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Yet another simultaneous connection question

Discussion in 'Subwoofers' started by Gary_W, Aug 12, 2005.

  1. Gary_W

    Gary_W
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    Hi all,

    My SVS PB12 Ultra is in the UK. It's been at Heathrow since yesterday morning at 6am (along with a few BA passengers...). I won't be getting it until at least Tuesday (couriers, customs, rhubarb rhubarb....)

    Anyway, in an attempt to avoid thinking about airline staff letting it bounce around, I would again like to take the unwell horse that is simultaneous connection and give it another good thrashing. Lots of stuff to read if you can be bothered, followed by 2 questions.

    I'm planning on connecting both LFE and high level cables simultaneously, but NOT using them together. Theory goes that I will have my speakers set to SMALL in the receiver setup and hence all bass <100Hz will go to the SVS via the LFE cable. As the SVS crossover will be set at around 40Hz, the high level cables will never get a look in whilst I'm watching a movie, as nothing remotely near that frequency will be coming along the cables. This will mean there will never be doubling of bass notes. Are we all agreed? Talk to me :)

    For music, I will have 2 choices. If I select 'standard' stereo mode, my receiver's bass management stays on, the speakers are set to SMALL and everything <100Hz is sent to the sub via the LFE cable. If I choose 'direct' mode on the amp, the LFE element is gone. Therefore, everything goes to the speakers and the sub starts to cut in at 40Hz (the selected crossover point). Have I got this one right?

    Now for the questions:-

    1. SVS claim that always using the LFE cable and not the high level is best. Even for music. The theory goes that if you feed your main stereo pair the full frequency range, they will be receiving signals down below their capable range, resulting in them struggling and distorting. Therefore routing everything low to the sub is a great idea as the speakers are free to reproduce the range that they do best rather than giving distortion at its lower end. The only hole I can see in this theory is the fact that you are unable to use DIRECT mode, which (depending on the amp) can cheer up the sound quite considerably. Any more thoughts on this one?

    2. Rel claim that both connections should be used simultaneously for movies, and high frequency alone for music. They claim that the speaker setting in the receiver should always be 'large'. This makes no sense to me, as in movies this will surely mean doubling of bass notes at some frequencies, especially if the crossover on the sub is not as narrow as you'd like? For music, I like Rel's plan of using High level connections as it allows use of DIRECT mode. But if the SVS claim that speakers distort at the frequency extreme is true, will this outweigh the benefits of DIRECT mode in some cases?

    Sorry for my ramblings. I was hoping to fire the thing up over the weekend and try out all of the above for myself to see what works best. Had to get the frustration out somehow. SVS couldn't build my sub for 3 weeks as the veneer cabinets were stuck in customs at that end. :thumbsdow

    Any thoughts on the above gratefully received :D

    Gary
     
  2. Nimby

    Nimby
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    I do admire your optimism. :D

    The answers to your questions are:

    a) Any thursday evening (in September) by appointment.

    b) 42

    c) e = mc^2

    d) 7 @ 4 shillings and 6 pence each.

    Regards
    Nimby
     
  3. bob1

    bob1
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    Did you forget to take your tablets today? :rolleyes: :D
     
  4. Gary_W

    Gary_W
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    Now I'm confused.

    I asked questions 1 and 2. You answered a,b,c and d.

    Good answers, but I'm not sure of the order ;)
     
  5. Nimby

    Nimby
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    I was thinking....

    SVS strongly suggests the use of LFE/ low level connection almost completely to the exclusion of high level connections. Though they grudgingly fit the right terminals. But what do you do if you are passionate about music and don't give a monkey's about DVD film? You use the high level connections and ignore SVS advice. They do have a point about speaker woofers distorting. But only they (SVS) have the luxury of offering very high level, very low distortion outputs that REL can only dream about. So in theory the SVS could replace your speakers' bottom end.

    Meanwhile REL pushes high level connections and subtle underpinning of full range speakers at modest levels. They have to IMHO because their subs can't compete at high levels or low frequencies like the SVS models. The RELs simply run out of steam.

    But! You can't seriously use the passive 6dB/octave internal crossover of the SVS high-level connections to feed your speakers with a bass-emasculated signal.

