Why front towers 3 ft from wall?

NicholasY · 10-04-2004, 12:23 PM

Hi, I am new to the forum. I am currently building a home theater in my new house. I have all the cabling ran and the drywall is going to be hung tomorrow.

The speakers I will be using are the Infinity Prelude MTS's, two towers and two subs in the front, and two towers for the sides. I have read that the front towers should be placed at least three feet from the wall, (I am assuming that means the front of the speaker should be as least three feet from the wall as speaker depth varies.)

I am wondering if I should mount the towers on the wall as I will be wall mounting a Panasonic 42" Plasma TV to make the setup more wife friendly.

Why does everyone recommend setting speakers away from the wall??? I want the ultimate performance out of my preludes so I don't want to limit their performance.

Fast responses are greatly appreciated

Here is my room dimensions Width 15' Length 24' Height 7'

GrahamT · 10-04-2004, 12:41 PM

Speakers are sometimes designed to compensate for baffle step loss. This means they have a fairly flat frequency response when placed out in the room, but when placed against a wall you can get up to a 6 dB increase in the bass and midrange frequencies. This is why the manufacturer says to place them away from the wall. Read the manual, it should say how far away from the wall to place them.
If you want to put them against the wall any way, maybe try adjusting the bass and treble until it sounds good to you.

Wayne A. Pflughaupt · 10-04-2004, 01:12 PM

Nicholas,

Quote:

I have read that the front towers should be placed at least three feet from the wall...

Whenever you see speaker advice that exhibits a “one size fits all” philosophy, feel free to take it with a grain of salt.

The truth is, all speakers are different, and so are the rooms they go in. Assuming a specific speaker make and model, what works best (as far as placement) in one room won’t necessarily work in another.

For instance, room size and dimensions are an important factor in a speaker’s bass response. Take as an example a speaker that sounds well-balanced in a particular room: If you move it to a significantly smaller room, it will sound bass heavy. Move it to a room that’s significantly larger, bass will sound weak and anemic.

Thus, placing speakers close to a wall or not is a method fine-tuning its bass output. As Graham noted, the closer a speaker is to the wall, the more bass (and to a lesser extent, midrange) response improves.

That’s good and fine if the speaker is weak in those areas and needs some help, but if the speaker already has substantial bass output, putting it against the wall will probably be “too much of a good thing,” as it were. In that case moving the speaker out from the wall will “tone down” it’s bass output and at the same time improve midrange clarity.

As always, it’s best to experiment with location. If that’s not possible, the receiver’s tone controls can also be used judiciously to compensate.

Regards,
Wayne A. Pflughaupt

NicholasY · 10-04-2004, 04:56 PM

Thanks for the feedback guys. I have read the owners manual and it says to keep the front towers at least 3' away from the side walls, but it does not say how far from the front wall they should be.

I will definitely test the placement. I now understand what differences I should be watching for.

Are there any other speaker placement tips I should know?

SethH · 10-04-2004, 05:23 PM

Make sure you properly calibrate the system as this will help you determine the best placement for the speakers (meaning you should at least roughly calibrate in each location to get the best results).

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NicholasY · 10-04-2004, 06:11 PM

Seth,
Thanks, I will do that.

I have a Denon 2900 DVD, and a Denon 3805 Receiver, which one should I caliberate as I noticed both have speaker caliberation menus?

Kevin C Brown · 10-04-2004, 08:38 PM

Also make sure that the distance from the front wall to the speaker, and from the side wall to the speaker are not equal. Creates additional problems with standing waves.

NicholasY · 10-05-2004, 10:41 AM

Kevin,
Okay, thanks for the advice guys.

cabreau · 10-05-2004, 11:51 AM

Quote:

Kevin C Brown
October 5th, 2004
04:48 PM

Also make sure that the distance from the front wall to the speaker, and from the side wall to the speaker are not equal. Creates additional problems with standing waves.
a

Why is that Kevin? I'm not familiar with this?

Chris_Liberti · 10-05-2004, 06:18 PM

There are 3 reasons for positioning speakers away from walls.

1) in order to limit the increase in SPL by wall loading the driver. Flatter response can usually be had by keeping the speaker from the wall

2) in order to not block the port on a ported loudspeaker

3) so that the soundwave can reflect off of the wall with a dipole or bipole loudspeaker.

ChrisWiggles · 10-05-2004, 06:47 PM

SBIR is a reason to keep your speakers further away. Freq response is usually better, as well as imaging especially.

Kevin C Brown · 10-05-2004, 08:12 PM

cabreau- I think the technical argument goes something like: if those two distances are the same, then you are reinforcing the room nodes that will be produced by each distance. The whole idea (for low frequencies) is that you want the room nodes spread out over the most number of frequencies possible (less audible), not concentrated into a few (more audible).