Resonance behind TV/entertainment center...

Whadyasay
Whadyasay Posts: 300
edited February 2009 in Speakers
Wasn't sure where the best section for this topic was, so I figured I'd try here.

I have my system set up as follows......


sal2qc4.jpg


...with the shelving about 13" out from the rear wall and the rear of the TV about 22" out. I'm getting some pretty substantial standing wave resonance back behind there at around 50-55Hz or so. It stands out and you can really hear/feel it when you put your head near or in that area while sound is playing. I was thinking of taking some corner bass traps, putting them together like so....


trapsmp8.jpg


...and mounting that to the wall right behind the TV in hopes of breaking up some of those standing waves with that parallel area behind the TV. The whole thing will end up being 2-ft square and 1-foot out at the peak. Does this seem like something that will help? That's really the only sound resonance/peak that's bothering me about my setup. It's definitely coming more from the main speakers than the sub, since I've tried sine wave test tones through them separately....and I really don't want to push the whole thing back farther towards the wall for several reasons.
Polk LSi9 Mains, Polk LSIC Center, Polk RT25i Surrounds, Polk M3II Rear Surround, SVS PB10-ISD Sub, Denon AVR 2809 (as digital pre/pro only), Sony BDP-S350, Oppo DV-981HD, Cambridge Audio Azur 540C (CD), Marantz MM9000 5-ch amp, Outlaw ICBM, Panasonic th-42PX85u HDTV, Behringer BFD Pro, Monster Power HTS 2600 Conditioner
Post edited by Whadyasay on
· Share on FacebookShare on Twitter

Comments

  • Igo
    Igo Posts: 411
    edited January 2009
    Experiment. I used an area rug behind my TV for the same reasons but I didn't have a serious problem.

    That's a very nice looking set up by the way.

    522_1_big.jpg
    ...Link to my System Showcase...
    "ES - Kind'a simple but I like it"

    Sony ES STR-DA4300ES 7.1
    Sony ES SACD SCD-C2000ES
    Sony 400 Disc CD CDP-CX455
    Infinity BU-2 Sub-Woofer
    Polk Audio RT800i Towers
    Polk Audio CS400i Center
    Polk Audio FXiA6 Surrounds
    Sennheiser HD 280 Pro Headphones
    DH-Labs T-14 Speaker Cables
    Panamax Max 500 DBS Line Conditioner
    Panasonic TH-50PZ85U 50'-Plasma
    Play Station III - BluRay
    Logitech Harmony 550 Remote
    Logitech diNovo Mini Keyboard
    · Share on FacebookShare on Twitter
  • Hawkeye
    Hawkeye Posts: 1,313
    edited January 2009
    I would install 2 or 3 GIK Monster Bass Traps behind the rig. One may be enough but doubtful. Trying to absorb 50-55 Hz with that tiny thing you're suggesting won't give you any large improvement IMO..

