About to invest in room treatments; GIK, RealTraps, DIY -- what is your experience?

@hilde45, stubborn nulls or deep partial nulls just need more bass traps and in the right place which are the corners. All corners can be considered, This means the wall to ceiling corner and the wall/wall corners. And unfortunately they must be BIG.

Superchunk corner bass traps that go from floor to ceiling are very effective and easy to DIY cheaply. Mine have turned out well and look great. A 2’ x 4’ OC703 or similar panel is cut in half giving 2 x 2’ square sections that are then cut on the diagonal providing you with 4 triangular pieces that are then stacked one above the other until they reach from floor to ceiling. This is what it takes to absorb bass frequencies which as we all know are long wavelengths. Google for easy DIY plans. In previous posts I have provided links to programs that will analyse the modal region of your room. They all show bass build up in corners.

See link for start of Bass Trap
https://i.imgur.com/Lwx8NTR.jpg

@corelli, nice clean layout you have. Am I mistaken and you referred to bass traps on your rear wall. If so I am afraid that they will not be true bass traps and wonder what professional said they were. They will provide broad-band absorption but for bass will need to be in some corner and a whole lot deeper. Ignore this If I misunderstood you.

I have noticed some suspect advice from Foley at Acoustic Fields.

Thank you Lemonhaze. I have seen some instructional videos on how to make corner traps. They look easy-ish. (I’m not that handy but this seems doable.)

I posted a single scan to Avnirvana and got some interesting feedback from Earl. https://www.avnirvana.com/threads/how-much-can-the-results-of-two-identical-scans-vary.8061/post-608...

Appreciate the input.

Having watched a bunch of Dennis Foley videos -- which seem sensible -- can anyone tell me what you found problematic with what he says or does? 

nolojunko, excellent posts!    ditto lemonhaze.

When dealing with bass peaks or nulls, the corners are the obvious places, but you also look at the frequency of those nulls/peaks and consider your room dimension and where those nodes are for each null/peak.

Are you just using two main full range speakers @hilde45, or do you have subs?  When you look at the cost and complexity and esthetics of bass control, sub-arrays make a lot of sense. I personally would still want acoustic control in addition, but it does make for a far more controllable problem.

w.r.t. Foley, https://www.digistar.cl/Forum/viewtopic.php?p=1681#p1681   Then the post after that one, and maybe a web search.

@audio2design Thanks -- I’m trying to correlate the factors you mention. The room is quite irregular in some ways, so it’s lack of closed-ness and rectangularity makes it hard to know what the standards might be. I know there are ways to do it, but I’m quickly getting over my head.

I have one sub dedicated to listening and another in the house I can try out along with the first to do measurements. I am convinced about swarms/arrays but I cannot go there, in this room. I will do it eventually, but for now, I’m optimizing a less-than-perfect room.

Thanks for the info, re: Foley.

This seems like the mortal blow, since this technology is their killer app (if I gleaned their message correctly):

Aside from all that - what do you all think about using activated carbon in bass traps? For me it of itself makes some sense

Activated carbon actually does have some useful acoustic absorption properties. That much is true. Somewhere I have a couple of papers and some research on that. It is even used in some types of "ear defender" headsets, for industrial hearing protection. It's better than foam for that. However, in studios, it does not perform better than more traditional bass traps, and doesn't even get to the same level of efficiency. Then there's the cost, and the weight... it would have to be much, much better than other types of bass trap to be justifiable.

Comparing my local prices for materials it would be ca. 10x more expensive

And there you have it! It mostly certainly will not be ten times better, nor five times, nor even twice... To justify an increase of ten times in the cost, one would expect to have a rather substantial increase in performance. That isn't the case. There are already very good bass traps that can do the same job for a fraction of the price, and at a fraction of the weight: panel traps, limp membrane traps, Helmholtz resonators, even plain old porous absorption. All are proven to work at low frequencies, and to work effectively, at lower cost and lower weight. So there's no real benefit here... except to the pocket of the manufacturer!

@hilde45 :   With respect to your bass issues you are presently seeing on your room sweeps, I guess I'd just say two things:

First, any data must be quite specific (frequency, +-db, left speaker or right speaker, mic placement, listening position in relation to speakers and in relation to room length, and show graphs/waterfall).  Also, I'm assuming you have no corner or front-wall bass traps in place yet?  If you have traps in place, what are they and where they are helps to answer specific questions.  You won't get much good advice with such a general question.  The second thing is partially addressed above: where is the listening position in relation to the front wall (and to the speakers).  At 6.5' from the front wall, I'd assume you are likely 13-15 feet from the front wall.  That would position you at half-way between the front and rear(?).  Or, are you already at the standard 38% recommended to avoid nulls.  No modes on your sweeps?

If what you are seeing on the sweeps before treating is just a couple of nulls, that's exceptional.   Treating is easy at that point.

Are you measuring each speaker separately?  Do they some very close graphs/issues?

Just a general response to a general issue is, bass traps/corner traps can be the product of known specific concerns.  It is pretty straight forward.  However, generally, a corner unit should be 34" wide for effectiveness, and maybe floor to ceiling, maybe not.  They usually won't cure the problems by themselves.   

You can reach out to the acoustics thread at Gearslutz forum if you provide pretty specific data - only then would you get good advice, including type and placement of LF treatment.  You can also tap into some great guys who have tested, built, installed treatment professionally.  But, you have to have all your data (room dimensions, speaker/listening locations, room sweep data).