Acoustics, speaker placement, subwoofers

Discussion in 'Speakers' started by Riotvan, Jun 9, 2018.

  1. Thad E Ginathom

    Thad E Ginathom Friend

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    I don't know what to say.

    But I suppose that if something is not as good at position A, moves, through an arc of goodness, to being not as good at position B, then there must have been an optimum point. You found heaven at 63.5 degrees. Enjoy!
     
  2. atomicbob

    atomicbob dScope Yoda

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    Having the panel away from the ceiling increases the panel's efficacy. The sound must travel through panel, air, bounce at ceiling back through air and then through the panel again. That's a feature. :D

    Welcome to "physics is a bitch" 101. Reflections mixing with the direct field create a comb filter. Wearing headphones avoids all the room acoustic issues, though with their own set of problems. Listen in a well designed acoustically control room or mastering room and you will never forget the auditory experience. The clarity is incredible. Differences between equipment seem minuscule by comparison of a well acoustically treated vs. an untreated room.

    Here is a presentation my colleague and I gave Jan 2017 on the topic of room treatments. While oriented to location recording / meatball mixing, the principles also apply in general for recreational listening. My part focused on unwrapping the Energy Time Curve (ETC) measurement with examples.

    http://www.aes-media.org/sections/pnw/pnwrecaps/2017/johnston_smith_mix_jan2017/
     
  3. Riotvan

    Riotvan Got lost for three weeks at Delft City Hall

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    Yep that was the idea, works for basstraps in corners too but there it's best to have no gaps to the bottom, top and sides otherwise you get reduced effectiveness(correct me if i'm wrong). So i just went with superchunks, more expensive but works very well. And i can just move em around easily, they just stack on top of each other.

    Going to check out the presentation, thanks!
     
  4. Riotvan

    Riotvan Got lost for three weeks at Delft City Hall

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    Anyone have experience with BK subs? Considering a pair of XLS200-FF's, they have a paint option that matches my speakers and are not much more expensive then diy. The idea is to stack my nearfields on them and go full range. I already tested with my current 10" sub and it sounds better the closer it is to the speakers but of course having one sub for stereo is not optimal for certain music.

    The current sub works just as good whether placed left or right so that leads me to believe double subs will work fine.
     
  5. Kernel Kurtz

    Kernel Kurtz Almost "Made"

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    Mine are less toed than that, but my listening position is only about 4 feet from the back wall. I like the reflected sound better if they don't cross before that wall.

    Certainly the best "bang for the buck" I've found.

    That's what I do. The speakers and subs placements are carefully measured and recorded, so it is easy to recreate when I move them
     
    Last edited: Jul 11, 2018
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  6. Kernel Kurtz

    Kernel Kurtz Almost "Made"

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    I just went with the 2x4 rockwool boards - 2 per trap. Used some prefabbed frame material and just cut to size. The boards were a bit too thick for the frames so I had to bend them a bit. I've since found some different frame material that is better. I may redo them.

    [​IMG]

    I only needed half height, but you could easily make them 2x6 or 2x8 with 3 or 4 boards each respectively. 2x8 traps would be quite heavy.

    [​IMG]

    I covered them with burlap for now. It is cheap and acoustically transparent. I've bought some speaker cloth since - it was more expensive than the rest of the materials combined. I'm going to work on my hot glue gun skills for a bit before I attempt that part. Once you get the hang of it you can make any angular shape you want. Like to stop the mixed reflections behind the TV (those speakers are bipolars BTW).

    [​IMG]
     
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  7. direstraitsfan98

    direstraitsfan98 D2Girls v2.0

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    Setup guide and review for Skylan 4P24 stands incoming. In short, they are extremely well built and solid as a rock, once weighted down. Cannot recommend them enough. Keep your eyes peeled for a comprehensive guide with lots of photos.

    [​IMG]

    (Just finished making them a moment ago, excuse their dusty appearance)
     
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  8. direstraitsfan98

    direstraitsfan98 D2Girls v2.0

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    So I wanted to see your guys' take on this topic. Speaker break in? I was wondering if my kef ls50 are actually already ready to play and fully broken in out of the box. I read that KEF stress tests all their drivers. But maybe that's before assembly, and once they're assembled they just box them up. Perhaps during their assembly they somehow get stiff again and need to be broken in once again.
     
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  9. spwath

    spwath Collegiate hijinks master

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    I don't understand: what can make a speaker stand $560/pair? Couldn't a bunch of cinder blocks do the same job for next to nothing, though a bit less pretty, but a wood casing could be put around it.
     
