How close to the wall can you place floor speakers

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I am working on my HT design and would like to place my floorstanding speakers fairly close to the front wall behind a fabric frame. The location is tight - but it's near a corner that will be filled with a mineral wool base-trap. How close can I place the rear ports to the mineral wool without affecting the bass ? Is 3 - 6 inches too close?

Lewis, welcome. Allowing at least 3" of "breathing room" for rear ports is generally considered to be adequate so that no bad effect results. Although that shouldn't be a problem with what you propose, the "behind a fabric frame" part may be troublesome. Either the fabric or frame itself may absorb/diffract/reflect sound.

I agree with John about allowing at least 3", I would go more, to let the low bass filter into the room. Not sure I like your idea of having them back up to mineral wool, this may absorb to much of what you DO want to filter into the room. I have Owens Corning 703 cut into superchunks from floor to ceiling. My Axiom m60's are placed between them and the screen, but not in front of the bass traps. I also am not sure why you want to cover up your mains? Depending on the fabric you use, it WILL possibly affect your various low/high/mid frequencies.

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Lewis, welcome. Allowing at least 3" of "breathing room" for rear ports is generally considered to be adequate so that no bad effect results. Although that shouldn't be a problem with what you propose, the "behind a fabric frame" part may be troublesome. Either the fabric or frame itself may absorb/diffract/reflect sound.

Hi John - thanks for the feedback. I am thinking of making the fabric frames out of Guilford of Maine cloth and having the speakers quite close to the fabric itself so I don't think there will be a problem there. That stuff is rated acoustically transparent. Also, the frame will be nothing more than a skeleton to stretch the cloth over - sort of like the false walls people are using to hide all the speakers in dedicated home theaters. Mind you, I am not sure if all those false walls are being done with front only ported speakers....

I have some renders done up of my room in SketchUp but I can't seem to figure out how to post them here on the forum. I think I need to find a place to load the pics before I can attach a "link" to them? It would become clearer if I could show you a pic of what I am trying to do.

Thanks again.

Lewis

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I agree with John about allowing at least 3", I would go more, to let the low bass filter into the room. Not sure I like your idea of having them back up to mineral wool, this may absorb to much of what you DO want to filter into the room. I have Owens Corning 703 cut into superchunks from floor to ceiling. My Axiom m60's are placed between them and the screen, but not in front of the bass traps. I also am not sure why you want to cover up your mains? Depending on the fabric you use, it WILL possibly affect your various low/high/mid frequencies.

Hmmm......I hear you on the mineral wool being in the line of fire of the rear ports. The superchunks are in fact what I am planning for the corners in the front - whether I use mineral wool or OC703 is a function of what I can obtain - if the coefficients are similar....

The reason for hiding the mains (and the center speaker too for that matter) is purely a function of taste and wanting a "clean" appearance in the front of the theater when entering the room. However, that's the beauty of sketchup - costs nothing to explore other options !

I am planning on having at least some treatment on the front wall around the screen as well (the screen will be on the wall itself) so there will be some treatments behind the speakers regardless.

Hey Lewis,

Yes, the 703 and mineral wool should perform the same for superchunks. I'm guessing you'll be able to easily remove the coverings if needed once in place? In the 1.5 yrs I've had my m60's, I'm constantly tweaking the position from the side/back walls and "toe in" to get it just perfect.

In regards to treating the front wall, I would do some more reading on that subject. Most of the experts, from Realtraps, GIK, etc..., will tell you there is no real benefit for treating the front wall.

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Hey Lewis,

Yes, the 703 and mineral wool should perform the same for superchunks. I'm guessing you'll be able to easily remove the coverings if needed once in place? In the 1.5 yrs I've had my m60's, I'm constantly tweaking the position from the side/back walls and "toe in" to get it just perfect.

In regards to treating the front wall, I would do some more reading on that subject. Most of the experts, from Realtraps, GIK, etc..., will tell you there is no real benefit for treating the front wall.

I seem to keep finding arguements from both camps on the front wall treatment, and have come to the conclusion that it's really only required when there's a false wall and the screen is on the false wall, creating a cavity behind that can cause comb filtering effects with the sound reflecting from the original wall and back of the screen - sort of like a resonant cavity of sorts. I don't really have that construction in my plans, but there are a couple of "mostly GOM fabic" columns and a piece across the top between them, so I can treat or untreat even after the room is finished. Whatever I do, the screen is going hard up against the front wall to maximize the viewing distance. I'm still trading off a little as my room is 18' in depth and based on all the calcs that I have done, I really should have 20' for 2 rows to prevent the back row from going up against the back wall, but hey, life is all about comprimises anyway.

I just learned all about photo-hosting and I am going to attempt to post a thread with my Sketchup model of my ht design. You will be able to clearly see the issue with the placement of the floorstanding speakers behind the left/right columns on each side of the stage then. I'm hell bent on hiding these front speakers and can almost pull it off as you will see, but I always like to leave my options open so I will keep playing with the geometry.

I had a look at your theater pics and like your set-up. The constrast of the speakers and other colors in the room really makes them pop and lends an air of "seriousness" to your set-up

It looks like you are running a 2.35 screen - I'll be back to badger you with some questions on that in the near future as that's the way I want to go as well. My HT is going to be strictly movies - no HDTV.

Keep an eye out for my SketchUp picture thread attempt here shortly and let me know your thoughts after you see them.

Thanks again for your insight and advice.

Lewis