Sound correction in small room

Some add-ons I figured out this weekend or forgot to mention:

1) The problems occur at louder volume/listening levels, about 90-95db

2) Problems also occur with louder music (louder as in typical rock music vs. mellow or acoustic music)

These two points may be obvious to some…

3: I do have speaker isolation planned with bamboo boards (some would call them cutting boards from Ikea..) to put on the carpet and then the floor spikes..  Haven’t added them on yet as I am still scooting the speakers all over the place testing different positions…

Ok, so here’s where things stand:

1) Let’s get this out of the way 1st…  I tried to not so discreetly allude to the fact that this room is already wayyy over budget…  So far over budget that had I known what the room itself was going to actually cost I would have had to at minimum drastically alter my component purchases (which in hindsight could have been done differently but what’s done is done…) or forego the project altogether…  If there is a comma in the price (e.g., $1,000+…) it is not gonna happen.  As it stands, anything that costs a couple of hundred bucks brings out a heavy sigh…  Not complaining, just stating the facts as they are….

2) GIk agreed that my speakers close to the front wall is an appropriate placement.  I was so focused on making sure I was giving accurate information I forgot to dive in to the logistics of why this works but regardless, he agreed when I said it sounded the best so far…

3) Need to get those panels constructed and hung

3a) still investigating best placement for the panels.  It seems the 1st and 2nd reflection points are the main idea here but honestly, they both may be covered by a single panel.  Ironically, my wife doesn’t have a small mirror in the house so have to go find one.  Should this be correct, this opens up the option of placing some panels either behind the speakers on the front wall or on the back wall (keeping in mind I am talking about panels, not bass traps)

4) Seems to be a pretty common consensus that bass traps need to happen so I will get on this. 

4a) spoke with GIK and got recommendations (very helpful by the way, just as many have mentioned) basically it comes down to me being on the right track with the panels and adding bass traps in all 4 corners of the room.  The total is approximately $700 but I can’t tell exactly as the website and my computer are not playing nice with each other as I can’t add the traps to my cart…

4b) I need to investigate the DIY route for building bass traps and am still looking for recommendations for material so I can compare prices with GIK.  It seems the OC 703 could be a component but either need to use it in combination with something different (alternating 703 and 703 FRK) or use something different altogether.  If I am reading correctly, it seems something with FRK needs to be involved so the bass trap doesn’t suck the life out of all the mid and high frequencies… Thoughts?

4c) triangular pattern that stacks up on top of each other (pancake style) vs. panels that are simply placed in the corner.  It seems the triangle option has more mass and therefore should absorb lower frequencies and do a better job overall when compared to panels placed in the corner.  Am I interpreting correctly?  Cost/benefit?

4d) as I stated earlier, I don’t want to be that guy that plugs a business for information and then goes somewhere else..  I need to do the aforementioned price comparison and if it is comparable, or at least somewhat in the ballpark of reasonable, I will use GIK but if there is a big difference then I gotta consider the alternatives..

5) components on the table – I can see how the table might be a reflector o’ sound and I do have a small rack style stand (3 shelves, maybe 2.5’x2.5’x2.5’) that I can easily swap in.  Thoughts?

6) Did some research on what was mentioned.  My interpretation:  Room nodes/modes = 2 “beams” of the same frequency meet and either create a peak (in phase) which amplifies the frequency or null (out of phase) which negates the frequency and cancels it out.. there’s a lot of math after this…  At this level, it makes sense. Am I correct in my interpretation?

7) @auxinput, thanks for the graph/chart.  I honestly can’t say that it all makes sense to me but from what I can decipher (as demonstrated in point #5 directly above) it seems the bass traps and panels will be a big part of the solution, if not the solution.. is this an accurate interpretation?