    Gordon
    2 Channel -
    Martin Logan Spire, 2 JL Audio F112 subs
    McIntosh C1000 Controller with Tube pre amp, 2 MC501 amplifiers, MD1K Transport & DAC, MR-88 Tuner
    WireWorld Eclipse 6.0 speaker wire and jumpers, Eclipse 5^2 Squared Balanced IC's. Silver Eclipse PCs (5)
    Symposium Rollerblocks 2+ (16)Black Diamond Racing Mk 3 pits (8)
    · Share on FacebookShare on Twitter
  • Whadyasay
    Whadyasay Posts: 300
    edited January 2009
    Not trying to absorb it as much as maybe help break up the parallel facing surfaces. It helped a bit when I put a guitar case back there, but I can't leave my guitar case back there. We'll see....I might end up going that route anyway.
    Polk LSi9 Mains, Polk LSIC Center, Polk RT25i Surrounds, Polk M3II Rear Surround, SVS PB10-ISD Sub, Denon AVR 2809 (as digital pre/pro only), Sony BDP-S350, Oppo DV-981HD, Cambridge Audio Azur 540C (CD), Marantz MM9000 5-ch amp, Outlaw ICBM, Panasonic th-42PX85u HDTV, Behringer BFD Pro, Monster Power HTS 2600 Conditioner
    · Share on FacebookShare on Twitter
  • thsmith
    thsmith Posts: 6,082
    edited January 2009
    Take a look at the link in my sig, this helped my resonance issues significaintly
    Speakers: SDA-1C (most all the goodies)
    Preamp: Joule Electra LA-150 MKII SE
    Amp: Wright WPA 50-50 EAT KT88s
    Analog: Marantz TT-15S1 MBS Glider SL| Wright WPP100C Amperex BB 6er5 and 7316 & WPM-100 SUT
    Digital: Mac mini 2.3GHz dual-core i5 8g RAM 1.5 TB HDD Music Server Amarra (memory play) - USB - W4S DAC 2
    Cables: Mits S3 IC and Spk cables| PS Audio PCs
    · Share on FacebookShare on Twitter
  • Whadyasay
    Whadyasay Posts: 300
    edited January 2009
    Thanks, thsmith and Hawkeye. I'm actually looking into those right now. Most of my walls are actually concrete behind a coating layer, so there's no give or energy absorption to them. Once I got my right main speaker out of the corner, it helped with a lot of things, with the sub there mainly filling things out and pressurizing the room nicely. The Audyssey MultEQ XT on my Denon also evened things out pretty nicely. It's just that one nasty resonance that you can really localize back behind the TV, and you can hear it's effect when doing a voice test back behind there, too.
    Polk LSi9 Mains, Polk LSIC Center, Polk RT25i Surrounds, Polk M3II Rear Surround, SVS PB10-ISD Sub, Denon AVR 2809 (as digital pre/pro only), Sony BDP-S350, Oppo DV-981HD, Cambridge Audio Azur 540C (CD), Marantz MM9000 5-ch amp, Outlaw ICBM, Panasonic th-42PX85u HDTV, Behringer BFD Pro, Monster Power HTS 2600 Conditioner
    · Share on FacebookShare on Twitter
  • Whadyasay
    Whadyasay Posts: 300
    edited January 2009
    After more testing....I was wrong with my numbers! :p

    The 'resonance' is actually in the 100-120Hz region. The 50Hz is obviously much lower and that's a slight boost in the room, but that's been tamed a bit with the BFD/ParaEQ on the sub. I was reading off the wrong numbers that I had written down while measuring. :eek:

    So yeah, that 50hz thing wouldn't be the whole TV/wall area, but at 100-120Hz, it should be within the reaches of some wall treatment back there.
    Polk LSi9 Mains, Polk LSIC Center, Polk RT25i Surrounds, Polk M3II Rear Surround, SVS PB10-ISD Sub, Denon AVR 2809 (as digital pre/pro only), Sony BDP-S350, Oppo DV-981HD, Cambridge Audio Azur 540C (CD), Marantz MM9000 5-ch amp, Outlaw ICBM, Panasonic th-42PX85u HDTV, Behringer BFD Pro, Monster Power HTS 2600 Conditioner
    · Share on FacebookShare on Twitter
  • MedfordDawg
    MedfordDawg Posts: 10
    edited January 2009
    Whadyasay, how are you mounting your center over your tv? I am looking for some kind of shelf like that, but the back of my tv is straight down. It looks like yours might be too. I have a samsung ln46a630. Thanks.
    · Share on FacebookShare on Twitter
  • Whadyasay
    Whadyasay Posts: 300
    edited January 2009
    MedfordDawg wrote: »
    Whadyasay, how are you mounting your center over your tv? I am looking for some kind of shelf like that, but the back of my tv is straight down. It looks like yours might be too. I have a samsung ln46a630. Thanks.

