Subwoofer Rca inputs

Discussion in 'Archived Threads 2001-2004' started by Shanil, Dec 11, 2002.

  1. Shanil

    Shanil Extra

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    I have a Jamo E4.1 sub. It has 2 Rca inputs (L & R).
    Should I just use the L input, or both L & R inputs?
    I read shomwhere that by using both inputs you can get a
    6dB gain from the input voltage of the processor.
     
  2. John Garcia

    John Garcia Executive Producer

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    Yes, use both. While there is a gain from using this method, after calibration you end up with the same SPL, while using less amp power to achieve it (giving you more headroom on the sub).
     
  3. Ted Lee

    Ted Lee Lead Actor

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    hey...there's john ahead of me. what a surprise! [​IMG]
    i didn't know you could do that to subs. do you just use a rca splitter?
     
  4. Vince Maskeeper

    Vince Maskeeper Producer

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    While the short answer is what John said (It might help to split the line in two and run to both inputs), the truth is more complicated.

    Of course realize, that:
    1) Not all subwoofers sum the 2 inputs (Left and Right) in such a way that gives a boost by using both.
    2) Splitting a single signal from the receiver into 2 signals results in a net loss of voltage, when you then sum them back together by connecting to both connectors on the sub-- and common sense would tell you that you're not going to be able to get something for nothing. Depending on the method of the split and the method of the sum- you might be doing nothing--- and might be introducing a reduction of quality in the process.
    3) The issue of amp headroom isn't cut and dry- it's more relative. Understand of course that by summing the two signals this might mean less push at the preamp stage- the concept is essentially moot: you end up with the same output, by adjusting at either gain stage- it results the same finished product-- robbing peter to pay paul if you will. It isn't technically using less amp power in one method or the other- it's just an issue of how you get gain into the amp. To be honest, in some configurations having less gain at the sub and more at the preamp might be advantagous.

    I would say that if right now you are running into only one input on the sub and can get calibrated level without pushing either the preamp output or the attenuation on sub, then I wouldn't bother changing it. Splitting the signal in two and running to both jacks won't provide anything more than gain- which you could achieve by raising the preamp output or raising the knob on the sub amp--- and if you're already calbrated using ref tones- you have all the gain you need.

    -Vince
     
  5. chella

    chella Stunt Coordinator

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    If your sub has auto-on facility - to wake up on signal - it may be good idea to split the signal to both L & R. This makes the sub more sensitive.
     
  6. Bill Kane

    Bill Kane Screenwriter

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  7. Mindain

    Mindain Extra

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    Could splitting the two make your sub not have as much as a punch? My sub says R and l/lfe I currently have my wire split into both. Does this reduce the quality and loudness?
     
  8. Vince Maskeeper

    Vince Maskeeper Producer

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    It could, depending on the quality of the splitter, the quality of the cables and a few more complicated issues such as impedance mismatches.

    The only advantage you're going to POSSIBLY achieve from splitting the line in two is an overall gain boost-- but by adding splitters and extra wiring you run the risk of degrading the signal. If you can take a single line from your receiver to your sub and can get calibrated level from your sub-- then I wouldn't bother trying to split the lines as it's obvious you already have sufficient gain... and so it's not worth risking the potential signal degrading by splitting, IMHO.

    -Vince
     

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