flush mounted in wall studio monitor, any advantages???

[Greggo]

I am thinking about building a false wall, or perhaps more accurately a gigantic speaker cabinet that blends into the walls of a media room (about 15 x 17 in size) to allow for large sealed woofer volume and also flush mount drivers on a continuous baffle to minimize difraction effects. Not sure if this makes sense or not but I remember seeing a really cool posting on a audio forum where an engineer had done this with some modest vifa drivers and claimed to have achieved very good sound. Are there any advantages to this type of approach? I think audio engineers refer to this approach as soffit mounted studio monitors but I am not sure. I would probably go three way active, and use sealed bass drivers since I would have plenty of volume to work with as I would place the baffles about 12-15 inches out from the wall and then run them floor to ceiling and side to side so the drivers had plenty of room, maybe even enough for infinite baffle bass.... Any thoughts?

[BassAwdyO]

sounds like a good plan to me... You wont have to compensate for baffle step(the transition from half space to omni radiation) and wont suffer so much from reflections/diffraction

[Variac]

Generally speakers sound better away from a wall. They sound more "airy"

So I think it would be better to have the mids and tweets in a bump that stick out a ways from the wall. The bass doesn't care, and it WILL solve baffle step issues.

A reason regular speakers sound wrong pushed against wall is that they already have baffle step correction..so the bass is emphasized.

[B4]

Yes. I agree that they sound better away from the wall, and yes you will compensate for baffle step if they are flush mounted. In the world of comprimise you must figure out what will work for you. there are trade-0ffs with both ways. It is cheaper to compensate for baffle step then to build a wall.

By building a false wall you will also control some room resonance problems also, that is another benefit of a false wall.

[Dumbass]

From the man himself:

Q: In your VTL box design, why is the JX92S fitted in the wide face when it is common knowledge that the box should be as narrow as possible?

A: 'Common knowledge' and scientific fact are often very different. The narrow front face is a fashion concept supported by some very questionable marketing rational. The indisputable scientific fact is that the ideal mounting for a loudspeaker is an infinitely large flat baffle and this is the concept used for all loudspeaker analyses. A wide baffle always sounds better.

Q: What are the recommended advantages of positioning loudspeakers as close to the wall as possible?

A: This positioning secures, to some extent, the advantages described in the previous question. In addition it minimises the time delayed reflections from the rear wall which contribute to confused imaging.

Q: Will placing next to a wall ruin the stereo image?

A: We cannot see any reason why this would impair imaging. Possibly more than any other manufacturer, we have concerned ourselves with accurate and stable imaging and certainly would not promote a design that would impair this.

http://www.ejjordan.co.uk/faq.html#faq16

The reason wall-mounted speakers might sound bad is because they were designed to be placed out in the room, or because there's a load of crizznap between the speakers, which is what most people do with their hi-fi. Speakers wall-mounted on a large wall are projecting directly into half-space, with no reflections from the wall.

What seems weird, to me, are the people who have dedicated media rooms, place the speakers away from the wall, and then do everything they can to treat the back wall!

[navin]

Originally posted by Greggo
I am thinking about building a false wall,...about 15 x 17 in size...about 12-15 inches out from the wall and then run them floor to ceiling and side to side so the drivers had plenty of room, maybe even enough for infinite baffle bass.... Any thoughts?

lets assume a 8 ft ceiling. and lets assume you build the wall allongthe narrow side of the room (15 ft). 4 8x4 sheets of 19-25mm marine grade ply wood would be the baffle.

your wall will encolse a box of about 15x8x1 = 120 cu. ft. do you need that volume. I would recommend that the wall only be 6" deep with the are immediately behind the woofer well damped. You could use 2"x6" beams of wood to brace the box. First attach these to the rear wall and then add the baffle.

even with a 6" wall you will have a huge box. With such a wall about 1/5 of the box volume will be taken up by bracing. Net box volume will be about 45-50 cu. ft. Should be enough for the most demanding woofer install.

[mgoedeke]

Why not go all the way and build a studio monitor type speaker? You might want to recess the inner side of the "speakers" and angle the "baffle" in a little bit (and use a more directive speaker while you're at it like something along the lines of Gedde's Summa) or a nice co-ax? Common sense audio will oversell you a little P.Audio co-ax that might do the trick nicely for not too much money, though I would not try the single capacitor crossover they recommend becasue I feel it misses out on the potential of the drive units. The usual italian and french suspects also have nice co-axes (so do Radian and Tannoy might also have a suitable ceiling speaker)

[navin]

Originally posted by mgoedeke
...Common sense audio will oversell you a little P.Audio co-ax that might do the trick nicely for not too much money..

how do these compare to the Jordan JX92?

[ralphs99]

Hi Greggo,

I tend to agree with B4. Building a wall is a big undertaking and will likely create as many problems as it solves.

Soffit advantages: No baffle step. Fewer diffraction issues.
Soffit disadvantages: Room modes. Wall resonances.

Soffit mounted studio monitors are usually decoupled from the supporting wall in order not to excite the wall. The supporting wall is made very solid often with a concrete cubby hole for the monitor. That takes care of the wall resonances. Imagine the problems with baffle resonances multiplied by the size of the wall.

Studios are designed by professional acousticians who have the knowledge, experience and tools to accurately predict the major room modes. The rest of us have to make do with simpler tools and experimentation. With freestanding speakers you have much more control over room modes.

Baffle step isn't such a big problem. It can be equalised out fairly easily.

Diffraction is a hot topic. Personally I don't feel it has as large an effect on the overall speaker sound as other factors. In particularly I try to control directivity to minimise illuminating the baffle at higher frequencies thus side stepping the problem to a large degree.

So in a domestic situation I would strongly advocate free standing speakers.

Cheers,
Ralph.

[mgoedeke]

The compromize ito what it allows you to get away with WAF is another factor to considder and the baffle has to be decoupled from the speakers (a book on studio design would be my 1st move)

Diffraction is indeed a hot topic and not because of the lobing and the baffle step but becasue of the time-delayed (non-minimum phase component) more strongly localizing the speaker. I would probably treat the terminus of a co-ax with foam and watch carefully what the measurements show (you can see the harmonic structure of the diffraction caused ripple on FR plots)

just my 2c of course