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Bl Question - Double Bl, But At What Cost?

Discussion in 'General Car Audio Discussions' started by Fryguy, Dec 30, 2003.

  1. Fryguy

    Fryguy Full Member

    Mr. wiggins, mr expert, help me understand something here:

    Say you have a 2-ohm driver with a BL of 15.9 or so, let it be a brahma.

    Now say you have 2 amps that give it ~1200 watts, one at 1 ohm, and one at 4 ohm (specifically a crossfire bmf1000d and a pg tantrum 1200.1). I want this to be a learning experience, so if the specific amps effect the experiement in a strange way, please explain this and also still explain the general concept.

    Wiring in series doubles BL. So we could run the brahma in series with the tantrum, and double the bl at no cost to wattage. I know that BL is N/A and not N/P, but wouldn't voltage be either constant, or the same in both situations? Please explain this. P = IV.

    Also, if it ends up not mattering, what about inductance? How would that play in, and would it be smarter to go parallel to keep inductance low if BL becomes a non-factor?
     
    Fryguy, Dec 30, 2003
    #1
  2. deyton

    deyton Full Member

    Well I can say that voltage (and therefore current as well) will not be constant (nor the same :p) because V = IxR (Ohm's Law) and P = IxV, so P=V²/R and P=i²R.

    So i'm thinking F=Bli, there's no difference in force and therefore output. Bl doubles, current is halved, so the force is the same.
     
    deyton, Dec 31, 2003
    #2
  3. sandt38

    sandt38 Full Member

    :stupid:

    Just kidding. Well fielded Deyton
     
    sandt38, Dec 31, 2003
    #3
  4. DanWiggins

    DanWiggins Full Member

    Excellent reply, Deyton! Current is the key, and you have to remember impedance...:)

    Dan Wiggins
    Adire Audio
     
    DanWiggins, Dec 31, 2003
    #4
  5. Fryguy

    Fryguy Full Member

    So then it would be better to get the crossfire, so that inductance stays low?
     
    Fryguy, Jan 1, 2004
    #5
  6. jlaine

    jlaine Full Member

    How do you look at things?

    Which amp is cheaper...

    4 ohm offers a typically higher damping factor... (marketing point)

    Plus they are typically *less* prone to the ever so great magic smoke release - higher current designs always seem to like dying unexpectedly, while a higher voltage design have always exhibited a longer life span with me.
     
    jlaine, Jan 1, 2004
    #6
  7. Warbleed

    Warbleed Full Member

    Yep, always gotta remember what Re you are looking at before looking at BL.

    That's why I always look at Qes when comparing drivers. :)

    I'd personally recommend ignoring BL altogether, and just looking at Qes, since BL is so easily manipulated and without carefully looking, often gives a false impression about the motor strength of a given driver.
     
    Warbleed, Jan 3, 2004
    #7