Will changing the driver of my low-end sub do any good?

Discussion in 'Archived Threads 2001-2004' started by NickSo, Apr 14, 2002.

  1. NickSo

    NickSo Producer

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    I have a passive 12" "AudioSource SW Three" subwoofer i got from Damark a couple years ago...

    My ht addiction has expanded since then, and im in serious need of more bass...

    I dont have much money, so i was thinking of just replacing the driver.

    The enclosure is a simple box with a port (sorry, im not too knowledged in building speaker enclosures and stuff)

    Seeing how a SVS ISD is only $129, i could probably find the old driver for cheap (hopefully :p) )

    So would replacing the driver for my sub do any good for my bass???

    Also, what cheap 12" Drivers do you guys recommend?
     
  2. Dustin B

    Dustin B Producer

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    The problem you will run into is that Audio Source box will be too small (not driver hole, internal volume), have a port that is too narrow and be tuned to high for a higher output 12" driver. The result will be port noise and the utilization of only a fraction of what a decent 12" driver is capable of.

    If you can get access to the tools to build a box, then you can do a lot with very little money.

    Check my twins post. Total cost per sub was just over $500 CDN including the amp.
     
  3. NickSo

    NickSo Producer

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    Hmm, if i put a better driver in there despite the small volume and port, would it still sound better than the stock?

    Coz im thinking if i can get a good driver for now, if the imrpovement is okay, itll tide me over until i can build an enclosure myself when i get some $...

    I know it sounds like im wasting a perfectly good driver on a crappy box, but i dont have much money to spend on all the materials right now.

    Also, what is port noise (and how does it sound?)?
     
  4. Mark Larson

    Mark Larson Supporting Actor

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    Port noise is just a whooshing/whistling sound, caused by the driver moving more air than the port can flow.

    May be remedied by enlarging the hole and putting a larger dia port in (only a PVC pipe).
     
  5. NickSo

    NickSo Producer

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    Hmm, how much bigger would the port have to be???

    Would MORE ports work??? :b
     
  6. NickSo

    NickSo Producer

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    What if i build a bigger box, but use my existing driver?

    I dont have the tools to make the bottom panel with the holes. I can use the existing plate at the bottom, but rip off the sides and top and just cut peices of MDF thats taller than what i have now, but same width, and just nail the panels onto the bottom panel???

    Then when i get more $, ill just replace the driver in my modified sub...

    Anybody?
     
  7. jeff lam

    jeff lam Screenwriter

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    Exactly how big is your existing sub and port. How well are they constructed? Take some measurements and maybe we can help. I would suggest replacing the driver in your existing enclosure rather than building a new enclosure for the existing driver. Of course it would be ideal to build an optimal enclosure for the new driver but since you say that can't be done... What's the internal volume of the box and the port length/diameter?
     
  8. Richard Greene

    Richard Greene Stunt Coordinator

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    I have built many subwoofers for friends starting out with an old speaker enclosure(s) they had in their garage or basement. The enclosure must be sturdy 3/4" wood (usually it's fine grain particle board) with at least two cubic feet internal volume, or I won't waste my time.
    The rebuilt subwoofer should be sealed -- so the port must be plugged or removed. Build a new box if you want a ported sub -- sealed subs have a much larger matgin of error concerning enclosure size.
    The Dayton 12" DVC (Parts Express) is the best home driver I could find for a 2 cubic foot box. An enclosure under 2 cubic feet stuffed with 1.5lbs. polyester stuffing per cubic foot can "appear" to be two cubic feet or more to the driver (see attached article):
    http://integra.cyberglobe.net/caraud...ces/fiberfill/
    Changing the driver of a ported subwoofer without sealing or removing the port will sound good only if you are a very lucky speaker builder (don't waste your time).
     
