[aceinc]

Danny spent way more time on the phone with me today than I deserved, and I appreciate that.

We discussed an OB system. One thing I did not get around to asking about was the placement of the speakers which would be OB 12" H or W woofer assemblies, and NX-Otica MTM squawker and tweeter assemblies.

I am limited in where I can place these speakers due to room size & aesthetics. The room is ~15'x25'x8.5' ~3,200 cu. ft. The front wall is 15' wide. The front baffle of the speakers are about 27" off the front wall, the inside edge of the cabinets are about 40" off the side walls. There may be a few inches of play but not much. The main listening position is in about the middle of the room say 12' off the front wall.

My concern is, from what I have read, OB speakers in general and these speakers in particular want to be 3'-4' into the room. Additionally I have read they like a bigger room as well.

What are the experiences from the assembled masses?

[bdp24]

Your room is plenty big enough. However, dipoles should be, if at all possible, at least 5' from the wall behind them. That 5' distance creates a 10 millisecond delay of the sound coming from the rear of the speaker in relation to the sound from the speakers front side. Sound travels roughly 1' per millisecond, so the sound from the dipoles rear travels 5' to the wall behind it, and another 5' to return to the speaker plane---the rear sound is therefore delayed 10 ms in relation to the front sound. A 10 ms time difference between two sounds is required by our ear/brain to perceive those two sounds as separate events. Anything less than that is interpreted as one event, and the rear sound will be perceived as smearing of the front sound, rather than the separate ambiance a dipole can provide.

As for distance to side walls, I have and listen only to planars, which have a figure-of-8 radiation pattern---sound to the speakers two sides is cancelled. They can therefore can be placed fairly close to side walls without a sonic penalty. Non-planars are a different story.

[Captainhemo]

I just mentioned this  over in the DIY forum but ...
I think Danny generally recommends  36"  as a minimum from the front/side walls  with additional deistance being better.  The  subs however can be   laced up fairly clsoe to  the side walls as  there are nulls at the sides.  You can even lay the subs down on their sides if you  wish

jay

[aceinc]

Jay, I think up weird stuff, and thought that if I had a large room, and lots of money, drive 4 of the OB 12" per side with two cabinets at right angles to one another. One on its side on the floor the second one on top in the vertical orientation. In the "L" formed by the two cabinets bring up a baffle with a line array of OB mids & tweeters.

This is a very crude line drawing using paint of my pipe dream.

[aceinc]

Jay, So what are the ramifications if I do not have the clearance?

Will it sound like poo?

Should I scrap OB?

I tend to buy stuff on craigslist. I have a pair of ESS Classic speakers with a Heil AMT running in dipole mode, and they sound OK in the positions we are talking about. But they do not put out any bass in dipole, the bass is ported. I have also had a pair of Carver AL III which also sounded decent in those positions, but again no OB bass.

[corndog71]

My room is smaller than yours and I got my OB subs to work quite well.  It may take some experimentation but yes, they do really need to be pulled away from the front wall.  I started with the subs close to the sides and my main speakers closer together but this collapsed the width of the soundstage too much.  I swapped them around and found an even better position for my mains and the subs seem fine closer to the middle yet still pulled out so that the baffles are around 36" from the front wall.

[ebag4]

My room is smaller than yours and I got my OB subs to work quite well.  It may take some experimentation but yes, they do really need to be pulled away from the front wall.

X1

My room is much smaller than yours.  The servo subs are outstanding in small rooms, fantastic detailed bass and no boom.  As mentioned by others, you will need to get them out into the room, mine are about 4.5'.  For reference:




Best,
Ed

[mlundy57]

My room is 10' x 13' x 8'. I have the speakers pulled 3' off the front wall, 6' apart (2' to each side wall) and 8' from the listening position.

I have listened to them in my living room before (20' x 25' x 8'). In this room they sounded best 5' off the front wall, 8' apart and 10' to the LP. 

I've found that if the speakers are closer to the front wall than 3', in addition to timing issues the soundstage gets smaller.

Mike

[aceinc]

Since aesthetics and matrimonial bliss are more important than acoustics to me, the question becomes (for me) will a pair of these speakers perform better given the constraints than what I currently have, which is a choice between;

B&W 802 Matrix S3
and
KEF 105.4

I have both of these speakers which are in stock condition and could potentially be tweaked. They both sound quite good in the room.

[mlundy57]

I dont know about the KEFs but the combination of the NX-Otica MTMs and OB subwoofers blow the 802 Diamonds away, especially if yo upgrade the crossover components in the MTM section.

If you cant get the full 3' away from the wall you can effectively increase the distance from the wall by toeing the subs in. Also, a combination of absorption & difraction can help timing and soundstage imaging.

You are still trying for 3' from the driver to the wall but by angling them the path to the wall is longer than it would be if the dervers are facing straight abead.

Mike

Oops, you said 802 Matrix S3s. I dont know what they sound like. I do know what the 802 Diamonds sound like. Sorry

[AKLegal]

My NX-Otica MTMs and H Frames are only 3 feet from the wall behind them but I have bass traps/absorption panels behind them. 

[aceinc]

Mike, I don't know what the Diamonds sound like, so we're even. Some people say the Matrix sound better than the Diamonds, but some people will say most anything. The KEFs and the B&Ws sound different, but not really better than the other.

