Shiva passive sub

Discussion in 'Home Theater Projects' started by Bhavesh, Mar 7, 2004.

  1. Bhavesh

    Bhavesh Stunt Coordinator

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    Hi everyone. Great forum!

    I'm new to DIY speaker building, but I have access to woodworking tools, soldering iron, etc.

    I live in South Africa, so when it comes to importing a subs from HSU or SVS, etc. the shipping costs are just a killer. Plus I don't want to fork over the equivalent of a 10-day overseas holiday to Bali for a sub. So I've decided to go the DIY route.

    Basically I'm hoping to achieve the performance of the $125 Dayton 10'' assembled sub or better with my DIY project. I have a budget of US$ 250 which includes shipping of the driver to my home; as that is what it would cost me to get the Dayton 10'' plus a 220V transformer from PE, or to buy a Sony WM500 locally.

    I have a Pioneer VSX-D812 receiver to do the bass management and the lowest setting on the LFE crossover is 100Hz. It has a sub pre-out.

    I'm really interested in the Shiva Mark IV subwoofer driver and the reference designs are another plus.

    I have an old Sony Mini Stereo sitting around doing nothing, rated at
    105+105 watts DIN (8 ohms at 1kHz)
    130+130 watts RMS (8 ohms at 1kHz, 10%THD)
    that I'd like to use to power a passive sub made using the Shiva. Is this a good idea?

    My room dimension are:
    Room Length: 15 ft
    Room Width: 13 ft
    Room Height: 9 ft

    The usage will be 60% HT, 40% music. I'm more interested in lower extension than higher SPLs.

    Are the sub kits with all the accessories from Adireaudio worth getting too?

    Thanks for reading and I look forward to your responses. Any other driver suggestions using Partsexpress drivers etc. will also be welcome.

    After a days web-surfing, I'm leaning heavily towards the 85L vented design. I'm just a bit worried about how to do the wiring when it comes down to it.
     
  2. Brian Fellmeth

    Brian Fellmeth Supporting Actor

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    That might be pushing it, but in any case you should aquire your amp locally. This avoids the need for any 220 Volt transformer. You don't need a plate amp or any kind of dedicated "subwoofer amp", but it does have to have some muscle. Any old stereo amp or even receiver that has some good power will work fine.
     
  3. Bhavesh

    Bhavesh Stunt Coordinator

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    Hi Brian.

    Maybe I shouldn't have said "mini".Here's a bit more info and a pic of the amp I want to use:

    houseof220.com/sonymhcgrx8.htm

    Thats a 6.5'' woofer for reference sake.
    I don't really listen that loud. I think it should be enough if I wire each of the channels to a voice coil. The amp can only take 8-16Ohm loads.
     
  4. Justin Ward

    Justin Ward Supporting Actor

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    One thing I found limiting about a mini-system type amp is the extension. Since most mini-systems have speakers that can't extend much below say 50hz, the amps are attenuated pretty steeply below that. You could try it, I did it for a while but you are going to be holding the sub back from what it can really do.
     
  5. ThomasW

    ThomasW Cinematographer

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    Bhavesh,

    Why don't you post a list of drivers that you have available locally? It's possible there maybe something that would provide good performance at a affordable price.

    Note that some car audio woofers work quite well for home audio.
     
  6. ColinM

    ColinM Cinematographer

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    The JBL GT120 goes for around $50 USD and can be used in virtually any sealed enclosure with about the same capabilities as the Shiva, perhaps there's a distributor in S Africa.

    Good luck!
     
  7. Bhavesh

    Bhavesh Stunt Coordinator

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    Hi people. Thanks for all the replies.

    Justin, the mini system has a pre-out for something called a "super woofer", maybe they're refering to a sub. So if it has a sub pre-out I'm hoping it won't attenuate the LFE. On the other hand the lowest frequency shown on the graphic equalizer of the mini system display is 63hZ, so maybe you're right. I'm willing to take a gamble and try it out first. If it doesn't work, then I'll just buy an amp locally, after trying to power it directly with my Pioneer VSX-812 receiver.

    ThomasW. I'll do some checking on whats available locally. I know the Sony car Xplod sub drivers are available. But aren't car drivers supposed to give boomy bass?

    ColinM, thanks for the advice. If you can provide some linked reviews I'd be grateful.

    Its just that I have now got my heart set on the Shiva after reading so many great reviews on it. Plus I know some furniture people who can help with the cabinet. Since theres a reference box design specifically for the Shiva, I have more confidence in the final product.

    Plus the exchange rate is so good at the moment. I have estimated the shipping as $35 using USPS surface mail (6-8 weeks). Maybe I'll send another email to Adire as nobody has responded yet.
     
  8. ThomasW

    ThomasW Cinematographer

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    If the Sony are the best locally available drivers then go with something else.......
     
  9. Bhavesh

    Bhavesh Stunt Coordinator

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    I actually have found a solution to the amp problem. My receiver is 6 channels and has pre-outs for all channels. Its rated at 6*100 watts @ 8ohms but is probably more like 6*60 watts. The surround back channel can be used to power a passive sub. So I use the sony mini stereo to power the surround speakers and the receiver to power the L, R, C and sub.

    Another question I've heard that the DAYTON 12" DVC SUBWOOFER Part Number 295-185 is a clone of the Shiva. Is this true? Can I use the same 85L reference Shiva vented design with it? I'd actually prefer to buy from Partsexpress.

