I wanna DIY Sub!

Discussion in 'Home Theater Projects' started by Justin_D, Feb 19, 2004.

  1. Justin_D

    Justin_D Stunt Coordinator

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    I'm thinking about doing this, if I convince my teacher who is quite liberal, for a school project.

    Here is what I want to do, and this will be my first

    --A "space conservative" sub: not necessarily Sunfire small, but small enough to be taken to college.
    --Goes down to 20hz (or lower) accurately
    --NOT BOOMY
    --Probably a 12" Driver

    I have a Velodyne CHT-12 right now. I could sell it, or combine it with this DIY.

    Is this going to be beyond my scope? How much is this going to cost? Can you suggest some amps and drivers?
     
  2. Travis Cain

    Travis Cain Stunt Coordinator

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    It might be better if you told us how much you're willing to spend rather than ask us how much it will cost. It would also help if we knew when you would have to have it done by. I'll assume you're looking for "bang for the buck"..

    That said, for an amp I would suggest a 250 watt plate amp from http://www.partsexpress.com which go for $128. If you have a couple months before your project needs to be done, it might be worth waiting to buy it as it goes on sale quite often..

    For 12" drivers, I would suggest an Adire Audio Shiva, however they were just "revamped" to Mk IV and are currently out of stock until next month I think. They go for $125. One of the great things about the Shiva is that Adire offers several different box designs depending on what kind of sound you're looking for so you don't have to do the work of making the calculations. Since you're looking for that sweet 20hz, perhaps an Adire alignment ported design might work out for you as it's less than 20" cubed so you should be able to bring it to school although it'll be pretty heavy. You can find more info about the Shiva and it's box variations at http://www.adireaudio.com

    If waiting for the Shiva doesn't work out for when you need your project completed, another option would be the Dayton 12" Titanic Mk III for $160 at partsexpress.com but if you chose that route you'd have to design the box yourself. It's not incredibly difficult to do, but it will take a little time and researching.

    As it's your first creation I would lean towards the Shiva as the box designing and blueprints are done for you. And as it's a really popular driver in this forum you might be able to pick up a used one and save a few bucks..


    There is certainly a ton of other drivers & amps that can make outstanding subs.. But you'll be hard pressed to find better value per dollar IMHO..
     
  3. Ryan T

    Ryan T Second Unit

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    If your going for a small sub that can go down to 20 Hz and lower your going to need a very powerful amp and a LT circuit. You'll also need a nice high excursion driver that can take lot of power (maybe an AV12?) to hit the lower notes with any authority. The more you can increase the size of the enclosure the less power you need to get the driver going. That one of the trade offs of small enclosures.



    Ryan
     
  4. Justin_D

    Justin_D Stunt Coordinator

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    Thanks alot Travis!
    That was very informative. I have been looking @ Shivas before you even mentioned them. I was very unsure about amping it though. $400 would be the prefered maximum. I can wait. I may just do it for me, myself, and I. Screw school and their time limits! I wanna be able to take my time so I don't make TOO many mistakes. I like how w/ the MKIV I don't have to design my own box. I don't think I'm ready for THAT yet. Do you know any websites other than diysubwoofers.org that are good the inform me of the task ahead?
     
  5. Justin_D

    Justin_D Stunt Coordinator

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    I have no idea what sub that is...
     
  6. Justin_D

    Justin_D Stunt Coordinator

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    I am now torn between the Tempest and the MkIV. I like that the MkIV is smaller, but I think the Tempest would really kick it into high gear when it comes to the bottom end. I know I'm probably getting into the territory of "not movable" stuff, but couldn't I just build the Tempest into a simple cyllindar design w/ a port similar to Warrick's sub? Obviously costs have gone down since he bought his!

    I am also curious. Would this 250 watt plate amp be enough to power a monster like the Tempest?

    I'll just keep editing this post :) The more I look, the more I like the look, size, and simplicity of a of a cylendar sub w/ a port on top. Would there be a passive radiator involved? Do I HAVE to have it? Is it optional? Would it be worth it?
     
