JL 8w7 built in cabinet

[adwilk]

Can we help this guy model a sub for a built in cabinet? Its in THIS THREAD

Thanks y'all....

 

[Adam]

Unless it's at Amazon with an "Add to Shopping Cart" button, then I'm useless to you. There are plenty of folks here that can, though (as you know).

Nice little loop that you created with your thread links. Went to the original, which then directed me here.

 

[adwilk]

Nice little loop that you created with your thread links. Went to the original, which then directed me here.

Exactly, while you can buy non-disposable coffee cups, I can link threads... I wonder who wins?

 

[Adam]

I wonder who wins?

Everybody, brother. Everybody.

[Yeah, I had nothing.]

 

[adwilk]

/thread

 

[Bushka]

Thanks Adwilk, I'm the guy who needs all the help.

Based on discussion in this forum, and some phone calls to SpeakerCraft, I'm looking to install 5 ceiling speakers (SpeakerCraft AIM7 Three's) to go with a Samsung 6000 LCD/LED. Based on my neophyte knowledge of audio set up, I need a receiver to connect the TV and the BluRay, the cable box, and speakers. I guess I need a separate amp for the subwoofer, which adwilk recommends to be JL Audio 8W7. Of course the wife requires that no audio equipment be visible other than the speakers in the ceiling (RF remote for receiver and hopefully cable box). This room doubles as a living room and entertainment, you get the idea.

So now it looks like we're looking at a DIY job to build the sub box into the built-in cabinet. It will fit into the area between the fireplace enclosure and the short wall to the right. By the time the stone veneer is put on the fireplace, the cabinet will be about 45" wide by about 21" deep. This isn't completely DIY as I have a cabinet maker who will do the built-in cabinets to the left and right of the fireplace.

I'm going to post a CAD drawing tonight if I can to see if I'm understanding what we're doing.

Thanks for any comments/suggestions.

 

[adwilk]

To clarify, the subwoofer will be created using the JL8w7 as the speaker and the OAudio Bash Amplifier.

http://www.oaudio.com/500W_SUBAMP.html


My suggestion is not buying a commercially produced device. The two components listed above allow you to build your own. It will connect directly to the receiver.

 

[Bushka]

I understand, adwilk. Oddly enough, I can't access your link as my malware detector is saying that link contains some kind of infection. It doesn't like anything from www.oaudio.com. Sheesh, nothing's easy anymore!

 

[Bushka]

OK, so I've gone to the Oaudio site (had to disable Malware detector) and it seems fine. I don't know about the accessibility issue as I'm still unsure how the box, driver and amp come together. Is the box divided down at the bottom with the driver facing downward and sound coming out of the open toe kick area, and then the amp is mounted on the side of the box? If so, then I would probably be able to access anything I needed by removing the plate amp. It seems to be a large enough opening to allow access to the driver, assuming the driver can be removed from the backside.

Here's a drawing. Is this what we are talking about, conceptually? If I can get dimensions and other important measurements I'm sure I can put together a design the cabinet maker can follow. Would 3/4" plywood be stiff enough, or is MDF preferred?

 

[annunaki]

What are the allowable dimensions you have for the sub enclosure space? This will determine what application/orientation will work best for the driver.

Will the driver front fire through the grille of the cabinet opening?

You will want to line the cabinet with a heavy duty foam to isolate the enclosure from the cabinet. They make sheets of heavy duty foam that are available for purchase in varying thicknesses from www.mcmaster.com

 

[lsiberian]

http://www.drmarksays.com/wp-content/uploads/2008/07/jl-audio-8w7-3pro.pdf

Go with his design he's an expert and considers all factors.

 

[Bushka]

http://www.drmarksays.com/wp-content/uploads/2008/07/jl-audio-8w7-3pro.pdf

Go with his design he's an expert and considers all factors.

I saw this the other day. My problem is that I have to decode what much of it means. I can figure out Vb as Volume of the box (interior or exterior?), but what is Vtotal? Also it looks like the opening is 2.5" by 6", but what is the 37 some odd inch dimension for? What is "one side flared"? What materials are best to use?

