Muddy bass, waterfall peaks - AVS Forum
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post #1 of 6 Old 09-27-2013, 11:47 PM - Thread Starter
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I don't have much experience with these, but I'm getting some pretty muddy sounding bass with my stereo monitor setup.  I did a quick and dirty waterfall with FuzzMeasure and the laptop's built in microphone (don't have my measurement mic with me unfortunately).  The two big peaks are at about 116 Hz and 174 Hz.  I assume the long decays mean I have room modes?  I played tones at those two frequencies, and I can't hear or feel anything resonating, but when I walk around the room I can easily find nulls where I can hardly hear the tones.

 

The room has a vaulted ceiling as you can see.  Behind the camera in the picture, the vaulted ceiling drops down to 8' flat for the kitchen.  The living room is 14' deep with the vault, then the kitchen area is 10' deep.

 

So my guess is this is being caused by my vaulted ceiling?  The ceiling is about 79" above the speakers, so does that correspond to the 174 Hz mode?  I know I'm almost centered right under the peak of the vault, so I'm not sure if that's the best or worst place to be in the room.

 

P.S.  I'm new here so hopefully this is in the right place.  The S in AVS stands for science right, so you guys like this kind of data and analysis right?

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post #2 of 6 Old 09-28-2013, 10:43 AM
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Originally Posted by TechnicalLee View Post

So my guess is this is being caused by my vaulted ceiling?

All rooms have peaks and nulls and ringing. The solution is bass traps. The more traps you can manage, the closer you'll get to a flat response. There are other considerations as well, such as taming "early" reflections. This short article is mainly about home recording, but all the same principles apply to hi-fi and home theater too:

Acoustic Basics

--Ethan
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post #3 of 6 Old 09-28-2013, 07:46 PM - Thread Starter
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I realize all rooms are going to have some degree of modal ringing, but this room seems worse than most for some reason I have yet to understand.  I know bass traps are the best way to take care of it, but I want to know if there are simpler solutions to try before going that route (such as moving things).  I'm really hoping someone can look at the data and have a specific suggestion related to my setup.  Here are some specific questions that come to mind:

 

What is the basis of the peaks being at 116 and 174 Hz?

Why do I have two peaks as opposed to one, three, four, etc?

What is the relation to the room shape (especially the vaulted ceiling)?

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post #4 of 6 Old 09-28-2013, 08:15 PM
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1. Remove an exterior wall. Bass will almost certainly improve but critters will get in.
2 some get smoother results with 2 or more non co located subs. Good technical reasons this works.
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post #5 of 6 Old 09-29-2013, 12:00 AM
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Quote:
Originally Posted by TechnicalLee View Post

What is the basis of the peaks being at 116 and 174 Hz?
They look like the 2nd and 3rd modes (multiples of a 58Hz resonance) due to a roughly 9.75 ft dimension. Both will peak at/near a boundry.

You said your ceiling is 79 inches above your speakers. Are the middle of your woofers roughly 38 inches off the floor?

Is your seating the chair in the pic? If so, is that where you measured from?

Sanjay
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post #6 of 6 Old 09-29-2013, 12:06 PM
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Quote:
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I realize all rooms are going to have some degree of modal ringing, but this room seems worse than most for some reason I have yet to understand.

All home-sized rooms are that bad. Really.
Quote:
I want to know if there are simpler solutions to try before going that route (such as moving things).

Sure, experimenting with loudspeaker and listener placement is always a good first step. But even with those as optimized, all rooms still have peaks and nulls and ringing.
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What is the basis of the peaks being at 116 and 174 Hz?
Why do I have two peaks as opposed to one, three, four, etc?
What is the relation to the room shape (especially the vaulted ceiling)?

It's impossible to know without being there in person to experiment.

--Ethan

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