# Where to look?

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#### maLx

Hi, All.

So in the process of fixing my room. I don't need the silver bullet answer, but I'd just like to know from some of the people here what process you would go through to solve the following:

I have a loudspeaker placed in my room. It's fairly flat when measured outside. When I place in my room, I have three bass nulls at my listening position. I have one at 60hz, one at 100hz, and one at 200hz.

I'm thinking these might be due to floor to ceiling reflections. My speaker is 3ft off the floor, 6 feet from the ceiling. Those measurements are 1/2 the wavelength of 60 and 100hz. See what I'm getting with? So some treatment on the ceiling should help.

I already have treatments in the corners of the room that fixed the muddy sound of the room.

Again, just a general question and would like some advice on where to look to solve the issue.

I am not interested in moving the speaker to a different location so please don't suggest that. This is more of an practice and learning experience rather than a final placement of the speaker.

Let me know and thanks!

Cheers,
J

#### AllenB

Paid Member
I'm thinking these might be due to floor to ceiling reflections. My speaker is 3ft off the floor, 6 feet from the ceiling. Those measurements are 1/2 the wavelength of 60 and 100hz. See what I'm getting with?
I don't think this is right. How far is your listening position, how high are your ears from the floor, how high is your ceiling?

#### maLx

9ft ceilings, I’m 8 feet from

#### maLx

Ears are about 4 from the floor but I’m on a couch. Back wall is far away.

#### AllenB

Paid Member
I would guess that your floor has the dimensions to cause a null a little over 200Hz and your ceiling at around 100Hz, should it be that simple.

#### maLx

Cool thanks! I’m
Going to do some
More testing on this but that’s what I was thinking as well and just wanted a second opinion.

#### william2001

Paid Member
Use REW to play a test tone at your problem frequency. Walk the room with an SPL meter (a phone app works). A null at your listening position means there's somewhere else in the room that's loud at that frequency. Placing appropriate treatment there can help. I was able to greatly correct very deep nulls at 155Hz and 180Hz due to SBIR with treatment on the front wall along with speaker placement, as an example. Velocity based treatment quickly loses effectiveness below 100Hz. Something pressure based is likely much more effective if done properly.

#### Think

...
My speaker is 3ft off the floor, 6 feet from the ceiling. Those measurements are 1/2 the wavelength of 60 and 100hz. See what I'm getting with? So some treatment on the ceiling should help.
...
IMO it is always better to treat the cause instead of the symptoms. So move the speakers up or down. Distances from middle of the woofer to the floor, ceiling and walls should never be the same or a multiple of each other.

The golden ratio is 1hi (~1.618) or about 5:8; try to use this ratio as much as practically possible.

Your ceiling is 3+6= 9 feet. 9/Phi = ~5.5 feet; put the middle of the woofer 5.5 feet from the floor or ceiling.

Do the same with distances to rear and side walls.
5.5/phi= ~3.4 feet
3.4/phi= ~2.1 feet
These would be good distances from side and back walls to start with.

After correct speaker placement, adding 1 or more sealed sub(bass)woofer(s) (1 in a corner) might work better then treating the room.

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