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  1. #1
    seeking solace in music
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    JR149s in parallel - is possible?

    A little advice here please from speaker enthusiasts.

    I am building a home theatre using JR149s and JR150s. These speakers are renowned particularly for their ability to reproduce the human voice. My problem is setting up a "centre speaker" for the HT.

    I could try using only ONE JR149 under the screen but that would weigh the tweeter on one side and the midrange on the other. I would much prefer to use TWO JR149s beside each other (on their sides) with tweeters facing extreme left and right. This would seem to balance out the voices coming off the screen.

    Now, how do I go about that, as far as wiring goes? As there is only one Centre Speaker input on the Receiver can I just connect both speaker cables together onto one set of spades? By doing this am I likely to cause damage by sharing the signal and maybe attracting clipping? Do I need to shut out the crossovers and perhaps introduce an electronic crossover?

    I don't want to just try anything without some advice as parts are hard to come by for these speakers.

    Any replies would be most welcome.

    Slippers On

  2. #2
    Class of the clown GMichael's Avatar
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    That would be wiring the two center speakers in parallel. This will lower your resistance and could hurt your receiver depending on how much current your speakers draw and how loud you play them. If you wire them in series you should be fine. This will double the resistance but will not cause a problem. The output level should not suffer at all.
    To wire in series"

    + from receiver to + on one speaker.
    - from first speaker to + on the other
    - from second speaker to - on the receiver.

    Good to go.


    Sorry that I couldn't write more. Must run.
    Last edited by GMichael; 12-06-2007 at 06:18 AM.
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  3. #3
    I took a headstart... basite's Avatar
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    Quote Originally Posted by GMichael
    + from receiver to + on one speaker.
    - from first speaker to + on the other
    - from second speaker to - on the receiver.

    that's wiring them in serie...

    wiring in parallell is just 2 cables from the amp. one full speaker cable for each speaker.

    If those speakers' impedence is 8 ohm or higher, it won't be a problem to wire them in parallell. Do mind that you'll have a 6db increase though...
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  4. #4
    Loving This kexodusc's Avatar
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    Quote Originally Posted by basite
    that's wiring them in serie...

    wiring in parallell is just 2 cables from the amp. one full speaker cable for each speaker.

    If those speakers' impedence is 8 ohm or higher, it won't be a problem to wire them in parallell. Do mind that you'll have a 6db increase though...
    Correct, wiring them in parallel connects the positives to the positives and the negatives to the negatives.

    Even if the speakers are rated 8 ohms, I still wouldn't advise wiring them in parallel unless you know what the impedance plot looks like across all frequencies, or you are confident your receiver can handle low impedance loads.
    If those speakers have an impedance dip below 4 ohms (extremely common in 8 ohm rated speakers), wiring them in parallel will present half that number to the amp. I'm not aware of many a/v receivers that are comfortable with 2 ohm loads or less. All it takes is one big music spike at the right frequency and you may exceed the current capabilities of your amp. If you're lucky the sound will clip, if you're not so lucky you could damage the speaker, amp, or both.

    Setting a speaker on it's side isn't so bad really - If you're really worried about the tweeter and woofer being off-balance to the left or right, position the speaker such that the tweeter is lined up perfectly center with the sweet spot. the improved vertical dispersion will help offset the fact the speaker likely isn't standing at the same height as the front mains.

    To be honest, if you're sitting 8-10 feet away you've got a farily forgiving window of dispersion so the tweeter/midwoofer asymmetry isn't really an issue. I'm guessing you can't hear the difference until you sit considerably far off axis, at which point the entire front soundstage tends to collapse to the nearest speaker anyway. And you dont' have to worry about impedance.

  5. #5
    Class of the clown GMichael's Avatar
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    Quote Originally Posted by basite
    that's wiring them in serie...

    wiring in parallell is just 2 cables from the amp. one full speaker cable for each speaker.

    If those speakers' impedence is 8 ohm or higher, it won't be a problem to wire them in parallell. Do mind that you'll have a 6db increase though...
    Thanks, fixed my typo.
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  6. #6
    Forum Regular audio amateur's Avatar
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    Are you all sure connecting two pairs of wire from one output is parallel wiring? Because I'm not.

    On a side note I believe parallel wiring gives a +3dB increase and not 6. (unless you factor in that you've got an extra speaker playing, which itself yields + 6dB (i think)).

    Cheers

  7. #7
    Loving This kexodusc's Avatar
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    Quote Originally Posted by audio amateur
    Are you all sure connecting two pairs of wire from one output is parallel wiring? Because I'm not.
    What else could it possibly be?

