How to connect my amp to a cab?

Discussion in 'Ampage Area' started by Gretscher, Oct 11, 2021.

  1. Gretscher

    Gretscher Electromatic

    34
    Aug 31, 2021
    Gretschland
    Hello everyone. I have a Koch Studiotone with 4, 8 and 16 ohm outputs. I want to connect this to my Brunetti cab. It has 2x12 inch speakers of 16 ohms each. If I use the 8ohm output of my Koch amplifier and I plug that speaker cable into the mono input of 8ohm, it only works with 1 speaker. What's wrong here?
     
  2. stevo

    stevo Friend of Fred

    May 1, 2012
    Atlanta
    You have a loose wire I suspect? Your two 16 ohm speakers are likely in parallel and are therefore supposed to present 8 ohms. So one wire could be loose and just one speaker would work. If in series, nothing would work.
     
  3. Gretscher

    Gretscher Electromatic

    34
    Aug 31, 2021
    Gretschland
    I just checked but no loose wire.
     
  4. stevo

    stevo Friend of Fred

    May 1, 2012
    Atlanta
    I had a feeling you might say that. Maybe a dead speaker? Do you have a multimeter and a soldering iron? You might have to test each speaker separately. But not seeing this, it's hard to be definitive on what to do next.
     
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  5. OzzPocket

    OzzPocket Synchromatic

    572
    Aug 11, 2020
    NYS
    Silly question, but do you know if the non-working speaker is actually functional? Have you got another amp you can try the cab with?
     
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  6. swivel

    swivel Country Gent

    May 13, 2018
    PNW
    If the wires are connected together to both speakers and only one is working, then you have a bad speaker. Normally they would be connected + to + and - to -, then off the end to the jack.

    However, the use of the word "MONO" throws me off a bit. Maybe that cab is wired for stereo and if you only plug into the "Mono" labeled jack, you only get one speaker? That seems likely.
     
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  7. Gretscher

    Gretscher Electromatic

    34
    Aug 31, 2021
    Gretschland
    The other speaker is 100 percent good; If I put the speaker cable in the other input of the cab, the other speaker works but the other does not...
     
  8. Gretscher

    Gretscher Electromatic

    34
    Aug 31, 2021
    Gretschland
    Yes that's right. But what can I do now?
     
  9. Gretscher

    Gretscher Electromatic

    34
    Aug 31, 2021
    Gretschland
    I'll take some pictures
     
  10. swivel

    swivel Country Gent

    May 13, 2018
    PNW
    On line I see there are two input jacks. Each labeled 16 ohms. We dont know how it's wired, but is it possible that each is just a jack for each speaker? (Are the speakers wired together one speaker to the other not at the jacks?) If so, you need a Y cable or to split the cable from the amp to each of those jacks.

    OK, I see your pics now. Hmmm... It appears those two jacks are maybe wired in parallel already, but....... one labeled " MONO 8 ohms" would make sense then and both should be working. But how does it ever work as "two 16 ohm STEREO" then if they are tied together? Those Cliff style jacks are confusing to me, maybe they are wired to separate when you plug into the second jack?

    This still doesn't solve why one is not working though.
     
    Last edited: Oct 11, 2021
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  11. swivel

    swivel Country Gent

    May 13, 2018
    PNW
    So you are saying that each speaker works and only that speaker works if you plug into it's own jack? (right jack makes the right speaker work, left jack makes the left speaker work. That would indicate to me that you need a Y cable or two outputs on your amp. With a Y cable you would use your amps 8 ohm output.
     
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  12. wabash slim

    wabash slim I Bleed Orange

    Age:
    72
    Feb 10, 2010
    lafayette in
    There's the problem. Two speakers set up independent of each other for stereo use. Use a Y connector, or rewire the speakers in parallel.
     
  13. GlenP

    GlenP Country Gent

    Jul 23, 2019
    WA
    You might try searching the web for a user manual for that cabinet, it might have been designed for use with a particular amp head with corresponding outputs. I suspect that those input jacks are switched, (as in ON/OFF type of a switchable jack) which of the poles are active depends on if a plug is inserted in the jack or not. If you can find a manual and the speakers are not working according to those instructions, then maybe you have a dirty connection between the contacts within a switched jack?
     
    Last edited: Oct 12, 2021
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  14. Randy99CL

    Randy99CL Country Gent

    Feb 17, 2020
    Albuquerque
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  15. Hammerhands

    Hammerhands Country Gent

    Aug 26, 2011
    Winnipeg
    http://www.brunetti.it/MANUALS/ENG/Dual Cab (16 Ohm) - ENG.pdf

    I think that one of the jacks’ switches isn’t working right.

    That would solve the problem for good. I recall reading Marshall had problems with the switching on jacks like this.

    Is there such a thing as a Y speaker cable? It looks like there’s one by EarCandy and one by Horizon Cables. There’s also some adaptors on Amazon for $6, but I’m not sure if they are suitable for a speaker signal. On Reverb there is an even more expensive y-splitter by Pro Cables N Sound. Weber has one that looks…cheap…but probably works fine. https://www.tedweber.com/y-cable/

    Which jack switch isn’t working? Looking at the picture, I think on the left mono jack the switch isn’t being used? When nothing is plugged into the right jack, you should have continuity from one side to the other, when the plug is in, it should break the continuity.
     
    Last edited: Oct 12, 2021
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  16. thunder58

    thunder58 Super Moderator Staff Member

    Age:
    62
    Dec 23, 2010
    tappan ny
    Admin Post
    @Hammerhands , that's great you were able to find that owners manual . @Gretscher , you should print that out ( note the far right diagram has a faded area too ) That " Y " cable is also a great option
     
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  17. wabash slim

    wabash slim I Bleed Orange

    Age:
    72
    Feb 10, 2010
    lafayette in
    Just rewire the bin. If the Y is a coax/signal cable, you probably don't want to use it for speaker level. Simplest thing would be to rewire the cab in parallel and use a simple Switchcraft 1/4" female connector.
     
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  18. Gretscher

    Gretscher Electromatic

    34
    Aug 31, 2021
    Gretschland
    Like this?

    [​IMG]
     
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  19. Ricochet

    Ricochet Senior Gretsch-Talker

    Nov 13, 2009
    Monkey Island
    Did the cab work last week?

    Switching jacks are notorious for crapping out.
     
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