Tip of the Day: Speaker Placement & Early Reflections

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admin

Audioholics Robot
Staff member
Give your speakers plenty of space to breathe around and in front. Things like TVs, Shelves, Other Speakers, Coffee Tables and Walls create secondary sound sources that smear the presentation through early reflection and diffraction. Let the speaker be the only thing sending early cues to your ears.


Discuss "Tip of the Day: Speaker Placement & Early Reflections" here. Read the article.
 
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utopianemo

Junior Audioholic
This tip and the article on sealed vs. ported brings up a question I had. I know that, generally speaking, you want to have your speakers away from the back wall a bit, especially if they're rear ported.

I am interested in purchasing some MTM speakers to mount on a wall, flanking the projector screen. I called a certain ID manufacturer to enquire if their sealed MTM-style LCRs could be wall mounted. They assured me the speakers would sound great that way.

This led me to believe sealed speakers of this type would generally perform well whether mounted on stands or directly on a wall. Is this incorrect? Should a speaker have boundary compensation or specifically be touted as an "on-wall" model for it to perform well on a wall?
 
gene

gene

Audioholics Master Chief
Administrator
This tip and the article on sealed vs. ported brings up a question I had. I know that, generally speaking, you want to have your speakers away from the back wall a bit, especially if they're rear ported.

I am interested in purchasing some MTM speakers to mount on a wall, flanking the projector screen. I called a certain ID manufacturer to enquire if their sealed MTM-style LCRs could be wall mounted. They assured me the speakers would sound great that way.

This led me to believe sealed speakers of this type would generally perform well whether mounted on stands or directly on a wall. Is this incorrect? Should a speaker have boundary compensation or specifically be touted as an "on-wall" model for it to perform well on a wall?
Usually manufacturers that produce on-wall speakers tweak the crossovers to compensate for the 2pi loading effect. However, I've had good success plugging a rear port and placing speakers a few inches off a back wall so don't let that scare you. This is especially true if you're going to bass manage them.
 
monkish54

monkish54

Audioholic General
As long as they tweak the Baffle Step Compensation, you should be good to go.

When you make a FS/BS Speaker, generally there is 3-4db BSC. When you put that speaker on-wall, less BSC is needed as the bass reflects right off the wall.

Just ask them if they will adjust the BSC for users who intend to mount them. :D

Happy listening!!

*If it was Salk, I'm sure Jim (Dennis) would be more than willing to adjust the BSC!
 
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utopianemo

Junior Audioholic
It was Emotiva and they said that both the XRC 6.2 and the XRC 5.2 could be mounted as-is on the wall without problems. I was a bit surprised because their older speakers had a boundary compensation switch, and these don't.

I do plan to bass manage whatever speakers I end up purchasing.

I would rather buy towers but the room is also a play room; I had the delight of coming in the other day to find my 4-year-old poking my bookshelf speaker in the tweeter with a 4" metal rod....again . Thankfully it's an aluminum dome and they're old speakers. But I have to keep the next ones out of harm's way.
 
monkish54

monkish54

Audioholic General
Perhaps they didn't give the speaker much BSC to begin with since it's designed to be used as a center as well.

I'm fairly curious. I might just ask them.
 
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utopianemo

Junior Audioholic
If you ask them, let me know.

Now that I think about it, why design the speaker with any BSC at all? I mean, as a default we treat reflections as something to be curbed/controlled. It's common for people to put absorption panels on the front wall for that purpose, isn't it?
 
monkish54

monkish54

Audioholic General
If you ask them, let me know.

Now that I think about it, why design the speaker with any BSC at all? I mean, as a default we treat reflections as something to be curbed/controlled. It's common for people to put absorption panels on the front wall for that purpose, isn't it?
Will do!

Very good question.

I'm sure you know what BS is, but i'll give a VERY brief explanation. Depending on the cabinet width, frequencies above point X will diffract off of the cabinet, and frequencies below point X will wrap around it. When the frequencies wrap around, the SPL of those frequencies (at the listening position) is attenuated by a good amount (depending on placement). The frequencies that don't wrap around will be "normal" volume (and some will diffract off the cabinet causing peaks) and the balance will be off.

The panels aren't used as a substitute for BSC for a few different reasons, but mostly because the BSC filter doesn't reduce the wrapping around, but reduces the SPL of the frequencies that don't wrap around so they match.

Panels on the front wall are used to reduce early reflections which can be harmful to imaging and timbre.

Here is a good article about BSC:

http://www.salksound.com/wp/?p=42

**Please feel free to correct me if necessary! :D
 
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monkish54

monkish54

Audioholic General
If you ask them, let me know.
Emotiva returned my email. They told me the person who told you that was mistaken. Neither speaker is meant to be used on-wall. They are meant to be stand mounted in-room, even in the case of use as center. :D
 
GranteedEV

GranteedEV

Audioholic Ninja
I thought I would clarify something about this tip. I tried to keep it concise but reading it again I realized it might be a bit misleading. The 5 meter travel distance is "added" to the travel distance of the direct sound. Without getting into a bunch of convoluted trigonometry, my only point is that if you measure the perpendicular distance of the speaker from the side wall, it should be around or above 2.5 meters - or as close to it as is practical.
 
