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I've personally done a comparison of lined vs unlined on 2 identical sonotube subs. The unlined sub had a boomy sound to it compared to the lined sub. There was minimal difference on SPL output between the 2 subs. Both subs had identical cabinets, subwoofers and plate amps.
What about lining 50% vs. unlined vs. lined 100%? Did you happen to take any frequency response measurements between the two at the time?



I would not un-line it completely but lining 100% will effectively over dampen the enclosure. 25% to 50% lining should be ideal in damping reflections.


This was a very well executed build and looks quite good. I forgot to mention that earlier.



On a side note, I am surprised many of the sonotube designs I have seen are almost always lacking any bracing. Sure it is a fairly dense material, but they are typically high in surface area over a long length. Cabinet resonances could be audible at higher frequencies. I am unsure as I have never tested one first hand though.
 

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Discussion Starter · #43 ·
Most subs use some sort of damping material inside; I applied a full-coverage coat of thick carpet glue to hold the carpet on the exterior and I think it dampens the tube. Just my impression. When I apply carpet again, I'll use a bit less.
 

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Most subs use some sort of damping material inside; I applied a full-coverage coat of thick carpet glue to hold the carpet on the exterior and I think it dampens the tube. Just my impression. When I apply carpet again, I'll use a bit less.
I am referencing the egg crate foam you used internally. The exterior does not matter. The interior is over-damped limiting your output some. In a vented enclosure no more than 25%-50% of the internal surfaces should have damping material. With a cylindrical enclosure, 25% coverage is probably suitable.
 

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Discussion Starter · #45 ·
I got you; I was referring to your statement about minimizing resonance in a long cylinder, whether it be internal or external-same wall, right? No disrespect, but until I find more support for using less material inside it's going to stay. Another hard-core enthusiast had used a substantial amount of additional material in the form of a pillow inside his tube and said measurements were markedly improved-I believe the posts were here
 

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I got you; I was referring to your statement about minimizing resonance in a long cylinder, whether it be internal or external-same wall, right? No disrespect, but until I find more support for using less material inside it's going to stay. Another hard-core enthusiast had used a substantial amount of additional material in the form of a pillow inside his tube and said measurements were markedly improved-I believe the posts were here

Without knowing the 'Q' alignment of the other user's enclosure it is difficult to determine why a large mount of fill would have a positive effect.

Here is what I posted in another thread similar to yours:

Nearly all of the vented designs showcased on the site tend to be Larger Low Tuned designs with Chebyshev type alignments. These are "over-damped" enclosures by design typically yielding system 'Q's in the neighborhood of .57 QTC or so with out the requirement of damping enclosure mterial. By completely lining the vented enclosure with absorptive damping material, one is choking off some of the air movement to a degree that the enclosure is designed to take advantage of.

Now, I am not against using well placed damping or reflection absorption materials (8lb ft^3 density mineral wool/rockwool), but lining an entire vented enclosure with it is simply not necessary and begins to be counter productive (increasing impedance peak frequency, further reduction of system 'Q', along with slightly lowering output).

As for specific measurements, output differences will be smallish sometimes more sometimes less. It will be dependent upon the frequency and the system 'Q' in which the driver is aligned with. I have not had a chance to measure this specifically but I will see what I can dig up for you.
 

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Discussion Starter · #48 ·
How do you like the PG2200, ironglen? I might pick one up.
I have no pro-amp experience, but the pg likes a higher input level than my onkyo 806 provides, so I'm using a samson s-convert to boost it. It seems well designed/built. Now, with my inexpensive 5.0 speakers, I have the sub level out at -6db with both samson's at max gain and it blends well. I have yet to see it clip, while the signal lights constantly light up and stay on for brief periods. The stock pg (no fan mod) is quiet enough from the listening position(at least from my perspective), perhaps 18' away. It looks nice in my custom wall rack too (I covered the super-bright blue power led with a felt sticky-it was a bit annoying.
 

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On a side note, I am surprised many of the sonotube designs I have seen are almost always lacking any bracing. Sure it is a fairly dense material, but they are typically high in surface area over a long length. Cabinet resonances could be audible at higher frequencies. I am unsure as I have never tested one first hand though.
They endcaps provide all the bracing one would need - they essentially lock the tube into a rigid cylinder. You can try to compress even a very tall one like my own right in the middle, which would be its weakest point, and you will have no success. It's very strong because it's a cylider, so either the entire shape flexes or none of it flexes. Also, since most of these are large volume designs, the fixed max force the driver can create is spread over a much larger area than other types of designs, so internal pressure is very low at all audible frequencies.
 