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  10. Priidik

    Priidik Friend

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    Probably nothing.
    But then, when these weigh a lot, then these are probably close to being worth the price.
    High mass makes for better stands (pushes the resonant freq below the bass cutoff and are just more stable).
     
  11. AdvanTech

    AdvanTech Friend

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    I think it’s real, but I don’t think it’s significant enough to really change a speakers presentation. It’ll probably ‘relax and open up’ in subtle ways.
     
  12. yotacowboy

    yotacowboy McRibs Kind of Guy

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    Break in or burn in is mostly the driver's spider and surround becoming more compliant. More compliant suspension = lower Fs. More compliant suspension = lower Qts.

    http://www.gr-research.com/myths.htm

    I'm guessing stress testing at KEF factory is not running them for more than an hour.
     
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  13. fraggler

    fraggler A Happy & Busy Life

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    I have a subwoofer placement question for you all. In my living room/AV space, I have basically no wall space except for near my front speakers for a subwoofer. No idea how good it will sound at the listening position. To satisfy my strong desire for visual symmetry and to potentially even out the bass, I am thinking of nuking my budget and getting a second sub and using the two as speaker stands for my front speakers. If they are only 4 to 5 feet apart, am I likely to get any of the benefits of 2 subs (beyond spls) or possibly introduce more problems? One sub is likely more than enough for my small space, so maybe put a single sub directly in the middle and build the AV rack around it? I am trying to sort this out now so I can take advantage of the bundle discount that SVS has when you buy 2 together as well as utilize Amazon's payment plan to stretch the purchase out a little. Any suggestions or thoughts?
     
  14. Kernel Kurtz

    Kernel Kurtz Almost "Made"

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    Using subs as stands can work fine, I have seen it done with good results. The disadvantage is that the optimum placement for your subs may not be the same as the optimum placement for your speakers, so you lose that flexibility. If space is limited you don't have this flexibility anyway so no loss there,

    I would not build a cabinet or rack around your sub(s). Regardless of which direction the driver fires there is still going to be a lot of energy radiated from it in all directions and you probably won't be wanting to enclose that, at least not without careful thought and ideally some acoustic measurement beforehand.

    As always I highly recommend buying a calibrated microphone and learning to use software such as REW. They are well under $100 and it really is one of the best investments you can make in a speaker setup, especially with subs.
     
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  15. pedalhead

    pedalhead Friend

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    As @Kernel Kurtz says, definitely worth getting REW and a mic. If I had to guess, I'd say by having the subs close to the same wall you risk compounding issues (particularly those pesky nulls) caused by rearward reflections to the wall. Depends on a ton of room factors of course, but I wouldn't go spending money on two subs unless you can be more flexible with the room setup imho.
     
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  16. yotacowboy

    yotacowboy McRibs Kind of Guy

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    if you've got enough signal cable length to do so, simply place the subs at the listening position and walk around the room and see where the response sounds best/measures the best. then place the subs where it sounds the best/measures the best when the subs were stacked in the listening position.

    next step after this would be to go REW + mic.
     
    Last edited: Aug 5, 2018
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  17. Riotvan

    Riotvan Got lost for three weeks at Delft City Hall

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    Recently bought a measurement mic to fine tune my system. Also got a nice BK sub in matching silver, really happy now and i learned a few things as well. Main one is that setting your speakers up down to a mm of precision matters. I was getting some brightness/sibilance from the right speaker. Turns out the speakers were misaligned by several mm. Adjusted that and it's great again, guess it's critical for nearfield setups where you hear more direct sound from the speakers. Another one is using a mic and RTA is very handy. Got two dips in the low end, might be fixable with another sub but with the sub off they are also there just lower in volume, most likely the room i guess. Don't really hear them with a sinesweep, maybe i'm measuring it wrong...
     
  18. Pibroch

    Pibroch Rando

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    Toeing in about 45 degrees here, while listening position forms an equilateral triangle with the 2 speakers. This means listening about 15 degrees off axis. Speakers are Geithain RL906. This placement gives a spectacularly large sweet spot so staging is wonderful and treble is just right with the speakers left at their factory settings for most of the recordings I listen to. If you are to the left of centre you are closer to the left speaker but compensated by being more off-axis with it and more on-axis with the right speaker. Got this idea from marketing blurb for the Grimm speakers designed by the famous engineer Bruno Putzeys who advocates this practice.

    The other thing is if you have an easily moveable listening chair you can move backwards and forwards to adjust for treble (and bass depending on your room acoustics) for individual recordings - effectively you are adjusting toe-in without having to mess around with actual speaker placement.
     
    Last edited: Oct 1, 2018

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