Wiring Cabs, Speaker OHMS all in one thread

Discussion in 'The Squawk Box' started by JakeM, Feb 19, 2011.

  1. JakeM

    JakeM Senior Member

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    I don't know about you guys but since I have joined here I have experienced many people asking the same questions regarding Ohms, I'm not going to go into Ohms law at the moment, that's what wikipedia is for.:hmm:

    I guess the purpose of this thread is to keep a wiring library of sorts like they have in the tonefreaks section. All members are invited to upload pics of their cabs, wiring diagrams with explanations of what speakers you chose and what way you have the wiring configured.1*10, 1*12, 2*10, 2*12, 2*15, 2*10+12, 4*10, 4*12, 4*15, 6*12. Whatever you have either generic or custom, upload a pic and a quick explanation.

    This is not a "What speakers should I pick thread?", "what cab gives :slash:tone?" this is to help keep all questions regarding speakers, cabs and wiring together

    Sorry for my ramblings but I hope this thread will be of benefit to many here

    Cheers,
    G'luck Jake:thumb:

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  2. crompo

    crompo Senior Member

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    Also what about mixing wattage ??

    Say i had 2 greenbacks (25 watts) & 2 Vintage 30's (70 watts i think?) all of the same impedence in a quad box. What is the max rating of the quad ?

    Any info on this would be good. I know people sometimes mix types - especially in a combo.
     
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  3. rocknhorse1

    rocknhorse1 Senior Member

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    the wattage is whatever the wattage of the speakers add up to. just because they are mixed, doesn't change anything.
     
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  4. JakeM

    JakeM Senior Member

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    so does anyone think this will be a good idea or what?

    jake
     
  5. JakeM

    JakeM Senior Member

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    so does anyone think this will be a good idea or what?

    jake
     
  6. Tuya Customs

    Tuya Customs Senior Member

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    Very good idea. Thanks Jake.

    Actually its the lowest wattage speaks X amount of speakers in cab. So 2 25 watt green backs and 2 60 watt V30s makes a 100 watt cab.



    Also its typically to have your cab be a third or twice the power of your amp. Ohms mismatches are never good. :thumb:
     
  7. hipofutura

    hipofutura Senior Member

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    This works as long as there isn't a huge disparity between the speaker's handling capabilities. If you mix 15 watt speakers with 50 watt speakers and then exceed the 15 watt limitation, you will cook the smaller speakers.

    You are constrained by the power handling capacity of the smallest speaker.
     
  8. Grand Pappy

    Grand Pappy Senior Member

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    I have a combo tube amp (the boogie in my avatar) loaded w/ an 8ohm speaker. in the back of the amp it has 1 ea 8ohm input and 2 ea 4ohm inputs if I want to run 2 8ohm speakers.
    What if I want to run 1 ea 8ohm and 1 ea 16ohm speaker.
    Which jacks should I use? Or, is this a bad idea?
     
  9. JakeM

    JakeM Senior Member

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    It's generally a bad Idea to mismatch the impedance. Many speaker manufactures offer various versions of the same model to accommodate different amps. Pappy, there doesn't seem to be an option for you to work those combinations together

    jake
     
  10. Seneca SS

    Seneca SS Senior Member

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    so what your saying is if my amp is 2x12 speakers at 4 ohm's and i want to run a aditional 2x12 cabinet it should also be 4 ohm ???:hmm:
     
  11. >Photi G<

    >Photi G< Senior Member

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    For all those man-enough to handle it, Here's a well drawn guide to... :shock:

    SPEAKER MISMATCHING!
     

    Attached Files:

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  12. opalburn

    opalburn Senior Member

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    so basically.... as long as the ohm rating on the speaker is higher than the ohm rating of the amp, it's all good?
     
  13. GitFiddle

    GitFiddle Premium Member

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    SteveGangi and Pepe like this.
  14. >Photi G<

    >Photi G< Senior Member

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    Yes. If you have a 16&#937; cab and your amp only has an 8&#937; output, you can hook it up. If you really want to be safe, however, you can reduce the OT primary impedance by pulling a pair of power tubes. This doubles the impedance of the outputs, so an 8&#937; tab becomes a 16&#937; tap, etc.
     
  15. PapaSquash

    PapaSquash Senior Member

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    In Photi's examples of the Mesa cabs this assumes that the wiring behind the jacks are all parallel, right?

    My problem is that I have a Bassman (it says "4 ohms total" on the back)
    I have a 4ohm 2x12 now (2 eights in parallel) It's all good but the drummer wants another cab over on the snare side

    If I want to use the ext jack, I figure I need two different cabs. Adding a 16ohm cab in the ext would give me 3.2ohms total. Even a 32ohm cab only gets me to 3.5555 unless my math is wrong

    I really want two eights: one in each jack, parallel to give me four total.

    I suppose I could make my current cab switchable to 16, get another 16, and run them both for 8ohms total and live with a one-step mismatch.

    Is there anything wrong with my thinking on this?
     
  16. >Photi G<

    >Photi G< Senior Member

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    Almost all amps have speaker jacks wired in parallel. Fenders, however, have a weird switching thing going on with their extension jacks. It depends on the model. Which one do you have, Papa?
     
  17. PapaSquash

    PapaSquash Senior Member

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    I have a late 70 or very early 71 Silverface Bassman (50 watt, ab165 circuit) Yes, looking at the schematic, they are parallel and they have a switch that supposedly shorts output if nothing is plugged into the speaker out jack. Intended to protect the OT. It means you can't use the ext jack alone, but doesn't seem to do anything to change the impedance or connect up to a different tap on the OT or anything.

    I've never turned it on without a cab plugged in and never intend to, so I don't know what it really does, but I know of someone, who I consider reliable, who used to claim that he got weak signal out of the ext jack on his bassman with nothing plugged into the speaker jack. So it may not work all that well.
     
  18. PunkerJon

    PunkerJon Senior Member

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    I have an Orange RV50 combo with two 8 ohm V30 60 watt speakers (wired in series to equal 16 ohms). I want to make a 2x12 cabinet with two 8 ohm 80 watt speaker (wired in series to be 16 ohms). Is OK to mix wattages in this case. My amp has the outputs to accommodate this, just wondering about the wattage differential. Thanks PJ
     
  19. JakeM

    JakeM Senior Member

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    punkerjon: mixing wattages is fine as long as you don't exceed the power rating of the lowest powered speakers so mixing both of these will be fine

    Opal: yes technically you could run that but I can't emphasize enough how important it is to match your ohms, it's the best option and won't leave you worrying

    Wyoming: Yes if you amp has two 4ohm speaker ohm outs then yes using an extra 212 will be fine
     
  20. GitFiddle

    GitFiddle Premium Member

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    Ok Photi, I have to ask. How are you inserting the ohm symbols from the text window? Are you inserting ascii, html codes?
     

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