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good idea or kill your amp

Discussion in 'Home Cinema Speakers' started by Craig C, Mar 28, 2001.

  1. Craig C

    Craig C
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    This is allways a subject that gets people going.
    What is to stop you using two speakers for left surround channel and two for right. You could have two at the sides and two behind, would this give you a more cinematic feel?
    How should it be done, parallel, or series?
    who knows the maths of it? half the load or double the load on the amp?
    Over to you guys and galls.
     
  2. mart.stokes

    mart.stokes
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    Just don't do it in parallel. Do it in series. in parallel (this is the simple 1970s "O" level version, the laws of physics may have changed since then!) it is 1/xohms + 1/yohms = 1/totalohms where x and y are the impedence of the two speakers. So two 8 ohm speakers would give a 4 ohm load. In series it is xohms + yohms = totalohms, much better.
     
  3. General Skanky

    General Skanky
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    And for the sound, if you look at some of the installs featured, you'll see they have 4 surrounds like you ask, so it must give a good spread of sound, but I haven't ever tried myself. You need someone like Gordon on that one.

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    Douch!!......Wot's da madder, da CIA got you pushing too many penzils?

    Work: www.hughes-tv.co.uk
     
  4. Paul D

    Paul D
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    I've heard a couple of setups with speakers along the walls (akin to true cinemas). But found when the sound was supposed to go behind, ie the car chase scene from ronin. the cars dissappear behind you on screen but sound comes from the side of you. Cinemas have to compromise the sound, to acommodate lots of seating positions. Mind you i still have to hear EX surround yet. So with a dedicated rear speaker(s), this may now work! Give it a try.....

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  5. Ramius

    Ramius
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    Hi

    mart has the maths correct but it's advisable to connect them in parallel NOT series.

    No two speakers will be exactly identical, even if they are the same model from the same manufacturer. This means that they will act slightly different from each other when presented with the same input signal. When wired in series, these differences will cause distortion in the form of back EMF.

    So you'll have to make sure your amp can handle the resulting load.

    Cheers
     
  6. dUnKle

    dUnKle
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    My Denon allows for two pairs of rear speakers to be used, either seperatly or together, but I have yet to try it.

    Im not sure if its worth the hassle of the wiring or not, afterall it gets confusing with just five speaker let alone seven. I currently have a pair of bi-poles on the side wall and am still considering putting my old tannoy m2 in the rear corners.

    Anybody tried it, whats it like
     
  7. Black 5

    Black 5
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    Duncan,

    My processor gives me the option to use both sets of rear speakers in tandem if the signal isn't 'EX' or 'ES' and my impression is that it does give a general reinforcement to the sound. However, in my set up, these speakers are not that far apart and they are all identical models.

    I would imagine that depending upon the compromise caused by speaker positioning you could lose a lot of the specifically directional sound - don't forget, the soundtracks you are going to be most interested in, have been mixed specifically in anticipation of you using a DD5.1 system (etc). There are a lot of subtleties to most soundtracks which are only revealed by a really good dvd player, particularly where spacial sound is concerned, and you may (if you can hear it now) lose a lot of that.

    How can you go about balancing out the speaker volumes - wouldn't you have to compromise on a setting for both speakers - different types/brands would create a particular problem? Also, if you measure the distance to the speakers, thus allowing the processor to work out delays etc, which speaker would you use?

    I suppose you could try it and see if it was any good. Using speakers with a lower (nominal only) impedance can result in a greater load on the amp and it should be up to the job, but speaker impedance varies a lot with frequency so the maths aren't as easy as they sound I believe.
     

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