How to modify an Audiosource SW-15 sub?

Discussion in 'Archived Threads 2001-2004' started by Gregory WC, Jan 20, 2003.

  1. Gregory WC

    Gregory WC Auditioning

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    I just received the audiosource sw-15 sub from amazon.com Dang this sucker is huge!!! Anyway after correct placement I too find this sub to be rather boomy. Can anybody describe in full on how to do the polyfill mod? I have searched these forums and audioreview.com and still can't find how the mod is done in full detail. Also I've read by replacing the 4 wooden legs on the bottom of the sub with 4 spikes can help increase bass response. Any tips, thoughts, or even links would be appreciated. Thanks.
     
  2. Jose G

    Jose G Supporting Actor

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    This is what an HTF buddy of mine said in his post:

    "The single best thing you can do using the STOCK driver and cabinet is make the cabinet deader, stronger, and dampen the walls.

    On the cheap, use 1-1/2" hard wood dowles vertical and horizontal inside. You can cut them for a pressure fit to the walls. They have to be a clean square cut!!!
    Always use good wood glue where they make contact to the wall and each other. Where the dowels cross each other on the inside, pre drill, then glue them together and run a wood screw threw them.

    Spray can deadener can be used on the walls, port tubes and dowels. Rubberized car spay can under coating can be used instead of the expensive stuff you see at the car install places, BUT "make sure it has dried 24-hours" as the fumes it gives off while drying will "eat on" the woofer and surround.
    You can also use roofing felt if you have access to it. The undercoating seems to work better.

    Stuff it with 2 1/2-lbs of fluffed up poly fill, if it doesn't have that much already.

    These small and cheap modds will tone down the boom factor mucho and it will sound much better...."

    This is some other info I found:

    Go to audioreview.com and read the reviews about how to mod it and buy 4-5 pounds of polyfill from Wal Mart for $10, get some feet spikes at partsexpress.com ($20) and you have your self something you will most definetly FEEL!

    You can polyfill anything! Rule of thumb for 100% stuffing is 1 lb of Acousta Stuff or polyfill, per 1 cubic ft of internal cabinet air space less driver and port.

    Good luck!
     
  3. Gregory WC

    Gregory WC Auditioning

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    Upon closer examination of the sub I noticed polyfill blocking the 2 ports. It looks as though it came from the factory like this. Shouldn't the ports be clear for airflow?
     
  4. Jose G

    Jose G Supporting Actor

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    I believe that's correct. This article might help. The format is not great in terms of the graphs, though. Someone else who has actually moded this sub might come along with more info. Good luck!
     
  5. Michael_Hml

    Michael_Hml Stunt Coordinator

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    Do a search over in the DIY forum on here... there are a couple of threads about modding this sub. I believe someone else also replaced the driver and had excellent results.

    -Mike
     
  6. John F. Palacio

    John F. Palacio Supporting Actor

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  7. Jose G

    Jose G Supporting Actor

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    John,
    I agree with you on placement issues, proper set up, etc., and I agree with the fact that if you pay good money for a high quality sub- you shouldn't have to mod it; however, many people here look for the best bang for their buck- which for many means to buy a less expensive sub and mod it to make it respond like a more expensive unit. This has been a trend here with the Sony and Audiosource subs. They are not much money and for a little effort and very little extra cost- you could go from "boomy" to "better"- whatever that may mean for the individual. Also, many DIY folk might want to mod something like the SW-15 before starting out on a full scale DIY sub project. Others would be happy by changing the driver and doing other mods as well to insure that they are going from "boomy" to much better- even "tight." Your point is well taken, though. In fact, I recently bought a little sub and didn't want to have to mod it, because I do plan on building my own sub and will mod that to death when I have to mod.

    Gregory- it seems my cut and paste didn't work- as soon as I get home I'll paste in the article. Sorry about that.
     
  8. Gregory WC

    Gregory WC Auditioning

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    Thanks everyone for your time. Jose I'm looking forward to that article.
    Thanks!
     
  9. Jose G

    Jose G Supporting Actor

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    Just got in- this may help with the poly mod aspect. My other file on sub mods is gone- can't find it [​IMG] If I can surf and find it again I will post it for you, but I'm not sure where I got that one from. Anyway, here's the polyfill article I was originally referring to (as I said the formating on the data tables is off and the link to that site no longer is functional):

    Make a small box act like a larger one with polyester fiberfill
    By
    TOM NOUSAINE



    The word "FIBER" is turning up in a lot of hip conversations these days – you know, the ones that take place in art galleries, bistros, and install bays. In the galleries, they're talking about the fiber-optic conduits through which compressed digital audio and video will travel when the Intergalactic Superhighway concludes the long and winding road to our homes. In the bistros, they're talking about the colon-scrubbing glory of fiber-rich delicacies like oatmeal quesadillas and bran flan. But, to us – the few, the proud, the mighty Box Builders – fiber means dacron-polyester fiberfill, that magic and powerful ingredient that helps deliver maximum bass from a tiny space.