    Quote Originally Posted by audio amateur
    On a side note I believe parallel wiring gives a +3dB increase and not 6. (unless you factor in that you've got an extra speaker playing, which itself yields + 6dB (i think)).

    Cheers
    The parallel wiring in a constant voltage will result in +3 dB from the doubling of speakers, plus an additional 3 dB from the doubling of wattage.
    Since we level match our receivers (hopefully) the plus 6 dB really doesn't apply here anyway, we'll lower the speaker level to the center channel to offset the +6 dB and corresponding wattage output will hence be reduced.

  8. #8
    Forum Regular audio amateur's Avatar
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    Quote Originally Posted by kexodusc
    The parallel wiring in a constant voltage will result in +3 dB from the doubling of speakers, plus an additional 3 dB from the doubling of wattage.
    I thought a doubling of 'acoustic sources' meant +6dB, but i guess I'm wrong (at least that's what I remember from acoustics class, but that shows you how much I payed attention )
    For the wiring, I always thought the speakers had to be 'interwired', which means basically having some sort of direct connection between them, but i'm guessing this is done at the output, where both pairs of wires are touching each other. So yes same difference. I hadn't thought about it in that way (as I've mostly only ever looked at sub driver parallel & series wiring diagrams)

  9. #9
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    Parallel or Series

    Thanks guys. Lots of healthy discussion here, just what I expected.
    You can obviously see my dilema...if I don't get it correct from the beginning.


    The JR149 relevent specs (quoted from original sales sheet) are:-

    Power Handling 60 watts programme. Suitable for 20 - 100 watt amplifier.
    Sensitivity 83db ref. 1 watt into 8 Ohms. Suitable for outputs 4 - 16 Ohms.

    The Receiver (Pioneer VSA-AX10) puts out 170w per channel at 6 Ohms.

    A good point has been raised here regarding a possible volume change. As long as the safety issues are covered then I can reduce volume of the centre channel to match the seating position. In fact the receiver has a little microphone for auto-adjust the theatre set-up.



    The room dimensions will be 8m by 5m. (roughly 15ft by 24ft ).


    What effect would 'series' have?

    On occassion I have seen speakers doubled up, such as ELS57s. I wonder which method they use.

    Slippers On

  10. #10
    Loving This kexodusc's Avatar
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    Quote Originally Posted by Slippers On
    Thanks guys. Lots of healthy discussion here, just what I expected.
    You can obviously see my dilema...if I don't get it correct from the beginning.


    The JR149 relevent specs (quoted from original sales sheet) are:-

    Power Handling 60 watts programme. Suitable for 20 - 100 watt amplifier.
    Sensitivity 83db ref. 1 watt into 8 Ohms. Suitable for outputs 4 - 16 Ohms.

    The Receiver (Pioneer VSA-AX10) puts out 170w per channel at 6 Ohms.

    A good point has been raised here regarding a possible volume change. As long as the safety issues are covered then I can reduce volume of the centre channel to match the seating position. In fact the receiver has a little microphone for auto-adjust the theatre set-up.



    The room dimensions will be 8m by 5m. (roughly 15ft by 24ft ).


    What effect would 'series' have?

    On occassion I have seen speakers doubled up, such as ELS57s. I wonder which method they use.

    Slippers On
    Series would increase the impedance and the volume output by 3 dB.
    How far back is your seating position from where the speaker(s) will be positioned?

  11. #11
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    Quote Originally Posted by kexodusc
    Series would increase the impedance and the volume output by 3 dB.
    How far back is your seating position from where the speaker(s) will be positioned?
    The room is not completed yet, but I would expect to have a seating position around 5-6mts (15-18ft) from the front speakers.


    I am going to throw another spanner into the works here..... at the moment I have a pair of JR149s wired up in a small analogue listening room. I've just realized that I have a JR Sub-woofer connected up to these in what seems to be a parallel set-up. However there does not seem to be any change whatsoever to the volume output.

    Now this might be because even though the sub is connected to the same terminals of the amp, the sub has its own amp also wired into the set-up. The sub's amp controls the volume of the sub only, yet the main amp's volume control raises or lowers the three speakers at the same time.

    This is the wiring:- Red and Black leads going from Sub-woofer into one end of sub-amp. Another set of red and black cables going from other end of sub-amp onto Main Amp's speaker terminals - meeting up with the left and right JR149 speakers.

    Effectively this appears that the sub is in parallel with the L&R speakers, albeit that the sub has its own amp (and crossover control) in between. There does not seem to be any adverse effect on this set-up, in fact this is what the JRSub was designed to do.

    Hard to get my head around this one.

    Slippers On

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