Tips on Using REW Room Calculator

[rimmi2002]

Hi, I’ve been messing around with the REW room calculator and it seems like a great planning tool, especially for a rectangular room like mine. I was wondering if anyone has links to good tutorials on how to use it properly. The one good video I found wasn’t in English. Overall I think I have a good hang of it from what messing aorund with it, but just wanted to make sure I'm not missing any subtle nuances.

Also, a newbie question about placing subwoofers and speakers and measuring distance from walls:

For the back/side/height measurement, is it:

1. From the edge of the speaker to the respective wall
2. From the center of the speaker (overall volume-wise) to the respective wall
3. From the center of the driver to the respective wall — so for the back wall, it would be speaker depth + empty space, and for height/length it would be ~½ of the speaker’s height or length + the space between the speaker and the wall?

 

[NTK]

The distances will be from the acoustic center of the subwoofer, and the location of which depends on the subwoofer design. If it is a dual opposed (force cancelling) design, for example something like a KEF KC62 or KC92, because of symmetry, the acoustic center is at the center of box.

If the sub is front firing sealed or front ported, the acoustic center will be in front of the driver and is beyond the front plane of the subwoofer. How far it is will depend on the size of the cone, the front baffle size, and the depth of the subwoofer. My guess of a very rough estimate would be about 0.7x the diameter of the cone.

Please refer to this presentation for more details:
https://www.aes-media.org/sections/uk/meetings/AESUK_lecture_0604.pdf

 

[Keith_W]

Whilst what NTK says is true, we should also remember that REW's room calculator is an approximation. It can only model rectangular rooms. It can't take into account openings in rooms or large pieces of furniture. It is useful for predicting the best places to put your subs, but quite often other more important considerations dictate subwoofer positioning.

I would start by identifying suitable spots to place your sub in your room. In the room sim, place one sub at each of these spots. Then un-tick the sub and look at the effect. Don't forget that delays, phase adjustment, and gains can also improve the result. But start with placement first.

As always, the last word is always in-room measurements.