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DIY Subwoofer Help???

Discussion in 'Archived Threads 2001-2004' started by Christopher Fisher, Feb 11, 2002.

  1. Christopher Fisher

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    Hello,

    I am getting into the DIY Area and have built some GR Research Paradox 1's which I love but now I want a subwoofer. Based on research here and elsewhere online I have decided to take the plunge into DIY subwoofers. I have looked into various drivers, specifically the Adire Shiva and tempest, been playing around the LspCAd as well. I am a college student and live in a dorm room that is fairly small. The dimensions in meters are 2.55 Height, Depth 5.145, and Width is 3.63.

    The system is going to be used for both Music and HT and will play from about 60 Hz down, my bookshelves drop off quickly after that. I don't have any particluar space requirements but nothing rediculously large, something under 300 liters. I can do Adire tempest, shiva, etc. I am a blank slate and am just looking for ideas. I want something that will extend fairly low, at least flat to 20 Hz, it should not be too difficult based on my small room. The choice of driver, amp (pro/plate), eq, does not matter. The sub is being built by a local woodworker, I lack the tools and experience, and is going to be build out of Void Free ply. Adire recommended this and will allow me to finish with Tung Oil to match my bookshelves. Any suggestions???
     
  2. with up to 300L to work with and seemingly anything semi-resonable for a budget, the possibilities are endless.

    can you tell me a few things that will help both myselfs and others to set you up.

    put a $$ amount to your budget < what?

    does volume really matter?..ie you really don't care if it is 50L vs 300L?

    What type of SPL goals are you after? something pretty good, or something that will level the dorm?

    More spl or sq oriented?
     
  3. Christopher Fisher

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    Okay,
    As far as price let's say about 500 dollars for everything besides the wood/box. So 500 total for drivers, amp, ports, etc. Less would be nice but I am certainly willing to spend more if need be. I have learned to do things right the first time. As far as SPL Goals I have been playing with LspCAD and I would like something that is fairly flat from about 20hz-60hz, preferably above 100 dbs and as high as 105-110 db. I was playing with a pair of Shivas in 88.5 ltrs each earlier and was looking nice. Anything lower would be a bonus and I am not sure about how much bass content is really below 20Hz. I want something plenty loud but I won't be leveling my dorm, I just would like to know that I can. The extra headroom would be nice... [​IMG] That is why I started looking at dual sub setups, with both drivers easily cruising i figured it would sound much smoother and more relaxed. The drivers would not be under any stress. I want both SQ/SPL but probably leaned more toward SQ. I want a seamless blend between my bookshelves and my sub. The bookshelves drop like a rock under 60hz so my sub needs to handle things smoothly to the point.
     
  4. ArmenK

    ArmenK Stunt Coordinator

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    Im in a similar situation. I think I have decided to build a Tempest sonotube, somewhere around 280L looks good too me. Its not too big and the frequency response looks good
     
  5. Christopher Fisher

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    I really do not want to build a sonosub tube based subwoofer. I am trying to match my speakers which are a raw oak which was stained with tung oil. Anybody else?
     
  6. Try the Tempest SBB4 alignment

    Tempest=$150

    pair of 3" Flared ports=$38

    4lbs of Accustuff=$40

    Behringer Feedback Destroyer (parametric EQ)=$129

    PE 250w plate amp (boost disabled)=$130 (on sale right now)

    Total=$487 plus shipping.

    ..and you get ~110db from 20hz on up=)

    Plus: Adire has the wood plans that you can give to the box maker=)...just oak veneer it to match your mains=)
     
  7. Christopher Fisher

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    Thanks for the suggestions...

    Couple of other comments however.

    1. How is the Q going to affect the sound? Around .5 or .6 is considered very damped and tight with .707 being a nice medium between HT and SQ. Anything above that as being overly boomy. However some people even considered .707 as being loose. How does the Q affect the sound, I really want something that is tight for music. The blend with my mains is critical, I want it to be smooth.

    I assume that I can make something that is very smooth for music but will still vibrate stuff for HT. I have read lots of strengths/weaknesses for both sealed and ported but can anyone elaborate if they have experience with both. The traditional advantadge with ported I thought was deep extension and volume but with various sealed designs I have been able to get over 100 dbs at or below 20 hz. Why go ported?

    2. I have seen lots of talk about the Berringer Feedback destroyer, I know basically what it does but is it a necessity. Also, does it have RCA inputs, if not how do a connect it? If I use it to boost the low end of sealed sub, it eats up power correct? Do I need a lot of power to compensate?

    Also, most of the designs I have been playing around with have given me bass levels of 105 dbs and up. I know this is loud but have no concept of how loud. What is an adaquate or really impressive level of bass?

    I know I have been asking a lot of questions but I am trying to learn and build a tremendous sub. Thanks!!!
     
