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4 ohm versus 15 ohm

Discussion in 'Amp Central Station' started by golfnut, Oct 9, 2018.

  1. golfnut

    golfnut Tele-Afflicted

    Age:
    58
    Jan 15, 2008
    Canada
    I'm considering a speaker replacement for my Allen Accomplice. I'm considering putting a Celestion Gold in it. It has an ohm tap and supports 4 ohm or 16 ohm. Is there an advantage to one over the other? Tone? Some other reason or doesn't matter?
     

  2. golfnut

    golfnut Tele-Afflicted

    Age:
    58
    Jan 15, 2008
    Canada
    Actually it would be 8 0hm or 15 ohm. I got confuses as the accomplice has 6L6's and it would be a an 80ohm speaker (4ohm setting on amp) or 15 ohm speaker (8 ohm setting on amp)
    So just wondering what the difference would be between the 2 options.
     

  3. Tele Jr

    Tele Jr Tele-Holic

    607
    May 15, 2004
    Minneapolis, MN
    I would recommend going with a 16 ohm. You could use full power at 16 ohms, and also get the so called power reduction effect at 4 ohms of the favorable mis-match, that could give you another tone shaping option and make it sound sweeter at lower volumes.
     

  4. zombiwoof

    zombiwoof Tele-Holic

    755
    Oct 17, 2008
    Tujunga California
    Speakers labeled 15 ohms (like old Celestions) or 16 ohms are basically the same, and should be set to 16 ohms on your amp.
    Al
     

  5. sliberty

    sliberty Tele-Afflicted

    Mar 19, 2007
    East Brunswick, NJ
    Some believe that you should always use the highest impedance tap on your amp because you are using all of the output transformer’s windings instead of tapping in at a partial point and using less of the windings. I can’t say that I have ever A/B’d this with the same model speaker (the only way you’d actually know), but it sounds plausible that thee would be a difference in the sound.
     
    Wally likes this.

  6. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    THE OP’s amp is a tube amp. That power production vis a vis wide mismatching does not function in the tube world as it does with solid state amps.....and a mismatch of 16 versus 4 ohms is dangerous with a tube amp. The power difference is also not as great in Tube amps as it is in solid state when mismatching. Tube amps function best and most efficiently with a matched load.
    The ‘mismatches’ that the OP describes are actually not mismatches but rather account for the difference between 6V6 and 6L6 tubes in the primary side of the OT. With 6V6’s, one would want the OT tap and the speaker impedance to be identical. With 6L6’s, the speaker impedance needs to be double that of the OT tap in order to yields a true match when all four variables in the equation are considered....power tube impedance, OT primary impedance, OT secondary impedance and speaker impedance.

    To the OP’s question, there is a difference in induction between the different taps. Some prefer the full winding....others may prefer a partial winding. Lend an ear and make a choice???
    And......there are some rare OT’s that do not ‘tap’ a single winding but have separate secondary windings for the different impedance. I am going to think that the different windings in such OT’s still exhibit the difference in induction as that is dependent on the number of winds in each ‘tap’.
    There are those choose to mismatch in either direction...100% to the high side or 50% to the low side...for the sonic differences. I prefer matched loads. Ommv...
     

  7. golfnut

    golfnut Tele-Afflicted

    Age:
    58
    Jan 15, 2008
    Canada
    I completely misunderstood how my amp worked. I completely understand now.
     

  8. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    Golfnut, I hope that my assumptions about the situation with that Allen is correct. If you have a manual, you can either confirm or disprove my assumptions. The situation you describe is what led me to my conclusions as that is how it works with a Fender amp...or any other tube amp, ime. Take a Twin Reverb. If you remove two of the power tubes to halve the output, the impedance the power tubes show to the primary demands that one speaker be disconnected....or by some other means an 8 ohm load is used rather than the specified 4 ohm load with all power tubes in. Your description of the ‘mismatching’ with 6L6 power tubes versus 6V6’s is the same situation.
     

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