Maybe there is an FAQ for DIY jobs I need to look for. If not, I'm sure the others will help me so I can actually build or have something built to the correct specs.

Thanks again!

 

[lsiberian]

I saw this the other day. My problem is that I have to decode what much of it means. I can figure out Vb as Volume of the box (interior or exterior?), but what is Vtotal? Also it looks like the opening is 2.5" by 6", but what is the 37 some odd inch dimension for? What is "one side flared"? What materials are best to use?

Maybe there is an FAQ for DIY jobs I need to look for. If not, I'm sure the others will help me so I can actually build or have something built to the correct specs.

Thanks again!

The things to pay attention to are the port dimensions and the Vb(internal volume.)

You can use Boxnotes to get the right Vb for your dimensions.

 

[Bushka]

Where did everybody go?

Anyway, I found Boxnotes and downloaded it. I guess what I am seeing is that there will be an acceptable solution for the subwoofer installation. This will allow me to go ahead and get the speakers on order. I won't move ahead with the sub until the cabinets are ready to be built, which could be a month or more away. I'll do what I can with Boxnotes and get back to this forum with my results. Hopefully then someone can guide me along with the details.

Thanks for all the advice!

 

[Bushka]

I'm Back

Hi all. Unfortunately I had to put this project on hold for awhile, which turned into a loooong time. I'm finally ready to have the cabinets built so I need to figure out whether I can build a subwoofer into the cabinet.

Just as a recap, I need to build a sub, or locate a sub, inside the cabinet so that it won't be visible. The idea I was trying to accomplish was to build the box into the cabinet (see prior drawing in post above) and allow the box to vent out the bottom near the floor. I won't be having any screen doors - everything will be solid wood which complicates things.

I looked at boxnotes and tried to figure out what everything means. I also looked at the assembly example and see that he uses PVC pipe to vent the speakers out of the box. Are those necessary? Of course in this situation I am trying to vent the box at the bottom front near the floor, kind of like an open toe kick.

Here's an updated pic of the space. I note that the outlets in the wall might interfere with a sub box.

Maybe I need to contact the Boxnotes guy, but I'm hoping to get a little direction on this project. First of all, is it going to work? I want to vent out the toe kick but boxnotes seems to be very specific as to where and how to vent (using PVC, too). Also, how do I determine the size of the box? Do I start with the size of the speaker, get a volume, and then work out the dimensions?

Any help is appreciated!

 

[annunaki]

Hi all. Unfortunately I had to put this project on hold for awhile, which turned into a loooong time. I'm finally ready to have the cabinets built so I need to figure out whether I can build a subwoofer into the cabinet.

Just as a recap, I need to build a sub, or locate a sub, inside the cabinet so that it won't be visible. The idea I was trying to accomplish was to build the box into the cabinet (see prior drawing in post above) and allow the box to vent out the bottom near the floor. I won't be having any screen doors - everything will be solid wood which complicates things.

I looked at boxnotes and tried to figure out what everything means. I also looked at the assembly example and see that he uses PVC pipe to vent the speakers out of the box. Are those necessary? Of course in this situation I am trying to vent the box at the bottom front near the floor, kind of like an open toe kick.

Here's an updated pic of the space. I note that the outlets in the wall might interfere with a sub box.

Maybe I need to contact the Boxnotes guy, but I'm hoping to get a little direction on this project. First of all, is it going to work? I want to vent out the toe kick but boxnotes seems to be very specific as to where and how to vent (using PVC, too). Also, how do I determine the size of the box? Do I start with the size of the speaker, get a volume, and then work out the dimensions?

Any help is appreciated!

PVC is not required for venting. A slot vent can be built with wood (recommended with W7 series drivers) to accommodate any size vent. With vented enclosures, vent surface area, vent length, and net enclosure volume all contribute to determine tuning frequency. The shape of the vent does not come into play here necessarily.

