Taming the "mud" in the bonus room from HELL!!!

Discussion in 'Archived Threads 2001-2004' started by Ronnie Ferrell, Nov 20, 2002.

  1. Ronnie Ferrell

    Ronnie Ferrell Second Unit

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    I need some serious help with room treatment. Here is some photos of the room I am trying to tame:
    UPDATED: With photos of the installed tube traps.
    The room is not a dedicated HT room. Right now it is a 2-channel system with a dedicated sub. Hopfully Santa will bring me a HT receiver! Also I have to keep WAF in mind with whatever I do. The main thing that needs controlling is the "muddy" bass. Pretty much (as you can see in the pics) my room is a reversed "megaphone" shape. And I have no idea how to model this room. The bass from the seated position on the couch is bad below 80hz. The best way to describe it is "muddy" and irritating. If I had a ported sub, I would expect some slight muddy sound, but I built a mid-Q sealed tempest sub. The volume is not the issue. My "not so technical listening" to a sign sweep sounds pretty even with very few peaks and drop outs. But when I listen to music etc, the bass just sounds wrong. Placement of the sub has minimal effect on the sound I am hearing. Placement does help control the gain, but has little effect on the "muddy" sound.
    Does anyone else have a room shaped like this that you have tamed?
    Has anyone tried Jon Risch's DIY tube traps?
    DIY Bass Trap pictures
    Any advise will be much appreciated!
    Ronnie
     
  2. Have have built a pair of helmolts resonator type of tube traps (sealed at one end and tuned to 1/4wavelength) for my nasty 63hz boom. They were both 10" in diameter. While they only reduced the peak a few db's (2-3), they did noticably break down the 63 ringing. The tube traps with the BFD to equalize worked out well for me in the end.
     
  3. Brian Bunge

    Brian Bunge Producer

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    Ronnie,
    My question still remains that if this is a "bonus room" why the hell does WAF come into play at all?! [​IMG] I still think you should rotate the room 90 degrees if nothing else.
     
  4. Dave Poehlman

    Dave Poehlman Producer

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  5. Ronnie Ferrell

    Ronnie Ferrell Second Unit

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    Brian-
    I actually got permission to do a 90 degree rotation to the room last night! I am going to try that this weekend. I think my complaining about the sound is finally getting to the wife and she wants me to shut up about it already! [​IMG] (just kidding) She had not really listened to the system since I incorporated the sub. She actually noticed the muddy sound while we watch a movie last night. I think I will still need some bass traps or something for anyone who happens to sit on that side of the room.
    Dave-
    Well on the left side of the system there is a closet. It is set back a few feet.
    [​IMG]
    I am also porbably losing some of the higher frequescies equally on both sides! [​IMG]
    180 degrees would be out of the question. The Entertainment Center would be out in the middle of the room. The back wall that has the couch against now is only 57" tall.
    I went Saturday to get a DB meter from RS and they were out. I will swing by the one near my office on the way home tonight...
    Thanks!
    Ronnie
     
  6. Dave Poehlman

    Dave Poehlman Producer

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  7. Ronnie Ferrell

    Ronnie Ferrell Second Unit

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    My digital ELPH sucks at taking pictures at that range. The mains look like the are toed out and past the edge of the wall. Here is a better picture of my mains placement. Actually they still looked a little toes out, but they are parallel with the back wall...
    [​IMG]
    I have played with their placement a good bit. Toed in a little, toed in a lot, moved forward and back, etc. I have no complaints with them! The soundstage I get from them is just amazing!
    Hopefully the 90 degree shift will help a lot. If not I will crank out some tube traps and let you know how they perform!
    Ronnie
    EDIT--
    Oops! You edited your original post before I finished my reply! [​IMG]
    I concur with the 90 degree room shift. The more I think about it, it IS the way to go! Now if I can bribe the next door neighbor to help me move this stuff on Saturday! [​IMG]
     
  8. Bryan Michael

    Bryan Michael Supporting Actor

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    maybe put the tv on the wall opsite of the window?
     
