Dual 18" 2245H Woofers Built Into Wall and Tuned To 20Hz With Pictures...

[hightechhick]

The goal of this thread is to share my completed dual 18" 2245H project with pictures.

This project started in early January 2009 and was completed in August of 2009. I did not count how many man weeks it took to complete this project, but there were ten people involved and I would like to thank them formally now

The goals for this project were to improve the appearance of the existing 2245H installation while adding another, drastically improve the acoustics of the room, improve the appearance of the room, and increase the stage area by ~50%.

I have information on the fire rated wall carpet. Please post on this thread if you are interested.

The next project is to replace the satellite speakers shown here with a pair of 4435 clones I already have parts for. BTW these are Peavey PR12's that are now bi-amped with the Peavey version of the JBL 2206H woofers and JBL 2426H mid/high horn drivers.

Given:
-Both subwoofers are the JBL 2245H.
-Both subwoofer cabinets are 12 cubic feet and tuned to 20Hz.
-The cabinets were designed using WinISD beta (thanks Rob!).
-The ~9db boost at 20Hz was accomplished using a parametric EQ.
-The original room was ~3,000 sq. ft. with acoustic tile ceiling, office carpet floor, 12' 5/8" drywall on with all perpendicular wall angles.

-The finished room is ~3,000 sq. ft. with acoustic tile ceiling, office carpet floor, 12' 5/8" drywall covered with 5' horizontal fire rated wall carpet along the sides centered at standing ear level. The wall behind the stage was broken into thirds with the two outer sections being angled at 22.5 degrees. The wall behind the stage was also completely fire rated wall carpeted except for the 10' projection screen.

-The 2245H's were both installed in 3/4" plywood cabinets that were built into the new angled wall sections. I emphasized internal cabinet bracing in this design which really made a noticeable improvement in sound quality.

-This room is the Senior High youth room (The Shore) at my local church. Church is cool with our audio projects because it gives us a way to use our energy in a positive way that many can benefit from (it keeps us off the streets...).

[hightechhick]

Here is the room before the project. The walls were so reflective it was difficult to talk in this room not to mention how bad the audio was.

[hightechhick]

Here is the beginning of the built in 2245H subwoofer cabinet framing. We had to use metal studs to comply with local fire codes In case you are wondering if these tend to rattle, the answer is yes. Extra care had to be taken to secure them... I was able to use plywood for the cabinets because I convinced the fire marshall they are furniture and not part of the building. I nearly had to install a sprinkler above each woofer cabinet, but I did not have to because the non-woofer portion of the cabinet was made out of 5/8" type X drywall. I'm glad I asked because rework would have been - a bummer.

[hightechhick]

Here is the area we built the cabinets in.

[hightechhick]

Here is the beginning of one cabinet. I had to make them triangle shape to fit in the angle wall behind the stage. I wondered if this shape has any drawbacks? It sounds very similar to other 2245H cabinets I have built. I used ~1" pink fiberglass insulation on both back sides. Vertical bracing was installed before the fiberglass was applied. The vertical bracing was offset of vertical center by design. Much more bracing was installed as the cabinets were built.

[hightechhick]

Here are both cabinets installed the framing. Notice the front of the ports are protruding by 1/4" to make them flush with the future wall carpet.

[hightechhick]

Here are the 2245H built in cabinets with drywall installed.

[hightechhick]

Here the fire rated wall carpet is being installed. (Thanks Jason ). The plywood was spackled, primed, and speaker/woofer ports spray painted black before the carpet was installed. It was amazing how the room began to sound better at this point!

[hightechhick]

Here is one 2245H mounted in the wall cabinet before the protective grill was installed. Notice the three single gang boxes installed to the right. The upper is a hotel type Intermatic wall timer for the future mini power amp rack that will sit on the stage in front of the right most woofer. I desperately wanted to make a built in rack for the amplifier, but there was insufficient depth of the angle wall. The timer controls a single gang outlet that will be at floor level of the stage. This solves the problem of others accidentally leaving the subwoofer amp on for days at a time as its power source is not controlled by the sound booth. The unfinished single gang box at the bottom is for the return of both subwoofer speaker cables. I use the heaviest low voltage lighting cable I can find (12 gauge I believe) which has a polarized jacket and is much less expensive than labeled speaker cable of the same gauge.

[hightechhick]

Here is an actual screen shot of the primed and painted wall between the angled subwoofer cabinets. I used Porter Paint's Silken Touch interior paint in pure white with Eggshell gloss. This works great for DIY wall projector screens IMHO. The camera was lower then the center of the picture which is why the sides are "trapped".

[hightechhick]

Here is a shot of the finished wall carpet behind the stage with wall carpet also running at standing ear height along both walls. The room at this point sounds tremendously better!

The next project is to replace the satellite speakers shown here with a pair of 4435 clones I already have parts for. BTW these are Peavey PR12's that are now bi-amped with the Peavey version of the JBL 2206H woofers and JBL 2426H mid/high horn drivers.

[jbl4ever]

Nice job Hightechick. With almost 3 decades in the commercial carpentry
field I have worked with fire treated lumber. It does cost almost 2x as
much. It is usually a light pink or deep purple in color. It does meet all
the fire requirements. Have used it in the Playboy building and the ATT
towers plus to many to think of. It comes in 3/4" plywood and 2x4 and larger.
If you have to frame more put in some header bridging to help brake up
the vibration nodes. If the back side is not finished lay the back layer
down instead of standing the sheets up. Put a double layer on it. Their is
also core board at 1 and 1/4'' thick but is only 24'' wide
Also use 20 gauge or thicker metal studs. All of the above will not be found
at your box stores but a good building supply house.

[Fred Sanford]

Nice work, I admire your dedication.

Two quick questions come to mind: are those 2245Hs for live PA (microphone & instrument) use, or like a DJ system? And, is that timer rated for the draw you'll see with sub amps? I've seen those things go up in smoke with heavy loads on them.

je

[hightechhick]

This system is used for several things. It is used for live PA, some DJ type playback, and my off hours personal listening. I used the 2245H's because I am very familiar with them. I like listening to Virgil Fox pipe organ media, so I designed a system that is ~flat to 20Hz.

The timer switch is rated for 15 amps if memory serves. I am using one stereo amplifier for the subs which is on its own leg of an existing circuit. I never put an Amprobe on it to see what it draws, but it has never been a problem.

Nice work, I admire your dedication.

Two quick questions come to mind: are those 2245Hs for live PA (microphone & instrument) use, or like a DJ system? And, is that timer rated for the draw you'll see with sub amps? I've seen those things go up in smoke with heavy loads on them.

je

[hightechhick]

Great input! I could have saved some headaches by using the treated studs. This information would be very helpful to other building in commercial settings.

Nice job Hightechick. With almost 3 decades in the commercial carpentry
field I have worked with fire treated lumber. It does cost almost 2x as
much. It is usually a light pink or deep purple in color. It does meet all
the fire requirements. Have used it in the Playboy building and the ATT
towers plus to many to think of. It comes in 3/4" plywood and 2x4 and larger.
If you have to frame more put in some header bridging to help brake up
the vibration nodes. If the back side is not finished lay the back layer
down instead of standing the sheets up. Put a double layer on it. Their is
also core board at 1 and 1/4'' thick but is only 24'' wide
Also use 20 gauge or thicker metal studs. All of the above will not be found
at your box stores but a good building supply house.