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Why are .....

Discussion in 'Home Cinema Speakers' started by vee_cee, Jan 23, 2003.

  1. vee_cee

    vee_cee
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    Subwoofer cables single phono to phono?

    Most subs on the market have L and R phono's, why?

    And all the amps I demod only had single preout?

    I've noticed that it is possible to get phono splitters, does using one of these make a difference?

    Also, which would be better of the following

    a) amp ----- single phono to phono----splitter----sub

    or

    b) amp ----- splitter----- phono to phono pair----sub

    Cheers
    VC
     
  2. activeservo

    activeservo
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    Run a phono cable from sub out on amp and then using a Y-splitter insert into subs left and right inputs and there you have it .This is the best way to hook up the sub and also adds around 3db ,meaning more bass.Hope this helps.
     
  3. timothyw

    timothyw
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    Decent stereo amps (ie not av amps) will often have twin phono pre outs (ie exactly the signal that enters the amplifiers amplification stage, complete with volume, tone and bass controls etc). If someone with one of these (and not a home cinema set up) should want to use a subwoofer to deepen their bass they would connect these pre outs to the L&R phono's on their sub, and then adjust the subs internal crossover to blend with their main speakers.
    This should provide better quality than a speaker level input, as none of the distortion inherent in going through the amplification stage is carried into the sub.
    All the amps that you demoed were presumably AV amps and as such only had single sub outs. You can get some amps which allow you to have stereo subs, but obviously this would be for use with 2 subs. I'm not convinced you'd hear any difference from using a splitter to distribute the signal into both inputs on the sub, unless you needed the extra level for some reason, although by all means try it out if you want.
     
  4. bob007

    bob007
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    My understaning though probably wrong is.

    1) Only a mono signal is sent, so only one cable is needed.

    2) Gives you the option of connecting via L and R if your amp has this capability. Most av amps only have the option of connecting via a single output.

    3) Think that some flagship models might have stereo low level outputs but probably found more on separate processors.

    4) Some say a difference can be heard or it makes a difference, think it's a bit of "suck it and see" myself. If you are going to try it may be cheaper depending on cable length to go single phono to splitter.
     
  5. 7ThGuest

    7ThGuest
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    Hi Bob

    As with everything in the speaker world, but well not go down that road again eh ;)

    I have just tried this with my PS 1000. After several discussions at the local dealers it's another split camp for and against (does something, does nothing)

    RS reckoned does nothing wasting your money thats why we don't stock splitters.

    Global will give you 3 - 6 db increase and (the reason I went for it) prevents lag if the sub only has an auto sensor ie cannot be switched on permanently. You can get (supposedly) an Ixos for about 8 squid. Having said that I trawled Newcastle trying all normal outlets to no avail so popped into Maplins (not the holiday camp - for petrolhead) and picked a gold plated splitter for 4:99.

    As for does it work, well I watched K19 this afternoon and definitely had to turn the sub down from where I had it set before (new amp just installed as well, so not conclusive) and will have to play some old faves to see if the response is any different.

    Will lyk if there is a change.

    Regards

    7ThGuest :)
     
  6. E Hinge

    E Hinge
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    The oracle has spoken. I wonder why manufacturers actually bother to make splitters when such reknowned hifi authorities state that they are a waste of money
     
  7. vee_cee

    vee_cee
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    Thanks for the replies

    Looks like i'll have to make time to do some tests

    I'll post with any findings

    Cheers
    VC
     
  8. iwatkins

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    That was a question I was going to ask but the other way around (sort of).

    My sub has a single phono input. But my amp (Sony STR-VA555ES) has a pair of sub pre-outs. The preouts are not labelled L and R so i've just got a single cable going from the first sub preout to the sub input.

    I've had to turn the gain on the sub up to 8.5 out of 10 to get it to the right level after setting up everything else.

    So, if I combined the two sub preouts into a single input on the sub I would get a louder output for the same gain level on the sub ?

    I've had a look through the amps manual and it says nothing about why there are two pre-outs, i.e. if they are a L & R output but still LFE. I kind of assumed that LFE is LFE and has no L & R component.

    Think I've confused myself there ;)

    Cheers

    Ian
     
  9. mandlebrot

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    7ThGuest: If you were to look in your PS1000 manual it does tell you that you will get a gain if you use a splitter so RS are talking rubbish again. I certainly don't need the gain so don't use it, god my sub is only set at about the quarter mark has it is, I would however try it if it tightened the bass up even more but I've not seen any evidence or even suggestion of that.
     
