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Acoustics doing my head in

Discussion in 'Home Cinema Speakers' started by Smurfin, Sep 29, 2003.

  1. Smurfin

    Smurfin
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    I've lived with my setup/home/AV room for a few days now....and it's really bugging me.

    On an LFE sweep I have a huge dip between 60hz-40hz (we're talking 10db at least), which then rises to a +8db peak from 35hz-25hz....not good!

    I plan on buying a BFD this week, but can someone advise what connectors I need for twin sub operation? (can a single BFD be used on a twin sub setup? Please don't tell me I need to buy two of the buggers:rolleyes: ) Hopefully this should sort out the LFE frequency response, but the problems only just start there....

    Pics can be found on page 3 here:

    http://www.avforums.com/forums/showthread.php?s=&threadid=94907

    Basically the screenwall is totally carpetted, the side walls have offcuts on them (only a little though positioned forward from the speakers and just below ear height), and the rear wall has a big piece on it. The trouble is....the room is STILL too live.

    I was on the phone earlier to someone, and while I was talking I walked into the room: they immediately noticed the echo, which isn't good:confused:

    So what else can I do? I don't want to spend any more money (buns stop laughing;)), as the last of my shares money has been blown on converting the room for my AV purposes.....but it's already winding me up as the room sounds too lively (at high volumes).

    Ideas?

    Cheers
    Matt
     
  2. alexs2

    alexs2
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    Matt.....dealing with room acoustics can be a real pain.
    From what I can see of your room,it's essentially oblong,with the 2 sets of walls being ideal reflective surfaces.
    Whilst the BFD may well solve your LF problems,it may not remove the echo that your friend noticed.
    You may have to experiment with moving the positions of the speakers relative to the various walls,in an effort to break up the resonant modes of the room,and other than either digital room correction or things like Tube Traps,neither of which are cheap,you may be left with things less than ideal.
    The following link may help you calculate the room modes
    http://www.guidetohometheater.com/shownews.cgi?388

    One of the reasons I sold the Linn Keltiks I previously had was that whilst they worked beautifully in my previous house with brick walls and a suspended timber floor,they just didn't in my current timber framed 250yr old place.....so they had to go.

    Hope that link helps.
     
  3. Smurfin

    Smurfin
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    Thanks Alex. One of the problems I have is that the soundstage has to be pretty much fixed (due to the size of the room, where the door is etc). I can't even moved my speakers around bar toeing them in or out.

    I'll try the link above but I'm wondering if I'll have to go down the Auralex route (or something similar).

    Anyone wanna split a box of pyramids? ;)
     
  4. Apocalypse

    Apocalypse
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    Matt - The BFD has 2 engines, with a single sub you only use one of them so in your case you use 2 so you'll be fine with a single BFD.

    Here is a review of the BFD with a dual sub setup : http://www.snapbug.ws/brucekreviewofbfd.htm

    Here is an RCA --> 6.3mm jack for connecting the BFD to your processor : http://www.ishop.co.uk/ishop/923/shopscr1919.html

    As has been said the BFD can do nothing about your live room, I myself currently have a live room and anyday now my Auralex room treatments should arrive so I'll be able to tell you what they perform like.
     
  5. Smurfin

    Smurfin
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    Thanks:)
     
  6. Spligsey

    Spligsey
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    Smurf.

    You could use a slightly gippo version of Auralex.

    Carpet underlay.

    I used to have a 'DIY' studio in my spare room.
    It was made out of 4x2 timber, double plasterboard with Rockwool insulation, and covered (all walls & ceiling -: dont expect you to do the ceiling) with carpet underlay
    (the rubbery rippled stuff)

    It was incredibly dead once inside.

    Felt like my ears had gone pop each time i went in there.

    Adz
     
  7. Smurfin

    Smurfin
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    gippo version lol!:)
     
  8. Ian J

    Ian J
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    I hate to admit it but I feel that the expertise on room acoustics is on another forum.

    The flat earthers on Zerogain seem to have a good grasp of this subject so get yourself over here search on acoustics and you will have enough to read to keep you out of mischief for a while
     
  9. Smurfin

    Smurfin
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    Thanks for the link Ian. Now where's that smilie with a halo above it?;):devil:
     
  10. Dimmy

    Dimmy
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    Did this help your acoustics???