  9. Brian Bunge

    Brian Bunge Producer

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    Ronnie,
    Cool! Maybe you should now start bitching about how much better things will sound with a 7.1 receiver! [​IMG]
     
  10. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    Ronnie, today I bought the parts, and am currently designing and building my own clone of the ASC type bass tube trap very similar to John Risch's traps.
    I just made the cut list and it looks like each one will weigh more than 20lbs so right now I'm trying to figure out a way to float them in the corners of my room. (perhaps with a shelf bracket)
    From my understanding, these don't have an opening so they arn't hemlholtz resonators right? These are basically just hollow fiberglass capsules to be placed in the corners to help control the bass.
    I will be making four 16" diameter 4 foot long cylinders that should cover a very good range of bass as well be a lot more effective than the smaller ones. I probably won't use the plastic lining on one half though as I don't understand why it's there. (possibly to diffuse highs and only absorb bass?)
    My one question is if my room has problems with upper bass of 60hz and up only, then should I make smaller traps to be more effective? After viewing the graphs at ASC it looks like the bigger traps perform better in every way which is why I am choosing the monster size. [​IMG]
    If you wait till this weekend, I will be taking measurements and be testing the performance of these traps and see how each one affects the bass response (with graphs and such). I'll also make a page on how to build them if they are successful like the acoustic panels.
    Some things you can try before buying anything:
    Try moving both the subwoofer and the seating location around the room (perhaps keep track with a grid and move in 1-2 foot increments).
    Try adjusting the crossover point on the plate amp from 40, to 80, to the highest and try phase from 0-90-180.
    Maybe try using the high pass inputs on the plate amp and not using the receiver's crossover.
     
  11. Greg Monfort

    Greg Monfort Supporting Actor

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    FWIW, I believe that if you can't/won't rotate it 180deg, then better to leave it in the current orientation rather than rotating 90deg in either direction.

    Adding basstraps in the corners of the room is a must do regardless of orientation (more than one may be required in the two alcoves) as well as three sided floor to top of equipment cab diffusor panels behind the mains, and another diffusor panel behind the sofa and extending up the slope. Pulling the sofa away from the wall should help also.

    If basstraps won't fit in the alcoves then hinged diaphramatic absorbers to close them off flush with the speaker wall should work just as well (or maybe even better), placing the sub in front of it. Instead of an absorber behind the sofa, a bookcase partially filled with paperbacks, mags, doll collection, or other well damped objects to create a diffuse wall will work just as well and be more WAF.

    Last, but not least, experiment with lowering the Q of the sub since you're sitting on the high acoustic impedance side of the room.

    If you rotate only 90deg you'll have a lopsided reflective mess you'll never be able to completely compensate out without damping the entire ceiling and will still need all the other room tweaks for best performance.


    GM
     
  12. Ronnie Ferrell

    Ronnie Ferrell Second Unit

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    Brian-
    Yeah, the 7.1 would be nice. I think I am pretty much sold on the R-756 over the R-863. I forgot that if I wanted to take full advantage of the 863, I would need to build 2 more speakers, driving the cost even higher. I still hope to make it by the local shop to here the R-863 though. The Sherwood rep I talked to said the amp stages sound almost identical in both receivers. I will keep you posted! [​IMG]
    Chris- I can't wait to here what your findings are! That is the exact size of trap I am thinking of building.
    I am going to shift the furniture 90 degrees this weekend. That will put the TV on the back wall opposite the window. My troublesome wall will then be to my left when seated on the couch. Even with the shift, I think I will still need 1 or 2 traps along that wall.
    I know most, if not all of my problems are caused by the short 57" wall and the huge sloping roofline that it is meets. I can move to the edge of the couch, or sit on the ottoman, and 90% of the muddy sound goes away. Anywhere along the short wall the bass really sounds bad. This is a lot more noticeable with music CD's. An electric bass just sounds like a constant muddy sound.
    From what I have read on the bass traps, they are supposed to help this very thing!
    You mentioned the plastic wrap. I also think that it is over the top. I think it is suppose to reflect waves that make it through the trap, back into the trap. I could be very wrong about this though...
    Keep me posted!
    Ronnie
     