    It's actually a combined TV mount/center mount that I built out of 2x4's and bolted down to that Salamander shelf. It ends up being two posts extending up behind the TV, and two 8" steel L-brackets that extend out over the top to support the speaker. Not the most elegant thing, but it does the job.


    standfx2.jpg
    Polk LSi9 Mains, Polk LSIC Center, Polk RT25i Surrounds, Polk M3II Rear Surround, SVS PB10-ISD Sub, Denon AVR 2809 (as digital pre/pro only), Sony BDP-S350, Oppo DV-981HD, Cambridge Audio Azur 540C (CD), Marantz MM9000 5-ch amp, Outlaw ICBM, Panasonic th-42PX85u HDTV, Behringer BFD Pro, Monster Power HTS 2600 Conditioner
    · Share on FacebookShare on Twitter
  • MedfordDawg
    MedfordDawg Posts: 10
    edited January 2009
    That is very cool. I hadn't even thought about getting that involved with a bracket system, but have found no other satisfactory solutions. I will be studying that schematic!
    · Share on FacebookShare on Twitter
  • Igo
    Igo Posts: 411
    edited January 2009
    If there is a wall stud anywhere close behind the TV, you can improvise almost anything. Draw something up and have a metal shop put it together for you.
    ...Link to my System Showcase...
    "ES - Kind'a simple but I like it"

    Sony ES STR-DA4300ES 7.1
    Sony ES SACD SCD-C2000ES
    Sony 400 Disc CD CDP-CX455
    Infinity BU-2 Sub-Woofer
    Polk Audio RT800i Towers
    Polk Audio CS400i Center
    Polk Audio FXiA6 Surrounds
    Sennheiser HD 280 Pro Headphones
    DH-Labs T-14 Speaker Cables
    Panamax Max 500 DBS Line Conditioner
    Panasonic TH-50PZ85U 50'-Plasma
    Play Station III - BluRay
    Logitech Harmony 550 Remote
    Logitech diNovo Mini Keyboard
    · Share on FacebookShare on Twitter
  • Whadyasay
    Whadyasay Posts: 300
    edited January 2009
    MedfordDawg wrote: »
    That is very cool. I hadn't even thought about getting that involved with a bracket system, but have found no other satisfactory solutions. I will be studying that schematic!

    I used a basic standard plasma wall mount to attach to the wood frame. You have to do some pretty precise measurements to know how high the TV will sit when attached...at least I had to because I had less than an inch of wiggle room on either end. 30" high ended up being right on for the height of my TV, which is a 42" Panasonic, and the kind of shelf dimensions I was using. But with your Samsung which I assume is a 46", you better check the overall height and see how high the two tall posts have to be. I used two 8" brackets because I attached them after mounting the TV, over the back side of the posts. They only ended up extending about 4.5 inches past the front surface of the posts, which was pretty much the overall depth of the mounted TV, but I still had the full length behind to support the rear edge of the center speaker.

    The reason I even went this far was that the actual included tabletop stand for the TV was too wide to fit in that truncated space on the shelf by a whopping .25"! So i had to figure out a way of combining a new tabletop moiunt and speaker shelf in one. If you're still using your tabletop stand, you could probably rig up some sort of shelf support using the wall-mount screwholes on the TV itself. Something as simple as....


    shelfayl7.jpg

    Just find the right threading for your TV's mount holes, and go to a Home Depot and see if they have them in 3-5" lengths.
    Polk LSi9 Mains, Polk LSIC Center, Polk RT25i Surrounds, Polk M3II Rear Surround, SVS PB10-ISD Sub, Denon AVR 2809 (as digital pre/pro only), Sony BDP-S350, Oppo DV-981HD, Cambridge Audio Azur 540C (CD), Marantz MM9000 5-ch amp, Outlaw ICBM, Panasonic th-42PX85u HDTV, Behringer BFD Pro, Monster Power HTS 2600 Conditioner
    · Share on FacebookShare on Twitter
  • MedfordDawg
    MedfordDawg Posts: 10
    edited January 2009
    Igo wrote: »
    If there is a wall stud anywhere close behind the TV, you can improvise almost anything. Draw something up and have a metal shop put it together for you.

    The problem that I have with that is that my tv sits on a cabinet that is set up catty corner in a corner, which leads to two angled walls and a lot of dead space behind. I am afraid I will have to do something along the lines of Whadaysay's set up. I haven't found anything commercially that will work on top of the tv, so it is to the drawing board I go!

    Well, actually, Whadaysay may have already done that, it may just be to the workshop I go. :)
    · Share on FacebookShare on Twitter
  • Igo
    Igo Posts: 411
    edited January 2009
    MedfordDawg wrote: »
    The problem that I have with that is that my tv sits on a cabinet that is set up catty corner in a corner, which leads to two angled walls and a lot of dead space behind. I am afraid I will have to do something along the lines of Whadaysay's set up. I haven't found anything commercially that will work on top of the tv, so it is to the drawing board I go!

