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How do 2-way or 3-way cabs send a signal to a second cab (or sub)?

Discussion in 'Amps and Cabs [BG]' started by Blankandson, Oct 14, 2013.


  1. Blankandson

    Blankandson Supporting Member

    Oct 20, 2010
    Gallatin, Tennessee
    I've noticed several cabs available are either 2-way or 3-way cabs. I know the greenboy cabs have the splitter inside the box. Assuming the first cab is 8 0hm, what happens to the signal when a second 8 Ohm cab is attached? Again, since many cabs have two input/outputs on the back, I'm assuming the second cab is connected to the first cab. If the second cab is coming from the amp, then it is getting all of the signal. All this is assuming the splitter is IN THE CAB. Does the sub get all of the signal even though it might only use 40hz - 800hz?
     
  2. Foz

    Foz

    Jul 26, 2008
    Jax FL USA
    yes
     
  3. In either case the cabs are run in parallel. So each cab has its own cross over network, and each sees the same signal sent to them regardless of how you hook them up.
     
  4. Blankandson

    Blankandson Supporting Member

    Oct 20, 2010
    Gallatin, Tennessee
    This may seem like an easy answer but I'm pretty dumb when it comes to electronics. If I plug in a 3-way into one jack (on my amp) and plug in a sub into the second jack, then the entire signal is now split 50-50. But since my sub can only go up to (for example) 800 Hz, then everything sent to it higher than 800 Hz is lost. In that case, the signal going to the HF and midF in the 3-way is slightly less. The bass will be a little louder, but the HF and MF will be slightly less loud. So would a stand-alone 3-way be a better solution? I know - this is probably an easy one for most of you. But I'm still in school here. Thanks.
     
  5. For the most part yes, but depending on the cabs/amps you use you can make up the mid content with your EQ or with some clever cross over trickery.

    Pretty much you need to start working with specifics to get more solid answers.
     
  6. Foz

    Foz

    Jul 26, 2008
    Jax FL USA
    yes
     
  7. +1
     
  8. Blankandson

    Blankandson Supporting Member

    Oct 20, 2010
    Gallatin, Tennessee
    Sorry to be so long between posts - just now getting into my hotel room. What I'm looking at is either the 12/6/1 or 15/6/1, either one with the matching sub. Haven't decided yet between the MB500 Fusion or MB800 Fusion. Cost isn't a factor. I don't really think I'd need the extra power of the MB800 but that might be a better match to the 15/6/1. I'm close to a decision, but not quite ready to pull the trigger. Also a 6-string is in the future so I have to consider that as well.
    Thanks.
     
  9. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009
    alpha-music.com
    what? no, don't do that.

    if you just plug a dedicated sub cab into your bass amp along with this full-range cab, both cabs still get everything; the total wattage is split between the two boxes (evenly if they're both the same ohm load, un-even if not, with the lower-ohm cab getting more of the power).

    you want a sub cab to only get frequencies in the "sub" range, like from 40Hz to 120Hz, but you do that by giving it its own separate power amp channel and only feeding 40 to 120Hz into that amp.
     
  10. tom-g

    tom-g

    Oct 2, 2007
    The fEARful subs have a low pass filter incoorporated so that is not a requirement.
     
  11. Both cabs will 'see' a full-range signal, whether you run each one directly from the amp or daisy-chain the cabs together. The 'output' jack on a cab is connected directly to the 'input' jack. It's just there in case your amp only has one output jack but you want to run two cabs. Think of it as a power strip.

    The three-way cab will divvy up the signal to each of its three drivers appropriately.

    The sub will electronically ignore everything above 120Hz or so all by itself-no operator intervention required.

    Your amp will have no idea that any of this has happened--it will just do it's thing, pumping out full-range signals to each cab. The cabs know how to handle it from there.

    If you are serious about a Greenboy cab, you might want to hold off on the sub. You probably won't need it.
     
  12. Oobly

    Oobly

    Jun 19, 2008
    The fEARful midrange driver and high frequency drivers have resistor networks to attenuate them since they are more efficient than the low frequency driver. The circuit has provision for a switch to bypass them when you use a sub with the cab so you get more mids and highs again to match the increased lows.

    Some use an adjustable attenuator on the high frequency driver and a switch on the mid range circuit. In that case you switch out the mid attenuator and simply turn up the highs.

    You can get more specifics from whichever authorised builder will make it for you and can probably specify just how you want your cab to be configured.

    Some people even use 2 subs and a headcase (with the mid and high drivers in), but full cab and sub is more optimal.

    I have a 15/6/1 and all the parts to build a sub, but I haven't got around to it. The 15/6/1 is plenty loud enough for me :) I would recommend a 12/6/1 and sub as a more portable and flexible option.
     
  13. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Great discussion and suggestion. The Greenboy full-range enclosures, amongst others, do a tremendous job on their own without benefit of an addt'l sub. Of course, YMMV.

    Riis
     
  14. Once again at this point we need to know which specfic cabs the OP is thinking of using.

    With a fEARful 15/6/1 and 15sub, he does in fact just plug both into his amp and the internal passive cross overs take care of everything.

    If he is talking about some other cabs, then the particulars are up in the air until he gives us some specifics.


    IMHO the fEARful and fEARless lines make a lot of this preatty simple, and that is one of their strengths. All the leg work has been thought through.
     
  15. The first thing to do is audition these things. They get bloody loud with enough power by all accounts.

    You might be all set with a 12/6, amp on 2 and PA support, or blasting 300 doom fans from the stage with a 1515/66 and 1200W.
     
  16. wcriley

    wcriley

    Apr 5, 2010
    Western PA
    For the most part, this is only true of active subs.
     
  17. Blankandson

    Blankandson Supporting Member

    Oct 20, 2010
    Gallatin, Tennessee
    I tried to set up a demo last week in Nashville but Mark (at BNA) was leaving town as I was arriving. Thanks.

    BTW When I mention the FearFul 15/6/1 to other musicians I get a lot of what I'm hearing here. Just go with the 12/6 and no sub.
     
  18. Well Mark is a touring musician as well as a cab builder. So it is understandable that he is sometimes not available. If you swing through there again some time soon hit him up for a demo.

    See I would go the other way. I would say that for your money the 15/6 is the way to go. It isnt that much more to build, and its a lot more cab. You can always turn the volume knob down.
     
  19. -1
    The fearful sub has its own passive filter unlike regular subs, no active processing required.
     
  20. -1 to you DUW.

    Ol Bill Criley was referencing the 120hz reference. The fEARful sub has a much higher LPF that matches the woofer in the mid loaded cabs.
     

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