Blog Categories

Baffle Wall Case Study: Acoustic Frontiers Demo Room

This article is a case study of how we designed and built the THX style baffle wall in the Acoustic Frontiers demo room. A baffle wall can be thought of as a false wall into which speakers are ‘flush’ mounted and can be built in front of the existing wall in a home theater or instead of the front wall. There are many acoustical benefits to baffle walls including reduced increased low frequency headroom and smoother frequency response due to reduced speaker boundary interference and diffraction.

 

Step 1: Speaker Selection

The first step is to select the speakers that will be installed in the baffle wall. There are obviously many ways to select loudspeakers. For a home theater that replicates the commercial cinema experience narrow down your selection based on loudspeakers that can reproduce THX reference level 105dB peaks. You might also want to choose loudspeakers that are designed to be baffle wall mounted (many are not and have baffle step compensation circuits that cause bass boost if mounted in a baffle wall).

Speaker size dictates baffle wall framing requirements. Deep, heavy speakers may require special shelves or thicker studs to support their weight. In wall speakers will require a more standardized framing approach.

In our demo room we selected the Procella Audio P610, a full range speaker capable of 105dB peaks in our room and expressly designed for baffle wall mounting.

 

Step 2: Speaker Lateral Layout

The next step is to determine where the left, center and right speakers will go since the baffle wall needs to be designed around their locations. This is done by following the speaker layout rules.

In the Acoustic Frontiers demo room we used a large screen for a 50 degree viewing angle (see our home theater viewing angles article). Because of the narrow width of the room we chose to place the left and right speakers inside the edges of the Seymour Screen Excellence 4K acoustically transparent screen rather than outside, which would have resulted in the speakers being located close to room corners (an acoustically sub optimal location).

 

Step 3: Subwoofer Selection / Layout

The subwoofer system must be designed to provide consistent, THX reference level bass (115dB peaks) to the primary seats in the home theater. Typically this means two or four subwoofers, some of which will be located at the front of the room. A baffle wall provides a great opportunity to hide subwoofers and so the subwoofer selection and layout process should be done before completing the baffle wall design.

The demo room has four subs, two front and two rear. The two front subs are shallow format Procella Audio P10. These are dual 10″ driver subwoofers, 7″ deep with side input cabling. Procella Audio also make dual 15″ and dual 18″ subwoofers.

Subwoofers are typically the deepest object in any baffle wall and most high performance 12″ subs are 20″ deep with rear entry cabling. This means the front of the baffle wall ends up maybe 22″ off the front wall without using shallow format or in wall subwoofers. Alternatives to shallow format Procella Audio subwoofers are few and far between – our extensive search has led us to in wall subwoofer from Triad and Artison.

 

Step 4: Screen Selection / Speaker Vertical Location

The fourth step is to determine the screen size and vertical location. This must be done in order to position the speakers appropriately relative to the screen center.

The vertical location of the screen is chosen such that the top of the screen does not exceed 15 degrees from the position of the viewers. Once this is done we can locate the left, center and right channel speakers relative to the screen. We do this by placing the speakers such that their acoustical center (typically midway between high frequency and midrange drivers) is between 1/2 and 5/8 of screen height.

 

Step 5: Baffle Wall Design

Now that we know the locations, dimensions and weight of speakers and subwoofers we can layout the framing such that they are supported and sufficient clearance is left around them.

In wide or tall rooms the baffle wall can be built as three individual sections around each speaker, or can have cut outs to allow the space behind the wall to function as a bass trap.

Baffle wall design is one of our consulting services, typically following on from theater design. Done correctly it should allow any competent craftsman to build a baffle wall optimized for your specific room, speakers and subwoofers.

 

Step 6: Baffle Wall Build

It’s important to build a mechanically solid wall without gaps between framing members to avoid buzzes, rattles or resonances that can result from a poorly assembled structure.

 

Step 7: Baffle Wall Finishing

There are many options for finishing the baffle wall including paint, foam and fabric. In this particular room we installed fabric track and stretched black speaker grille cloth fabric over the whole wall.

14 thoughts on “Baffle Wall Case Study: Acoustic Frontiers Demo Room”

  1. What fabric track did you use? I’m making a baffle wall and like the final picture on the way yours turned out. Did you put anything over the frame except the fabric track and speaker grill cloth? Any sound absorbent or dampening material? Foam etc?

  2. Nyal, thank you for the very informative write up on the baffle wall.

    In situations where the baffle wall is built upon a decoupled stage ( to minimize vibrations from the sub woofers) how is the attachment of the baffle to the room walls and ceiling handled? Is there a method of decoupling employed such as the use of DC05 clips, so as not to overide the stage decoupling efforts?

    Thanks
    Steve S.

    1. Hi Steve,

      Yes, there are a number of RSIC isolation clips that work for the purpose of isolating baffle wall from wall and ceiling structures. If you are using hat channel in the walls and ceilings we generally tie into this.

      We don’t normally specify decoupled stages, though I know quite a few designers that do. The reason is that we like to spread the subs around the room to smooth out the low frequencies. If I was designing a baffle wall to sit on top of an isolated stage then I’d tie the baffle wall into the stage and then use the aforementioned RSIC clips to decouple the baffle wall from the room walls and ceiling.

      Thanks,

      Nyal

  3. Any chance we could see a few pics of the finished baffle wall?

    What did you use to cover over the speakers?

    Thanks,

    Rob

  4. Are the speakers simply placed in the spaces? Are they attached in any way? What is the gap between the speaker sides and baffle wall space? Do you fill that with anything and some type of refraction still obviously occur at the interface? If you could literally attach the speaker to the baffle wall with no gap, would that be a benefit or a problem?

    1. If you are using box speakers, then you just place them in the openings, and use something to decouple them from the shelf that they sit on such as sorbothane or foam feet. I’d also advise adding some foam around the speaker edge to prevent it moving over time resulting in hard contact of speaker cabinet to baffle wall, which will lead to buzzing and rattling.

  5. IF……you were to use rear ported speakers, would the insulation behind the baffle wall simply absorb the majority of the port sound? Or would you plug the ports?

    IF….. you used a regular speaker with baffle step compensation, would this be mitigated or improved if you set your small speaker rolloff frequency at 80 or 100hz, assuming that the baffle step occurs below these frequencies?

    1. Ports are used to extend the LF performance of a speaker. Port tuning is normally below 60Hz, so if you are using subs and crossing over the main speakers to the subs (i.e. bass management) then you can plug the ports.

      Baffle step compensation circuits are normally set with corner frequencies quite high, say 800Hz or more depending on the speaker’s baffle width. In a baffle wall there is no loss from the transition from half to full space, so you’ll now have a boost below the baffle step compensation corner frequency. This site has some good basic info on baffle step compensation circuitry and how it works: http://sound.whsites.net/bafflestep.htm

Leave a Reply to Louis Cédric Cancel reply

Your email address will not be published. Required fields are marked *