Crossover Advice

Discussion in 'Audio Visual' started by kakariki, Apr 11, 2014.

  1. kakariki

    kakariki New Member

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    Hi All
    I'm setting up a rumpus room with a basic surround sound system and need some some advice. I have a surround amp with fronts, centre, rears, but no subwoofer output, and I have a set of surround speakers with a powered subwoofer. Any ideas how I can connect the subwoofer in?
    I was wondering about connecting it in parallel with the centre speaker and putting a suitable inductor in the line to only let the low frequencies through, I gather a 6db/octave setup would be ok.
    I've also heard about going across the front speakers, pos to left and neg to right.
    Thanks in advance.
    Barry

    P.S. Anywhere to buy fig.8 speaker wire cheap.
     
  2. ChoppedLiver

    ChoppedLiver Member

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    I suggest you go read up on just What a surround system is supposed to do.

    but to answer your questions in brief.

    Hooking into the center channel - No. its a vocal channel.
    Cross wiring from other speakers - No. you'll probably damage the amplifier.
    Cheap fig 8 cable, jaycar, altronics, ebay, auto barn, jb hifi, just to name a few.

    first order crossover (6db) is the worst possible thing you could do for a sub channel.
     
  3. Red Spade

    Red Spade Member

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    I wrote an article to cover the question of how to hook up a subwoofer here:

    http://www.stereo.net.au/articles/articles/subwoofer-setup-a-basic-guide/

    You need a sub that has speaker level inputs. Then you can connect it using speaker cable with no problem. I talk about this in the article.

    Adding an inductor is not a good solution. It will lower the damping factor, decrease efficiency, apply a fixed crossover where you need an adjustable one and it will probably not give you the required filtering.

    Connecting a sub in parallel with any of the other speakers suggests that you are not using a dedicated sub amp. Connect a sub in parallel with the centre, and you will lower the impedance seen by the amp. The amp may not be stable running this way, but your sub will run at a level that is too low. A sub requires more power.
     
  4. OP
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    kakariki

    kakariki New Member

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    re

    Hi
    Thanks for the info, very helpful.
    Barry
     
  5. OP
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    kakariki

    kakariki New Member

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    Hi
    Another question after sorting out this problem.
    I want to control the volume of just the rear speakers, what size pot's would I need.
    Thanks Barry
     
  6. Stooge007

    Stooge007 Member

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    is there a setting on the amp that can do this?

    i can control the level of every channel individually, through my amp
     
  7. Red Spade

    Red Spade Member

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    This should be covered in the settings on your AV receiver. Check the manual!
     
  8. OP
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    kakariki

    kakariki New Member

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    Hi
    The amp doesn't have this adjustment, it's a karaoke amp that just happens to have surround sound. The amp is in a rumpus room and I want to run a seperate pair of speakers off the rears that will be on the adjacent deck just to supply some music sound if we are outside, but I need to be able to turn them off, or down if we are only inside.
    Barry
     
  9. Red Spade

    Red Spade Member

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    If you want to add a pot as a passive attenuator, that has to go between pre and power amps. In your case, it sounds like you are wanting an attenuator that will work on the amplifier output, in which case you need an Lpad variable attenuator, such as you can pick up from Jaycar. I'm not sure what value to suggest but I don't think you will have much choice of values, so you may just want to try the biggest value you can find. They cost about $15 each. Keep in mind they have limited power and are typically used for a tweeter where a 5w unit is probably fine.
     
  10. Stooge007

    Stooge007 Member

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  11. OP
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    kakariki

    kakariki New Member

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  12. OP
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    kakariki

    kakariki New Member

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    I thought that if the main rear speakers are always connected directly to the amp output and I only want to control the volume of a second set of rears in parallel to these I could simply do it with a pot.
     

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