Help with Planning Room Treatment for Bloated Bass in Room

[rimmi2002]

Hi, I have a 30' L x 15' W x 10' H HT / dual-use bonus room and I need to treat it for better sound (Room Schematic Below). I was happy with my setup until I listened to two of my friends’ setups and realized what good, tight bass sounds—and more importantly, feels—like. After that, it’s hard to ignore how bloated/muddy my low-end response is. So I have set out on a journey to fix my bass.



Disclaimer: When you look at the Room Schematic, you'll realize the setup is less than ideal. (Speakers fire in the wrong direction / I sit close to the wall (18-24" away) / speakers are mounted high, etc.) It's our bonus room and we spend most of our free time here, so I have to be respectful of my spouse's preference. So I am stuck with the configuration I have, trying to make the best of it.



My Setup:

1. AVR: Onkyo NR7100 receiver + minidsp 2x4HD for subs.

2. Speakers: Ascend Acoustics Sierra 2's (NON-EX) (Front 3) with 2x In ceiling Monoprice speakers for rear

3. Subs: 2x Rythmik FV18

4. Benq Q HT4550 Projector with 150" Screen.



My Room Schematic and Pics.

My Room SPL curve and RT60M time Curve:
Red - Mine Rt60 with no Treatment
Purple - Mine RT60 with first batch of trial treatment (see below for details)

(Calibrate with Dirac Lives, Subs + (Subs+Fronts) Time/Phase aligned with REW with multiple manual PEQs used to flatten response from ~30-70hz.

Cyan --> Friend with 2.1 setup 2x Focal Sopra and Paradigm sub15 (older version of XR13); Bar none the best system I have ever heard Bass and Vocals. Better than any theater. (Manually calibrate with no EQ)
Blue --> 5x monoprice satellite speakers + SVS SB12 setup. Yamaha basic EQ.

SPL Graph for all 3 systems.

RT60M Measurements for 3 systems:

My Assessment: My RT60M is too high (see measurments below), leading to bloated bass. My room has very little furniture in one half. All walls, ceiling, and floor are reflective, leading to very high reverb times overall, but especially very high for bass, which is compounded by me sitting close to the wall. My ears in sitting position are about 18-24" away from the wall, given the way the couch is positioned.

Trial: I tested by placing 9 layers of 3” x 16” x 48” Roxul Safe’n’Sound mats wrapped in breathable cotton fabric (just for trial), and it’s made a huge difference in my room acoustics already. You see a 0.3–0.4s dip in bass RT60M time and, more importantly, bass already sounds much punchier and louder, despite little change in the SPL curve. It also shows a ~0.3–0.4 second faster decay time for lower frequency on REW measurements.

My Plan:

have wife approval to make bass traps to make our bass/sound better.

1. Plan is to make large 17"x17"x24" or 24"x24"x34" corner traps in all 4 corners, then corner traps for the recessed ceiling. If more are needed (likely will be), I’ll go for the corner between the ceiling and the back wall.
2. I can also make structures (sitting stools) to hold large amounts of Roxul Safe’n’Sound stacked in one area that I can move around to find the best spots for them.
3. If I end up “deading” the room while doing this, I can start adding scatter plates to the traps.
4. Long-term plan: Once bass is managed, I can try traps behind the speakers and back wall to help with mid to high frequencies to balance them out as needed.

Budget: I’ll likely need to treat the room a lot, so it’s tough to buy all this treatment. I am hoping to do it DIY around a $1,500 budget for the whole room.


Questions:

1. For these thick porous traps, what is the most effective material to use? I hear high-density stuff like Roxul Safe’n’Sound doesn't work as well as low-density stuff?
2. How can I be ultra-safe with so much fiberglass in the room? I don't feel safe with only having acoustically transparent fabric as the last barrier, especially when the fan or heat is blowing air at them regularly. I can close three sides of each trap with MDF or plywood, but for the front-facing face, I was thinking of adding a 0.5" layer of high-quality neoprene from Foam Factory in front of the fiberglass. It will allow sound through but should make it nearly impossible for any fibers to escape.
   
   Any thoughts if this seems reasonable? It should not affect the function of the trap in any way, correct? Is there a better way to do this?
3. In another post I made on ASR, Kemmler3D recommended building membrane traps from VPR. (Thank you for that; I had no idea that was possible). Kemmler or anyone else—based on my scenario, do you feel that might be more effective?

I wrote a long ass thread. Thank you for reading through it all and for your input!

 

[Keith_W]

@Bjorn do you think his bass problem is due to his seating position against the wall?

 

[rdenney]

According to Toole, any loose fill will work. Try spun polyester filler instead of the fiberglass if you are worried about dangerous fibers.

Deeper is better, but uncoupled to the wall is also helpful. In a similar rectangular room, I killed an unpleasant echo by hanging a heavy 9x12-foot rug on one wall, opposite the speakers, hanging from a board attached to the top of the wall just below the ceiling and leaving a 2” air gap between the wall and the rug. It may not be officially correct, but it worked.