  10. 7ThGuest

    7ThGuest
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    Hi Mandlebrot

    You are quite right re the gain I have my sub set at 10 however, I was more interested with reducing any lag than anything.

    And, as always there is always something else to try to make the system better ;)

    Regards

    7ThGuest :)
     
  11. lynx

    lynx
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    My sub 'perked up' when a second phono input was fed to it.Sounded strangely flat after reverting to a single phono.
     
  12. mandlebrot

    mandlebrot
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    7ThGuest: You are dam right about always trying to find ways of improving the system, the only problem is I always find the expensive ways :D Trying to get a better projector now, it never stops does it :D
     
  13. William Shin

    William Shin
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  14. Brox

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    When using a Y splitter with my Kef sub the output level increased noticably, Kef recommends this.
     
  15. timothyw

    timothyw
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    Well that question somewhat depends on how you define quality bass TBH. Adding a power amp to your setup will give your system more headroom, which usually leads to it delivering cleaner, louder bass with less distortion. This will not, however, increase the depth of bass that your main speakers can reproduce.
    The main benefit of adding a subwoofer to any system is that it will extend the systems low frequency response far lower than any traditional loudspeaker is likely to go. To wire a subwoofer up the best possible solution would be thus:
    [​IMG]
    Clearly this requires an amp with a pre/power loop (or a seperate pre amplifier and power amp). The active cross-over would typically be set at 80hz. On some subwoofers it may be the case that they have such an active crossover on board, however typically they are just low pass filters (ie no high frequency outputs coming back out). When using an external cross over, intuitively it is clear that the subwoofer's should be set to 'off', or as high as possible otherwise.

    The above represents the best possible solutions as it means that the stereo pair is not wasting any of its capacity on reproducing bass better reproduced on the sub. If this setup is not an option, the next best compromise would be to have the subwoofer on a pre-amp output, with the subwoofers internal crossover set so as to blend smoothly with the main speakers natural low end roll-off.

    (Note: This message refers to stereo amplifiers, rather than av amps which typically have their own bass management to achieve the above)
     
  16. William Shin

    William Shin
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    Thanks, Timothy
    Great help! I might ask some more questions in some other relevant threads. :D
     
  17. mspiteri

    mspiteri
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    Can you recommend a good subwoofer Y splitter cable? I cannot seem to find any. QED and IXOS specifically do not seem to do one.

    Mark
     
  18. tk2001

    tk2001
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    3 - 6 db increase?

    Wouldn't this increase in volume be completely pointless if you had your subwoofer calibrated to 75dB?
     
  19. DodgeTheViper

    DodgeTheViper
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    Ixos do make a ' Y ' splitter !!!
     
  20. 7ThGuest

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    Ixos definitely do a splitter for about 8 squid, my local dealer just managed to get one after 2 weeks!!

    However, got a gold plated one at maplins for 4:99 off the shelf.

    tk2001, I'm certainly no expert but by getting the increase you can turn the volume down so there is less strain on the system :cool: Don't know if thats technically the best way to describe it but I am sure (hope) somebody will post a more refined answer.

    Regards

    7ThGuest :)
     
  21. Apocalypse

    Apocalypse
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    Timothy - That picture must be of a very rare subwoofer because I've never seen a sub that has all those phono inputs. For the "High" method of connection the L & R jacks are used with high pass L & R jacks to effectively bi-amp which does indeed give a superior performance. If as you say the sub also had seperate Sub-In jacks this would be ideal but like I said I've never seen a sub with all those options and I've used subs from Paradigm, B&W and Velodyne.

    People should note that although the "high" method of connection is superior for music it's useless for movies as Timothy has said, because the high method favours the front mains it means you have no seperate LFE channel and you cannot use THX processing obviously as setting the Fronts to small is not an option.

    P.S - This post is assuming that diagram is of a real sub, if not then it only mirrors what Timothy said, just curious if there is a sub out there with those options.

    Phil
     
  22. Lowrider

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    I have the best I could find:

    Monster Cable YM2F-H T splitter
     
  23. timothyw

    timothyw
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  24. 7ThGuest

    7ThGuest
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    Ain't it amasin' how these things grow!!

    Still can't tell on the lag but db's are definitely better, just go and p@~~ the missues off :D :D

    7ThGuest :)
     

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