  13. Ronnie Ferrell

    Ronnie Ferrell Second Unit

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    I decided to not rotate the room 90 degrees this weekend. Instead, I built four ASC clone tube traps.
    Taming the room from Hell, (part 1- Installing two tube traps.)
    I did not take any pictures of the build process because Chris Tsutsui is doing an awesome job of it on his web site here. (Chris, I hope you don't mind me posting a link.)
    Mine are four feet tall with a 14" diameter. The recipe is Jon Risch's and can be found here. (2/3 down the page)
    All I can say is WOW!!! I have only got 2 of them installed right now and 90% of my mud problem is GONE! I only have the traps covered with poly-fil right now. I will finish the other two up this weekend and cover them all with the burlap.
    I doubted the traps the whole time I was making them. I am definitely a believer now! Madonna's "Drowned World/Substitute For Love" from the "Ray of light" CD use to actually hurt when I played it. It was just a sea of muddy bass "sound" (if you could even call it that...) that was just "in the room." Its a "cooked" bass note anyway. Now with the traps, the bass is low and tight. It is coming from the soundstage and is not just an annoying "blob" of sound inside my head.
    The kick drum on Mary-Chapin Carpenter's "I feel luck" from "Come On Come" use to be this annoying thud that sounded like it was inside my head. It now sounds like a kick drum, center stage!!!
    I highly suggest these to anyone that has standing wave problems!
    Ronnie
     
  14. Dave Poehlman

    Dave Poehlman Producer

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    Interesting.. looking at them you wouldn't think they would make that much of a difference in a room that size. Congrats.
     
  15. Ronnie Ferrell

    Ronnie Ferrell Second Unit

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  16. Aaron_Smith

    Aaron_Smith Stunt Coordinator

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    I was also amazed at the difference that a few bass traps made when I built my home studio. Back to the "rotating the room" theory-- I'm not sure that rotating the listening room will have much affect on your bass problem. Sounds like the main problem is standing room modes, which are going to be there independent of equipment orientation. However, placement of your subwoofer should have a significant affect-- different locations along the wall will either cancel or reinforce bass harmonics.
    The tapered shape of your room is an advantage-- the fewer parallel walls you have, the better. Getting the SPL meter is a good idea, it's hard to treat this stuff subjectively.
    At any rate, I would check the internet (do a google search)for studio room acoustics and try to follow those principles- most studios are built with a "dead" end behind the listening equipment, a "live" diffuse end behind the listening position, and bass absorption targeted specifically for standing room modes (which can be calculated). More than anything it's a trial-and-error process. Good luck.
     
  17. Ronnie Ferrell

    Ronnie Ferrell Second Unit

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    Aaron-
    Thanks for the studio room google idea! I will give it a look.
    The first thing I did was move the sub around. It is not where it is in the posted picture. It is now on the right hand wall from the seated position. With this room there is no way I can corner load the sub. I did this before adding any bass traps. I finished up another trap last night. It really did not help out any more than just the first two. I have always heard that more does not always equal better when it comes it room treatment. And that trial and error IS the key! [​IMG]
    I still have a pretty bad 59hz hump when seated on the couch. I know it must be loading up between the slope and short back wall. If I move forward another 18" the 59hz hump disappears. But I already have the couch pulled out from the back wall as far the wife will let me. I am thinking of hanging and 23" by 7' wide acoustical panel 4" off the sloping ceiling right above the couch. I can hang it with screw eyelets and picture haning wire from the ceiling joist. If it does not help, I can fill the drywall holes and paint over them very easily.
    I'm just waiting for the day when the wife finally says, enough already! I think the hanging panel might do it! [​IMG]
    Ronnie
     
  18. Aaron_Smith

    Aaron_Smith Stunt Coordinator

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    By the way- great job on the sub, and thanks for taking such detailed pictures on the construction process. I'm about to finish my sealed Tempest box... much like yours but without the fancy dados and rabbets. Didn't want to spring for a dado stack. [​IMG] At any rate- so far, so good. The day that I get some sort of nice finish on it will be a good day for all involved-- I think my wife gets more concerned every day she has to look at that big nasty MDF box sitting in the garage.
     