    I prefer to use high level (stereo) connections with my floorstanders running full range. They overlap, but I don't care. I even have my SVS cylinder rolling off at 60Hz instead of the theoretical 40Hz (38Hz -3dB) of my speakers. Because it all sounds best that way to me. It works superbly well on music and is thunderous on film given a 3dB lift to the sub gain.

    Using the internal sub crossover to roll-off the speakers the sound quality on music was reduced to that of an inferior 60s Japanese amplifier. It was just awful.

    Following threads elsewhere I discovered that LFE loses some signal that goes down the cables to the (fullrange) speakers. So if you have both HI & Lo connected simultaneously for DVD film you should get a little more information out of your sub and/or your speakers that way.

    You have the luxury of a posh receiver to mess about with your audio signals. I stick to quality stereo amplification with an add-on processor for the rear channels on film. I believe this gives me a level of sound quality unmatched by complex modern receivers with all the digital bells and whistles which would only be getting between me and my music.

    Even though I detect a loss of sound quality with the surround processor connected I am willing to put up with this on film. I cheat by letting my DVD player do the processing. It sounds better that way.

    But all this is pure personal opinion and anybody else's opinion is just as worthy of discussion and trial in your own system. This is supposed to be an open discussion forum after all. Rambling even seems to be approved of. :)

    Nimby
     
  6. eviljohn2

    eviljohn2
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    I like people rambling knowledgably - particularly the knowledgable crowd of yourself, Nic and Steve.EX amongst several others. :)
     
  7. Gary_W

    Gary_W
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    Nimby - Thanks for the in-depth reply.

    I'm not planning on using the outputs of the SVS at all. I'm planning on using the high level inputs piggy backed off the output terminals on the speaker. If I understand it correctly, my speakers -3dB point is 40Hz, so that's going to be my starting point for the tweaking. The speakers and the sub will get fed everything, but the sub won't bother working until around the 40Hz mark. I suspect that the crossover will end up a touch higher, depending on my ears and the SPL meter that I've ordered with the system. Please put me right here if I have the wrong end of the stick.

    My receiver isn't that posh at all :) It will hopefully be upgraded next year. It has but one crossover frequency, that being 100Hz. I strongly suspect that, with most receivers, direct mode with high level connection will sound best. In my case, the output can probably use all the help it can get, so time will tell whether direct sounds best or the SVS 'use all the electronics you can' approach wins. I'll certainly post the outcome when the goods finally arrive. If 'direct' mode on my current receiver gives no benefit over regular 'stereo' mode, then I shall do away with the high level cables altogether. Until I upgrade, then I'll try again with mind and ears open :)

    Can you clarify further what you mean by

    "Following threads elsewhere I discovered that LFE loses some signal that goes down the cables to the (fullrange) speakers. So if you have both HI & Lo connected simultaneously for DVD film you should get a little more information out of your sub and/or your speakers that way."

    I'm not quite grasping this concept.

    I understand that some films have music / effects in the stereo field that go into the sub bass region that are not encoded on the LFE track. Rel tech support told me this much when I was researching what to buy.

    With Rel's method, the full range signal goes to the stereo pair and the sub bass is reproduced by the fact that the sub has a high level input that that takes over at the subs crossover point.

    With the SVS method of just using the LFE cable for films and setting the speakers to 'small', the receiver takes anything <100Hz from the stereo pair and routes it to the .1 channel. I cannot get why this would give you any less information. If anything, it would give a smoother transition as the digital filter in the amp would surely be more accurate than the analogue effort in the sub?

    Any chance you can explain the missing link here for me?

    Thanks

    Gary
     
  8. Nimby

    Nimby
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    Hi Gary

    I hadn't forgotten you but couldn't find the thread I wanted to quote from. (and still haven't) :blush:

    Read Leggaire's post 7 in this thread. He covers some of the issues about rear speaker bass missing from the LFE subwoofer feed and other useful details with great clarity.

    http://www.hometheaterforum.com/htf...readid=37721&highlight=high+level+connections

    EDIT: You should read the whole thread of course. This was what I was looking for. :smashin:

    I think you correctly covered most of it in your last post anyway. :)

    Nimby
     
  9. Gary_W

    Gary_W
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    Hi Nimby,

    Thanks for taking the time to reply.

