BMR Philharmonitor problem - speaker gods save me

Discussion in 'Speakers' started by Hooncake, Sep 30, 2016.

  1. Hooncake

    Hooncake Mid-Fi Purgatory Redemption

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    SOLUTIONSS




    Long story short I recently received my stands for the BMR and decided to move them from my desk to the living room.
    Ever since then I noticed the bass frequency 200- 35hz has gone to hell and various positioning has not helped.

    Room is 15.7 x 12.1' and 9' high.
    laminated cheap wood floor, cement walls.

    I tried the 38% rule, golden cardas ratio, 1 foot away from the wall like Dennis suggested but all gives me the same problem. I've tried various permutations of speaker placement of 1-5 feet away from the front wall and listening position of 4-10 feet from the speakers.

    Me and @thegunner100 took some measurements tonight.
    [​IMG]

    The Red is 1 foot away from the wall and the Blue is 38% away from the wall. Cardas ratio looks pretty much the same.
    There is a valley of death 40-70hz. Imaging is fuzzy.


    [​IMG]
    This is my living room in rough positioning.
    I have tried putting 4x8' 4" bass traps in the front two corners which may have more or less done nothing as I suspected.

    Is there no saving my bass null? I don't understand because despite wide range of speaker placement (1 foot - middle of the room) this problem exists. I thought depending on where you place the speakers, you get null at difference positions but the problem more or less seems constant. Is this within the realm of fixable with moar bass traps and panels? GIK acoustic recommended two 6" bass trap/diffuser thing on back wall as well as putting 2 more bass traps in ceiling front corners.

    I'm afraid to waste more money without real guarantee for solution.

    Speaker gods please help. :(
     
    Last edited: Oct 5, 2016
  2. haywood

    haywood Almost "Made"

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    Not a speaker god but is bass dead everywhere in the room or just your listening position? If everywhere then maybe the stands are a problem, if your listening position is in a null point then you'll have to try more positioning and/or room treatments.
     
  3. Hooncake

    Hooncake Mid-Fi Purgatory Redemption

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    hmm I think its null point, I have to try more positions tomorrow. Been reading up on room modes and 50 hz bass null seems to be the problem I am having similar to other people on forums.

    I think short of heavily treating the room, this will be a pretty difficult fix..unless someone has a suggestion =\
     
    Last edited: Oct 1, 2016
  4. uncola

    uncola Friend

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    weird that your room is so awful. wouldn't another speaker have the same issues? I saw you list the speakers already on usauadiomart :p no shame in that if they aren't working for you
     
  5. Hooncake

    Hooncake Mid-Fi Purgatory Redemption

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    It's either sell or fix, fate will decide. :(
     
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  6. thegunner100

    thegunner100 Hentai Master Chief

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    @Hooncake Maybe we can take the OSMT from my house to yours after your visit, so that we can run a few tests. We'll also have the mic stand for more accurate measurements.
     
  7. Hooncake

    Hooncake Mid-Fi Purgatory Redemption

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    hmm I think that's a good idea. I'll hit you up in the afternoon. Thanks man.
    Been reading and went on to some room mode calculator website. Seems pretty spot on that I'll be experiencing severe null at 50hz frequency range.

    I've mustered up some energy. I'm gonna make a trip to NJ in the near future buy some crap load OC or similar product and build 6" thick bass traps. Retail is just way too expensive.
     
  8. yotacowboy

    yotacowboy McRibs Kind of Guy

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    I think it sounds like a null based on your ceiling height.

    consider building a tube-style bass trap by stacking three of these in a corner: http://www.mcmaster.com/#5556k85/=14enxd3

    wrap with burlap and you've basically built an $800 ASC Tube Trap.
     
  9. Hooncake

    Hooncake Mid-Fi Purgatory Redemption

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    Hmm definitely bass null problem aftr some testing. Will report back with more speaker placement measurement and solutions.

    I think so far what I have read and experienced is that bass null is nearly impractical to treat with bass traps.. Especially not 4" ones. Need much thicker and off the wall. Impractial and costly for my situation now. I think best option is to find new speaker placement and listening position with compromises.

    If anyone can share how they go about treating bass nulls I would appreciate.
     
  10. yotacowboy

    yotacowboy McRibs Kind of Guy

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    try taking some measurements with your speakers sitting on the floor - remember, your room is 3-dimensional; just moving things around in 2-dimensions might not let measurements expose the problem fully.
     
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  11. haywood

    haywood Almost "Made"

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    Have you tried a subwoofer in that room? You could do a sub crawl to find a spot that'd provide good bass and set up the Phils (or whatever you get to replace them) to suit your listening position.
     
  12. Ninja Pirate

    Ninja Pirate Friend

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    From what I've seen, bass null is usually the back wall from the speakers. Have the exact same issue in my bedroom with the BMR's and have not resolved it fully (minidsp helps somewhat).
     
  13. purr1n

    purr1n Finding his inner redneck

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    1. The room null is fairly normal.
    2. Stop using Cardas Golden Schlong ratio. It's bullshit. You don't want to be bound by rules or equations, especially from someone who sells cables. Experimentation is crucial.
    3. Try using the wider part of the room. Rearrange speakers and couch so side walls are far away. Imaging is fuzzy because of the first reflection echos from the side walls. Long narrow rooms arrangements have never worked well for me.
    4. Bass traps, unless they are the size of industrial refrigerators are bullshit. They will not correct peaks or nulls in the bass. Don't waste your money on bass traps. Acoustic panels or refractors are a different story.
     