  19. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    I'm glad to hear the traps worked out for you.
    I finished two traps with burlap stapled while my two other traps just need the burlap. I covered them with two black trash bags for now and they're in the back corners of my room.
    I actually used a different approach with the build process as I had to find a much easier way to build them by myself. I ended up using 70lb twine and a $20 stapler from home depot to assemble the three others. It worked out fine and I edit my page with the new process and 30+ pics in time.
    I also graphed the before/after in-room response of my overall 2 channel system.
    The response changed from +/- 5db to +/- 4db with a peak at 90 and dip at 82db. (during a fairly loud tone sweep 25-160hz)
    The traps primarily reduced a 2db dip in the response which was a first order resonance near 63hz. They did not affect the peaks all that much though the overall plot became a bit smoother. I was kind of expecting a bit more of a change than helping a dip by 2db but I'm pleased with the sonic results.
    The bass has become more detailed and is a lot less distracting in movies. The 2 tempests also integrate with the mains better as it's getting very hard to isolate when the subs begin to play. The room has taken another step towards "dead" as it is now quieter with the four huge 16" diameter 4ft tall traps. Movies are incredibly detailed and unplugged/live performances just shine in a room that doesn't acoustically exist. It does have somewhat of an effect on the comfort level of the room but I have my open door, window, and computer fans to help add ambience.
    As far as cost, these 4 ended up costing about $160+ due to me having to pay for a $25 ban saw blade because of a complaining master carpenter. It also cost $30 more for a stapler and twine. I'd say it was worth it though (just barely) because not only did I help fix a dip which is something equalization has trouble with, but I now have the option of parametric equalizion to reduce my +/-4db response to an even happier obsessive compulsive number.
    I don't think I'd be doing the para eqing anytime soon though as the bass is quite suitable as it is. Not to mention my room which now looks like it either has greek columns in the four corners, or has industrial air ducts running through it. [​IMG]
     
  20. Ronnie Ferrell

    Ronnie Ferrell Second Unit

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    Chris--
    I don't have a DB meter to check my response yet. I do not think the traps reduced any peaks that I had. The main thing they did was remove the standing waves. I get the same thing you describe. Before the traps I had long sustained bass sound. Kinda like the bass was echoing like a hand clap does in an empty room. I don't know if that is what was actually happening, it is just the best way I can describe it.
    Anyway with the traps, my bass became clean and tight! I still had a bad hump at 60hz. A little more moving of the sub fixed it though. Now the hump has moved down to around 38Hz and is smaller. I can live with this, because it kinda gives movies that extra little "oomph" on the low end and I do not notice it with music.
    FYI: I did all of my traps by myself. What I did to get the insulation on is this. I made 2 lassos with string and secured the insulation at each end of the trap with them. The lasso strings are about 25 to 30 feet long. I then spiraled the string by rolling the trap on the floor. Each sting goes half way down the trap. I tucked and aligned the insulation as I went. I made sure not the pull too tight, but made sure the insulation was the same diameter as the end caps. I used a slip knot to secure each string to itself in the middle. Then I easily wrapped the outer hog wire around the trap and stapled it on. After that I undid the slip knot and carefully removed the strings from the trap, only pulling a 1/4 turn of the trap at a time, releasing the pressure on the insulation.
    This worked like a charm!
    Aaron_Smith--
    [​IMG][​IMG][​IMG][​IMG] I have the same situation with the wife! Except my sub is already in the house! I am having to wait until Spring to finish it because of how long it takes pure Tung Oil to cure in the winter. The wife does not say anything verbally. It is the blank look on her face that get me every time she walks into the bonus room. I don't think she says anything (verbally at least) because she knows how happy doing all this makes me!
    Keep us posted on how the sub sounds when you finish it! FYI: I was under whelmed with mine until I found the correct room placement for it.
    Ronnie
     

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