Positive to tip, Negative to sleeve for an extension cab jack?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by dB, Feb 21, 2012.

  1. dB

    dB Member

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    Is that the standard for wiring up the jack in an extension cab?
     
  2. smolder

    smolder Gold Supporting Member

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    For all speaker cabs, yes. Unless your working with a JBL speaker, which are often wired backwards.
     
  3. dB

    dB Member

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    that was my next question...i'm using scumback speakers with a Two Rock Studio Pro 35. The folks at Two Rock told to make sure I wire the cabinet out of phase, as all of their reverb amps are designed to be run that way.

    I didn't want to wire the cab out of phase, but I figured I could just switch the terminal connections at the speaker...ie, tip to negative speaker terminal, and sleeve to positive speaker terminal. This will achieve the same effect, right?
     
  4. donnyjaguar

    donnyjaguar Member

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    Sounds like nonsense to me.
     
  5. dB

    dB Member

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    it's really not that nonsensical.
     
  6. walterw

    walterw Gold Supporting Member

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    sure.

    the idea is just that fender-style reverb amps have an extra gain stage which flips the polarity (and it is polarity, not "phase"), so reversing the leads on the speaker gives you an amp that fires in the same direction as most other amps.

    it doesn't change the sound either way unless you're running the amp with another amp at the same time (although it can change the way the guitar feeds back; kimock has shared some interesting stuff about how he long ago figured out which polarity worked best to get the feedback and sustain he wanted out of which guitars he used, so he attends to that detail with his guitar rigs.)
     
  7. jay42

    jay42 Member

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    It's helpful to build a 6" reverse cable. Switchcraft in-line female to a standard 280 plug with the wires crossed. You don't have to think about it until you're up an running. If the two cabs are out of phase, you'll know. Reverse one to prove it to yourself, then decide which way to wire the extension cab.

    People like Suhr claim there's difference between phases...one will sound better in any amp. The cable is a useful item.
     
  8. Husky

    Husky Gold Supporting Member

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    Well I don't know about absolute phase by itself. Even the guitar pickups will flip that.
    I have absolutely heard an interaction though in a combo when the speaker is very close to the tubes /Output transformer and it wasn't small.
    I ran in to this with EC's 5E8A Tweed Twin.

    As far as the reverb channel yes it has an extra gain stage so the phase on the reverb channel is flipped but then again the normal channel is not.
     
  9. jay42

    jay42 Member

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    I have a friend who says the same thing. He differentiated between the first note pushing the speaker out or pulling it in. I think he preferred pull. How do you test that -- with a 9V?
     
  10. Husky

    Husky Gold Supporting Member

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    I dont know if people can hear the difference between push or pull since it isnt the first note really, you are talking about AC. However there is some interaction between the amp depending on the circumstances
    To make sure the contacts on the speaker are not miss marked and your complete cabinet wiring is correct a 1.5~9V battery Plus on Plus Neg on neg will make the speakers push out that is correct. With some amps though like the 5E8A the interaction between the speaker and the transformer or tubes made it sound better flipped.
     
  11. Tone_Terrific

    Tone_Terrific Member

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    The idea is (at least to me) to get the speakers 'in phase' with the input signal so that a positive in yields a forward push of the cone.
    I notice that touching a pup pole with a string, or metal whatever, with the volume up will pulse speaker.
    You can see it or feel the cone move.
    However, changing channels, fx, guitars, etc may all switch the polarity. If you can determine which wiring on your spkr results in the fwd push, you have a starting point.
    Or, just skip all the futzing around and swap/reverse the spkr wiring to get the preferred result, since, as usual, YMMV
     
  12. donnyjaguar

    donnyjaguar Member

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    I personally wouldn't mis-wire my speaker cable to invert the phase. You're asking for trouble with this. Like the other poster said, what difference does it make when you consider some pickups (and how they're wired) will have different polarisation anyway.
     
  13. doctorx

    doctorx Member

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    /THREAD
     
  14. Husky

    Husky Gold Supporting Member

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    Yes but if the speaker pushes forward when the string approaches the magnet it will suck in as the string moves away from the magnet. That is how we test pickup phase when dealing with an unknown. You are seeing vibrations that move pretty fast. I still bet you cant hear the difference in a double blind test if it is a head with a separate cabinet. A Combo could be an entirely different story.

    You are not going to hurt anything by flipping the speaker phase. Sometimes it is mandatory when using two amps. Most amps with 2 channels are not in phase with each other either.

    It would pretty easy and quick to make a flipped speaker cable and see if you can hear a difference or install a phase switch on the amp.
     
  15. Tone_Terrific

    Tone_Terrific Member

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    Lots of previous threads and testimonials as to how effective this is.
     
  16. Husky

    Husky Gold Supporting Member

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    I put a switch on a Badger 18 and have yet to find someone who can pick it out more than 50% of the time average. It does make a difference in some combo amps though for sure. Not saying there isn't a difference otherwise but I have yet to find someone who can pick it out in a controlled test. :munch
     
  17. Tone_Terrific

    Tone_Terrific Member

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    Kimock (I'm just the messenger:stir) says that once you know the effect, you will get it every time.
     
  18. Husky

    Husky Gold Supporting Member

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    As much as I respect Steve and he an I have chatted about this before....until someone shows me they can always pick it out in double blind tests it is a mute point to everyone I have had listen to it. You would have to show me you can pick this out on any amp as well since there could be phase relationship issue in the layout of a particular amp from the in to the output. In my world I dont have a disbelief but I need real proof with my own eyes and ears before I will confirm something. I'm not a faith based person but more scientific and a skeptic. If I had enough requests I would at this point put a phase switch on the amp so the customer could choose. I advise those who feel there could be a difference to try a flipped cable and play on whichever one sounds right to them and move on towards playing music. It would take someone 10 minutes to figure it out for his rig and then they are done. As I explained previously most amp flip phase when using an effects loop or lead to Rhythm channels anyway. So you might have a hard time flipping cables while switching channels. Granted a Dumble lead channel is in phase with the clean channel but a Dumbleator for the effects loop flips the phase. Obviously this didn't bug Alexander Dumble too much then. :hiP

    Your quote right?
     
    Last edited: Feb 24, 2012

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