'll need a splitter.
  8. notanaggie

    notanaggie Guest

    Sep 30, 2003
    If you don't have a parallel switch you can use bridge mono, but you still connect to the A and B outs separately, and you have to flip one of the connectors over to get the speaker the right phase.

    That's assuming you are using 2 pin type banana plugs .....harder to do with speakon.....
  9. Petebass


    Dec 22, 2002
    QLD Australia
    you won't fark em up at all. But the 1x15 will be considerably quiter that the 2x12 given the same amount of power, so you'd have to run that side of the power amp much harder to balance the 2 cabs.

    Why don't you get 2 cabs with the same nominal impedance?

  10. because i'm gonna be getting the glockenklang double (2x12) which is 500w and is available in 4 or 8ohm. to get the most from the cab i would get the 4ohm version.

    if, in the future i decide i need to add more cabs, and should those cabs be the 15 or 2x10, i would need to get the 8ohm version. but i may never need to get additional cabs. so getting the 8ohm version of the double would just be limiting myself.

    make sense?

  11. Petebass


    Dec 22, 2002
    QLD Australia
    Aren't the 15 or 2x10 available in 4 ohm versions? I'd be looking to make both cabs 4 ohms if possible.
  12. yes, both the 15 and 2x10 are available in 4ohm, trouble is, at 4ohm, my power amp puts out 500w, and the cabs can only handle 300 & 400w respectivly.

  13. Dont worry about running a 300w-400w cab with a power amp running 500w. More headroom the better.

    POWER IS GOOD.....

  14. Petebass


    Dec 22, 2002
    QLD Australia
    Yes it is possible to blow those speakers with that amp, but you'd have to be doing something silly or trying pretty hard.

    A 500w per side amp doesn't put out 500w the whole time you're playing. A majority of the notes you play wall cause the amp to output something like 200w per side even with the amp turned up all the way. When you see the clip light flick on, that's a momentary burst of 500w per side. Those speakers should be able to take that without too much drama.

    Common sense prevails though. If the speakers are farting or complaining in any way, you'll have to turn the amp down a bit. In fact you probably will. Do you realise how loud this rig is gonna be? 1000w through a 15 and 4x10...... I use 400w with that speaker configuration and I can drown out drum kits.
  15. Not to mention better for the speakers.

    You're far better off pushing the speakers to their limits and then winding off than running a highly-stressed out amp into hardy speakers as you'll burn out the voice coil with the excessive current that starts to pump down the line when your amp starts a'clippin...
  16. wow, you learn something new every day!

    i know what you mean, 1000w through a 2x12/1x15. 2x12/2x10, or even 2x12/2x12 would be stupendously loud :D :bassist:
    the only time i would add the other cab is a) i need more volume (unlikely) or b) i want to add a bit more high (2x10) or low (1x15) to the sound. i will probably (read, hopefully!) never need to add another cab, but if i did, i just wanted to make sure the 8+4ohm was doable, but evidently i needent worry about that.

    thanks for all the help, and look out for a "finally got my new rig together!" thread in the near future

  17. Petebass


    Dec 22, 2002
    QLD Australia
    and you know what, it took me years of solid gigging to learn what TB can teach you in a week. I hope you guys appreciate that!
  18. Fuzzbass

    Fuzzbass P5 with overdrive Gold Supporting Member

    Just wanted to add that impedance imbalance isn't necessarily a big deal. I sometimes run a 4-ohm 3x10 (102dB sensitivity) over an 8-ohm 1x15 (99dB sensitivity). When I run them in stereo and set them so that both are equally loud to my ears, the gain knobs on each channel are usually dead even. Also, when I run the cabs in parallel off of one channel, the cabs sound even. Go figure...

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