My Dual 12" Sub Project

[annunaki]

I do not need to load driver dimensions to save???

I usually input the following parameters (I am pretty sure these are all that is entered):

Fs
Qts
Qms
Vas
Le
Re
Sd
Nominal impedance
Xmax
Pe
Number of voice coils
Parallel or series


I let the program calculate the rest. I then check to make sure that the parameters givenb are accurate with what came with the driver.

Depending upon the sub, I will input the dimensions but otherwise I just save it at that point.

 

[jinjuku]

Is Pe RMS or Max?

For connection, I don't really know what they want if there is only on voice coil. I left it at series and the measurements took.

The box shape button doesn't work however.

Thanks. I was feeling like Chewbacca working on the Falcon...

 

[annunaki]

Is Pe RMS or Max?

For connection, I don't really know what they want if there is only on voice coil. I left it at series and the measurements took.

The box shape button doesn't work however.

Thanks. I was feeling like Chewbacca working on the Falcon...

Pe is thermal power handling. RMS is usually the most accurate there. I believe there is only one voice coil on those drivers. Set it to single coil parallel connection.

 

[bmccord]

If you do a search for my user name, you will find several versions of that. There are cad plan and all. I think. I may have erased them from my photobucket. Who knows.

 

[jinjuku]

Proper Amount of stuffing

Hi All, here is a quick and dirty pic. My question is this: The stuffing is simply R13 insulation. Is it enough to line the opposing surface to the drivers?

Yes, I am using 1" dowel rods, screwed and glued to stiffen/brace the cabinet.

 

[annunaki]

Hi All, here is a quick and dirty pic. My question is this: The stuffing is simply R13 insulation. Is it enough to line the opposing surface to the drivers?

Yes, I am using 1" dowel rods, screwed and glued to stiffen/brace the cabinet.

It should be enough. You should have put some rods between the other walls too.

 

[WmAx]

It should be enough. You should have put some rods between the other walls too.

Refer to my post #14 in the following thread where this same poster already asked this question [but apparently did not like the answers I provided him]

http://forums.audioholics.com/forums/showthread.php?p=319320#post319320

The question is: enough to do what? Effectively absorb acoustical energy >500-700Hz? What is the practical application of this relatively high frequency band where absorption starts with the material in question when considering the bandwidth in which a subwoofer operates?

-Chris

 

[annunaki]

Refer to my post #14 in the following thread where this same poster already asked this question [but apparently did not like the answers I provided him]

http://forums.audioholics.com/forums/showthread.php?p=319320#post319320

The question is: enough to do what? Effectively absorb acoustical energy >500-700Hz? What is the practical application of this relatively high frequency band where absorption starts with the material in question when considering the bandwidth in which a subwoofer operates?

-Chris

Enough to make him feel good, really. I understand that absorption materials are unnecessary in these types of enclosures. Some just like to add them for piece of mind.

 

[WmAx]

Enough to make him feel good, really. I understand that absorption materials are unnecessary in these types of enclosures. Some just like to add them for piece of mind.

I see. Well, if the user desires true piece of mind, then he should apply the type(s) and amount(s) of damping that I specified so that if there is a benefit, it will be realized.

If the low density fiberglass is to have an appreciable effect in this application, it must fill the entire volume and be packed into the space in a relatively dense manner.

-Chris

 

[Rob Babcock]

Loooking good! Let us know how it sounds.

 

[jinjuku]

Thanks,

Honestly I have received conflicting information of to dampen/not to dampen. I thought the general rule of thumb is to stuff sealed enclosure and line ported enclosures. This is my first DIY so I expect a few missteps. I will stick with the lined enclosure for now. If the R13 isn't that absorptive, then hopefully I am out nothing more than $10 and minimal bad effect of the sound.

One of the problems is sourcing the mineral board or other dampening materials listed. I couldn't even find 1" MDF for pete sake

 

[jinjuku]

Fired the thing up and it does what I thought. I wish it played a bit louder at low volume, but when you hop on that thing... dear gawd. Not bad for $568. There was more cost over that in tools, but those I get to use again.

You can literally feel everything vibrate. Pics coming.

 

[jinjuku]

Pics arrived

I would say this clocked in somewhere around a 3 on a difficulty scale of 10 (10 being hard). The cuts were pretty easy to make. The router took a few practice runs.

