Simple False Corner

[PrestonTom]

I am showing off the result of my latest project. The attached file shows a fairly simple false corner.

Although it is half a corner, maybe we should call it a "false wall". This was inspired and designed by modifying some very helpful info that I found in various threads. My goals were create a false corner that was 1) portable, 2) somewhat unobtrusive and having some design elements that would compliment the listening room 3) not alienate my girl friend and 4) not cause irreversible modifications to my K-Horns. I'll post the construction details and hopefully inspire some others. It is a fairly simple build. It only requires a single 4x8 sheet of MDF a, some 2x4's and moulding (which can also be chosen to compliment your specific application).

Importantly, it allows one to put their K-Horns in a corner (this is critical and if you're not doing this already, you are in store for a big improvement) and perhaps also to space them apart for improved imaging. Again, this capitalizes on the work of others, but includes some details that may solve some individual problems.

Good luck and I hope this is helpful.

-Tom

[PrestonTom]

Step One: mount 2 brackets with small screws (less than 3/4"). These do not have to be massive and will be used to pull the false corner to the cabinet (actually the pipe foam insulation on the horizontal - which is removed in this photo). The pipe insulation acts to seal or close the volume (the final flare of the horn). Since the foam is somewaht air-tight (just try and blow through it to see this) it only needs to be a snug fit. You will not need a lot of brute force to make this sufficiently tight.

[PrestonTom]

Step Two: Use a piece of thin plywood for later attachment to the brackets. Then drill a pair of holes to receive the toggle bolts. I used bolts that were 5" long. By mounting this plate you can be less precise in drilling the corresponding holes in the false corner (that the toggle bolts will go through). Also, by using toggle bolts you are not drilling into the actual cabinet. This a can also be unfastened and re-fastened a number of times without chewing up the wood. Remember that doing this on the right side of the cabinet is easier. If mounting on the left side, you will need to avoid the crossover. You will notice some flex in the plywood plate. This is okay. You are not trying to directly couple the false corner to the cabinet. In fact the pipe foam (attached later to the horizontal) will create the seal and also help dampen the vibration to the false corner (via the impedance mismatches between the cabinet/pipe foam/false corner). You do not want sympathetic vibration in the false corner. This possible vibration is also minimized since the false corner is sufficiently massive and dense (thanks to the MDF construction with loads of nails and glue and bracing) - the beast will eventually weigh 96 lbs. I know since I had to carry it up the stairs.

[Daddy Dee]

Interesting solution. Hope you can post some pics when you get everything in place.

[PrestonTom]

Step Three: This depicts the bracing with the MDF nailed on one side. Use plenty to nails and glue to stiffen up this structure. I chose to orient the 2x4s on the thin side so the total thickness is only 2.5" thick (the MDF was 1/2"). This was a design decision and certainly one could use 3/4" MDF and also re-orient the 2x4s in the other direction (if you do so you will need longer toggle bolts).

Incidentally all materials are available at Home Depot and if you do not have a truck you can get the MDF in 2x4 or 4x4 sheets ( I used 4 2x4 sheets). By mounting the MDF up on the 2x4s (see bottom of picture) I was able to lift the entire corner to about 51.5" (since the MDF is only 48") before the final trim goes on. Incidentally the bottom pair of 2x4s were oriented in the wide direction so the MDF would fit on top of them. In order to get the proper width, the 2x4 were ripped down their length. This is trivial with a table saw but a bit tricky if you are using a circular saw. However the final trim moulding will cover the 2x4s and most mistakes.

This total height will clear the top of the speaker cabinet. The front half was not as tall. This was a design issue since I did not want the back of the corner (which faces my front hall to be too obtrusive - again it is a series of compromises) But the front should be at least as tall as the bass bin. Notice the center/vertical 2x4 runs the entire height (and is notched). If you are using small sheets of MDF (as done here with 2' x 4' sheets) and making the front half not as tall, then make sure this center "post" is constructed this way.

At this point you should align the false corner with the cabinet and mark the holes (on the false corner) where the toggle bolts will go through (if you look carefully you can see them in the photos on the right side in the 2nd 2x4 down from the top). Note that my false corner has a strip of pipe foam that is glued (contact cement) on the very bottom of the structure. Put this on now before making the measure. The pipe foam was 1.5" diam and then cut down the middle. This gives an airtight seal on the bottom and allows you to slide the false corner into position.It also adds to the height of the false corner - so take this into account. It also protects my hardwood floors from scratches. It is best to use contact cement rather then mechanical fasteners because they might scratch the floor or snag a carpet.

The verticals on the left side (you are looking at the outside of the corner - not the speaker side) will later have 1x3" poplar (or pine) ripped to the proper width and nailed (finish nails) to the edges as well as the horizontals (tops). this will add an extra 3/4" and provide a smooth surface for painting (as opposed to the rough 2x4 material. Include this thickness in your measurements.

[PrestonTom]

Step Three continued.

