Wall mount vs. book shelf question

[Mtn. Steel]

I thought I was sold on the speaker company LCR-2. I called them and they said that their bookshelf speakers (even though front ported) should not be wall mounted. Energy C-50 and C-100 claim to be wall mountable. I DO NOT WANT SPEAKER STANDS OR FLOOR STANDERS due to floor space and wifely restrictions. My viewing room (read living room) does not have a bookshelf. If I were to make a few nice, small wooden wall shelves (like for a plant) could I then put bookshelfs on them even though wall clearance would be 2-3 inches from the wall?? Or could I just wall mount the TSC speakers anyway??

I could get the TSC LRC and 2 surrounds for about $220.00 (amazingly, that is about my budget). I am sure that they would blow the socks off of my Costco Panny speakers.

 

[j_garcia]

You can wall mount any speaker you like, but that does not mean it will be optimal sound wise for them. Sealed speakers tend to work better for wall mounting, so you might modify your search for sealed ones. Perhaps some NHTs on closeout somewhere as they are closing down? Using an actual bookshelf is worse than wall mounting IMHO, but not by a lot.

 

[jostenmeat]

Using an actual bookshelf is worse than wall mounting IMHO, but not by a lot.

Could you please elaborate, j? I might be wall mounting a speaker in the near future.

 

[j_garcia]

Boundary effects with a shelf are greater because you have more near-by surfaces, meaning you are adding more places for sound waves to collect/reflect and additional objects that will have sympathetic resonance(s).

In a typical room, the sound will tend to collect at the walls, and having the speaker close to the wall means you get more interference with the sound of that speaker. For surrounds, not a big deal, but for mains it can be a problem.

boundary effect : A sound reflection effect due to room modes ( standing waves) which accumulates at walls. sound wave reflections appear to make the localized sound level increase as all of the room modes terminate at the boundary (wall). Essentially as the wavefront approaches the wall, the amounts of molecular motion become smaller and smaller while the pressure differences become greater and greater as the wall resists the motion of the air molecules, the wall becoming a pressure node. The rigidity of the wall surface determines how much the pressure rises, i.e., how much of the pressure is reflected versus how much is absorbed. This occurs on a mode-by-mode basis at each resonant frequency. At very low frequencies, nothing large is rigid. However, at higher frequencies, boundary effect is more pronounced, e.g., frequencies above 100 Hz in a room with typical walls.

 

[DD66000]

Could you please elaborate, j? I might be wall mounting a speaker in the near future.

Speakers that are designed to be wall mounted will sound much better (onwall) than using a bookshelf speaker near or wall mounted. In any case, keep speakers away from the corners to prevent early first reflections.

I use speakers that are designed for both freestanding and onwall, there is some difference in sound, between the two setups. Freestanding produces a deeper soundstage.

 

[no. 5]

Could you please elaborate, j? I might be wall mounting a speaker in the near future.

There are two things to be considered when wall mounting speakers.

First, the wall will make an acoustic reflection of the speaker, so there will be some amount of phase difference between the direct and reflected sound causing cancellations at some frequencies; for example, a wall mounted speaker that is twelve inches deep will have an acoustical copy of itself twenty-four inches behind itself, this will result in a cancellation somewhere around 280Hz. Because twenty-four inches is half a wavelength of 282.5Hz, and a half wavelength offset will put the two signals 180 degrees out of phase.

The fact is that this is unavoidable, but the directivity of the speaker, the strength of the reflection and the distance of the reflective surface all play a role in what frequencies, and to what extent, this creates a problem.

Second, a wall mounted speaker no longer radiates into full space, but half space. This will result in an increase of SPL as the directivity of the speaker decreases, so at 100Hz where most speakers are omnidirectional, there will be a 6dB increase in SPL (relative to free space), but at 20kHz where most speakers are highly directional, there will be a minimum (if any) increase of SPL. This problem can be addressed if you have an EQ with a shelving filter and the right corner frequency.

And never put a speaker in a bookshelf, or other cubbyhole, as the resonances of the space will seriously mess up the speaker's frequency response.

 

[Mtn. Steel]

There are two things to be considered when wall mounting speakers.

First, the wall will make an acoustic reflection of the speaker, so there will be some amount of phase difference between the direct and reflected sound causing cancellations at some frequencies; for example, a wall mounted speaker that is twelve inches deep will have an acoustical copy of itself twenty-four inches behind itself, this will result in a cancellation somewhere around 280Hz. Because twenty-four inches is half a wavelength of 282.5Hz, and a half wavelength offset will put the two signals 180 degrees out of phase.

The fact is that this is unavoidable, but the directivity of the speaker, the strength of the reflection and the distance of the reflective surface all play a role in what frequencies, and to what extent, this creates a problem.

Second, a wall mounted speaker no longer radiates into full space, but half space. This will result in an increase of SPL as the directivity of the speaker decreases, so at 100Hz where most speakers are omnidirectional, there will be a 6dB increase in SPL (relative to free space), but at 20kHz where most speakers are highly directional, there will be a minimum (if any) increase of SPL. This problem can be addressed if you have an EQ with a shelving filter and the right corner frequency.

And never put a speaker in a bookshelf, or other cubbyhole, as the resonances of the space will seriously mess up the speaker's frequency response.

You know what!? That is exactly what I was thinking! J/K! I do not doubt one once of that as truth, but those words have never entered my brain whilst listening to speakers....perhaps they should? In any case, thanks for the reply. The one thing that this website has done for me, is that I now KNOW that I need to make a pilgrimage to Denver for a "listening session" before I buy ANYTHING!

 

[DD66000]

You know what!? That is exactly what I was thinking! J/K! I do not doubt one once of that as truth, but those words have never entered my brain whilst listening to speakers....perhaps they should? In any case, thanks for the reply. The one thing that this website has done for me, is that I now KNOW that I need to make a pilgrimage to Denver for a "listening session" before I buy ANYTHING!

If you are going to wall mount, then make sure the speakers you buy are designed to be wall mounted, as their engineering design will take into account the boundry reinforcement of the wall. Never use bookshelf speakers for wall mounts. Most wall mount speakers I've ever seen are only about 5~6" deep.

 

[no. 5]

...but those words have never entered my brain whilst listening to speakers....perhaps they should?

When listening? Nah, listening is for enjoying music.

When setting up a system on the other hand...