# Stereo Speakers placement with REW, and Room mode questions



## mc_lover (Aug 25, 2012)

hello there,
I have used Rew for a few days and a bit familiar with Waterfall graph.
I believe I somewhat understand how sound pressure decays.

- My next question is with the REW software, Is there a guideline, a way to properly setup stereo speakers by looking at the graph?

- How can I know exactly that certain frequency like 40hz-50hz is a room mode not a bass boom from improperly setup loudspeakers?

- In a small room like 4 by 8 meters, what would be a good RT60 value? during a range of 2000-4000 Hz?

that's all for now.
thank you


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## AudiocRaver (Jun 6, 2012)

mc_lover said:


> - My next question is with the REW software, Is there a guideline, a way to properly setup stereo speakers by looking at the graph?


A few things come to mind. Setting up speakers often involves making changes to the room, too. (1) Room resonance modes can be corrected, in varying degrees, by alternate speaker placement, rearranging furniture, using absorptive materials and bass traps, moving walls, applying equalization electronically, yes it can get quite involved. Room EQ Wizard shows you what those room resonance modes are. (2) Above the frequencies of the room modes, the graphs can guide you to trying out room treatments to tame reflections and lower RT 60. Electronic EQ is another option, _ideally_ after room treatment options have been exhausted. (3) If speakers are placed close to walls or room corners, they can become very boomy there, which would show up on the graphs as well. (4) Early reflections can also be spotted on the graphs, with the help of a tape measure and some sound wave delay time calculations.

Edit: These were in random order, the best order to attack them in would probably be 3-1-4-2.


> - How can I know exactly that certain frequency like 40hz-50hz is a room mode not a bass boom from improperly setup loudspeakers?


Room EQ Wizard has a feature that tells you what your main room resonance modes are. Speaker placement close to walls or room corners accentuates low-frequency response in general - the amount of that effect can only be determined by moving them and re-measuring.


> - In a small room like 4 by 8 meters, what would be a good RT60 value? during a range of 2000-4000 Hz?


Ideally, you would like to get RT 60 below .4 seconds or so at all frequencies below 8 kHz. It will probably be somewhat higher below 250 Hz.


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