  7. Ryan T

    Ryan T Second Unit

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    how much power will be enough depends on the enclosure size and if its vented or sealed. I have my tempest in a huge vented enclosure and 250 watts is plenty to bottom out the driver. But if i go put that amp on my 25 Liter sealed shiva I cant get it very close to Xmax.

    What size enclosure are you looking at? I would say definatly go for the tempest if you can live with the large enclosure. I've messed with bot hsubs (well my shiva was a MkIII) and the tempest really does have a lot more power in the low end. Thats not to say the shiva is a slouch by any means its just it doesnt shake the room witth the same authority as the tempest does.


    Ryan
     
  8. Ryan T

    Ryan T Second Unit

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    If you are porting the sub you will not be using a passive radiator. a passive radiator cannot be down or up fireing it has the be mounted verticaly so unless you lay the sub on its side you cant use a passive radiator [​IMG] well you could spend a lot of time mounting one on the side...

    My tempest i have now is a monster. You wouldnt be able to move it unless you had two people. Here are a few real quick pics. The top left is the sub without the sock over it, top right is with sock and in my bedroom/listening room, last pic on bottom is the top endcap with the port.

    http://www.geocities.com/ryatod/tempest.html

    I've gotten very good results in terms of output with my really tiny shiva. Its 25 liters as i mentioned above. The external dimensions are about 13"x13"x13". With that size enclosure its pretty portable but you'll loose everything below 36 Hz or so unless you make a LT circuit. The other draw back is it takes a TON of power. The enclosure is so small that it takes a lot to compress and decompress the air. The LT circuit would only make the power consumtion worse but you would get the last octaves back.


    Ryan
     
  9. Wayne Ernst

    Wayne Ernst Cinematographer

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    The driver that Jim posted a picture of is from Elemental Designs, runs $270 and can be found at the following site:
    Nice Driver


    ** I have to admit, I knew nothing about this driver before Jim posted the picture. However, I looked at the properties for the picture, and found the source where it was located - then back-tracked to the Elemental Web site.

    Enjoy! [​IMG]
     
  10. Allen Ross

    Allen Ross Supporting Actor

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    Justin, nothing is too big to move when it comes to subs, If i had the cash i would build a another 9 cuft tempest for my dorm, i still got some closet space. The best investment i ever did was the 17 bucks i have spent on the casters, it makes it so nice.
     
  11. Wayne Ernst

    Wayne Ernst Cinematographer

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    Nothing is too big to move - correct! That is what casters, wheels, etc. are for.

    However, when the wife or significant other come into the picture, then, yes, the size of the cabinet can be a big issue.

    Finally, You have to consider the area you are going to set your subwoofer on/in. If you build it so it comes out with excessive weight, just be sure the flooring structure can handle it. Most homes would be OK. Trailer houses would not be. Actually, I saw the leg of a bunk bed go through the floor of a trailer house before - which one might expect when you look at their construction.
     
  12. Seth_L

    Seth_L Screenwriter

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    If you want small but low response, you have to either use a really big driver in a sealed box with a lot of power, or port/PR the box.
     
  13. Justin_D

    Justin_D Stunt Coordinator

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    How would this Tempest w/ 250 watt amp compare to my Velodyne CHT-12? Also, should I get the 250 watt amp w/ the bass boost @ partsexpress?
     
  14. Ryan T

    Ryan T Second Unit

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    That depends on the allignment. What size box and what do you want to tune it too if its going to be proted? I would suggest fallowing one of adires plans they have on their site. They are easy to understand and all the calculations have already been done. If you get a decent sized enclosure and its ported 250 watts is usually enough for a tempest. I would opt for the plate amp without te bass boost. It is around 30 something Hz which will give you really loud output in that range but the overal sound wont be balanced.


    Ryan
     
  15. Travis Cain

    Travis Cain Stunt Coordinator

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    I second the notion of no bass boost..

    I would definately have recommended the Tempest over the Shiva but you said you wanted a "space conservative" box size, and a Tempest won't comply with that. Mine is the EBS alignment and let me tell you.. It's HUGE! It might not look like it when you look at the blueprints & measurements, but in reality, it's a monster.. I made mine front firing though, so putting casters on the bottom was easy and makes it moveable..
     

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