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Bass trapping - corners or walls?

I've been reading articles on the ASC website and it seems that they contradict themselves regarding placement of bass traps. Most of their placement articles discusses placing bass traps in the corners. But the article below actually says that traps in corners are not that important and that traps along the mid point of opposite walls are more beneficial. What gives?

http://www.tubetrap.com/bass_traps_articles/iar89.htm
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geoffkait's avatar
geoffkait
23,365 posts
 
For a stubborn 60 Hz standing wave in my room I once built a 15 foot long folded S shape Helmholtz resonator using 6” diameter PVC PIPE, PIPE ELBOWS, END CAP, pipe fitting nozzle, PVC purple prep, PVC cement and a grapefruit size ball of hollow fiber wool inside for internal damping. Problem solved.
auxinput
2,920 posts
 

I don't know enough about your 12" sheet metal tubes (which I assume are your DIY version of ASC).  I have no experience with ASC traps, so I can't comment.

I don't have any experience with Dennis Foley's product.  It might be good.  It could be another variation of tuned membrane, but he really doesn't say.  Keep in mind that they are $1,000+ each and are very huge.  They have a really large 16" depth (which means they are going to stick out in the room like a large footprint speaker).  They do have a very large 30x60 face, which would be good for low frequency capture.  If you have the money and the room to place them, they might work out well.  DIY tuned membrane panels at 55hz would be 6" to 7-1/2" deep depending on thickness of membrane (either 3/16" or 1/4").  You can build them as large as you want.  Mine are 24" x 36".  It is definitely an interesting design using dual damped front wall diaphragms and carbon damping.  Could work out very well.  Shipping will probably be very expensive (maybe 300-400 dollars each) because they are oversize and very heavy (I've read 150-225lbs each).

You would need 3 GIK Scopus traps ($750) to match the area of a Dennis Foley.  Or two of the 24x36 DIY panels.

handymann
380 posts
 
@geoffkait   Sounds interesting, but I don't have the space. @auxinput I would never buy the absorber from Foley-can't afford the shipping for one thing. Sounds like u solved your problem. Mine has too many problem frequencies for that. Although it may not sound like it from what I'm saying, my room sounds pretty good. RTA says the frequencies I mentioned are a little hot. 
swingfingers
44 posts
 
@auxinput,

I am considering GIK soffit traps to help me with a bass null, and I would be grateful if you could expand upon the comment you made above:
The thick GIK soffit traps really don't do much here.
It would be great to hear your experiences with these traps, their pros and cons, and why you don't think they would do much.  Thanks in a advance for your thoughts.
auxinput
2,920 posts
 
I tried the extra large soffit traps once.  They did not seem to do much with the very low 50-70hz area.  And since they were broadband, they seemed to suck the life out of the room (too much mid/high frequency absorption).  I have since moved onto the GIK Monster Bass Traps with Flexrange Limiter.  This seems to work well for 80 to 150hz absorption, but still allows some reflection of minds/highs.  I really love the Owens 703FRK panels, I think they work better than Monster Bass Trap for 80-150hz, but the foil definitely reflects upper mids and highs very much, so you need to be careful and experiment with placing.  

If you look at the testing results document for soffit, you will see that it does do limited absorption down in the 50-60 hz area, but it’s not very much (even for being 14” thick!).  Convention soffit and even Monster with Flex Range Limiter will not do much down this low.  Flex Range Limiter and Owens 703FK are really on,y good down to about 90hz (maybe somewhat at 80hz).

If you really have sub 80hz Bass nulls, the only way I have found to fix them is using limp mass tuned membrane bass traps.
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