John Sayers' Recording Studio Design Forum

Here is a method for a flush mounting that I developed a couple of years ago. It provides for a simple modification method when upgrading your monitors. It also helps isolate the speaker cabinet vibrations from the control room. The picture below depicts the basic design. The front bezel is clear in the picture to help visualize the whole setup.

Here is an outline of the method:

1. Create an opening that is large enough to accommodate your monitor or any monitors you might potentially use in the future, plus some extra room for sound absorption material. Building a larger space than what you presently need gives you the flexibility to upgrade. Avoid building any structures that directly couple the inner and outer framing.

2. Rigidly mount an adjustable shelf to the inner framing. Mounting to the inner framing isolates the cabinet vibrations from the control room. I've depicted small wooden rails attached to the shelf to maintain the monitor's lateral position. A belt clamp thens hold the monitor firmly to the shelf. The face of the monitor should be flush with the front wall.

3. Screw mount a rigid bezel to the outer framing. The bezel should be flush with both the front wall and the front of the speaker. The more massive and rigid the bezel the better. The opening should not contact the monitor cabinet, but the gap should be no more than 5mm (3/16 inch). You might have the idea of filling the gap with some sort of gasket, but this is both unnecessary and detrimental. Any gasket will increase the transfer of vibrations to the bezel, therefore, effectively increasing the cabinet radiation surface area. Gaps less than a half wavelength will have little effect on wave propagation. 5mm is less than 1/3 wavelength at 20kHz, so audible diffraction induced by the gap isn't an issue. In any case most tweeters radiate very little energy 90° off axis at 20kHz. When you upgrade your monitors all you need to do is remove the bezel and cut a larger size opening, readjust the shelf, then mount the new speaker and screw the bezel back in.

4. Fill the extra space in the mounting cavity with sound absorbing material like fiberglass. This will help absorb sound radiated from the monitor cabinet.

You might have noticed that a big part of this mounting method centers around isolating the monitor cabinet energy from the control room. Loudspeaker cabinets are almost invariably under-constructed and can radiate a significant amount to energy, resulting in coloration. If you follow these design principles, I think you'll hear a noticeable difference from a simple flush mount.

Hope you find this useful!:D

Thomas

Sorry for my lack of clarity. One of our English as a second language members asked me what "bezel' means. A bezel is a rim or frame that encompasses an object. The light blue front panel in my picture is the bezel.

I updated the picture with more labels and reworded some of my description in the post above to make things clearer.

Thomas

Well thanks...
I suppose this could be MDF or something with mass?

Rgd's
Ferry

Yes, MDF is a good choice for the bezel. An MDF/plywood laminate would work very well.

Thomas

Here is another drawing, in case anyone is having trouble envisioning the "big picture" of this design. The inner and outer framing are completely isolated from floor to ceiling. The speaker shelf is attached to the inner framing.


Thomas

Hi barefoot, why I cannot see any picture of the design from my broswer ?
is it attached somewhere ? thanks !
Feni

Feni,

You need to make sure you are logged into the forum. Try logging out then logging back in.

Thomas

Yes ! Done ! Thanx a lot !
Another great design, Thomas !
Feni

What about using a stand instead of the inner framing construction? That would lessen sound transmission to floor as well as lessen sound coloration by vibrations transmitted to the inner frame...

Or am I missing something?

Xspring,

A stand is perfectly fine. The main points of this design are to decouple the speaker from the front wall and make it easy to upgrade your speakers. Everything else is secondary. The reason I chose a shelf mounted to the rear wall is because it provides a large amount of decoupling with a rigid support. It also integrates easily with John's soffit design. But yes, variations on the speaker mounting are no problem.

Here is an example of how you might mount a speaker into an exiting soffit opening using my method. You would attach a frame inside near the front on which to mount the bezel. Then you could mount the speaker on a heavy stand.




Thomas

Bluefield Studios has posted some great construction pics and final pics of their bezel soffit implementation!
Studios Under Construction - Bluefield Studio

For the inside stand - what would be best - rigid attachment to the floor (concrete bolts) or sitting on neoprene?

Thanks

Hello Thomas. My small studio is located on an upper floor, and although it is just my personal studio and listening space, I am trying to treat this room the best I know how. After reading about placing monitors on a decoupler of some kind between the monitor and a massive stand such as concrete, I was concerned about the point load on my upstairs floor. Hence my interest in your soffit framing design.

I am just starting to frame my soffit enclosures, and checked here to update my familiarization with your concept. However, upon further inspection of the drawing above and this statement:



I must be missing a critical piece of puzzle Exactly WHAT isolates these frames from the room envelope, if they go from floor to ceiling as I see what looks like floor and ceiling plates in the framing picture, yet i see nothing that would decouple the inner frame. And since the monitor is rigidly mounted on the shelf which in turn is fastened to the inner frame, how does this isolate anything? It seems to me this directly couples the framing to the room envelope AND the front framing. Wouldn't this be a direct flanking path through the structure to other spaces in the building as well? What am I missing here please? Thanks.
fitZ

Yes, the monitor is strapped to the shelf that attaches to the inner frame. However, neither the monitor nor the shelf touches the outer frame. So there is no direct coupling.

Maybe the top view in my first drawing is misleading? If I remove the horizontal piece of outer framing that's under the monitor, does this make it clearer?

Thomas

Wow, that was fast. Ok, I understand that the monitor and inner frame are NOT touching, although, it would appear that they are STILL coupled via the floor and cieling, no? If the only thing that matters is the baffle on the front frame is NOT physically touching the monitor case, then let me ask you this.

Here is a picture of a TEMPORARY shelf, that I mounted to measure the geometry of the FRONT frame. I was going to remove this and build the inner frame to support the monitor. But from what you've told me, it would appear that as long as the shelf doesn't touch the front frame/baffle, then it would do the same thing, no? Actully, if this will work, I'll further support the shelf with a heavy duty brace back to the wall. Still seems like structural transmission will occur to the wall and then to the soffit face even though the frame/soffit face panel/ and the monitor do not touch. Hmmm. Could you comment on that? I'd sure hate to have these vibrations structurally transmit to the bedroom while my wife is sleeping.
Also, I see no studs at either frame, at the wall connections for a baffle to fasten to for stiffness. Is this unnecessessary?
In addition to that Thomas, I could have sworn that at one time, there was a previous design that used an EXTERIOR box to slide the monitor box into, with only a thin layer of decoupling material between them. What happened to the exterior box??? The reason I ask, is I was going to beef up my monitor cases by gluing a layer of 1" MDF to the existing monitor case with GREEN GLUE. And then slide this whole massive box into the box I am referring to in a previous design of yours. But now, I'm a little confused, expecially with gluing another layer of mass to the existing box.
Are these steps or concepts unnessessary now?

Anyway, the speaker you see in the picture is an OLD JBL studio monitor design, but sounds just fine for my humble purposes, although I plan on filling in the recessed baffle with a layer of MDF and moving the speaker forward flush with the new baffle(which will be flush with the soffit face(baffle extension?).


Thanks again Thomas, especially considering our dissimilar views on other subjects. I finally realized the rediculous nature of the Cave. Ha! You once again prove you are a gentleman.
fitz

fitZ