Crown's handle 1.5 ohms

Discussion in 'Archived Threads 2001-2004' started by Brandon B, Mar 10, 2002.

  1. Brandon B

    Brandon B Second Unit

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    Getting close to hooking up dual stryke HE15's to an amp. Since in series, these end up being 6 ohm drivers and in parallel they are 1.5, which way is better?

    My amp is a Crown Macrotech 3600VZ. Probably more than enough power either way. It's stable down to 2 ohms no problem, so is 1.5 pushing it?

    Only reason I even contemplate parallel is to use a separate 10 ga wire run to each voice coil to minimize damping losses. I will be calling Crown tomorrow to check with them too.

    Thoughts?

    BB
     
  2. Vince Bray

    Vince Bray Stunt Coordinator

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    How much power into 4ohms / 2ohms is that crown rated for?

    John J said that the in-box impedance would be more like 4ohms, or 2ohms in your case. It ought to be fine.

    Smoke 'em if you got 'em!
     
  3. Bob Sorel

    Bob Sorel Stunt Coordinator

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    Brandon, there's no problem running the VC's in parallel. I have been running my dual HE 15 that way for about a year and the Crown hasn't even whimpered. I've heard of some guys running the Crown's down to below 1 ohm without problems, but I don't want to be the person to recommend it.
     
  4. Brandon B

    Brandon B Second Unit

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    Spiffy. Thanks guys.
    The MA is rated at 1800 per side into 2 ohms, 1565 into 4.
    OK, time to test the post-stressed concrete slab they built my house on.[​IMG]
    BB
     
  5. Vince Bray

    Vince Bray Stunt Coordinator

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    With that amp you probably have plenty of juice to run the coils in series. If you care about the damping number, note that it is spec'd at 8ohms. Now, if I was to guess, I would say the damping goes down with impedance...

    Man, that is going to rock! Got any pics?
     
  6. Brandon B

    Brandon B Second Unit

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    I am actually building a rather different box than John J's design. It is sort of a triangular obelisk thing 6 feet tall with a welded steel skeleton, ply and MDF enclosure and a 1/2" triangular aluminum base plate.

    It will have a driver at the bottom and top on one of the sides, and 2 PRs on each side, so they balance triagularly.

    At this point, I have the skeleton welded and powder coated, and the base plate. I have pictures of those.

    Is there a way to post pix straight to the board?

    BB
     
  7. Brandon B

    Brandon B Second Unit

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    You're right about the damping, Vince. I did some calcs and it looks like one 10 gauge run to the VC's in series at 8 or 6 ohms will maintain better damping than 2 runs of 10 gauge at 2 or 1.5 ohms.
    Crowns gives their damping spec at 8 ohms (about 1350 in the pass band for the stryke). I think this will translate to mid 200's with about a 12 foot wire run.
    Oh well, I guess I'll just have to hope 1500 watts per driver is enough power.[​IMG]
    BB
     
  8. Vince Bray

    Vince Bray Stunt Coordinator

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  9. Greg_R

    Greg_R Screenwriter

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    I'm running VCs in parallel w. each channel of my K2 handling a driver. WARNING: the connector at each VC will not handle 2 10 gauge wires. I stripped a portion of wire ~16" from the end and pulled the wire through (so each VC is connected to one continuous wire).
     

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