    Well, actually, Whadaysay may have already done that, it may just be to the workshop I go. :)

    Exactly. I guess I should have said wall stud oof cabinet back or console frame and a half dozen other ridged objects that might be close by. If you are absolutely sure of your equipments location, anything came be beautifully crafted to do a custom job if you have the insight and sbility. Have at it.
    ...Link to my System Showcase...
    "ES - Kind'a simple but I like it"

    Sony ES STR-DA4300ES 7.1
    Sony ES SACD SCD-C2000ES
    Sony 400 Disc CD CDP-CX455
    Infinity BU-2 Sub-Woofer
    Polk Audio RT800i Towers
    Polk Audio CS400i Center
    Polk Audio FXiA6 Surrounds
    Sennheiser HD 280 Pro Headphones
    DH-Labs T-14 Speaker Cables
    Panamax Max 500 DBS Line Conditioner
    Panasonic TH-50PZ85U 50'-Plasma
    Play Station III - BluRay
    Logitech Harmony 550 Remote
    Logitech diNovo Mini Keyboard
    · Share on FacebookShare on Twitter
  • Whadyasay
    Whadyasay Posts: 300
    edited January 2009
    MedfordDawg wrote: »
    The problem that I have with that is that my tv sits on a cabinet that is set up catty corner in a corner, which leads to two angled walls and a lot of dead space behind. I am afraid I will have to do something along the lines of Whadaysay's set up. I haven't found anything commercially that will work on top of the tv, so it is to the drawing board I go!

    Well, actually, Whadaysay may have already done that, it may just be to the workshop I go. :)

    What model center speaker, and how heavy is it?
    Polk LSi9 Mains, Polk LSIC Center, Polk RT25i Surrounds, Polk M3II Rear Surround, SVS PB10-ISD Sub, Denon AVR 2809 (as digital pre/pro only), Sony BDP-S350, Oppo DV-981HD, Cambridge Audio Azur 540C (CD), Marantz MM9000 5-ch amp, Outlaw ICBM, Panasonic th-42PX85u HDTV, Behringer BFD Pro, Monster Power HTS 2600 Conditioner
    · Share on FacebookShare on Twitter
  • MedfordDawg
    MedfordDawg Posts: 10
    edited February 2009
    I have ordered and am waiting for the delivery of a CS2 center.
    · Share on FacebookShare on Twitter
  • Whadyasay
    Whadyasay Posts: 300
    edited February 2009
    MedfordDawg wrote: »
    I have ordered and am waiting for the delivery of a CS2 center.

    The specs list that at 17 lbs, so it should be fine to mount on a simple shelf supported by the TV's wall-mount screws as discussed above. The only thing you need to be careful of is that the TV isn't bumped into and cause it to wobble back and forth on its stand. From the looks of it....

    41eU43zMPzL._SS400_.jpg

    ...that stand isn't the sturdiest-looking thing. You could also bolt some 2x4's down to the tabletop (if it's wood/MDF) behind the TV and extend some sort of support beam to the top of your tv to rest the speaker on....padded with rubber bumpers between the beans and the TV, of course. That way, only part of the weight is supported by the TV and stand, whereas the other is supported by the 2x4's in back, if there's room.

    Or...you could get something like this...

    http://www.audioadvisor.com/prodinfo.asp?number=OMCCH1

    ...and just build some sort of wood thing in back to support those rear 'legs'.

    What kind of TV stand are you using?
    Polk LSi9 Mains, Polk LSIC Center, Polk RT25i Surrounds, Polk M3II Rear Surround, SVS PB10-ISD Sub, Denon AVR 2809 (as digital pre/pro only), Sony BDP-S350, Oppo DV-981HD, Cambridge Audio Azur 540C (CD), Marantz MM9000 5-ch amp, Outlaw ICBM, Panasonic th-42PX85u HDTV, Behringer BFD Pro, Monster Power HTS 2600 Conditioner
    · Share on FacebookShare on Twitter