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Err... is this a good idea????

Discussion in 'Amps [BG]' started by richntiff, Nov 2, 2012.

  1. richntiff

    richntiff

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    Ok - I found a cable on Ebay and here is the description:

    Connects from one amp to two speakers.

    This cable is wired in series, and provides many advantages over a parallel cable or standard connections available from speaker and amp jacks alone. Amps and speakers with multiple jacks only provide a parallel wired connection. This series cable will allow your amp to run safer, and turn up more, making the volume more manageable. Amps are not damaged by a larger ohm load, in fact, they are damaged by impedances that are too low.

    FIND THE TONE YOU WANT AT A LOWER VOLUME!!

    When plugged into two speakers the impedances are added together like this.

    4 ohm speaker cabinet + 4 ohm speaker cabinet = 8 ohm load to your amp

    or 8+8=16 / 16+16=32


    I'm FAR from an expert on amps/ohms/etc - but something about this doesn't seem correct - what says the TB pros about a cable that is wired in series to supposedly be able to run, say, two 4 ohm cabs at 4ohms apiece, 8ohm load to the amp?? Basically the cable is one 1/4" jack with two sets of cable/1/4" jacks - plug the one jack into the amp and one of each of the other jacks into each cab. Seems to me to be a recipe to melt or blow something.... :eyebrow:
  2. Primakurtz

    Primakurtz Registered Nihilist Supporting Member

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    Fear not - series cables and boxes are real, and useful. Rarely for bass, but often useful for guitar tube amps. Two 8 ohm cabs in series equals 16 ohms, which makes many tube amps happy... Whereas 4 ohms makes them very sad.
  3. B-string

    B-string Supporting Member

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    That is actually backwards. Does hold true for SS amps though.
  4. Primakurtz

    Primakurtz Registered Nihilist Supporting Member

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    Sorry if I wasn't clear. Many Marshall heads, for example can run at 8 or 16 ohms, but not 4, or much less 2. SS heads are different kettle of worms.
  5. richntiff

    richntiff

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    Wow thanks! That's good to know. The gears started turning when I saw it - I have a 4 ohm cab and am thinking about adding another (identical) 4 ohm cab to it. The resulting 2 ohm load had me needing to get a 2 ohm capable head right away - I could put that purchase off for awhile though...
  6. B-string

    B-string Supporting Member

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    Buy 2 cables and three matching cabs. You'll be back to a 4 ohm load and enough speaker area to crack plaster :D
  7. SurferJoe46

    SurferJoe46

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    Don't bother with those cables.

    You'll accidentally plug them into something that doesn't like it. Someday. Accidentally.

    Do this instead:::

    [​IMG]

    I had to do that for an old Peavey PA that required 16Ω and all I could find was a pair of 8Ω cabs - so I build this parallel/series box. Cheap.
  8. tjh

    tjh Supporting Member

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    ... just to clarify .. buy 3 MORE matching cabs (so you have 4 total) ... we are saying the same thing, just clearing up for others than the OP :)
  9. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

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    The only thing is, let's say your (solid state) amp is rated at 500 watts at 4 ohms. When you connect two 4-ohm cabinets to it with a series cable, you're presenting an 8-ohm load to the amp, and it will put out only about 300 watts max. But it will still be louder, in general, than one 4-ohm cab getting all 500 watts.

    I've made a couple series cables myself. Here's a couple pics of one, plus a free schematic. For Speakon[SUP]®[/SUP] connectors, tip = pin 1+ and ring = pin 1-. Make sure you use Elite cable, too.

    [​IMG]

    [​IMG]

    [​IMG]
  10. B-string

    B-string Supporting Member

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    Yep, four 4 ohm cabs + two serial speaker cables = a 4 ohm load and lots of speaker area :D
  11. richntiff

    richntiff

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    LOL - I think I will stick to two cabs. I understand the reduced wattage at 8 vs 4 ohms too - I still think a more powerful head is in my future (GAS...) but this could be an interim fix. Thanks everyone!!
  12. Arjank

    Arjank

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    I would only run cabinets in series if they are totally the same, else the power distribution is f.....up ;)
  13. sokolasty

    sokolasty

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    As far as I know, tube amps can work with proper load, i. e. 2 or 4 (Ampeg SVT 2 pro) and you need to select correct load with a switch. Tube amps cannot work with any other load as indicated. You cannot attach a 8ohm cabinet to SVT 2 pro, at least according to manual.

    Solid state can work with any load which is not lower as minimum, most commonly 2 or 4. If the minimum load is 4, you can attach 32ohm cabinet (i. e. headphones), 5,33 or 16 or 10 or whatever you want as long as it is not less as 4.
  14. JimmyM

    JimmyM Supporting Member

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    You CAN attach an 8 ohm cab to an SVT tube amp and I have done so without incident (only on rentals), but if you're going to be pushing any real volume with one, you can cause early wear and tear on the tubes and output transformer and possibly cause something catastrophic. It works for me because nobody ever lets me crank (nor do I want to), but it's not recommended by any means and will void your warranty if something bad happens.
  15. Mr. Foxen

    Mr. Foxen

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    Don't fuss about losing watts, they don't matter nearly as much as people make out.
  16. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

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    Dunno about that. Someone would have to be awful slow to miss the markings on this one.
  17. richntiff

    richntiff

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    I like that cable - I will probably build one just like it, but with 1/4' instead of speakon for the amp side - that will make it even tougher to mess up! Plus, I don't have so much gear that the opportunity will even be there :)
  18. Pilgrim

    Pilgrim Supporting Member

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    BEAUTIFUL work, Munji!
  19. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

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    Here's a picture of the quarter-inch version. I recommend color-coding with shrink tubing. BTW, these are not going to pull apart at the grafts. The cable will break first.

    [​IMG]

    [​IMG]
  20. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

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    Thanks. I love to solder.

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