a few questions, because its almost time for me to diy!

Discussion in 'Archived Threads 2001-2004' started by Fong, Oct 1, 2002.

  1. Fong

    Fong Stunt Coordinator

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    i plan on using a tempest with an ava250 in a sonotube. i wanted to model roughly off of the EBS alignment, but was wondering if there is a point where size would become an issue. i wanted to have something about 24" diameter x 48"-60" tall. would this raise the Q value above 0.707 (above the EBS alignment)? and at what point would i have to be concerned with loosing too much max spl? or should i just go w/ the EBS?
    this is taken from the adire vented tempest apps pdf:
     
  2. Fong

    Fong Stunt Coordinator

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    bump
     
  3. Fong

    Fong Stunt Coordinator

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    is there something wrong with my questions? or can no one answer them (or just dont want to)? could someone answer one of these questions so i can stop bumping this thread? at this point im just gonna pick something and go with it, but all i ask is for an answer to one of the above questions on this post. i think anybody deserves at least that.
     
  4. Dustin B

    Dustin B Producer

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    Nothing wrong with the question. Just on occation those who usually write answers sometimes run out of time and decide to leave the question for another to answer. When a bunch of us do it at the same time it can take a day or two to get a response. Next time just wait a little over a day and if your message has left the first page (then you can assume it got missed) then bump it, if it hasn't left the first page please don't.

    Anyways, yes you can go too big. Going bigger and tuning lower doesn't increase the Q, it lowers it. An enclosure can be underdamped, critically damped, or overdamped. Going to big results in underdamping and gives you an unwanted hump in response close to tuning. Critically damped is the point above which you start to form this bump. Overdamped does the opposite, and instead of causing a hump it has a curve with a slightly lower level in the last octave than a critically damped allignment. In othewords I wouldn't recommend going larger than the recommended EBS allignment for a single Tempest.

    If you can fit an enclosure that size, you may want to consider going with a dual Tempest setup. Do a search on Mike Strassburg's name in the DIY section and you'll find more details (basically 480L tuned to 16hz with a pair of 6" ports). Incredibly capable sub.
     
  5. Fong

    Fong Stunt Coordinator

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    thank you for your reply, dustin. i only bumped my post after it left the 1st page. my recent reply above was me giving up on this thread, as i didnt think anyone would answer because they havent already (i started this thread on oct.1, and its now the 4th). this is my 2nd post on this forum (i usually post on the speakers & subwoofers section), so i dont really know the response time on a typical thread.

    i might go with the EBS alignment then, but i'll definatly consider Mike Strassburg's design, i just dont know if i can spend that much money. im a poor college student, you know (computer engineering).
     
  6. Dustin B

    Dustin B Producer

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    How are you planning on powering it?

    Compared to commercial subs a dual Tempest isn't bad cost wise, as long as you don't get fancy on the finish. Say $300 for the drivers, $300 for a QSC RMX850 (less if you can find an appropriate used pro amp that is in decent shape). Plus enclosure costs (cost here depends mainly on the finish and if the local concrete contractors have reasonable sonotube prices).

    Single Tempest with a plate amp can easily be done for less than $400 total though.

    PS- Guess I should have looked at the date. I could have sworen it was only yesterday that I first saw it :b
     
  7. Fong

    Fong Stunt Coordinator

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    oh wow. i didnt think a dual tempest would cost so much. mike strassburg's sono cost ~$930 iirc. i think i'll stick with the EBS powered by the ava250, something that my budget will allow me.

    another quick question: why do some people use dowel rods in their sono? you used them, but patrick sun didnt. is it just for more bracing?

    p.s. i appreciate your help. i know that no one is obligated to reply to any post. i could have just tried putting something together from what i pieced together. its nice to have some help on your own project.
     
  8. Dustin B

    Dustin B Producer

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    Well bulk of the cost is the amp and driver. So if you double your amp requirements and your driver number you just about double the cost [​IMG] But you also get one hell of a sub [​IMG] Mike also went with an HS500 ($500 amp). A much cheaper pro amp new or used, or a decent 4 channel used amp could bring that portion of the cost down quite a bit. With some deal hunting on the amp I could see a dual Tempest being done for $650-$700.
    If I did it again I don't think I'd do the threaded rod. I might do the dowel, I'm not sure, let you know when I build my next sub. Cylinder isn't quite a sphere. So the dowels are just supposed to help hold the endcaps in place (take vertical strain off the tube and put it on the dowels). Not sure how much of a difference dowels will make, but they definately won't hurt anything.
     

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