    SEALED ENCLOSURE
    1.4-ft?Box


    Stuffing Density
    (lb/ft? )System Resonance
    (Fsb)Effective
    SizePercentage
    Gain

    056.61.4--
    0.7053.01.614%
    0.7552.71.721%
    1.5051.71.829%
    1.7550.81.936%
    2.6050.41.614%
    3.1052.61.2-14%


    It's no secret that you can use fiber- fill to make low-end magic; clever installers have been using it for years Take two boxes of the same size and type, insert the same woofer into each one, and stuff one with some fiber-fill – the one with the stuffing should kick out lower bass.

    In simple terms, it works like this: The fiberfill fools the woofer into thinking that it's in a larger box (one with more air, or internal volume, in it). than it really is. And, in general, the larger the box, the lower the bass you can get out of it.

    Fiberfill stuffing is a popular alternative for people who can't or don't want to allot a lot of space for a subwoofer box. A compound or Isobarik configuration, which pairs two woofers in one box, is another popular option, though it has some considerable downsides: For one thing, you have to buy two woofers. There is also a theoretical sensitivity loss (on the order of 6 dB) because you end up with twice the cone mass, though you can cut your losses – losing only a few dB SPL – by running a pair of the drivers in parallel.

    SEALED ENCLOSURE
    5.1-ft? Box


    Stuffing Density
    (lb/ft? )System Resonance
    (Fsb)Effective
    SizePercentage
    Gain

    042.05.1--
    0.2542.05.10%
    0.5041.25.814%
    0.7540.36.222%
    1.0039.46.527%
    1.2538.66.527%
    1.5040.25.69%


    The particulars of fiber stuffing are pretty interesting: The air inside your enclosure actually heats up as your woofer moves, making the air stiffer. (I'm absolutely serious.) When the enclosure is stuffed with fiber, the fibers wiggle, dissipating some of the heat and making the system work as though the box were larger. Theoretically, your woofer/box bass system can act like a system that's a maximum of 40 percent larger when you've latched onto the right stuffing recipe – in other words, if you have an enclosure that offers 1 cubic foot (1 ft? ) of internal volume, in a perfect world a good stuffing job will make it perform like an enclosure that offers 1.4 cubic feet of internal volume.

    There are three types of stuffing that are commonly used for this purpose: fiberglass insulation, long-fiber wool, and polyester fiberfill. Fiberfill is the best choice because it doesn't come loose and fly around and irritate your skin or lungs like fiberglass, it works as well as either of the others, it's a lot cheaper than wool, and moths hate it. I recently bought five 20-ounce bags of it at $1.99 a pop (a total of 6.26 pounds for $9.95) at Minnesota Fabrics; that turns out to be about $1.60 a pound. You should be able to find some at any fabric store or in the bedding section at friendly stores like K-Mart or Home Depot.

    To evaluate the effectiveness of box stuffing, I used an MLSSA analyzer to measure the impedance of three enclosures – 5.l-cubic-foot sealed, 1.4-cubic-foot sealed, and 1.4-cubic-foot ported (the port measured 3 inches in diameter and 6 inches in length) – with various densities of stuffing. For the sealed boxes, I was able to determine the effective box size – as enhanced by the stuffing – using the system's resonant-frequency and Qes values. For the ported box, I compared the tuned frequency of the empty enclosure to the tuned frequency of the stuffed enclosure, using the Speak for Windows computer program; this enabled me to find the effective box size that fit the actual resonant frequency I'd measured.

    PORTED ENCLOSURE
    1.4-ft? Box


    Stuffing Density
    (lb/ft? )System Resonance
    (Fsb)Effective
    SizePercentage
    Gain

    042.01.4--
    0.4039.11.614%
    0.8537.21.829%
    1.2535.21.936%
    1.4034.22.043%
    1.7535.21.936%


    In each case, the news was good – make that very good. With all three boxes, I enjoyed roughly 25 to 35 percent of "space gain" by using stuffing at a rate of 1 to 1.75 pounds per cubic foot of internal volume.

    When making system performance predictions, be aware that the Qes figure – and, therefore, the Qts figure – of the sealed boxes dropped. And with the ported box, the peak of the impedance curve on the lower side of the tuned frequency became heavily damped below the box's point of resonance. I also found that there is such a thing as too much of a good thing: System resonance (Fsb) rises again, beginning with densities of around 1.5 pounds of stuffing per cubic foot of box volume; this happens because the fibers are jammed so tightly together that they stop wiggling and, consequently, stop dissipating heat.

    I also found that stuffing gets less effective as box size increases. The morale: The bigger your box is, the harder it is to fool your woofer.

    A few rules of thumb: Stuff small enclosures – those with up to about 3 cubic feet of internal volume or less – with 1.5 pounds of fiberfill for each cubic foot of internal volume and you should get about a 30-percent increase in box volume without seriously affecting other performance variables. For larger enclosures, add stuffing at a rate of approximately 1 pound per cubic foot and you should get a virtual-space boost of about 25 percent. One thing's certain: You'll impress the heck out of your friends at the art gallery and bistro.
     

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