Below is a crude unscaled Paint drawing of the living room. The front wall has the Stereo cabinet on it. On the front wall is a ~4' opening to the foyer, on the fireplace wall is a ~30" opening to a hallway. The weird little lines on the outside of the box is where windows are. S1 & S2 are the "front" speakers, S3 & S4 are surrounds, S5 & S6 are rears, S7 & S8 are sub 1, S9 is sub 2. S1 & S2 is where the new speakers need to go. The empty space at the bay window side of the room has an over stuffed chair and a speaker boneyard at present. From the Front wall to the baffle of the front speakers is about 27"

[Mark Korda]

Hi Ace, with all those measurements your mind must be spinning. Just to throw another wrench into it I always wonder about old music halls and why the most bass deep instruments are always in the back, organ, tuba, double bass, ect.
   I live in a mobile home with the same size roughly of your room. I only have one and 2 speakers so I try to split the difference between the 2 stereo speakers. Even though real low bass is non-directional it gives me a more mental satisfaction so I don't favor one speaker, visually.
     If your a real sub-woofer devotee you should take all the advise given by the more accurate measurers and build your living room around the sub. Changing furniture around gives you a new fresh outlook anyway. Happy experimenting.
     Mark Korda

[aceinc]

I actually wanted to build a room in the back of my house as a dedicated HT/sound room, but I'm fighting the cost, my wife and the on-going cost of the increase in taxes.

Regarding the existing space, my choices are to flip the room around with the front wall being the Bay window wall, or pushing the couches back a bit and moving the speakers away from the wall. Doing that would block the entry from the hall.

I'm still waiting on someone to tell me whether being this close to the walls is a non starter, or just non optimal.

[aceinc]

One other question. I am leaning towards the W frame. Is there any advantage of using the H frame over the W frame? Or vice versa?

[bdp24]

One other question. I am leaning towards the W frame. Is there any advantage of using the H frame over the W frame? Or vice versa?

The H-frame is 4" taller than the W, 27.5 vs. 23.5. If you use the frame as a speaker stand, one may be better than the other (to get the speaker's tweeter at ear level, if so desired). The H structure is inherently better braced than the W (making it more non-resonant), but a brace can be added across the deep cavity on one side of the W-frame, tying the two side panels together. Double-thick side walls is also a good idea, two pieces of 3/4" MDF glued together.

[mlundy57]

I actually wanted to build a room in the back of my house as a dedicated HT/sound room, but I'm fighting the cost, my wife and the on-going cost of the increase in taxes.

Regarding the existing space, my choices are to flip the room around with the front wall being the Bay window wall, or pushing the couches back a bit and moving the speakers away from the wall. Doing that would block the entry from the hall.

I'm still waiting on someone to tell me whether being this close to the walls is a non starter, or just non optimal.

If it were me, I'd flip it around and make the wall with the bay window the front wall. Untreated, the window would cause some reflection issues. However, you can mitigate this with a combination of absorption and diffraction room treatments.

If you don't want the window covered all the time you can use freestanding panels that you move off to the side when you want light through the window and move in front of the window when you want to listen to music or watch a movie.

Another option for movable treatment panels would be to install a track (like a barn door style track) above the bay window and hang the panels from the track. This way you could just slide them back and forth as needed.

Mike

[aceinc]

Mike, flipping the room would not be easy. In wall wiring would change, the TV would block the window, leaving the only choice a ceiling mounted screen & projector. A lot of effort, expense and political (marital) capital would be involved. All this for a pair of speakers .

Forgot that I dropped a dedicated 20 amp circuit behind the stereo cabinet which would need to move as well.

[mlundy57]

Mike, flipping the room would not be easy. In wall wiring would change, the TV would block the window, leaving the only choice a ceiling mounted screen & projector. A lot of effort, expense and political (marital) capital would be involved. All this for a pair of speakers .

Forgot that I dropped a dedicated 20 amp circuit behind the stereo cabinet which would need to move as well.

Then that opening you have behind S2 may cause a problem with the timing of reflections between S1 and S2. Danny or someone else more knowledgeable than me regarding OB integration will need to chime in on the feasibility of OB with your current setup.

OB doesn't work in all situations. In it's current configuration I can't use OB in my living room. If I pulled the speakers 3' off the front wall the right speaker would be in the middle of the opening to the front foyer. If I rotated the furniture 90 degrees so that what is currently the right side wall became the front wall I could easily pull the speakers 3' or more off the wall. The problem is my wife says no.

The compromise is that the living room has floor standing speakers that can be as close as 18" to the wall for my wife and what had been a guest bedroom became my man cave. The room is smaller than ideal but I can set it up and/or change it around how I want. So I put both 2 channel and HT systems (they share the same front speakers) in this room. An additional bonus is that my wife and I can both watch the movies we like at the same time.

Mike

[gregfisk]

Then that opening you have behind S2 may cause a problem with the timing of reflections between S1 and S2. Danny or someone else more knowledgeable than me regarding OB integration will need to chime in on the feasibility of OB with your current setup.

OB doesn't work in all situations. In it's current configuration I can't use OB in my living room. If I pulled the speakers 3' off the front wall the right speaker would be in the middle of the opening to the front foyer. If I rotated the furniture 90 degrees so that what is currently the right side wall became the front wall I could easily pull the speakers 3' or more off the wall. The problem is my wife says no.

The compromise is that the living room has floor standing speakers that can be as close as 18" to the wall for my wife and what had been a guest bedroom became my man cave. The room is smaller than ideal but I can set it up and/or change it around how I want. So I put both 2 channel and HT systems (they share the same front speakers) in this room. An additional bonus is that my wife and I can both watch the movies we like at the same time.

Mike

Mike, you are the voice of reason... I ended up building a separate building altogether so my wife and I can get along. I think the OB speakers can work in the space the OP wants but room treatment seems like it would help. I had my OB super Vs around 2.5' from my front wall and I thought they worked O.K. Much better than the previous rear ported speakers that I owned. The caveat being the room is huge and OB subs loved being in that room. Now I'm in a 600 sq. ft. room with well over 3' behind the Super Vs  and they sound amazing to my ears. I'm pretty sure you can make them work with a little effort and I think it is well worth it. Just my opinion of course.

Greg