I think I need more bass traps but where to put them? - Home Theater Forum and Systems - HomeTheaterShack.com

 
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post #1 of 9 Old 10-29-16, 09:38 AM Thread Starter
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I think I need more bass traps but where to put them?

Hi guys, I already have bass traps in all four corners of my room but I still have some pretty bad room modes resulting in big peaks at 60/120hz and dips at 80/160hz. Here are the response curves for the left, right, and both speakers from REW prior to applying filters:

I think I need more bass traps but where to put them?-l-subs-baseline.jpgI think I need more bass traps but where to put them?-r-subs-baseline.jpgI think I need more bass traps but where to put them?-l-r-subs-baseline.jpg

I spent hours and days messing around with speaker placement and my current setup is the best I can do in terms of matching my target room response curve aside from these modes. Using REW it seems the peaks can be pretty easily dealt with. However, the dips are a different story. Even with a max gain of 16 I cannot get the dips to be even within +- 5db of my target curve.

So my question is...I assume I need more bass traps? If so, what is next logical position for them? Sidewalls? Front wall between the speakers? Front wall directly behind speakers? Back wall? If the answer is yes to all positions, then where should I start that would be most effective? Due to financial restrictions I would like to treat one area at a time. Thank you!
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post #2 of 9 Old 10-29-16, 10:22 AM
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Re: I think I need more bass traps but where to put them?

Have you tried moving the LP?


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post #3 of 9 Old 10-29-16, 11:00 AM
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Re: I think I need more bass traps but where to put them?

Agreed on the LP. Also, what are the bass traps you have? Have you treated the early reflections with thicker panels yet?

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post #4 of 9 Old 10-29-16, 11:15 AM Thread Starter
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Re: I think I need more bass traps but where to put them?

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willis7469 wrote: View Post
Have you tried moving the LP

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Unfortunately, my room is very limited. Its only 9x10x9 ft so my seating position is pretty much fixed width wise. The odd thing is that the wall directly behind the listening the position is about 37" tall, above which it opens up to my family room and kitchen. I have tried every conceivable front to back position of the LP in relation to the speakers and I was able to dial out some other peaks/dips I had. The graphs I attached is the best I can do in this room.

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Agreed on the LP. Also, what are the bass traps you have? Have you treated the early reflections with thicker panels yet?
Hi Bryan! Good to hear from you. Not sure if you remember me but you helped me with my initial purchase from GIK. I ended up with Softfit traps in the corners. I do have 242 panels at the first reflection point on the side walls but I am wondering if I should get the Monster Bass Trap (full range) there instead. Will a bass trap on the side wall help? I thought bass traps are only effective in the corners? Where would the most effective next addition of bass trap be?
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post #5 of 9 Old 10-30-16, 10:08 AM Thread Starter
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Re: I think I need more bass traps but where to put them?

Ok guys Ive given this more thought and analysis. I know that my Left and Right speakers have peaks at 60/120/180 and since I sit with my back right against the short back wall, I have to believe this is being caused by the length axial mode (10') which has max volume of all the modes at the extremes. On the other hand I have dips at around 70 and 200hz which corresponds to the nodes I have in the width axial mode (8' 9").

What I dont understand is if I want to try to address the length axial should the bass trap go directly behind the speaker or on the back wall behind the seating position? Even though the back wall is only 36" tall, it is only about 2" lower than my ear height. If I want to address the width axial mode do I put the bass trap at the first reflection point on the side wall?
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post #6 of 9 Old 10-30-16, 12:04 PM
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Re: I think I need more bass traps but where to put them?

The length mode would not show up where you are sitting. ALL bass builds up next to the wall. The modes front to back would show up at 1/2, 1/3, 1/4.

If it's width modes, the panels would need to be beside you, not at the reflection zones. Monsters aren't going to get to 60 flat on a wall but those or even 244's would do the 120 and 180.

If those area all peaks, they're likely harmonics of 30 Hz. If they were all in sequence, they would alternate peak, null, peak, etc.

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post #7 of 9 Old 10-30-16, 10:10 PM Thread Starter
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Re: I think I need more bass traps but where to put them?

thank you Bryan...I dont understand what you mean that I would hear the effects of the length axial mode where I am sitting. Since my back is right against the 36" back wall, wouldnt I hear all the axial mode modes of 57, 113, 170, and 226hz (modes at 10' length)?

Anyway, I did some experiments and I got a lot improvement by putting a spare 242 panel on the ground right next to the speaker, a 242 panel on a 2 ft stand at the first reflection point, and a Softfit Bass Trap on the ground against the side wall.. Makes me wonder if two Monster Bass traps instead of the 242s would give better results. What do you think?
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post #8 of 9 Old 10-31-16, 08:49 AM
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Re: I think I need more bass traps but where to put them?

When you sit against the wall you hear ALL bass frequencies as peaks - not just the room modes.

I think 244's would be fine on the sides. No need to do the Monsters.

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post #9 of 9 Old 10-31-16, 09:29 AM Thread Starter
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Re: I think I need more bass traps but where to put them?

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When you sit against the wall you hear ALL bass frequencies as peaks - not just the room modes.

I think 244's would be fine on the sides. No need to do the Monsters.
Thank you....actually I was wrong...I had put a 244 on the ground next to the speaker, a 244 on the Softfit at the first reflection point, and the Softfit was laid horizontally on the ground against the side wall at the midpoint. The interesting thing is I got better results with just the two 244 panels (removing the SoftFit on the ground) except for a deep null at 160hz which the Softfit on the ground seemed to do a much better job improving it by over 11db! Thats why I was wondering if the Monster Traps on the side would be better instead of my 244s and the Softfit on the ground.

Last edited by tboooe; 10-31-16 at 09:54 AM.
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