But I would suggest starting with moving the subs out from the wall and especially out from the corner of two walls. I’d try making the corner sub the end table for the “L” of the sofa and moving the other sub to behind the separate chair where the small folding brown table is now sitting. That might be enough to tame the bass, along with treatment for the wall behind the listening position.

Rick “too much wall/corner reinforcement” Denney

 

[DanielT]

If damping is needed then check out foam mattresses at IKEA, Walmart, or similar places. For example, this one for $50:


Then, cover them in fabric to match the decor in your room. That's up to your taste, creativity, and imagination to figure out what works for you regarding that.

I'm actually thinking about doing something like that in my apartment. Mattress plus cover with Curtain fabric - Linen - Patterned - Abstract - Bauhaus:


_____
Should you need diffusers, here's a thread for inspiration about such:

Wood acoustic diffusers have become a decorative item - loved the idea!

Hi As an acoustician I am tired to tell people not to think room treatment only as absorption. In most small rooms absorption often creates more issues than it solves. Diffusion is a better solution. However, all I hear: they are expensive, ugly and difficult to place in a room. I am hence...

audiosciencereview.com

 

[rimmi2002]

According to Toole, any loose fill will work. Try spun polyester filler instead of the fiberglass if you are worried about dangerous fibers.

Deeper is better, but uncoupled to the wall is also helpful. In a similar rectangular room, I killed an unpleasant echo by hanging a heavy 9x12-foot rug on one wall, opposite the speakers, hanging from a board attached to the top of the wall just below the ceiling and leaving a 2” air gap between the wall and the rug. It may not be officially correct, but it worked.

But I would suggest starting with moving the subs out from the wall and especially out from the corner of two walls. I’d try making the corner sub the end table for the “L” of the sofa and moving the other sub to behind the separate chair where the small folding brown table is now sitting. That might be enough to tame the bass, along with treatment for the wall behind the listening position.

Rick “too much wall/corner reinforcement” Denney

Thanks for the info. Rythmik recommended placing their subs in corner, they were more concerned about my midroom sub. when I isolate the RT60M by the subs, the Mid sub is actually much higher RT60 than the corner one (maybe the couch absorbs some). Its a fabric couch. Regardless ultimate test is sound, and the system sounds better on the "Seat 2" next to corner sub than "Seat 1" (Where I sit). I update teh schematic to reflect this.

do you think his bass problem is due to his seating position against the wall?

Seats against the wall are definitely not the best spot but as mentioned in the disclaimer I don't have much of a choice in this matter.


Lastly what do you guys think of this shredded foam stuff as filler? Anyone know what its flow resistivity is

 

[Bjorn]

@Bjorn do you think his bass problem is due to his seating position against the wall?

It becomes worse with that seating position for sure. Strong build up of resonances. In that case, the best treatment is using Modex Plate and ideally combined with a Broadsorbor on the outside for true broadband treatment. Or one of those, depending on budget and how much it can build out. Regular porous material becomes too thick for effective treatment.

Here's an example of such treatment. Looks pretty good IMO.

 

[rdenney]

Thanks for the info. Rythmik recommended placing their subs in corner, they were more concerned about my midroom sub. when I isolate the RT60M by the subs, the Mid sub is actually much higher RT60 than the corner one (maybe the couch absorbs some). Its a fabric couch. Regardless ultimate test is sound, and the system sounds better on the "Seat 2" next to corner sub than "Seat 1" (Where I sit). I update teh schematic to reflect this.
...

Try it. Rhythmik is probably looking for more bass reinforcement for those who want their living rooms to thump like a low-rider on Saturday night.

Rick "costs nothing to move stuff around provisionally to hear what happens" Denney

 

[rimmi2002]

Try it. Rhythmik is probably looking for more bass reinforcement for those who want their living rooms to thump like a low-rider on Saturday night.

Rick "costs nothing to move stuff around provisionally to hear what happens" Denney

Thank you. You’re right—it doesn’t hurt to try. I’ll start moving them around. Just wanted to clarify:

1. For the corner sub (move to end of couch, near the door): Should I have it face toward the screen, with the back to the couch, or should the back be to the wall behind and face toward the 30' room dimension?
2. For the midroom sub, it’s not tough to move it behind the single seat. (For direction on this one, anything is possible.) Should I have it fire directly into the seat, the opposite direction with the back to the seat, toward the movie screen, or toward the back wall?

Lastly, would it be beneficial to move the midroom sub along the back wall so it’s at the 1/4th or 3/4th position along the long back wall?


Thanks for your help and advice.

 

[rdenney]

I'd try various orientations. The only sub I've messed with recently fires down, so the sliver of experience that I have with subs isn't helpful. But with speakers in general, they bounce first and strongest off what they are aimed at.

Rick "thinking that in any real room, it will always come down to a bit of trial and error" Denney