Calling All Sonotube Builders For A Little Help On My Tempest X Build

[Maceo23]

Greetings all,

I will be getting underway on my first sonotube build this weekend. It is going to be a 300L tube tuned to 17hz. I just have a few question before I get started. I was wondering what everyone is using for sound deadening. Also, how to attach it to the inside of the tube. I figure I'd just use pink inuslation and some spray glue. I have heard that I need to peel out the inside coating of the tube also. I'm just trying to get all my ducks in a row before I start so hopefully I'll knock out the project in a couple of days. My last sub project took over 6 months, and I just don't have that kind of patience anymore. Thanks in advance for any input.

[funky_waves]

Egg crate foam is best for vented box, it absorbes sound and stays in the box, a vented box with fiberglass insulation will be shooting glass fibers into your room for a long time. It dosn't need much to hold it in, a few dobs of hot glue here and there works nice, and is clean and fast. There is a layer of wax paper for releasing the concrete that needs to come out, it peels out realy easy.

[brent_s]

funky_waves wrote:

Egg crate foam is best for vented box, it absorbes sound and stays in the box, a vented box with fiberglass insulation will be shooting glass fibers into your room for a long time..

Uhm, no...it doesn't work like that. Well, maybe if you tear the fibers loose into individual strands and place them in the port tube. Take a look at interior photos of any SVS and you'll find good old pink fiberglass insulation.

When purchasing egg crate foam, especially if you go the local craft store route, you might not know if you're getting closed cell or open cell. I'm pretty sure the closed cell has nearly zero impact and behaves closer to a solid body, actually taking some net volume away from your enclosure.

Either way, the purpose of the lining in most cases is to reduce unwanted frequencies and harmonics that make it through the crossover or are generated by the driver/port producing the fundamental. Fill, such as fiberglass, also has the similar volume increasing properties in a ported box as it does in a sealed.

I personally say go with R-13. Faced batting would make it a little easier to use your choice of adhesive to stick it to the walls. I used Loctite's PowerGrab in my last build to adhere R-19 faced (had it on hand from actually doing some work in the attic) to MDF.

-Brent

[funky_waves]

Well Fiberglass is a lot cheaper. It does put fibers into the air when the sub is run hard, not enough to see but enough to bother people with sensitive skin and or, breathing difficulties. I know a few people with sensitive skin and I used to use fiberglass and it realy bothered them, so now for all the vented enclosures I biuld, I use acoustical(egg crate) foam. Foam is a lot more expensive but its still a very small part of the cost.

It is true you have to use the right egg crate foam, PE sells it and a few other places.

[brent_s]

Nathan, if the insulation you used was so fragile that it would release fibers from the air movement in a subwoofer port, I'd hate to see what it was doing to the atmosphere of any house unlucky enough to have it for insulation. Do you happen to remember the manufacturer? How roughly did you handle the material before placing it in the sub? The Pink Panther stuff I've worked with takes quite a bit of effort to get it to give up any fibers. The 14 year old yellow stuff in my walls and floors, brand unknown, doesn't seem quite as densely woven/adhered, but I still wouldn't have any reservations using it in a sub.

-Brent

[thxgoon]

I used R13 in mine and have never seen anything shooting out of the top and have never dusted the top and found any fibers. This was a concern expressed to me as I was building but it has never been an issue. It just isn't true. If you lined the port then maybe but there isn't much in the way of velocity in the tube to 'blow' anything out. It's just pressure waves. Don't worry about it or if it makes you feel better put a piece of nylon stocking over the port opening to catch any flying debris. And eggcrate foam is not a 'small' part of the cost. If I recall it was over a $100 to line my tubes which is why I didn't use it. I haven't been sorry... Anyway..

As far as sound deadening, it is actually considered one of the best materials you can use. It's cheap and it works well. You won't need to peel anything out of the inside of the tubes, just spray, hold your breath and crawl inside What driver are you going to use? Are you posting a build thread? Please please please....

[funky_waves]

It was the same, pink panther. It just let tiny little fibers, out the ports, I was always carefull handleing it. It only happend under very high output.

You could never see it in the air but in a small room if you examined the dust off furniture you could see very small fibers in the dust. I only paid attention because people mentioned there skin was irritated after useing the sub. It happend on a couple different occasions.

I think the vibration breakes the fibers up and slowly releases them into the air in the box and they get blown out the port(s).

It wasn't a major problem, but I find foam easier to work with anyway, and it still dosn't cost much to line a box with.

[funky_waves]

thxgoon wrote:

there isn't much in the way of velocity in the tube to 'blow' anything out. It's just pressure waves.

Umm pressure waves, only when the port is at resonance and above is there pressure/sound waves going through the port, but you don't want that anyway. When the port is acting as a Helmholtz resonator the whole mass of air in the port(s) is moving in and out of the port(s) and can reach very high velocities, unless you have port(s) that are more than large enough for the application.
Also aerodynamically when the air is going into the port it is pulled from all around evenly, when moving out of the port it is directed straight out by the port walls.

[thxgoon]

funky_waves wrote:

Umm pressure waves, only when the port is at resonance and above is there pressure/sound waves going through the port, but you don't want that anyway.

Pressure waves in the sonotube, not the port. In practice and from experience this is just not an issue. Especially in a low tuned design.

[funky_waves]

thxgoon wrote:

Pressure waves in the sonotube, not the port. In practice and from experience this is just not an issue. Especially in a low tuned design.

Sorry saw "tube" thought port. Still pressure waves can lossen fibers from the batting, and the ports will take them out.

I am not saying it is a problem for most, only a very small percentage of people notice it, and even smaller percentage of those people have subs they drive very hard. The question was "what is better" I was just saying that that could be a possible issue with fiberglass. Therefore I feel foam is better for ported subs. IMO

I agree low tuned designs would be less of an issue because usualy low tones are short bursts and not very high percentage of movie, and even less of music, content. Higher tuned 25hz and up are in the range of music and the ports will be used a lot more.

[Maceo23]

Hey guys, thanks for the input. I didn't mean to start an argument. I'm gonna see if i can find some open cell foam in the next couple of days, if not, I'll just use some pink. I'll do a build thread as soon as I start.

[Mike P.]

If you are looking for foam go to WalMart. They sell it as a "mattress pad". It will be around 15 dollars for the twin size.

[Maceo23]

Thanks Mike,

I'll be heading there this afternoon.