Bi-Speakering better than Bi-Amping ?

Discussion in 'Home Cinema Speakers' started by IRobot, Jan 9, 2008.

  1. IRobot

    IRobot
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    Last October I replaced my rear iQ5's with a pair of MA RSFX and ever since they've just been gathering dust. A couple of days ago I was thinking what to do with them, sell them, put them in another room etc. Then I had a moment of genius, why not use them as additional fronts :thumbsup:.

    I was already using the spare channels in my AVR to bi-amp the fronts so I didn't even need to put any additional wiring in place. I just went back to single amp on the existing fronts and plugged the spare cables into the new fronts.

    DSCF0362 [800x600].JPG

    Good idea or not ? :smashin:
     
  2. ben.bayliss

    ben.bayliss
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    Not! The two spaced tweeters will create a very uneven interference pattern throughout the room.

    Fleshed out answer:

    Directly on axis, you will gain 6dB and all will be well, but as you move off axis the two sets of drivers/tweeters will now take differing times to reach the ear and these time/phase differences will create an interference pattern.

    You could splay each pair of speakers \ / like that which will separate the HF and make a wider, more even response but in a room that size there's really no point - you'll just be firing into the side wall!
     
  3. BlueWizard

    BlueWizard
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    ben.bayliss does have a point, but I think it assumes that every one is in the absolute perfect listening position. In reality, likely no one is in that position.

    Let me understand what you are saying. You have your A/V amp set up to Bi-Amp meaning two amps (L & R) for the high frequency speakers and two amps for the Low frequency speakers. If this is the case, and you intend to put the bridge/jumper back onto your main fronts, and then use the second set of amps to drive another set of fronts. In that case, you have nothing to lose by trying. You'll either like what you hear of you won't.

    Now, if you are planning to connect, for example, the two left front speakers to the same amp channel, that is, two speakers one amp, then we get into impedance problems. If both your existing speakers are 8 ohms, then no problem. If they are 6 ohm or 4 ohm, then we do have a problem. You can't let the impedance connected to single channel drop below 4 ohms rated impedance, or you could have problems with your amp.

    In the first case, where you are using 4 amps to drive four front speakers, there is no risk to the speakers or the amp, so go ahead and try. Just don't forget to put the little jumper back on to your existing front speakers to tie the high and low back together.

    Just one man's opinion.

    steve/bluewizard
     
  4. Member 96948

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    Not. Aside from the weird lobing issues the side by side treble and mid bass drivers will suffer, there just seems something wrong about driving four speakers in an average fashion when you drive two really well.

    The options are:

    Mount the spare iQ5s on the ceiling, inverted directly above the existing front iQ5s so at least your uneven treble/mid dispersion problem in the horizontal plane would be solved ensuring all listeners benefit. Bloody silly, if technically preferable.

    Better - Plug them into the 'Surround B' outputs on the amp and place in the rear corners behind the listening position. Using the user presets on the amp, you can then switch between di/bipole movie mode with the RSFX and direct radiating multichannel music mode with the iQ5s. Nice.

    Better Still - Flog them and put the money toward the subwoofer the picture indicates your system is lacking. That'll give you a performance leg-up that extra speakers will never deliver.

    Russell
     
  5. BlueWizard

    BlueWizard
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    Excellent points by Russ.Will who consistently knows his stuff.

    If you insist on using them, and you don't have anywhere else to use them, say in another room on a stereo or computer, then Russ's 'Better' option is pretty good.

    But I like his 'Better Still' option is really the best. The speakers you have are good speakers and should be worth some money to someone. Sell them and add that money to a good matching Sub, and you will have one righteous system.

    just a thought.

    Steve/BlueWizard
     
  6. IRobot

    IRobot
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    Each speaker's running on a seperate amp. There is a sub in the system, it's hiding behind the sofa.

    I've toed in the speakers so that all tweeters are aimed at the listening position like so:-

    DSCF0365 [800x600].JPG


    The real reason I tried this was because I listen to a fair amount of rock music like Rush, Marillion, Porcupine Tree etc. The iQ5's don't have enough punch in the mid/high base region for this kind of music. This experiment in doubling up the fronts hasn't really improved matters much.
     
  7. ben.bayliss

    ben.bayliss
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    I'm with Russ. It's just not worth it and even if you don't necessarily notice how bad it is in one position, it's gonna sound very different even only a foot or two in either direction. There's enough good theory to tell us that it's a bad idea and simply isn't worth it!

    If you're gonna splay the speakers, splay them outwards, not toeing them in as you've done. That way the HF of each pair will couple less and not become as coloured. As I said before though, in a room your size, there's no real point.

    Flog em and buy a shiny new toy! :)
     

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