Is 4 ohms or 16 ohms "better"?

Discussion in 'The Squawk Box' started by LJGriggs, Oct 15, 2015.

  1. LJGriggs

    LJGriggs Senior Member

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    I just received a new/used 2x12 cabinet with two 8 ohm speakers. My amp is switch selectable for 16, 8, and 4 ohms. Is it better to wire the two speakers in series for 16 ohms, or should I wire the speakers in parallel for 4 ohms.

    I did a search and found lots of info on how to wire speakers for impedance matching, but nothing on the possible benefits of running at the lower or higher setting.

    Does the impedance level have any detectable impact on the output volume or tone?

    (BTW, the rig in question is a Germino Masonette 25 watt head and a Tone Tubby 2x12 cabinet with their 8 ohm "hemp cone" speakers.)
     
  2. Marshall & Moonshine

    Marshall & Moonshine Senior Member

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    Here's a weird maybe answer:
    I emailed a guy at Mercury Magnetics about an OT and I forget how it came up or what it related to, but the short version was this-- if you're using the lower Impedance Settings, you're using less of your OT, or something to that effect.
    In your case, I'd just try both and see if there's any difference. I doubt it would be noticeable.
     
  3. hbucker

    hbucker Senior Member

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    I once experimented with a 410 cab and a 100 watt head - same question, 4 or 16 ohms.

    I went with what sounded better (or what I thought sounded better. The differences were subtle).

    I thought 16 ohms sounded a little more driven, salty, with less clean headroom. Again, these were subtle differences, but I thought I heard them. So I went with 16 ohms.

    FWIW...

    Your results may vary.
     
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  4. LJGriggs

    LJGriggs Senior Member

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  5. G Man

    G Man Senior Member

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    Regardless of what load you run it at, that cab/speaker combo should sound killer. Love me some hemp cones.
     
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  6. Shortscale

    Shortscale Premium Member

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    I've always wondered about this too...

    Good info in that other post
     
  7. Six Gun

    Six Gun Senior Member

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    16 Ohms is the ultimate because it uses all the windings in the OT.

    Always run 16 when you can.
     
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  8. Marshall & Moonshine

    Marshall & Moonshine Senior Member

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    even when 4 has been found to sound better?
     
  9. Six Gun

    Six Gun Senior Member

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    16 uses all the windings, 8 ohms uses 1/2 the windings and 4 ohms uses 1/4 of the ot windings. as long as the ot is matched with the speakers you will be fine. but if you have ca marshall w/ a 4x12 half stack use the. 16 ohms.

    it still sounds great at 4 ohms, but as a rule 16 will get you plenty.
     
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  10. Six Gun

    Six Gun Senior Member

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    If you have a small 18 watt marshall with a selectable OT, run the amp with a 16 ohm single speaker and it will use the OT's full potential.
     
  11. Big John

    Big John tastes like chicken V.I.P. Member

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    16 or 4...why not have both as an option? A pair of Cliff switching jacks is all you need.
     
  12. Custom53

    Custom53 Senior Member

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    No matter which setting make sure the Head and Cabinet match..
     
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  13. Six Gun

    Six Gun Senior Member

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    ________

    Amen,

    And if you have a mystery speaker cab and you don't know the ohms, use a multi-meter and plug-in a speaker cord to the speaker cab and get a reading on the 1/4" mono jack to know for sure. If you run a 4 ohms cab on the 16 ohms Head setting, well it will not be good if you dime the amp for a while. We have jacks with a small 12" pigtail and alligator clips to test speaker cabs. Some cabs have a bad speaker and measure as low as 2 ohms sometimes. If you don't know what's in the cab, find out.

    After you lose an OT on a good amp it wakes you up.

    This is why most cabs are stenciled or labeled on the rear in a touring band.
     
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  14. Marshall & Moonshine

    Marshall & Moonshine Senior Member

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    See, this is what I don't understand.... If you run it safely at 4ohms, and it sounds better to you that way, why is using the 16ohm tap the way to "get more out of your OT" or "use the whole winding"?
    I always thought that transformers were about ratios, not the actual number of turns, length of wire in coil, etc.... I'm sure the inductance changes, but could this also have something to do with the speakers being in parallel vs in series?
    I think you'd really have to do some switching to test that theory, but if the connections aren't soldered and you don't lose track of "what goes where", it could be done with a mic on one speaker.
    I don't know. I know that what the MercMag guy said goes along with Six Gun's explanation, I just don't see how or why that makes any difference. It's like telling me that 16ohm taps "have the electrolytes that speakers crave" ;) or something.
    I don't need an O-scope or cosmic spectrum analyzer to tell me which setup will give off more of an ultraviolet aura; just plug it in one way, plug it in the other and decide.
     
  15. KenG

    KenG Senior Member

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    :shock::laugh2:

    For safety sake I would go with the 2 speakers in parallel. Running a tube amp without a load is very bad, so with 2 speaker in parallel if one coil opens up (ie fails) there is still a load on the amp. In series when speaker fails the load is totally removed.
     
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  16. Marshall & Moonshine

    Marshall & Moonshine Senior Member

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    Not only this, but if one speaker in parallel burns out, the load impedance doubles, and depending on the wattage rating of the speaker vs amp output at the new ratio, could still get through the night, right?
     
  17. LPV

    LPV Senior Member

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    There are about a million combo owners who better run out and grab another cab then. Definitely shouldn't run a tube amp without a load but if sound stops coming out I would assume most people would shut off the amp. Ot s don't blow quite that easily. I'd be replacing one a year if that were the case.

    I find 16 sounds slightly better on a Marshall but in a band context it's lost.
     
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  18. SteveGangi

    SteveGangi V.I.P. Member

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    I have to agree.... not that it happens very often. It would take a huge amount of heat to wreck a transformer. You're more likely to pop a fuse, a resistor, or something else far quicker and more often.
     
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  19. Marshall & Moonshine

    Marshall & Moonshine Senior Member

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    So, what I guess I still don't understand is this: If a speaker burns out, does it become an open or a short? It seems to me that if it goes open, then it wouldn't draw any current, therefore nothing would happen. The voltage would go up and down on the primary side, but nothing would really "be moving" to burn anything up, if the speaker coil burns out.
    Most coils on electrical equipment burn into an open condition, although they probably experience a moment of short-circuit condition, where I think the damage could actually come from.
    Somehow, after all these years, and working as a ship's electrician, I still fail to grasp why an open circuit in the secondary would hurt the transformer.
     
  20. johan.b

    johan.b Senior Member

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    As you say, the voltage goes up., often to a point where the insulation fails and the primary shorts. This is why the practice of using shorting speaker jacks as on most fenders is better than the open jacks Marshall always used. Vox use a compromise in the old days with a 470 ohm resistor across the output jacks, so there was never a no load situation.
    J
     
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