  8. Travis G

    Travis G Stunt Coordinator

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    Hi Christopher
    IMHO Ported enclosures are the best choice for home theater subwoofers for several reasons. I'll start by pointing out that movies often have alot of deep bass in them. Music rarely has bass below 35 Hz (Except with some electronic, organ, and classical music like the cannons in the 1812 overture.)
    1. Less excursion is required of the driver at loud volumes = less distortion.
    2. Ported speakers can be about 3dB more sensitive then their sealed counterparts = they can require only 1/2 the ampifier power or give your amplifier twice the headroom.
    3. Sealed enclosures often require equalization to play flat to 20 Hz = even more excursion is required of the driver and more headroom is lost.
    It's a common misconseption that sealed enclosures have less distortion than vented ones but this is not necesarily true. A properly disigned vented enclosure will have less distortion when asked to play low frequencies at loud levels. It is true that well designed sealed enclosures will have better transient performance but all things considered I feel that ported subs are best for HT.
     
  9. Pete Mazz

    Pete Mazz Supporting Actor

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    Small room, great for music....build a sealed Tempest.

    Something around 4-5 cu ft will get you ~.7 Q. If you can, I'd go a little bigger, ~6-7 cu ft. If you decided, at a later date, you could always vent it, if proper thought was given when designed.

    I would get it built before spending money on the BFD, or similar. Listen to it in your room first, and move it around to different spots in the room (I prefer up front between the mains, myself). Buy, beg, borrow or steal a SPL meter to set it up with.

    Pete
     
  10. Kerry Hackney

    Kerry Hackney Stunt Coordinator

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    Christopher,
    I'll give you a completely biased suggestion [​IMG] Since you're going to use it for both movies and music why not go with a Tempest / Adire alignment. Depending on the room and what you do with EQ it will/can be flat below 20hz. In your dorm room you will almost certainly have some peaks that you'll have to deal with regardless of the design you choose. The Q of this alignment is .577
    [​IMG]
    The detailed plans are readily available. It is a very "musical" ported design and if you had any concerns you could always use port plugs for music and take them out for movies. In my case, I have been very happy with it as is. Size wise, it is only 214 Liters. Definitely not small but not a water heater either. I can't imagine that you would want for more or better bass quality.
    Also, WRT bass below 20hz. I really don't "hear" tones much below 21 or 22. I think most people feel more than hear those tones. Also, what you do hear is perceived at a comparatively low magnitude compared to a tone at say 50hz. Human hearing isn't very sensitive in the lowest octave. That isn't to say these low tones aren't important. They add a lot to the overall weight and impact of the music or more likely movie. There are a few music cd's around with really low content but for the most part, music disks don't delve heavily into the 20-30 range.
     
  11. Patrick Sun

    Patrick Sun Moderator
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    The Q of a subwoofer design will control the "peakiness" where the sub's response starts to fall as the frequency goes lower.

    If you have a high Q (up to 1), then at the "break" frequency where the response starts to fall, there will be a peak or boom at that frequency, thus it's not desirable. A critically damped Q=0.707 is a trade-off between low end extension and "tightness". A overdamped Q of 0.5 is basically like a sealed sub that doesn't go super-low, but has a more gradual fall-off, and is perceived a bit more "tight"
     
  12. jeff lam

    jeff lam Screenwriter

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    All the suggestions have been good ones, but you have to decide what you want. The tempest seems to be the most recommended. I will also recommend the tempest. Weather you want to build a sealed design or ported is up to you. A sealed design will most likely blend a little nicer with your paradox's but will not have the same extension and output as a ported enclosure. I would suggest looking at your HT/music listening. If you will use it for HT more, go ported. If you will use it for music more, than go sealed. In HT, a seamless transition between your paradox's and sub is not as critical as it is for music. That's my advise anyway for what its worth.
     
  13. Christopher Fisher

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    Great suggestions so far... Any more, perhaps Dan Wiggins of Adire can chime in here? If I have been getting extension via sealed tempests or even sealed shivas to below 20Hz at +100 dbs using LspCAD is a ported enclosure necessary? Also, does plugging ports in a ported system really turn it into a sealed box or is it like a leaky sealed box. I cannot believe the a plug ported box would sound exactly like a sealed box with the same airspace. One more thing... Most of my designs have been giving me about 105-110 db, about how loud is that? Is that adaquate for HT use?
     
  14. Kerry Hackney

    Kerry Hackney Stunt Coordinator

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    Christopher,
    WRT plugging ports... As long as the seal on the plug is airtight, the sub won't know the difference from a sealed enclosure. Sealed is sealed. Many of Dan's ported enclosures mimic sealed response. The 281's are also an example. They are heavily stuffed and have a relatively low Q. They have that same signature "quickness" that many like in sealed enclosures. In your room, I wouldn't sweat it either way. It isn't like the low to mid Q ported subs will sound vastly different or that they are harder to "blend" with a given speaker. Blending has to do with even response through the crossover region. Ported response usually has peaks well below that if you are using 80hz. In any event, the room modes are likely to give you way more trouble in blending than the difference between ported and sealed. FWIW, keep in mind too that you won't live in the dorm forever "hopefully" [​IMG] and you may end up in a larger space. You may want to build something you won't have to upgrade in a few years.
     
  15. Travis G

    Travis G Stunt Coordinator

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    Christopher,

    A lot of good points have been made. As you yourself pointed out the Tempest has alot of output down to 20 Hz even in a sealed box. So it sounds like your main issue will be distortion. As I mentioned less excursion = less distortion at loud levels. However a sealed sub will sound tighter so it's up to you to decide which is the best choice.

    BTW 20 Hz is definitley audible when it is loud enough.

    Travis
     

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