  9. NickSo

    NickSo Producer

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    Okay, the dimensions of the enclosure are:

    Height - 10 5/8"

    Width - 15 3/4"

    Length - 18 1/8"

    Port Dimensions:

    Diameter - 2 3/8"

    Length - 8 1/8"

    The enclosure is made of 3/4" MDF, built pretty solidly.

    Richard:

    Is there some way for me to just seal the port? Maybe just cover it with a peice of wood? Whats the difference in sound between sealed and ported (normally)?

    Thanks alot...
     
  10. Dustin B

    Dustin B Producer

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    Roughly that makes it just over 1 ft^3 and tuned to 35hz.

    I wouldn't use anything less than a 3" flared, and I actually used a 4" flared port for a Dayton 12"DVC. You'd need twice that volume before I would consider a ported DVC12" as an option. I also wouldn't tune any higher than 25hz.

    I aggree with Richard. Plug the port and stuff it with 1.5 pounds of polyfill. Pretty much your only option until you can build a proper enclosure.

    To plug the port you could glue and screw a piece of wood over it and caulk the seams. You could also just stuff a nerf ball or something similar into the port to plug it.
     
  11. NickSo

    NickSo Producer

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    Okay, so if I plugged the port, then stuffed it with poly fill, i could put a new driver in there???

    What would be wrong if I put a really good driver into my enclosure??? Would it sound WORSE than it is now, or would it just simply not sound AS GOOD as it COULD sound?

    Hmm, the dayton 12" DVC looks pretty good... Are there any other recommendations for any 12" woofers for my situation??? Possibly cheaper ones under or around $100 USD?

    Would the old driver for the SVS CS's be okay?
     
  12. Dustin B

    Dustin B Producer

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    Port tuning is related to the net volume of the enclosure, the diameter of the port and the length of the port. The larger the enclosure the shorter the port has to be to tune to a particular frequency. The wider the port the longer it has to be to tune to a particular frequency.

    The more air the driver can move the wider the port has to be to prevent port noise and compression.

    With sealed enclosures you can calculate a Q value for the enclosure using some T/S parameters from the driver. Q values over 0.8 sound aweful. 0.5 is consider critically damped. 0.5-0.577 is usually what a person will prefer. 0.6-0.707 will be good. A Dayton sealed in that enclosure will be in the 0.6-0.7 range.

    The only other 12" drivers I know of worth anything that are cheap would be the new BluePrint 1201 at $91. But it requires a larger enclosure for the same Q. Same with the Shiva. Your only other option would be if you could still find a used original SVS driver for $40-$50.

    You may also want to contact AudioSource to find out if there is any boosting or other filtering circuitry on the amp in your sub.
     
  13. NickSo

    NickSo Producer

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    Okay, thanks alot.. [​IMG] Ill ask around for the old driver...
    My amp is a passive amp, im powering it with a 200w Luxman amp.
     
  14. Dustin B

    Dustin B Producer

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    I think you meant your sub was passive, not?

    If so that is much better than using the amp built into a cheap sub.
     
  15. NickSo

    NickSo Producer

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    [​IMG] oops brain fart.. yeah, my SUB is passive... wat the..
    Yay, i found a person who's willing to sell his old SVS driver... so you guys think if i stuff it wtih polyfill and plug the port it would give an improvement?
     
  16. Juan Castillo

    Juan Castillo Second Unit

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    Heres a stupid suggestion. Why don't you just add a second sub? Dayton sells a 10" 100 watt powered sub through Parts Express. With all you are going to do. to yours, I would buy this second sub, use it for what its worth, then when it comes time to really upgrade, sell the two, or use them in another setup. Selling altered products is not the most profitable..
     
  17. Dustin B

    Dustin B Producer

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    I'd bet money that it would.
     
  18. NickSo

    NickSo Producer

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  19. Dustin B

    Dustin B Producer

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    #2
     
  20. NickSo

    NickSo Producer

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    nice [​IMG]
    now i just gotta convince my dad to let me take apart the sub :p)
     

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