dumb question....where's the 1st reflection point?

drphoto · « **on:** 7 Feb 2006, 05:38 pm »

Is it half way between the listener and the speaker? (assuming conventional cone/dome type speaker)

ctviggen · « **Reply #1 on:** 7 Feb 2006, 05:43 pm »

Most likely. You can also use the mirror trick. Sit in the sweetspot and have someone slid a mirror along the wall until you can see the speaker in the mirror. Just make sure it's the correct speaker! (I did this and was having a hard time until I realized the mirror on the "right" wall had a reflection of the left -- not right -- speaker.) I also did this by myself, which means a lot of getting up, moving the mirror, sitting down, etc.

Mike D · « **Reply #2 on:** 7 Feb 2006, 05:43 pm »

That is the way I understand it. Walls, floor, and ceiling included.

woodsyi · « **Reply #3 on:** 7 Feb 2006, 05:44 pm »

For mid to high frequency, it's the point where sound from your driver reflects off a surface to reach your ear. The easiest way to find it is to place a mirror (put a roll of duct tape behind it) on the wall, ceiling or floor, go to your sweet spot, and see if you see the driver on the mirror.

EProvenzano · « **Reply #4 on:** 7 Feb 2006, 05:49 pm »

Quote from: drphoto

Is it half way between the listener and the speaker? (assuming conventional cone/dome type speaker)

The first reflection will NOT be the half way point, especially for side wall refections.
Be sure to use the mirror trick to discover the appropriate point.

Good luck.
EP

MaxCast · « **Reply #5 on:** 7 Feb 2006, 06:19 pm »

I'm sure we all think of the left and right walls. I would think any wall closest to the ear would be first reflection point so keep that in mind as well.

randytsuch · « **Reply #6 on:** 7 Feb 2006, 06:24 pm »

I saw somewhere you care about any reflections that reach your ear within 20 msecs of the original.

20 msecs translates to 23 feet at the speed of sound, so you should worry about any wall that is closer than 23 feet to you.

I would think the closer the wall (so sooner the reflections arrives), the worse it will mess things up. A reflection from a closer wall will be louder than a reflection from a farther wall, I do remember a little physics still.

Randy

ted_b · « **Reply #7 on:** 7 Feb 2006, 06:50 pm »

Here's a formula for the sides (from my gallery, ripped from Ethan Winer's RealTraps website)

bpape · « **Reply #8 on:** 7 Feb 2006, 07:14 pm »

...and to expand a little, when you had the left speaker on the right wall - that's not wrong. You will actually have 2 points on each wall - 1 for each speaker. If you're doing HT, you'll have 3 in order to do the center too.

Repeat this process for each seat. 2 speakers, 3 seats, 6 points on each wall.