Newbie DIYer, opinions everybody please please please.........

Discussion in 'Home Theater Projects' started by Puneet_Juneja, Nov 18, 2003.

  1. Puneet_Juneja

    Puneet_Juneja Auditioning

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    hi every1 [​IMG]
    i have been lurking around on this forum for the past 1 month. Basically i m a newbie and have found this site to be really imformative. i have saved all the FAQ pages and my knowledge about audio gear has increased by many folds (thanks to all u sound fanatics).Though i don't plan making my own sub (yeah i m a bassoholic)but still i would like to continue learning from u guys.

    My ques is that suppose i go ahead with building my own sub and suppose i decide for a sealed enclosure with 2 tempest mated to a 1000w PE amp (just suppose), then how should i wire them to the amp.That is bcoz tempest has dual coils (i know that u guys know but still...), each with an impedance of 8ohms.If i connect the coils in parallel then impedance for each speaker reduces to 4 ohms. Now if i connect the 2 speakers in series to the mentioned amp then net impedance increases to 8ohms. On the other hand,if i connect the coils in series the impedance increases to 16ohms and the net impedance decreases again to 8 ohms on wiring the 2 speakers in parallel to the same amp.

    Now if i (please bear with me) again keep the VCs in parallel and then wiring the speakers in parallel, the net impedance drops dangerously low to 2ohms (hope i m right).

    That is where the problem lies. Isn't there anyway to wire 2 tempest or 2 AV15 such that the net impedance remains a healthy 4 ohms and the amp remains efficient as well as relatively cool while still keeping them together in a single enclosure and wired to a common amp?

    Thanks in advance

    P.S- Remember I m still a newbie so please take it easy on me and sorry for posting such question in DIY section
     
  2. TimForman

    TimForman Supporting Actor

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    I can't think of a way to do it. Perhaps someone else does. If I were to use two subs (and I do) I would put them in separate boxes with separate amps and run them from a split LFE out for home theater purposes. In most cases stacking the two sub boxes in a corner would give you the best results. You wouldn't need 1000W either. Two 250W PE amps would perform quite well.
     
  3. Greg Monfort

    Greg Monfort Supporting Actor

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    Well, you can short one coil of each driver and then wire them in parallel, but then you lose 6dB of dynamic headroom. Not a good plan, IMO. [​IMG]

    From one bassoholic to another, use four wired series/parallel in a corner loaded bipolar 20ft^3 cab. Now the amp is 'in the zone', each driver only 'feels' 250W so thermal power compression is vanishingly low, excursion distortion isn't an issue, yet there's enough displacement to damage all but concrete wall construction.

    Seems like a reasonable solution to me if you can't go IB or horn loaded. [​IMG]

    GM
     
  4. GrahamT

    GrahamT Supporting Actor

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    Also shorting the coil reduces power handling to 350W i think so that wouldn't work either. I agree with Tim that 1000W is too much. I have on Tempest with the 250 Watt amp and that is plenty. If you want that amp and a 4 Ohm load, instead of getting two Tempests, get a Tumult.
     
  5. Dan Wesnor

    Dan Wesnor Second Unit

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    You don't actually lose anything by wiring for 8 Ohms. It takes twice the voltage to get a given output level, but only half the amps, so the VA product stays the same, and that's really the amps limit. Also, because of the impedance rise in the bass zone, the amp draw will be much less and expected. And a 200W amp will drive a pair of Tempests to 116dB or so. 1000W gets you about 124dB, and will clip the drivers. So wire for 8 Ohms and don't worry about it.
     
  6. Puneet_Juneja

    Puneet_Juneja Auditioning

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    Thanks Dan
    U cleared my doubts and so did the Tumult option.

    Thanks everyone
     
  7. Aaron Howell

    Aaron Howell Stunt Coordinator

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    FYI, MCM 250 watt plate amps(model #50-6281A) are on sale for $99.95 right now. And orders over $100 get free shipping. My shiva's are loving them. The 350watt remote contolled amp is on sale for $159.
     

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