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Discussion in 'Home Theater Projects' started by Bill**H, Apr 2, 2004.
If so how do I keep it out of the ports?
You don't need to (or want to) completely stuff or fill a vented sub enclosure. This will change the modeling significantly. For a sub, you can get away with no absorptive material at all since the frequencies are below anything that the lining will absorb anyway. Nevertheless, most builders do line their enclosures with an inch or two of fiberglass, dacron, acoustic foam etc. It does help reduce coloration by damping cabinet resonances excited externally or from distortion/harmonic components created by the driver or electronics chain.
BTW, for sealed subs, heavy lining of filling can increase the apparent box volume... allowing a slightly smaller enclosure.
I understand your point about stuffing a sub, however, in this case not putting in stuffing would change the modeling wouldn't it? I don't think Adire is in the habit of telling you specific amounts of stuffing to use on a whim. If it makes it easier, I suppose you could use 64 ounces of batting or use a piece of grill cloth inside to keep the stuffing away from the ports. On the other hand, if you have front firing ports you get a fun little "indoor snow" effect when it blows out the ports
You're right. Sorry for oversimplifying. :b Yes, changing the amount of stuffing changes the enclosure Q which does have a minor effect on vented system modeling. I haven't read the Adire plans, but I doubt that they recommend stuffing the entire enclosure --such that keeping stuffing away from the driver or from having it "blow out the ports" is a problem...
If you get polyester "pillow" stuffing and don't tear it up into tiny pieces it shouldn't blow out of the ports. I just "fluff" it up to increase the loft.
On the other hand, if you pick up Polyester "clusters", it'll probably come out of the ports.
Remember, those ports move air "in and out" so it's not like it's a blower that's designed to shoot things out of the box.
IIRC, all of Adire's ported designs call for NO stuffing. So I'd only stuff it if you decide that you want to alter the sound.
The reference design for the Tempest in the vented Adire Alignment enclosure calls for 64 ounces of polyfil.
Maybe I'm thinking of the Shiva designs?
Yep. No stuffing in the vented Shiva designs. Interesting. There's another discussion going on about the amount of stuffing in a TL and the possible misconception that overstuffing is taboo. Apparently in some cases in helps even out the bass response which results in a perception of more bass.
I wouldn't be surprised if stuffing for the ported Tempest alignment comes from trying to keep the enclosure size as small as possible without further compromising frequency response and performance.
Well, I stuffed it close to Adire's wishes, I used 60 ounces of polyfil. It was the loose kind but, if you take it out of the package it will unroll like a sheet. I puled each sheet apart in 1/4's and stuffed it in each section of the enclosure. When I watched Matrix Revolutions the Sub belched out a little hand full of polyfil from each port sometime during the movie. It seems it has almost quit doing it now, it's getting less and less with each movie.
On a side note, if any of you can help me with my Behringer Feedback Destroyer please have a look at this thread.
I have it hooked up and set a house curve. I had to use all 12 filters and some of them have quite a bit of gain. It sounds good but, I think it can sound better with some help form somebody who knows their way around the BFD. I watched U-571 last night and had peaks of 105 dB at a -10 volume setting. Does this sound about right? I'm a little afraid to turn it up any more (the Sub or the volume on the receiver). I don't want to break my new sub before I find out if my BFD settings are okay.
Help if you can,
i need to stuff my ported Tempest enclosure as well. would rubber cement work well to make the polyfil stick to the inner walls ? i assume it would work great.
A good spray adhesive usually does the trick and can be purchased at your local craft store or from Parts Express. Many prefer 3M brand.
I've checked out U-571 earlier during the day, my reading is 104db at -15db below RL. I'm running a MidQ sealed Tempest from Adire. No EQ, corner load
I think I hit (at my seats, 9 feet from the RPTV) 109 dB on the SPL meter during "The Haunting" and I thought my room was going to explode. I don't normally listen to my DVD anywhere that loud anymore.