In hind sight a few things I would do differently:

1. With the thin wall PVC I really didn't need any internal support. Just glue into the routed holes and let it dry. Strong as an ox at that point. I think even over time with gravity on it, they will hold.

2. I should have put the PVC in LAST. It would have made reaching through the speaker holes and sealing the seams and corners MUCH easier.

3. Not have been cautious by not putting higher end drivers in (the Dayton RF 12"ers vs the Quatro). I was scared at screwing up a $260 pair of drivers. They model better at the lower frequency end of things.

4. Just used wood screws to mount the drivers, not the $3 mounting kit (Hex screws and T-Nuts).

5. Devise a way to make the speaker baffle both air tight and easy to remove.

Things I would do again:

1. Not use a plate amp when an external amp like the Behringer is at comparable cost. IMO the Behringer is the better amp.

2. Use 1" or 1 1/2" dowel rods for bracing. Forget about routing out braces. Dowel rods are rigid and rounded (air flow). Easy to work with.

3. Screw and glue. I know designs call for just glue and clamp. Screws helped speed up the build process.

4. Get table saw extension for running larger cuts. Saw won't bind and cuts will be uniform.

5. Use a non-silicon based RTV sealant. Worked great for keeping seams airtight.

All I have to do now is sand, seal, prime, and paint. Wife gets to choose the paint...

 

[annunaki]

Any plans on finishing it? How did the interior of the enclosure turn out? Any additional bracing? How does it do down real low (20hz-30hz)? I know you tuned it to 18hz or so.

Are those single coil 8 ohm subs? how do you have the amplifier wired? You only have one channel turned up? Is it run in mono (bridged) into 4 ohms??? If it is don't plan on the amplifier lasting too long?

 

[annunaki]

"2. Use 1" or 1 1/2" dowel rods for bracing. Forget about routing out braces. Dowel rods are rigid and rounded (air flow). Easy to work with."


While this seems like an easier route to go it's benefits are not nearly as realized as with window type routered braces. Well placed window bracing will do what 6 properly placed dowel rods would if used in the same manner. Who said enclosure building is supposed to be fast and easy. Taking the time and using proper techniques will yield much stronger results.

 

[jinjuku]

The box is solid with the dowel rods in place. Really solid. There are a total of 6 dowel rods. 3 horizontal and 3 vertical. There is no box buzz or anything. I think the dowel rods proved more than adequate.

The Quatros are 4 ohm each and wired in series. So 8 Ohm load. The Behringer is bridged mono and rated mono for 500 watts at 8 Ohm. The speakers are 250 watt RMS. So this should match up with the amp quite nicely.

I will be doing a paint finish vs. veneer. The inside finished up nicely. I will do some testing with some tones at a later date.

The thing simply "growls". Hits like a sledge hammer. My wife busted me. She heard it in the parking lot (she came home early). Oops I have to put it away now...

 

[annunaki]

It is a very good effort for your first build. It is great to see you tackle the diy route.

While I don't doubt the box is pretty stong, I think you would be thoroughly impressed at the difference between an enclosure braced like yours vs. a proper "window" braced box. When you rap your knuckes on some boxes I have done (with window type bracing) it sounds like hitting a tree trunk.

For the dowel method to equal the "window" method you would need roughly six dowels where each window would be placed. Three horizontal and three vertical.When I do window bracing I like it to tie all six panels together so it forms a totally solid structure.

Again, I commend you on your first build. I am glad you are happy with it.

 

[Rob Babcock]

The next step: adding a 2nd one!

 

[jinjuku]

What kind of setup is required to churn out window braces? I would really like to get into a table router, use 1/4" cut bit with a bearing and use a melamine board cutout as template guide for the bearing. I am assuming that is how you would economically do this.

I am not disagreeing with you on the window bracing vs. dowel rods. I only have so much at my disposal (read OTHER peoples tools ) to do this with. I had to drive 3 hours to my friends house in Ohio and had two evenings to get all the cuts and routes done. Assembly happened back here in Michigan.

Can't wait for the wife to finish her dissertation and get a job. Then we can get a house. We live in family housing right now. You can imagine how well this monster will go over with the neighbors!

I am so bitten by the bug it isn't funny. My wife is a saint.

 

[annunaki]

I actually have used a decent jigsaw for all of my cuts so far (other than cutting the large pieces). I have a good plunge route on my short list though.