Again, my deepest gratitude for the input..  It seems like I am making some headway, at least in theory at this point..  By all means, I am still open to input so feel free to chime in (but please make sure you read point #1, the second one, above)

You are correct in your understanding of what "room nodes" are.  I do not understand the math behind room nodes either, but the amroc page was really intended to show you what the "node frequencies" are and where they are the loudest (most pressure).  The locations where they are the loudest are the best places to put bass absorption panels (which are generally located in the front/rear corners).

If you were buying GIK, I recommended the Monster Bass Traps with the FlexRange Limiter because it excels in absorbing the 80-120 frequency range and it also does not absorb as much mids/highs.  You could get the triangle shaped bass traps if you wanted (these are the GIK TriTraps).  They will have only a little bit better absorption in the very low frequencies (such as 40-60hz), but it is not much better than the Monster Bass Traps.  However, the Monster Bass Traps with the FlexRange Limitor have a significantly better absorption in the 80-120hz area.  See measurement reports here:

http://gikacoustics.com/wp-content/uploads/2013/11/RAL-Report-FRT-Range-Limiter-Monster-Bass-Trap.pdf

http://gikacoustics.com/wp-content/uploads/2012/11/RAL-Tri-Trap-J-Mount.pdf

To give you a point of reference, I have 14 sound panels in my room.  Only 4 are full absorption types:

6 - Owens 703 FRK 2"

4 - Roxul Rockboard 80 2" (full absorption)

2 - Monster Bass Traps 7" with Flexrange Limiter

2 - Limp Mass panel bass panel tuned to 63 hz

Four of the 703 FRK are partially covered with towels - this was me tuning how much high-frequency reflections I actually had in the room.  The FRK panels actually worked very well in doing bass absorption down to 70-80 hz and would be an excellent alternative to the GIK Monster Bass Traps.

I did not double-up my FRK panels to make 4" panels.  I used black Guilford of Main fabric to cover them, which is more expensive at about $14 per yard from ATS Acoutics.  It requires 1.5 yards to cover one 2'x4' panel.  I just wrap the cloth around back and use spray glue to glue it on the back side of the panel (no side frame).  You could use duct tape if you wanted to.  The cloth is purely aesthetic and has no impact to the acoustics.  You can get very cheap burlap cloth (it would look crappy), but it would work fine.

Look in the ATS Acoustics clearance section for some deals.  They are currently selling grey burlap for $0.50/yard.

If you are under a tight budget, a 6-pack of 2" 703 FRK panels is $109 plus shipping from ATS Acoustics.  They are an excellent source and I have used them several times.  This will allow you to completely fill your front/rear corners (you can cut a panel in half to make a 2x2).  Just sit them in the corners at an angle.  They are VERY light and stiff enough that you don't need a frame.  You can use your existing 703 for 1st reflection or SBIR points.

I think the Monster Bass Traps with FlexRange limiter will probably be better, but they are significantly more expensive at $127 per panel.

Thinking about this further, the very low bass is always hard and expensive to treat.  The general broadband panels (even if they are very thick) are only average at absorbing the bass.  However, if you know the target frequency, you can get an effective panel.

We know that you have a room nodes at 55hz, 75h, 90hz, 110hz, and 111hz.  The FRK or Monster Bass Traps will effectively handle anything 75hz and above.  If you wanted to treat the 55hz problem, I would call GIK and have them make you a custom Scopus Tuned Membrane Bass Trap that is custom tuned to 55hz.  They have off-the-shelf models at T40, T70 and T100.  You would just be having them build a custom "T55" model (they will do this).  I suspect the price would be somewhere between $230 and $250 for a 2' x 2' panel.  It would probably be about 7-8" thick.  I would get a couple of them (at a minimum) and put them on the side wall floors near to the back corners (since amroc tells us that the 55Hz node is loudest on the side walls).

This is somewhat similar to my limp mass panel that is tuned to 63Hz.  I also plan to make another two limp mass panels that are tuned to 50Hz.  In my room, the 50hz also occurs on the side walls.  I will say that all my treatments have significantly increased the volume and definition of bass.  I am sitting at about the 10 foot spot in a room 17 feet long.