    Would it make much of a difference if I used the
    3" x 11-1/2" PORT TUBE DUAL FLARED - Part Number 269-932 iso
    PRECISION PORT 3" FLARED PORT TUBE KIT - Part Number 268-350 cut to the required size to give a 13-3/8'' length
    i.e How much difference about 2'' less of port length going to make.

    My Axiom M22 has a trapezoid shaped cabinent to reduce standing waves. If I use a trapezoidal shaped cabinet and keep the enclosure at 85L will I get the same results?
     
  10. Bhavesh

    Bhavesh Stunt Coordinator

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    Just an update. I've bought the DAYTON 12" DVC and 11-1/2" DUAL FLARED PORT TUBE from PE. Should arrive in 2 weeks. The precision port was listed as 5lbs so it would've bumped up the shipping costs.

    I have 16mm MDF at home, but it has a width of only 190mm so I'll have to make an octagonal shaped cabinet to fit the 30cm driver. Will let you guys know how it turns out and post pics if i can find a place to host them.
     
  11. Brian Fellmeth

    Brian Fellmeth Supporting Actor

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    16 MM MDF is a little skimpy for sub walls. Consider making a 32 cm or so square box out of wider plywood, then laminating the 16mm MDF on top of that- can join 19 cm strips to get the width. You want the cabinet walls to be at least 30mm thick, and using two dissimmilar materials will improve resonance- each material will damp the other when it tries to resonate.





    Yes, shape doesn't matter.
     
  12. Bhavesh

    Bhavesh Stunt Coordinator

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    Thanks for the tips Brian.
    Still deciding on cabinet options- are there any differences if suitably thick/strong Plastic tubing is used iso sonotube?
     
  13. Wayne Ernst

    Wayne Ernst Cinematographer

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    Bravesh,

    If 16mm MDF is all you have access to, you could consider "doubling up" the MDF to make it thicker for your cabinet.
     
  14. Bhavesh

    Bhavesh Stunt Coordinator

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    Didn't want to start a new thread for the same project -

    If I am quite confident in the dimensions of the cabinet, do I still need to use any stuffing? How about some polyester batting lining the inside? I've used WINISD to get the correct volume.

    Thanks
     
  15. Wayne Ernst

    Wayne Ernst Cinematographer

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    Bhavesh, Yes, polyfill or polyester batting is needed. If your sub is a ported sub, then you can get by with just lining the walls. However, if it's a sealed sub, then you can pack more stuffing into the cabinet.
     
  16. Bhavesh

    Bhavesh Stunt Coordinator

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    Well, my sub is complete[​IMG]

    Dayton 12'' DVC
    89.7L internal volume
    3" diameter, 11.5'' long dual flared port.

    I have named it Grond,
    after the battering ram used to destroy Minas Tirith's Gate during the Battle of the Pelennor; which took its name from Morgoth's Hammer of the Underworld.

    Building an octagonal sub was an absolute b#tch. Good thing I had a competent woodworker with a full workshop to do it for me. I guess in my case DIY stands for "Design-it-yourself"[​IMG]
    After a good coat of wood primer, I got it spray painted silver.

    Total expenditure including parts, woodworker's labour, supplies, customs and shipping the driver half way across the world by air [$95 on its own], equivalent to $300. Just a smidge above what I'd pay to buy a Sony WM-500 locally.

    I can't really describe what its like moving from never having a sub - to finally hearing all the LFE "hidden" in the soundtrack. The Sauron shockwave during the Fellowship of the Ring Prologue was amazing.

    Well here are some pics from during the construction process. Hope this works:
    http://bhavesh.0catch.com/DIY%20sub.htm

    I'll take a pic of the finished article tonight and post it later. Also be trying out some of the test tones, but I don't have a SPL meter.

    If anyone's interested there's a 250W Sub amp in the Parts Express Scratch and Dent section.
     
  17. Bhavesh

    Bhavesh Stunt Coordinator

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    I have added a pic of the finished sub to the link above.

    Boy those test tones should carry a health hazard warning! They pressurize the room and make the air seem denser[​IMG]
    Based on listening tests and when I stop feeling air from the port, I figure I get good output until the upper/mid 20's.
     
  18. Rory Buszka

    Rory Buszka Supporting Actor

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    You don't see many octagonal subs around, that's for sure. I see it's not powered. What amp are you using?
     
  19. Bhavesh

    Bhavesh Stunt Coordinator

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    Rory , There's a reason you don't see many of them, its very difficult to get those 67.5 degree angles correct. Another thing is, when working on the endcaps/baseplate: if you plane one of the edges, the side actually gets longer.

    Its a once off thing, I wouldn't do it again. Not that I'm unhappy with how it turned out.

    I'm waiting for the Parts Express 250W Subwoofer Amplifier to go on special. Also keeping an eye out locally for a decent second-hand stereo receiver/amp.But for now, I'm using an old Sony [Phoney][​IMG] Mini Stereo, rated at
    105+105 watts DIN (8 ohms at 1kHz)
    130+130 watts RMS (8 ohms at 1kHz, 10%THD)
    I have been warned that it may be attenuting the LFE, [still thinking its powering a 6.5'' woofer]. But I can live with it for a little longer.That said, I still get good output down to the mid 20's, based on some of the test tones I got off this forum.
     
  20. KyleGS

    KyleGS Second Unit

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    Are you getting any port noise with your set-up?
     

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