    I don't imagine it would too much!

    If it did - however, I might follow the same route as currently my room is so live it gives me a headache when listening at high volume levels :(
     
  11. Spligsey

    Spligsey
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    Yes, it did help a great deal in my studio, hence the bit about it being dead inside.

    Adz
     
  12. Smurfin

    Smurfin
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    Ok, my temporary solution for this (as I have to keep remembering this is a rented house:rolleyes:) is to buy more carpet like I have on the screenwall.

    For about £30 I think I can carpet the remaining walls. Now people mention up to ear height for HT rooms, is this ear height when you're sitting down or standing up, or simply up to the height of your speakers?

    I did another clap test just now, and clapping while I'm standing up gives alot of echo (yeeeuck), but when I clap my hands at speaker height it does sound much deader (but still a bit of echo).

    I'm wondering if my problems will be solved simply by extending my carpet treatment....and I also need to remember my M&Ks still need some breaking in. I forget that they're still relatively new sometimes:rolleyes:

    As a matter of interest, for M&K owners, how long after running @ moderate levels would you consider your speakers to be "broken in"?

    cheers
    Matt
     
  13. avanzato

    avanzato
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    Matt have you got any of that Wickes rigid insulation left and some liquid nails?

    I have one piece of board behind each L/R speaker and another board each side inside of them. The other two boards would be on the side walls but I have furniture in the way so they're leaning against that. This isn't enough treatment as I only got one pack :( but there is a noticable reduction in distortion at higher volumes. I'm still experimenting and as I'm not a paid up member of 'speed cinema' it's taking ages. ;)
     
  14. Smurfin

    Smurfin
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    LOL;)

    None left I'm afraid, and anything I put on the walls needs to be very thin due to the width of the room.

    Carpet should do the trick I think:)
     
  15. Dimmy

    Dimmy
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    Matt - from my very brief GCSE study of Physics I'd say your idea is along the right lines.

    I guessed Spiglsley's wasn't because surround speakers are supposed to have their sounds reflect horizontally on the walls (especially your Dipolar 77DS speakers). And obviously with Underlay everywhere that won't be hapenning for his setup.
     
  16. Smurfin

    Smurfin
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    Well the sides walls are completely carpetted up to a height of 1200mm, found matching screenwall carpet but in red for £2.49 per sq. metre.

    Today I managed to buy a BFD also, for a very reasonable £89 so I'm off to play:D
     
  17. Smurfin

    Smurfin
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    YES!!!!!!!!!!!!!!!!!

    Finally! After putting the carpet up on the side walls and playing a load of discs through it....I'm very very pleased:clap:

    The harshness has been all but knocked off, strangely things sound more solid than before, maybe it's psychological but the imaging is superb....it was good before but feels better.

    I was beginning to think I'd bought the wrong speakers - after spending £000s in the last couple of months, I don't mind telling you that I was a little concerned that I couldn't get it sounding how I wanted it to (like my old mission setup).

    The room is sounding utterly fantastic - played the pod race from episode 1 at reference level (dolby reference:eek: :eek: ) and the sound remained composed without sounding harsh!:devil:

    Played the intro to the LOTR FOTR R1 DD at reference also, although this still sounded a little bright (but way more bearable than before) - is this generally the case for most people @ true reference level?

    The only thing remaining to sort is the bass frequency response, which is like the Rocky mountains at the moment - full of peaks and one huge trough.

    I bought my BFD today so that should be sorted by the weekend:smashin:

    For anyone who has a dedicated room and wants something cheap to help acoustics, then get some cheapy carpet and whack it up on the walls.

    :)

    Cheers
    Matt

    PS I'll post a couple more pics when I can get them uploaded.
     
  18. Phil Hinton

    Phil Hinton
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    Sounds Good Matt, I may have to try that before spending mega money on the "proper" stuff.
     
  19. Spligsey

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    Well done Smurf.

    Glad to hear it sounds better.

    My walls are totally carpeted as well.

    I paid about £1.49 a linear metre ( a linear metre is well over what we know as a metre)

    Adz
     

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