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ohms problem

Discussion in 'Amps and Cabs [BG]' started by austin01bmx, Mar 13, 2002.


  1. austin01bmx

    austin01bmx

    Jan 8, 2002
    i have an 8 ohm head running through a 4 ohm cab and there is a ton of clipping. is there anyway to fix that problem of am i going to have to bhy a new head?
     
  2. splicer1

    splicer1

    Feb 16, 2001
    Torrance,Ca
    If your speakers are 4 ohm and you have 2 how about wiring them in a series instead of parallel to match your amp.+ of speaker1 goes to - of speaker2. Remaining - of spk 1 to amp and + of spk2 to amp. You will have an 8 ohm load assuming both speakers are 4 ohm. Hope that helps.
     
  3. austin01bmx

    austin01bmx

    Jan 8, 2002
    would i loose power that way?
    or could i use the preamp from the head and run it through a power amp at 4 ohms would that work?
     
  4. malibu

    malibu Guest

    Dec 26, 2001
    the power amp is already putting out more power than it would/should into an 8 ohm impedance -
    and it is losing power after being overdriven to clipping

    configuring cabs for 8 ohms is not always as simple as wiring together two 4 ohms in series, as there are some differences in speakers actual impedances -
    especially since you may have already ruined the 4 ohm speaker and you don't really know what it will actually be like in series now.
     
  5. splicer1

    splicer1

    Feb 16, 2001
    Torrance,Ca
    Are you sure the amp you have now has an 8 ohm output? Most amps go to a 4 ohm speaker load max.As for the clipping that is usually in the gain of the preamp.Is the gain cranked up too much?What kind of amp is it? You will lose some power but at least you won't run the risk of damaging your power amp.Any preamp can drive a power amp.I have my Sansamp Bass Driver( used as a preamp) going into the effects return of my SWR. That way it by passes the preamp on the SWR. Mike
     
  6. austin01bmx

    austin01bmx

    Jan 8, 2002
    i have the head out of a crate bx50 running through a 2x15 cab. its all i have now but i was wondering if i could use the crate head through a power amp?
     
  7. splicer1

    splicer1

    Feb 16, 2001
    Torrance,Ca
    Don't you mean preamp through the head? Whatever that power amp is (8 ohms) is what power the speakers will get.The preamp will not change the 8 ohm output of your head...
     
  8. austin01bmx

    austin01bmx

    Jan 8, 2002
    but if i use the headphones output on the 50 watt headinto another power amp would that work?
     
  9. malibu

    malibu Guest

    Dec 26, 2001
    signal for headphones/line out or the external speaker jack will need some sort of dummy load (resistance/impedance/ohms) before they could go into another amp - there are power attenuators that are designed to go between the amp and the speakers -- but not saying I recommend that sort of thing.

    if you have a 2x15 cab which is two 8 ohm speakers in parallel, you could match the 8 ohm load desired by your 50 watt RMS amp by using only one of them.
     
  10. austin01bmx

    austin01bmx

    Jan 8, 2002
    so what would i have to do to make this work
     
  11. malibu

    malibu Guest

    Dec 26, 2001
    it really is gonna be a bit easier if you had been more explicit in what your set-up is and more explicit in what you want to accomplish.

    if you're just trying to run some cab rated at 4 ohms from a combo's extension jack which expects to encounter an 8 ohm circuit, first thing people are gonna say is add 4 ohms in series -

    but once they see you're already trying to drive two 15'" cones - they'll either say add a tweeter in series, or run through a power attenuator to match the impedance (it'll just use amp energy to make heat)

    but then again it is 50 watts you want to drive into this cab . . .
    (1) so if there was an effects loop you might be able to send it out and not return it to the combo but to a seperate power amp. Does your combo have an fx loop ?

    (2) - it is again what you want to do -
    without having to get new equipment yet
    you might try to rig the 2x15 into one 8 ohm, maybe temporarily