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ironglen nice job! does it shake the foundation?
how thick is the area fo the lower endcap that attaches to the bottom of your sonotub? i'm trying to figure out how thick mine needs to be.. is 1inch thick enough?
where did you get your carpet?
 

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Discussion Starter · #51 · (Edited)
ironglen nice job! does it shake the foundation?
how thick is the area fo the lower endcap that attaches to the bottom of your sonotub? i'm trying to figure out how thick mine needs to be.. is 1inch thick enough?
where did you get your carpet?
Go with a plenty of thickness for adhesive surface-mine was two 1 1/8" plys glued together, plus the exterior 3/4" endcap. Next time I would 'trim' the inner ply so it adds adhesive surface area to contact the tube, yet would be lighter and allow my driver mounting bolts to reach through the material better- my 2 1/2" bolts barely threaded, and long, thin diameter bolts are hard to come by!

I got my carpet at lowe's/hd- it's hard to find now (out of season or something). I would go with the less fuzzy in retrospect-easier to clean/more durable...
 

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if i understand,you have 2 1/4 inches glued to the tube? thank you.. very good..:yes: i'm using 1inch birch ply. double will be ok..
 

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The difference in output:



It's your room. Swap the location of the SVS tube and your monster tube; you WILL notice a massive change. Right now, the SVS is up-tight against a pair of walls while the big tube is essentially next to a door/big opening. The difference you're hearing/feeling is simply placement within the room
 

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Discussion Starter · #54 ·
The difference in output:



It's your room. Swap the location of the SVS tube and your monster tube; you WILL notice a massive change. Right now, the SVS is up-tight against a pair of walls while the big tube is essentially next to a door/big opening. The difference you're hearing/feeling is simply placement within the room
I WISH that were the case-instead, the svs is up against...a rail that is 16ft from the wall, with the entire first floor open to upstairs. But since you're offering help:bigsmile: Do you still think it the next-to-railing placement would be better?

The front of the room doesn't get much better, actually, placement is not really an option up there as the sono is too big... sometimes I wish I had 2-4 16" sonotubes with 12" drivers instead:dunno:
 

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What's in that other corner, then? I'd still recommend swapping locations and see what you think - sometimes just a foot one way or another can have a VERY large impact on the perceived output of a subwoofer.
 

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Discussion Starter · #56 · (Edited)
What's in that other corner, then? I'd still recommend swapping locations and see what you think - sometimes just a foot one way or another can have a VERY large impact on the perceived output of a subwoofer.
The front left has stairs going down across the front of the room (no placement options), tv is mounted above the stairs (higher than the railing in the foreground, front right is a walkway to a bathroom and bedroom (only placement for a corner-placed small sono, which I may try), rear left near the LLT sono has a door to a room and along that wall must stay clear to come up the stairs(as seen in the drawing), rear right is the 'open' wall to downstairs. Now you see why I went with ceiling mounted mains and surrounds (5.1) and wall mounted center above the tv!:dumbcrazy:
If I ever have enough company, I'll do a 180 on the loveseat in the foreground and pull it away from the rail (it ends up 8' from the tv, a little close for 720p, but the sound is better than the back!) As long as they aren't too tall, say over 5-11, the back viewers are good to go! BTW, I pulled that table out of there along with the svs (sold it), and now have...MY recliner there! I have all the needed parts to build a couple ED 12" sonosubs to use-wherever. I may put one in my office/workroom and one in the aforementioned front right corner (not sure how good an idea that is), or whatever. I'm in no hurry to build those just yet.
 

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Welcome to the forum Dan. I look forward to some of your technical insights... :wave:

IronGlen,

That is one tough room. Open everywhere with very limited placement options. Any chance you can switch rooms?:hide:
 

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Discussion Starter · #58 ·
Well, I'm glad I went to the LLT Mal-X- it does the job really well, and digs deep. Also glad I went with the samson proamp, it has yet to clip, but the fan speeds up when a movie has extended impact, but I barely notice it:bigsmile: The good news is bass is very flat, so I don't have to eq (just wish I had room for different speakers, but it'll do. We'll move eventually anyways.
 

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Discussion Starter · #60 ·
Yup, I was standing in the walkway that is too narrow for, oh say a equipment rack, or a nice LLT sono, but maybe a 15" sono...depends on whether I want to get into blending more than one sub-I don't at this time, but it could happen. Did I say I'm really enjoying the proamped LLT?:D Highly recommended:T
 
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