    Last edited: Oct 4, 2016
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  14. cskippy

    cskippy Creamy warmpoo

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    When I was doing frequency response tests for my speakers I noticed that volume drastically changed the frequency response in the low end. This is near field mind you, so it might not make as much of a difference if the room comes more into play. Something to test though...
     
  15. purr1n

    purr1n Finding his inner redneck

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    room.png
     
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  16. zonto

    zonto Friend

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    I haven't measured my room yet, but there is evidence that speakers firing down the longer dimension of the room (how you have them) gives flatter bass response than firing down the shorter dimension. See http://realtraps.com/art_room-setup.htm, Figure 3. The same article says that you'll theoretically get the flattest bass response by sitting 38% of the way back in the room. See id. ("The 38 Percent Rule"). Peaks and nulls become worse the closer you sit to the rear wall.

    My gut says you're just going to have to minimize the bass null to the extent you can by speaker and sofa placement and improve imaging by absorbing the first reflection points. I'd focus on ensuring you are absorbing at first reflection points on the side walls, front wall, and rear wall (using your thickest traps behind you if you go that route, especially if your sofa is as close as your diagram). GiK recommended their Monster Bass Traps for placement behind my listening position at my old apartment where the couch was similarly close to the rear wall, but I moved before I tried anything. Left side reflection can likely be taken care of with curtains and a blackout liner. Also try a thick felt rug liner and large rug between you and the speakers to absorb floor reflections.
     
  17. Hooncake

    Hooncake Mid-Fi Purgatory Redemption

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    Writing a follow-up post just in case anyone wants to own a pair of speakers and run into similar problem in the future.
    Luckily @thegunner100 had a measuring mic and let me borrow it and I got to work over this week.

    The problem I experienced (mainly the 70 Hz death valley and uneven response 200 Hz and below) are almost entirely due to interaction with the room. Reading online, it seems like this problem is worse in smaller rooms.

    I tried many different positions in the room. Luckily (or unfortunately?) I don't have any furniture in the living room except a couch. The room echoes even with foot step creak on the cheap laminated floor.

    Some pictures for your entertainment. Without going into details, I took measurements at every 1 foot or every 6 inches and saved how the sub 200 Hz frequency dips and peaks.

    Some positions I tried.

    [​IMG]

    This is an example of how dips and peaks are affected.
    This particular graph is speaker position 1 foot away from the back wall and with changing listening positions.
    [​IMG]

    I was about to settle when I found this position:
    - 1 ft away from the wall
    - listening position 4-5 ft from the speakers.
    [​IMG]

    But then I decided to screw it and put my huge desk with 34"-ultrawide monitor in between.
    [​IMG]

    Surprisingly this produced the best graph (in my opinion)
    [​IMG]
    [​IMG]

    Although waterfall graph looks pretty crappy, it is somewhat of an improvement to all the other positions I've found...

    How does it sound?
    - unbelievably different experience listening to when they were mal-positioned.


    Part II will probably be with some acoustic panel/diffuser/bass trap. Really considering dropping lots of money on their Alpha panels. If anyone wants to deter me from doing so, PLEASE.

    Please correct any misinformation and appreciate any suggestion.

    TL;DR
    - Make some cool friends in life.
    - Speaker gods may or may not help you. Forge your own path
    - Don't blame Dennis Murphy, just yourself.
    - Speakers > headphones (if you have a good room or willing to experiment...)
     
    Last edited: Oct 5, 2016
  18. thegunner100

    thegunner100 Hentai Master Chief

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    Damn, it looks like you put a lot of work into this! I look forward to hearing the final result. And yes, do make some cool friends IRL! :)
     
  19. Serious

    Serious Inquisitive Frequency Response Plot

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    My room is about 10ft by 25ft or so and I seemed to prefer both speakers I've had in my room set up on the longer side of the room. That is with some basic side wall first reflection point absorption (thick pillows, sheepskin on the walls, blankets, ...). It's just not wide enough to set up speakers on the wide side without needing a lot of back wall absorption.

    (Thinking about it, the imaging was probably better when I had them set up in a very near field environment diagonally in my bed. The speakers sat left and right of one corner of the bed and I sat at the edge. Because of my sloped ceilings, that effectively avoided every direct reflection. The IR decayed to -20db immediately with only clean, diffuse decay with no peaks sticking out of it after that. Or maybe the imaging was better outdoors, but that didn't avoid floor bounce as well - there was no mattress between the floor and the speakers.)
    Are you saying your speakers had significant linearity issues in the bass? The soundstage network measurements often also show tweeter nonlinearity issues. How big were the changes? I've never seen such an issue with headphones for most realistic levels, but it still seems to be a thing with speakers. I think I've done such measurements for the HD800 and basically saw no FR changes with volume.
     
    Last edited: Oct 5, 2016
  20. cskippy

    cskippy Creamy warmpoo

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    No changes with headphones. There were some pretty big changes varying volume between 55dB and 85dB though, sometimes 10db difference in dips.
     
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