/13 ftr37 + matching cab impedance & outputs

Discussion in 'Amps and Cabs' started by JDandCoke, Apr 16, 2016.

  1. JDandCoke

    JDandCoke Member

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    So I finally picked up that ftr37 I mentioned when looking for clean amp suggestions. The documentation for this amp is extremely limiting and my search for answers has been less than specific.

    The amp has 5 outputs; 2x4ohm, 2x8ohm and a single 16ohm

    The cab has 2 inputs with no labelling, inside is a g12h and a blue, i can't find impedance labels on them (are they hidden on the underside or something?) I would assume both are 8ohm though since that seems to be by far the most common.

    So yea, pretty much my question is how best to connect these?

    The main problems I face are; is the cab series or parallel? why 2 sockets?
    how do the labels correspond to the outputs on the head? a single 16ohm makes sense, plug it into a 16ohm cab. 2x8ohm, does that mean a single output is 8ohm for a single 8ohm cab and if using both outputs (such as to 2 cabs) each cab should be 16ohm since they're parallel or both cabs 8ohm (and since they're labelled together meant to not be used with a single cab?)

    please help!
     
  2. markstullkc

    markstullkc Member

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    You need to call Fred. # is on the / website.
     
  3. JDandCoke

    JDandCoke Member

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    international calls hurt my soul :(

    edit: also it's Saturday, I'm back to work on Monday and no way I'm waiting till next weekend to get this roaring!
     
  4. Stormin

    Stormin Staff Member Gold Supporting Member

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    It should be pretty easy to determine series/parallel wiring. If it's series there will be a wire going from the + terminal of one speaker to the - terminal of the other. It has to be that way in a series 2x12. If not, parallel has a wire going from each speaker + and - to the jack or one speaker + and - to the other speaker + and -.

    The other easy way to determine the ohmage of the cab is to plug a speaker cable into it and measure the resistance from the tip to the ring of the other end of the cable. For a 16ohm cabin should measure around 15 something. For an 8 ohm cab is should measure around 7 something. It'll be less that the rated ohmage because a multimeter can measure the impedance component of the speaker load. The multimeter will get you close enough to tell 16 from 8 from 4 though.
     
  5. JDandCoke

    JDandCoke Member

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    Yea, it's mostly the amps outputs that have me stumped
     
  6. Stormin

    Stormin Staff Member Gold Supporting Member

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    Just measure the cab w a multimeter and plug into the closet input. Unless I'm missing something, it should be that easy.
     
  7. Grasley

    Grasley Member

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    Each speaker is independant of the other, hence the 2 jacks.....each speaker is 8 ohms so you hook it up at 8 ohms on the amp (both jacks on amp to both on cab)...if you use the half power switch you have to use the 2 4 ohm jacks on the amp.....theres usually a diagram in the cab that shows this
     
  8. Optimus Rhyme

    Optimus Rhyme Member

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    The rated ohm of each speaker should be somewhere on the speaker, usually where the solder connections are. Each speaker input is separate from one another. They are most likely 16 Ohm each. So it's as if you are using 2 individual 16 Ohm cabs.

    Using both at once would give you an 8 Ohm load - plug both speakers into the 8 ohm amp inputs.

    When using only one speaker, plug into the single 16 Ohm input.

    If the speakers are 8 Ohms, plug both into the 4 Ohm inputs. Using one speaker plug into a single 8 Ohm input on the amp.

    Pretty simple really. The possibility of the cab being wired in series with dual inputs is slim.
     
  9. Grasley

    Grasley Member

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    I actually have a pic of the amp to cab hook up diagram that comes with the amp.....not sure how to post it.....but it says full power use both 8 ohm taps and half power to use both 4 ohm taps
     
  10. JDandCoke

    JDandCoke Member

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    That's how I was expecting it to work; with the 8ohm label over both outputs indicating a total load in parallel rather than 8ohm each

    would be cool to see, mine was a preloved amp so I didn't get any of the documentation you'd get as new.
     
  11. ctman64

    ctman64 Supporting Member

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    Seems you have it figured out, but for additional clarification:

    The 8 and 4 ohm output jack groups are both in parallel, so it should match the total speaker load (e.g. two 16 ohm speakers in parallel, creating an 8 ohm total load, would therefore be plugged into the two 8 ohm outs, or, a single 8 ohm load would be plugged into just one of the jacks.)

    The dual jacks on the cabinet run to each individual speaker, which are each 16 ohms. Plugging in both will result in the above example - two 16 ohm speakers in parallel for a total 8 ohm load, both plugged into the 8 ohm jacks, or a single 16 ohm speaker plugged into the 16 ohm jack.

    When using the half-power function, you should select the impedance jack(s) on the amp with half the impedance of the speaker load - so, the two 16 ohm speakers with the 8 ohm total load would then be plugged into the 4 ohm jacks, or a single speaker at 16 ohms would be plugged into one of the 8 ohm jacks.
     

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