This is simply the the edge view from step three. The 1x3 poplar (or pine) will hide the 2x4s and edges of the MDF

[PrestonTom]

Step Four:

I chose to fill the voids with insulation. This picture shows far too much insulation being stuffed in there - I eventually removed some (and yes, it is very itchy). An alternative is to fill the cavities with sand. This may be a bit over the top however.

Note, since the toggle bolts go thorough a 2x4 brace the sand would not spill out.

Next step is to go ahead and attach the MDF on the other side with glue and nails

Then : Finish drilling the toggle bolts holes through the other side (MDF)

Then: drill a recess through the MDF for the head of the toggle bolt (a cap can fit into the recess and will be flush with the surface). Just make sure this cap or cover is removable.

[PrestonTom]

Step FIVE:

The edge trim (the 1x3) on the front vertical and tops was cut, routed and nailed on. Along with various other bits of trim and moulding. Make sure the tops are well secured since these may be the "handles" when you are moving the structure

This is your chance to match/blend/compliment the various kinds of interior details of your living room.

The WAF is a make or break at this point.

Spend some time on spackling and sanding (in the garage and not the living room - there will be dust everywhere)

I moved the beast upstairs (it weighs 96 lbs and I am not as young as used to be ...)

Ready for prime (two coats is best - I use the BIN products) and then two top coats.

We are very close to completion!

[PrestonTom]

Step SIX:

Attach some pipe foam insulation where the false corner meets the real wall. This helps with forming the corner, it also fills in any gaps since there is base molding on the existing wall. It also helps to minimize any dents or gouges in the existing wall.

[sunnysal]

what goes on the other side of the klipschorn to creat a corner? maybe I missed that photo? thanks, tony

[PrestonTom]

Step SEVEN:

Attach the pipe foam alng the horizontal surface of the cabinet (this is physically what the false corner will be hugging up to.

You may have noticed my K-Horns are on pads. This makes them easier to slide out of the corner. However, it does create an air gap in what should be the final flare of the horn. That is why I stuffed some small diameter foam insulation under the side edges (it can not be seen in this photo).

Now the false corner can be slid into position. At this point it is like dancing with a big woman. Because of the weight, slide the structure all the way back into the real wall (i.e., compress to pipe foam on the back edge). At the same time shove the bottom in tight. Now pull the top back to expose the toggles (yes, slide the bolts through the structure then attach the toggle on the inside of the corner and slide the toggle through the plywood plate (attached to the previously installed brackets). Now tighten up the toggles. This sounds deceptively easy - it is not since the false corner must be plumb and parallel with the cabinet and floor and also at a right angle to the wall. However you will get the hang of it. At this point a level will help.

You are now the proud owner of a one half of a false corner!!

[PrestonTom]

Things are complete. The real wall creates the other half of the corner. And you can move the cabinet along the wall and adjust the distance between the cabinets. This will allow you to adjust the width of the sound field. And in my case allowed me to place the K-Horns along the long wall (which opens up to a front entry way).

There are many good threads regarding false corners. But if you have been shy about building something that is very large or may require drilling/cutting into you walls or the K-Horn cabinet, then this might be an alternative. It is fairly simple to construct (in spite of my directions) and can be adapted to various environments. However it is not appropriate for a bringing a speaker away from the wall and into the room or for toeing in a cabinet (you need at least one real wall). However others have posted plans for those conditions.

I no longer have ready access to electroacoustic measurement equipment so I can not provide before-and-after measures. However the sound is fantastic. I hope this is useful for someone who has corner horns but has not been able to put them into corners.

Good luck,

-Tom

[Tom Mobley]

Looks pretty good Tom. Good work and pics too. WAF should be pretty high also. Funny how much those pieces of trim along the top make it look so much more like like part of the home.

PS is Tom your first name? I assumed it was, probably because my first name is Tom.

[sunnysal]

oh now I get it! nice work, looks great! regards, tony

[Daddy Dee]

Yes, I agree with Tom. It looks more like an architectural room divider than a false corner. Very nice.

[SilverSport]

Very nice...

Bill

[3dzapper]

Most excellent Tom! and as you say great WAF. I have filed this advice in my "in case" memory bank. Thanks for sharing.

Rick

[Deang]

A thread to bookmark. Excellent work Tom.

[PrestonTom]

I have attached another photo of the project.

I wanted to thank all of you for all the nice comments, this was especially gratifying since I know some of you have had 1st hand experience at dealing with this stuff - thanks

BTW, I know there have been various threads that advocate the importance of getting a good seal when shoving the K-Horn into the corner. Perhaps achieving this with the use of the pipe-insulation (closed cell) between the cabinet and the wall.

Let me second those opinions! It does make a noticeable difference and it is a fairly simple and inexpensive thing to do.

Alas, my K-Horns are now along the long wall (and forming the 90 deg listening-triangle). Life is almost perfect but I need to do something about that that "hole in the middle".

I am on the lookout for a center channel, preferably a La Scala or a Belle. You know, this quest (hobby) never ends.

-Tom

[ricktate]

Very nice, Rick