combining 15W and 50W speakers in 2x12 cab? Bad Idea?

Discussion in 'Amp Central Station' started by thebigk1961, Feb 9, 2015.

  1. thebigk1961

    thebigk1961 TDPRI Member

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    Hi to all,

    I have a 2x12 DIY cab which I built last year with a little help from my tdpri friends:cool: (thanks)

    Currently there is a 50w eminence cannabis rex and a weber blue dog (both 8ohm, 50W).

    It works great but I would like to put the blue dog in my Laney VC30 so I am looking for a new speaker to put in the 2x12. Right now I have a chance to buy a used weber blue dog but it is only 15W. So it would be a 50W eminence and a 15 weber running together in the 2x12. I have the parallel and series switch installed so I would be using it in both settings.

    I use the cab with my little amps (BF vibro champ, vox AC4TV, sometimes the Laney VC30) but also with my BF Bandmaster which is 40W.

    Is the 15W too little? Will it decrease the headroom or worse - is there a chance to blow the speaker?

    From what I read if you have two speakers the power handling adds up no matter wiring. So in either case it should give 50+15 = 65W in total.

    Ideally I would buy another weber (as I reallly like it) rated 30W or 50W but I am based in Europe and it is hard to get those here. I dont want to import because of the taxes, duties..

    I might get the 15W anyway and use it somewhere else but I was wondering if it is worth trying out this unequal combo...

    thanks for comments.

    pj
     
  2. muchxs

    muchxs Doctor of Teleocity

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    Except the 15 watt speaker is still a 15 watt speaker. That's the one you'll blow if you're hard on speakers.

    I'm not hard on speakers so I get away with things other people don't. Certain combinations are hard on speakers. Like... de- tuned guitars through an overdrive plugged into a cranked amp. That's a recipe for blowing speakers.
     
  3. thebigk1961

    thebigk1961 TDPRI Member

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    thanks, thats what I thought. Makes sense..

    I dont use any heavy distortion but then again cranking the amp is sometimes inevitable:)
     
  4. KC

    KC Friend of Leo's

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    like he said -- the weak link is the one that will blow. 40w bandmaster into a 15w speaker is a recipe for death. also: there's likely to be a big difference in speaker efficiency between the two, and once you get up to a 3dB difference or so, you only hear the louder speaker. The less-efficient speaker might as well not be there.
     
  5. BBill64

    BBill64 Tele-Afflicted

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    So long as the total power of all speakers in a cab is greater than the amp's rating, is there still a risk of blowing speakers with playing heavy like you describe?
     
  6. SteveGangi

    SteveGangi Tele-Holic

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    Using the Bandmaster, and assuming you have it cranked up to the full 40 Watts, you will be dumping 20 Watts of power into each of the two speakers. The 50 Watt speaker will be just fine, the 15 Watt speaker not so much. But you also can consider that most people do not turn it up to 10. So as long as you don't "dime it" you might be safe.

    Also, I would expect the smaller 15W speaker to break up sooner.

    Personally, I'd go with two 50W speakers (and two of the same sensitivity/efficiency). That way, you can play at any volume level you want, and not have to worry.
     
  7. Abu Twangy

    Abu Twangy Friend of Leo's

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    I got by with a vintage 20 watt 10" Oxford and a Fender Special Design 12" in a 40 watt Hot Rod Deluxe but then I don't push amps hard.

    I was anticipating a sudden change in my amp's sound during bigger gigs. :lol:
     
  8. thebigk1961

    thebigk1961 TDPRI Member

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    understood.

    It seems that as a back up or a temporary thing it is fine but having it like this as your main set up is not the smartest idea. I assumed that.

    Thanks for all of your responses.
     
  9. Paul G.

    Paul G. Friend of Leo's

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    There is no mechanism in your cabinet wiring that distributes power, so it is the impedance of the speaker that determines how power will be apportioned.

    If impedences are equal, in a 2 speaker cab, each speaker will draw half the power. Therefore, the final power handling of the cab will be 2X the handling of the lowest rated speaker.


    So a 15W + 15W = 30W cabinet,

    15W + 50W = 30W cabinet.

    15W + 200W = 30W cabinet.

    15W + 10,000W = 30W cabinet.

    You have been warned.

    P.
     
  10. JD0x0

    JD0x0 Poster Extraordinaire

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    Nothing wrong with that, but just know that total power handling is

    Lowest speaker wattage multiplied by number of speakers. (assuming impedance matches)

    So if you've got 3 100 watt speakers, and One 1 watt speaker. Your cab will have a maximum power handling of 4 watts. beyond that, you will blow the 1 watt speaker.

    2 100 watt speakers and 2 25 watt speakers = 100 watts. 25 watts x 4 speakers.

    I've got a cab with a 30 watt and a 65 watt speaker.
    With both speakers wired up, it only handles 60 watts. If I disconnect the 30 watt speaker, it can handle 65 watts.

    Your power handling is only as good as your weakest speaker.
     
  11. thebigk1961

    thebigk1961 TDPRI Member

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    perfect, finally I understand how it works!!!

    THANKS
     
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