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BFD and Main speakers.

Discussion in 'Home Cinema Speakers' started by pwiles1968, Oct 11, 2003.

  1. pwiles1968

    pwiles1968
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    I have a problem with a resonance in my room at 35hz, I am sure this frequency is the first harmonic of my room length, as I have to have my speakers at one end of the room and sit at the other there is a peak (or is it referred to as a null?) Either way sounds at 35Hz are louder.

    I say it is a problem, it can hear it with test tones, but it is not that distinguishable with music, although kick drums do sound good. The problem comes when I want to add a sub woofer in to my system, which I would like to do next year. I can place the sub to minimise the issue but the mains are fixed. I listen to music in source direct mode and the Marantz defaults the main speakers to large so I will still have the problem, which will be exaggerated further by the addition of a sub.

    Lengthy introduction I know but here is the question, I Bi-Amp the mains, I know could I place a BFD between the AV amp and Power amp and EQ my main speakers to suit the room? I could even roll off the fronts, but is it likely to affect sound quality? How good is the BFD A/D & D/A I know people use them for sub work but would they stand up to being used for Mid Bass duties or is it likely to degrade sound.

    Any comments or alternative suggestions would be appreciated. :smashin:

    Edit – I have just had a second thought, if were to get a sub and run it 180° out of phase with the main speakers would this counteract the room nodes?
     
  2. Apocalypse

    Apocalypse
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    The BFD does introduce degredation to the signal but with subwoofers this is no real problem, personally I wouldn't use a BFD with speakers. Room treatments are the route for me with speakers, not what you want to hear I know cos they aint cheap but you can DIY if you have the enthusiasm for it................I have the enthusiasm but lack the patience so I ordered Auralex treatments :blush:
     
  3. pwiles1968

    pwiles1968
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    I think I would have to get the sub first and see if it makes music too bass heavy, at the moment the system sounds really good so there is no urgency, would like more bass for movies hence the sub, I could go for an ASW 675 and X-over the signal to the power amps but this was more than I wanted to spend, was thinking more of BK XLS200 money.

    I assume room treatments for this sort of frequency are quite large, unfortunately the room must still look like a living room, and I do not fancy re-decorating over wall treatments. How big & expensive are bass traps?
     
  4. Ian J

    Ian J
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    All you need to know about acoustic room treatments from the experts here
     
  5. pwiles1968

    pwiles1968
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    Thanks Ian, Lot to read there not quite as expensive as I was expecting but it will add up if you have more than one problem, I will wait and see what happens when I get a sub and read the DIY article very closely.
     
  6. Apocalypse

    Apocalypse
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    Room treatments is one of those things where you have to take a leap of faith and hope they do the job, I have taken the plunge but I'm still waiting for them to arrive so can't comment yet.
     
  7. Smurfin

    Smurfin
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    I'm thoroughly sold on acoustic treatments after I tried some DIY cheapy solutions: and solutions they were.

    Acoustics should NEVER ever be underestimated imho....makes a whole world of difference. However, the day I move into a place where I can change almost nothing (e.g WAF, layout etc)...well I won't even look into it, because as soon as you start taking measurements you'll know exactly where the problems are and it will bug the shi*t out of you.
     
  8. avanzato

    avanzato
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    Your room is 4.91m long or there abouts?
    The null is where there is least sound.

    Personally I wouldn't use a BFD on the mains as cheap room treatments can take care of most problems above 500hz or so and it will degrade the sound a bit. For a sub any degredation the BFD adds is far outweighed by the reduction in room problems it provides.

    Membrane traps are the only thing that will help at low frequencies and not take up vast areas of your room. You have to remember that the best a treatment can do is remove 100% of the sound waves hitting it at any particular frequency. So surface area covered is proportional to the effectiveness of the treatment. This means it can get expensive.
     
  9. pwiles1968

    pwiles1968
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    16ft exactly, as I said I will wait until I get a sub and see what happens see if it gets too much. But a Bass trap will probably be what I need ( wild guess).


    I think the room actually sounds good and most of the time the Peak is not a problem as I said Kick Drums have some real punch.

    I was only experimenting with new ways to get a room plot when I found it, see http://www.avforums.com/forums/showthread.php?s=&threadid=92209&highlight=wav* I do wish I had not bothered. Because It does bug the hell out of me now I know it is there.
     
  10. NicolasB

    NicolasB
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    There are, of course, EQ devices that will not degrade a signal as much as a BFD does. Behringer's own UltraCurve Pro DEQ2496 will do a somewhat better job. Whether it's good enough is another story.
     
  11. Anodyne

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  12. avanzato

    avanzato
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    The Rane THX 44 is about £1400 and to complete the set you need the Rane THX 22 at about £600. Both only have one third octave graphic Eq for the low frequencies starting at 80hz and the Parametric bands are for high frequencies. I looked into them about 5 years ago and even then thought they seemed a bit crude on the adjustment side of things for the money. The Rane PE 17 parametric is closest to the BFD in its function but in the UK it costs near £500.
     
  13. Anodyne

    Anodyne
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    The Rane PE-17 looks good. I think it's the same one SVS sell with their Subs.

    Will
     

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