    I've just read the majority of that thread (skipped the bits where it almost broke out into fighting) and found it very interesting.

    I liked the comment from Tom V of SVS, basically stating that the only thing that makes bass <100Hz directional is a poor quality sub / local rattles of objects in the immediate vicinity. As he could sell people more subs by claiming the directional card, I give more credibility to his argument than the others on there. Oh, and he does do it for a living :)

    The thing that Leggaire seems to be missing (IMO) is that an explosion in the rear surrounds will have a wide range of frequencies, some of which will be <100Hz. Even if you set all speakers to small (as I intend to do for movies) then the directional part of the sound effect (i.e. the part of it above 100Hz) will still go to the appropriate speaker(s). The non-directional part goes to the sub. And if that sub does not have any directionality due to being properly designed, your ears should fool you into believing that the explosion was indeed behind you. Any flaws in my logic here?

    Of course, if you have 2 subs that rattle like a thing possessed as opposed to giving a clean output then I can see how having a rear sub would make all the difference to the way your brain hears it :D

    Gary
     
  10. Nimby

    Nimby
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    All true I think Gary. The speakers steer the perceived direction of any deep bass coming from the subwoofer. But, only if the subowofer is itself invisible in the sound field. Which is where low harmonic distortion is essential to avoid audible clues.

    Yet it seems obvious that a considerable degree of latitude is allowable in the actual details of surround sound reproduction. Though the better the system, its setup and care in positioning and calibration the better the audible illusion of a fully 3-dimensional immersion in a realistic soundfield becomes.

    It will be interesting to hear your reaction to having a serious subwoofer in your own system.

    Nimby
     
  11. Gary_W

    Gary_W
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    Thanks for the reply. I think I'm finally getting my head around it all...

    I really can't wait for it to turn up. The Bax Global tracking record said that it turned up at Heathrow at 6.30am on Thursday. Unfortunately, it seems to have made no progress since then, and checking the Bax website 8 times a day seems to do little to help it along :lease:

    I have so many films saved up that I am refusing to watch until it shows up. About to watch 'The Miller's crossing'. Apparantly superb, but the sound on it is only dolby surround. So it seems like a good candidate to get out of the way so my watching next week can be things that will reap greater rewards.

    Also, I keep digging out various CD's that give me the impression that there is much more there than I currently hear.

    Gary
     
  12. Nimby

    Nimby
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    If Bax don't ring you first thing on Monday morning then ring them. Or just ring them anyway to find out what's happening. They don't bite. :D

    They can also confirm how much you have to pay the driver and what delivery time is expected (or even if a more desirable date/time is possible to better suit your own arrangements). :)

    You can always ring in to work to tell them tou have a bad back. You won't be lying either. :devil:

    Dragging a heavy box and even the sub iteslf around on an old sheet, blanket or sleeping bag is far easier than lifting and staggering around the place like a cartoon character. Just be careful you don't damage the finish on the sub if you have bare floors.

    Nimby
     
  13. Gary_W

    Gary_W
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    I've already called them. Several times :D

    My closest airport is East Midlands, and it has to come up to the depot there to clear customs. I was told on Friday that it should make the road trip from Heathrow over the weekend. If this is the case (and I got the impression that they were guessing) then it may go through the customs process tomorrow and be on the lorry to me for Tuesday.

    They did say that I could pick it up if I wished. Call me old fashioned, but I paid the extra for home delivery due to the fact that lifting a 3 foot square box that weighs almost 11 stone did not appeal. It would be very cruel to finally get it and be in too much pain to sit down.

    Thanks for the advice on moving it around. Whilst I am fully in favour of experimentation, I strongly suspect that the first place it gets put that impresses me is where it will stay. If that happens to be in the doorway so be it :D

    To be honest, either front corner is possible. Might even be possible between the TV and one of the speakers. Rear corners are also do-able, though I really don't want to. For starters there is the fact that I'll have to run 8 or 9 meters of cable to it (including under a doorframe) and then there is the fact that my receiver has only one crossover frequency (100Hz). This might just about allow the bass to be localised, and I'd rather that be up front if that's the case. I have an extra long LFE cable coming in the box just in case, so I should have all the bases covered.

    Gary
     
  14. Nimby

    Nimby
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    And I thought I was impatient! :devil:

    Nimby
     

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