Full Range Speaker Position - AVS Forum
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post #1 of 7 Old 08-13-2010, 02:26 PM - Thread Starter
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So my front three speakers are large full range things (Vaf Research I66), from what I understand designed to be located away from walls (well thats the typical placement anyhow)

I am toying with the idea of placing them behind an AT screen, which would mean (in my case) they'd be right up against the front wall (they're front ported).

What information do I need to determine if this is a good idea or not?

Polar response charts?

Can any speaker be placed like this if appropriate treatment is done?

Also, assuming this can be done, whats the minimum distance I can have the screen in front of the speakers?

Edit: is this more an issue for the R and L then the center? Its likely my L and R will/can sit outside the screen width (room is 3.8m wide and screen 2.3m), which would mean I could bring them forward

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post #2 of 7 Old 08-14-2010, 01:14 AM
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Hi Peter,

This is a question that's had me intrigued for some time. My original plan for my new room was to have the front three speakers out in the room to keep them away frpm the walls as you have suggested, but I'm now heading towards an AT screen with speakers behind. Looking at all the build threads here it seems common to have speakers close to the wall, and I believe that this doesn't introduce any problems which can't be sorted with EQ.

Another design solution (which I've only noticed recently and appears to be more high end) is to build a baffle wall which is flush with the speaker front baffles. Apparently this adds 6bB to the speaker efficiency.

The minimum distance between the speaker and screen depends on the type of AT material being used. I understand that perf screens need more space than woven screens to avoid comb filtering. I think I've seen 300mm minimum quoted but can't remember where ??
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post #3 of 7 Old 08-14-2010, 03:26 AM
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Peter:

From a pure technical perspective, full range speakers should be 15' from anything; but, that isn't practical. Keeping speakers further from boundaries is more important in two channel rooms. In multi-channel applications, the speakers can be moved closer to walls; but, those walls need to be treated to avoid, among other things, the notch created by the boundary effect. The treatments need not be expensive.

PeterM is correct that the distance between the driver and the screen depends on the screen material.

Baffle mounting is another approach; but, without knowing the radiation characteristics of the speaker, it can be a bit dicey. Once in a built baffle, you're not going to move them a couple of inches (cm) one way or the other to snap the sound stage in place.

EDIT: The issues for the L/R are the same as for the center. The good news/bad news of this is the L/R are a different distance from the side walls than the center; but, again, doable.

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post #4 of 7 Old 08-14-2010, 03:24 PM - Thread Starter
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Hmm, ok thanks for the clarrification. Looking at the fabric that SMX use, which I think is the same stuff as the local guys I can have it 2-3 inches from the front of the speakers, this could work.....darn things (speakers) are about 425mm deep each

Dennis, when you say this is more an issue for 2 channel, is that becuase in a multi channel room the bass is being looked after by the subs?

Assuming a bunch of EQ is needed in such a scenario, is this something that ordinary receivers can do? or are dedicated EQs needed? I am pretty ignorant about this stuff.

TIP FOR ANYONE READING - NEVER, EVER, EVER BUY YOUR GEAR BEFORE YOU HAVE A ROOM.

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post #5 of 7 Old 08-14-2010, 04:16 PM
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Two channel uses the room as the surround processor. These environments need to have more reflections to provide that faux surround effect. Because of that, you cannot risk the notches and comb filtering. In multi-channel, we can push stuff closer to the wall and treat the problem. (Because they are full range, you also have the problem that the best location for smooth bass response is likely not the best positions for a great sound stage).

Some of the newer receiver based systems should not be overcome with this kind of situation ... certainly a standalone would provide a better result; but, we're splitting hairs here.

Maybe if the three of you can get your schedules together, I should slip down under.

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post #6 of 7 Old 08-14-2010, 10:35 PM - Thread Starter
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Quote:
Originally Posted by Dennis Erskine View Post

I should slip down under.

Thats the first time I've ever seen anyone refer to a 14+ hour flight as slipping down you're more then welcome however.

Ok so we can jam them in against the wall, its just treatments and the ability of a said screen to work that close to them.....lets see if I can sell them anyway and avoid the problems all together.......I hate buying things twice, really hate it.

I am sure my gear will provide you with a head ache come design time if I cant swap em out

Thanks again,

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post #7 of 7 Old 08-15-2010, 01:55 AM
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Quote:
Originally Posted by Dennis Erskine View Post

Maybe if the three of you can get your schedules together, I should slip down under.

Depends on how many beers you get into me at CEDIA !!
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