Author Topic: Bass Trap Fail  (Read 2137 times)

Offline OldiesButGoodies

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Bass Trap Fail
« on: February 25, 2016, 09:11:12 PM »
So I have this room mode in the basement around 50-70hz that is giving me a headache.  I thought I would use an old sofa as a bass trap by filling it with cotton batting.  Fun exercise,  did not change things (green is corrected graph):

2016-02-25_20-26-13_before_after by Jose Sifontes, on Flickr

The batting exercise involved filling every known cavity of a sofa with extra batting to tame the errant standing waves.  I think  the wood frame around the sofa serving as perpendicular barriers to the waves kind of ruined the effect:

Before -

IMG_1677-2.jpg by Jose Sifontes, on Flickr

After -

IMG_1678-2.jpg by Jose Sifontes, on Flickr

Bulging with batting:

IMG_1679-2.jpg by Jose Sifontes, on Flickr

Next - remove the crap load of batting I put inside the sofa and use it to build proper bass traps using wood frames and fabric. 

Here's the Dirac process (nine of these to get a full set of measurements) - fyi:



Now on to listen to some music...

OBG
« Last Edit: February 25, 2016, 09:18:46 PM by OldiesButGoodies »

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Offline MacGeek

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Re: Bass Trap Fail
« Reply #1 on: February 25, 2016, 09:32:39 PM »
OBG-Are you working on the suck-outs or the humps?  Suck outs are tough; do you have any room to try repositioning the speakers?
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Offline scorpio333

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Re: Bass Trap Fail
« Reply #2 on: February 25, 2016, 09:50:55 PM »
I forget where I read it, but it seems to work for me. Raised my sub up about 2' off the floor. I think it's 25% of the room height. It's free, can't hurt.

Offline papabearjew

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Re: Bass Trap Fail
« Reply #3 on: February 25, 2016, 10:29:53 PM »
OBG. You need help!

Offline F1nut

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Re: Bass Trap Fail
« Reply #4 on: February 26, 2016, 01:36:43 AM »
  'Political Correctness'.........defined

"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."
 

Offline Kingman

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Re: Bass Trap Fail
« Reply #5 on: February 26, 2016, 06:00:43 AM »
IN REALITY IT ONLY MATTERS WHAT IT SOUNDS LIKE TO YOU!!!!!

Offline Jim Pittsburgh

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Re: Bass Trap Fail
« Reply #6 on: February 26, 2016, 07:58:05 AM »
I like the idea of raising the height. Elevated and slightly up angled the sub in the garage  a few inches and it smoothed out the response quite a bit. Might be time for a sub crawl party!  Symmetry is pretty but not always the best for sound.

Had a discussion once with someone from Velodyne back in the day. His analogy of placement, especially for low frequency sound, was to think of sound similar to a river with tributaries and your seating position as where the river empties into the ocean.... nothing is perpendicular or straight line without producing an area congested by eddies,  currents and sand bars.
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Offline OldiesButGoodies

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Re: Bass Trap Fail
« Reply #7 on: February 26, 2016, 08:21:22 AM »
Eh, the node I am fighting is with the main speakers set to large.  The graph you see is for the mains - the subs are off during that measurement, so raising the sub will not affect that - looking to improve the mains dip in the 50-70 hz area.   

Need to continue moving the speakers and adding treatments, IMO.  Or move to a room that does not have crappy audio proportions.

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Offline schwarcw

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Re: Bass Trap Fail
« Reply #8 on: February 26, 2016, 08:57:23 AM »
Get some different software that shows you the low frequency drop outs have disappeared.   :laugh:  O0  :(|)  >:D
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Offline OldiesButGoodies

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Re: Bass Trap Fail
« Reply #9 on: February 26, 2016, 11:02:12 AM »
great idea - thanks!   

  :-\

TGIF!

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Offline bmwr75

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Re: Bass Trap Fail
« Reply #10 on: February 26, 2016, 12:33:31 PM »
Did you try leaning it up in the corner of the room?
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Offline geoffr

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Re: Bass Trap Fail
« Reply #11 on: February 26, 2016, 05:06:04 PM »
He'd have to duct tape the cushions to stay on.
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Offline papabearjew

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Re: Bass Trap Fail
« Reply #12 on: February 26, 2016, 06:24:30 PM »
You should try some Carver Amazing Loudspeakers Plats! Oh never mind, that ship has sailed...

Offline OldiesButGoodies

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Re: Bass Trap Fail
« Reply #13 on: February 26, 2016, 10:23:06 PM »
the Plats had the same dip (no need to be a brain surgeon to predict that),   and did not perform at all setup for HT.  >:D

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Offline OldiesButGoodies

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Re: Bass Trap Fail
« Reply #14 on: March 12, 2016, 08:06:43 PM »
Things sounding clearer with these proper traps I slapped together today. Two 12" x 12"x 85"  towers with fiber fluff inside, placed in the corners of the back wall.  I called Tom to ask him what kind of fiberglass to use and he suggested I look for a formula in the web to tailor the design to the frequencial issues my basement was having.  Of course,  I went straight to Ace,  formula be damned,  and bought a few sticks of wood and some generic R12 fiberglass (and a shed load of paint stirring sticks - they gave those to me in recognition of me being a frequent visitor).  So now I am stoked about room treatment.  Maybe I should look for that formula after all.  Why 12" x 12"?  because that is what I could do with the spare plywood I had. 

IMG_1216.jpg by Jose Sifontes, on Flickr

IMG_1217.jpg by Jose Sifontes, on Flickr

IMG_1218.jpg by Jose Sifontes, on Flickr

IMG_1221.jpg by Jose Sifontes, on Flickr

IMG_1223.jpg by Jose Sifontes, on Flickr

IMG_1225.jpg by Jose Sifontes, on Flickr
« Last Edit: March 12, 2016, 08:11:39 PM by OldiesButGoodies »

Spkr: VMPS RM40
Pre: McCormack RLD-1, Rotel 970BX Phono
Amps: Channel Islands Audio D-200 MkII 
Phono: VPI Aries 1,  Van de Hul Frog
CD: Oppo BDP-83 DAC: Young DSD DAC
Cass: Tascam 122MkII
R2R: Revox B77
Sub: Rhythmik FV 15HP

 

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