What you want to do is completely possible so long as the area will accommodate the required enclosure volume. I would recommend a very well braced and isolated enclosure here. It would seem to be a more challenging build however.

 

[GranteedEV]

I looked at boxnotes and tried to figure out what everything means. I also looked at the assembly example and see that he uses PVC pipe to vent the speakers out of the box. Are those necessary? Of course in this situation I am trying to vent the box at the bottom front near the floor, kind of like an open toe kick.

A hemholtz resonantor is a mass of something, that gets exited by internal box pressure and resonantes to create bass waves.

In this case, he was using a mass of air inside a PVC pipe.
You can also use a mass of air inside a folding wooden slot vent.

The main thing with a port/vent is that, because it's a pipe, it'll also have a quarter wave resonance - make sure that it can't be so long that anything in its passband (the frequency range it will be used in) isn't exciting the quarter wave resonance at a high/audible SPL. Normally you don't want a vent longer than around 42" imo for a 80hz crossover. IT'S the cross sectional area of the vent, that determines how long it needs to be to get the right volume/mass of air inside of it.

First of all, is it going to work? I want to vent out the toe kick but boxnotes seems to be very specific as to where and how to vent (using PVC, too). Also, how do I determine the size of the box? Do I start with the size of the speaker, get a volume, and then work out the dimensions

You need to start with the driver's theil/small parameters. It looks like TLS Guy modelled in the past so I would go with his dimensions for excellent results.

Also it looks like the opening is 2.5" by 6", but what is the 37 some odd inch dimension for?

You need to make a rectanglular prism "tube" with those dimensions inside of the enclosure, and that will be the mass of air that is tuned to resonate. It does not count as part of your (internal air volume). This rectangular prism can have an L-shaped bend as long as its total "line length" does not change. 37" is the length of the slot port, 2.5" x 6" is its cross sectional area.

 

[Bushka]

Thanks annunaki and GranteedEV. I'm suffering from a lack of knowledge of terminology and basic construction concepts for sub woofers. I don't want to appear that I want to be spoon fed what I have to do, but some more basic information would be very helpful. At this point I still have no idea what I have to build. Once I understand that part, I can put it together, or have the cabinet maker build it in.

For instance, I don't know what a "folding wooden slot vent" is, or a "rectangular prism." Prisms are triangular, so I'm sure I'm missing something.

I just assumed that I was going to build a box of a certain size as determined by the make/size of the speaker. Then I would mount the speaker pointing down into the top of the box, and the pressure wave/sound would come out of the toe kick area at the bottom of the box. Now it seems I have to enclose the front of the speaker cone in some sort of 2.5 by 6 inch box that is 37 inches long, and empties out into the toe kick area. This 37" box would wind its way back and forth inside the enclosure as needed. I'm pretty sure I'm missing something as the speaker is larger than 2.5 inches in diameter.

I'm getting to understand what I need to do little by little, but I think you guys are all so familiar with this stuff that it is easy to leave out the basic concepts of what I'm really trying to build.

I'm not normally such an idiot on things like this, but I really need some direction from step 1 so I don't begin to annoy everybody with dumb questions.

Thanks again!

 

[GranteedEV]

I think, you're a bit confused and need a visual aid.

Does this pic help any?

http://forums.audioholics.com/forums/showpost.php?p=437759&postcount=80

 

[Bushka]

Yes, Granteed, that helps some. However, I have a big issue that might have been missed due to the length of time I let this discussion sit quiet. What I'm trying to accomplish is to construct a subwoofer that can hide behind a solid wood cabinet. There won't be any speaker pointing out into the room from behind a grill. I was originally asking if I could build something inside the cabinet, and basically point the sub's speaker down and out the toe kick area. However, what I'm coming to realize is that the vent is for relieving pressure inside a box where the speaker is pointing out of the box, and the pressure is due to the motion from the backside of the cone. So the vent isn't meant to be the source of the speaker's sound, but just something to enhance the speaker's performance. I think this added to my confusion.

Does that make sense, and is there a solution? Or is it staring me in the face?