Question about possible DIY sub project

Discussion in 'Archived Threads 2001-2004' started by EarleD, Mar 5, 2001.

  1. EarleD

    EarleD Supporting Actor

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    I have been toying with the idea of using my pair of SVS 20-39's with a X-30 crossover and using them in stereo. I currently have a pair of Klipsch KG4.2 as my mains which seem to start rolling off at about 50hz. These are powered by an B&K 4420 amp(225watt/channel). The receiver powers the other 3 speakers. I would split the main preamp outs on my receiver(Denon3200) one set to the B&K and one set to the X-30 and then to the Fidek amp powering the sub. I would then set the Xover on the X-30 to about 50hz. I would also set the fronts to large. This should give me true full range mains.
    Then I want to build a monster sonosub for the LFE channel. Something that will make your ears and nose bleed I am thinking along the lines on 30" diameter tube maybe 5 feet long. Maybe 2 15" drivers, unsure about types, I'm kind of new to the DIY area of HT. Any suggestions? This sub would not be used for music listening only HT.
    I have read about the programs which tell you about the port length, tuning freq, etc. But I'm not very fluent in these type of deals, so if someone can run numbers for me it would be appreciated.
    Budget would be around $1000 with amp.
    Any ideas/suggestions/thoughts?
    Thanks
    Earle
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  2. Kyle Richardson

    Kyle Richardson Screenwriter

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    With that kind of a budget you could get a couple of Adire 15" Tempests or the new 18" Maelstrom and a nice quality professional amp like a Crest and be under a grand. Go to http://www.adireaudio.com/software.htm and download the lspCAD. It already has the numbers input for the Tempest so you can play around with enclosure volumes until you find one you like.
    2 Tempests with a 695L enclosure tuned to about 19hz would sound mighty fine!
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    See my home theater at www.hometheaterforum.com/bbs/equipment/28585.html
    Kyle Richardson
     
  3. DanWiggins

    DanWiggins Second Unit

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    Earle,
    Whatever drivers you end up selecting, I'd recommend considering the QSC RMX1450. It's a LOT of power for the price (1450W bridged into 4 ohms, 450W per channel into 4 ohms), very well built, and has a very quiet fan (by prosound amp standards). And it's available from a variety of on-line sources for under $500. We use the big brother, the PLX3402, as our reference brute amp. Never had a problem with it yet, it's rock solid, and gives us all the power we need for now (3400W into 4 ohms, bridged).
    Since you don't need a crossover (you have the LFE channel), you could either buy more drivers (for more bass), or a good EQ (Behringer Feedback Destroyer Pro, or a used Rane PEQ17, can usually be found for around $150, sometimes less).
    Dan Wiggins
    Adire Audio
     
  4. EarleD

    EarleD Supporting Actor

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    Kyle and Dan
    Thanks for the ideas and suggestions. Hopefully this will become a reality if the not too far future, but the wife facotr definatly applies. She doesnt seem to understand the need for more and deeper bass. Maybe one day she will understand.
    Here's a few more questions:
    1. Are there anyother external sub crossovers other than the X-30?
    2. What kind of performance gain would I gain over a dual Tempest tube over say a single/pair SVS 16-46 with their Samson amp?
    3. Would using the pair of 20-39's next to each speaker and another dedicated LFE sub cause any unexpected cancellation problems, other than what could happen using two subs. I found out that I get a flatter response with 1 sub in each rear corner, though if I load just one the impact is bigger.
    4. Size on the tube is not a problem(within reason guys). If I understand this stuff right, the bigger the enclosure the deeper and louder and flatter the response. Is this right?
    More is sure to follow so bear with me.
    Thanks again
    Earle
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  5. Kyle Richardson

    Kyle Richardson Screenwriter

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    1. There might be other crossovers out there but the X-30 is the most popular because of its price/performance ratio.
    2. Not very much, but a little. Remember the SVS originated from the DIY crowd so they are really a "professional DIY design" and are very good. The advantage you might have with a DIY is that you can customize it the way you want.
    3. Your original size suggestion is just fine. There is a point that getting larger will not help out that much more though. You could actually go a little smaller with your design and not sacrifice much performance.
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    See my home theater at www.hometheaterforum.com/bbs/equipment/28585.html
    Kyle Richardson
     
  6. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    >>>Here's a few more questions:
    1. Are there anyother external sub crossovers other than the X-30?
     
  7. EarleD

    EarleD Supporting Actor

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    Tom,
    This would be my first DIY speaker, i'm not afriad to try something new. I recently gutted the kitchen and started over so I guess I should be able to handle this.
    I currently have one 20-39 in each rear corner and get the flattest response in the prime seat. If I put both in the same corner I get much more impact in the prime seat, but it's impossible to balance the subs level. I just increased the gain on the receiver to compensate.
    The problem I had with the balancing the subs with the Fidek wide open is gone, both gains are wide open and the receivers sub level is a -5.
    The IB is probably outof my league.
    Its amazing, you get better subs and can suddenly shake a concrete slab. The only thing is now I want to crack it.
    Thanks
    Earle
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  8. Jack Gilvey

    Jack Gilvey Producer

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    Earle, the 24 cu.ft dual tempest sub TV described will not only crack your foundation, it'll get you cited, divorced, and deported...talk about a party! [​IMG]
    The size tube you mention, 5' by 30", gets you that 24 cu.ft. exactly, so that's one way to go. James Johnson's subs' specs are identical, but his is a more traditional, if battleship-sized, box. Check it out here , very impressive.
    I think that an infinite baffle (IB) is actually the easiest type to build, as it's just a box, or even a baffle, but you need a room/space for an enclosure, and the willingness to put a hole in the wall. The quality of the bass, however, is unparalled, and the quantity is no slouch,either. Rich Kraus' installation is detailed in this thread. You can see that the box itself is a small,simple affair.
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    http://content.communities.msn.com/i...&ID_Message=43
     

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