Bass response / Pink noise

[aps]

I’m looking to put some bass traps in the room and thought that they’d best be located where bass build-up is greatest. Is this correct? And, if so, then how does one use REW to measure the pink noise response at a given location?

Regards,
APS

[Wayne A. Pflughaupt]

Welcome to the Forum, Andrew!

I’m looking to put some bass traps in the room and thought that they’d best be located where bass build-up is greatest. Is this correct?

Doesn't the manufacturer make recommendations on where to locate the traps?

And, if so, then how does one use REW to measure the pink noise response at a given location?

It's no different from performing any other desired measurement, such as listen-position response: Just place the measurement mic at the location you wish to take a response reading.

Regards,
Wayne

[aps]

Wayne

Thanks. Yes, the manufacturers recommend the corners, tri-corners and wall-ceiling corners. My hope is to prioritise based on some measurements. I've been able to generate pink noise between 20-250Hz but all the measurements seem to use a log sweep. What am I doing wrong?

Regards
APS

[Wayne A. Pflughaupt]

It's been a while since I used the RTA feature, but there is an icon or something there that will freeze the reading. You can also save those readings to a jpg.

There might be an easier way, though, using just an SPL meter. Keep in mind that bass "chases" boundaries (sorry for the poor terminology). With broadband pink noise, and the meter set for C weighting, you'll find that the SPL reading will increase the closer you move to a room boundary, and more so at corners. As a "for instance," if you have a symmetrical room with shoebox dimensions, the lowest reading will be in the dead center of the room. Walk from there towards a wall and you'll see the reading increase. Walk from the wall towards a corner and the meter reading will increase further.

It's a little trickier in a non-symmetrical room, but the same roughly applies: the closer to a boundary you move, the more perceived bass levels increase.

Hope this helps.

Regards,
Wayne

[weverb]

APS,

What I did was, use REW to generate the pink noise from 30-300Hz. and then use a Radio Shack meter to just measure overall dB's in the corners. I walked around the room manually measuring the corners and writing down the numbers. I then went back and started adding panels to the corners with the highest spl reading first.

This may help explain it a little better:

http://www.realtraps.com/lf-noise.htm

[Moonfly]

weverb wrote:

APS,

What I did was, use REW to generate the pink noise from 30-300Hz. and then use a Radio Shack meter to just measure overall dB's in the corners. I walked around the room manually measuring the corners and writing down the numbers. I then went back and started adding panels to the corners with the highest spl reading first.

This may help explain it a little better:

http://www.realtraps.com/lf-noise.htm
at

This is probably the best way to do what the OP is trying to achieve, thing is though, shouldnt you only need to worry about overblown bass that directly affects the listeners in their seating positions. If there is overblown bass in a corner you never listen to material in, and its not having any noticeable adverse affects in the listening zone, then I would say there is no need to treat that area.

The hardest thing is going to be working out which areas of boundary gain are directly affecting the listening area so you can treat those. To do this, you will need to keep the spl mater in the center of your listening zone and watch for changes are you move your bass traps around the room.

So I think you need to do 2 things to achieve your goal. Firstly walk around your room and identify areas of boundary gain that may require treatment. Then set the SPL meter up in your listening zone, and place your bass traps in the areas previously identified to see where you positive effects are gained, or not.

[weverb]

Moonfly wrote:

The hardest thing is going to be working out which areas of boundary gain are directly affecting the listening area so you can treat those. To do this, you will need to keep the spl mater in the center of your listening zone and watch for changes are you move your bass traps around the room.

I think waterfall graphs will tell more.

[Moonfly]

Quite possibly