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haraldo

haraldo

Audioholic Spartan
The aspect of speaker placement and near wall placement is extremely complex and it's far more to this than just the simple properties of closed box or bass reflex, according to my experiences some closed box speakers need three feet to the front wall while some bass reflex or transmission line speakers may be placed very close to wall, and it's not about boundary compensation solely....
Well this is my claim, but I can't prove it !!!! :p

One example:
from my own experience.
I do have a pair of closed box Duntech PCL-15's, the response is extremely flat and well, they are not designed to be set close to a wall, so when you do this they simply sound bl¤##%¤ awful, like a broken old radio, extremely bad, and it's not only about frequency response I believe, or perhaps it is.... at least they seem to be completely lifeless, there is no precision, of course the upper bass region is quite affected by this close to wall placement but it's also a complete loss of stereo perspective, musicians seem to be completely "floating" around the room, just boring to listen to.....

Put the same speakers 6 feet from the front wall, quite close to the side walls and quite extreme angling..... and it's simply astonishing pure magic, just waaaaah :D

maybe it's frequency response, polar response, many other things..... I don't know but I spent more than a few months's to find an optimal speaker position for these speakers in one room, they are small, simple, and should be easy to position, and it's not like this at all.

Second example:
Other current speakers that I do have, a pair of Meadowlark Kestrel 2, they are transmission line and the TL ends in the front, so they should be less susceptible to near wall placement but still having the TL loading at the bottom I believe they should be somehow difficult in that aspect.... put the speakers almost anywhere in the room, even quite close to any wall and it works quite well.

These are two differences from two speakers that are different in construction, but still quite similar in other ways, two way, 1st order x-overs, flat frequency response, quite similar polar response, both have 6.5" woofers.

Some differences and many similarities but I have no idea why they behave so extremely different relating to near wall placements.
I never tried Boundary compensations, it would change the performance a bit but nowhere near close enough to make the Duntech's work near front wall......

Probably only one way to find out what works and what doesn't

TRY IT OUT :D
 
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utopianemo

Junior Audioholic
.... if you measure the perpendicular distance of the speaker from the side wall, it should be around or above 2.5 meters - or as close to it as is practical.
Over seven feet from the side wall for each speaker? My room is 20 feet wide; that would put my speakers about 5 feet apart. I guess this tip wasn't for me.
 
monkish54

monkish54

Audioholic General
Over seven feet from the side wall for each speaker? My room is 20 feet wide; that would put my speakers about 5 feet apart. I guess this tip wasn't for me.
How about 6 feet from the wall, and 7 feet apart?

This tip recommends you have the correct balance. You want your speakers to be far enough away from the walls as to allow reflections to be ~15-20ms for good imagining and soundstage. If you can't do 7 feet, do 6 etc. Do whatever you can that is practical. :D
 
haraldo

haraldo

Audioholic Spartan
How about 6 feet from the wall, and 7 feet apart?

This tip recommends you have the correct balance. You want your speakers to be far enough away from the walls as to allow reflections to be ~15-20ms for good imagining and soundstage. If you can't do 7 feet, do 6 etc. Do whatever you can that is practical. :D
Joachim Gerhard who founded German brand Audio Physic has written and said a lot of good things about speaker placements, his main tip is that speakers should be placed along the long side of the room and not the short side, as is usual, maybe this is not possible due to practical reasons.... but from an acoustic point of view this is quite logical I guess.

Check this link!
Setting up Loudspeakers in a Room
 
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Nuance AH

Audioholic General
I thought I would clarify something about this tip. I tried to keep it concise but reading it again I realized it might be a bit misleading. The 5 meter travel distance is "added" to the travel distance of the direct sound. Without getting into a bunch of convoluted trigonometry, my only point is that if you measure the perpendicular distance of the speaker from the side wall, it should be around or above 2.5 meters - or as close to it as is practical.
How far are you Phil 2's from the side walls?
 
GranteedEV

GranteedEV

Audioholic Ninja
How far are you Phil 2's from the side walls?
136cm. Best I can do in the width of room I have. I'd like to add an extra 3-4 feet on either side ;P

Then again, that's not distance to the first reflection point - it's just distance to the wall.
 
haraldo

haraldo

Audioholic Spartan
136cm. Best I can do in the width of room I have. I'd like to add an extra 3-4 feet on either side ;P

Then again, that's not distance to the first reflection point - it's just distance to the wall.
You can put diffusors onto the first reflection point and it will probably help you out a bit :p
 
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