Troubles with my new Shiva, please help!

Discussion in 'Home Theater Projects' started by BryanDO, Sep 9, 2004.

  1. BryanDO

    BryanDO Stunt Coordinator

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    Hey guys, I just built my first home audio sub. It consists of an Adire Shiva in a sealed 3 cu ft box and a 360 watt amp. After I put everything together, I fired it up and decided to test it with some Matrix. To my disappointment the sub was bottoming out constantly at low frequencies, the output wasnt all that loud either. I can also hear the sub working and moving at higher excursions before reaching its limits. The box is well sealed and all this was happening with just 1/4 power of the amp! It's in a very large basement and is in the corner. What can be wrong? Any help would be greatly appreciated as I'm very frustrated at this point.

    Thanks..
     
  2. DanWiggins

    DanWiggins Second Unit

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    Hmmm... Really big sealed box, lots of power, big room, sure recipe for bottoming. Especially for a HT subwoofer.

    But there is a solution! Drop a port in that box. Use an FP3, and make the center tube 5" long to tune you to 22 Hz. That will give you a LOT more output in the 20-50 Hz range.

    Also, please understand that the gain setting on the knob does NOT indicate the power out from the amp! Depending upon the output signal level from your receiver, you can reach full amp output with the gain knob barely turned on, or you may have to turn it all the way up. Completely dependent upon the signal fed. It's not a "power out" knob, just a level match knob.

    Dan Wiggins
    Adire Audio
     
  3. BryanDO

    BryanDO Stunt Coordinator

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    Thanks for the quick reply. The box used to be ported to 23hz using 2 3" ports, they werent flared. There was terrible port noise so I sealed the box. Would a single 3" flared port have port noise? If not I'll order one ASAP. Thanks again Dan.
     
  4. DanWiggins

    DanWiggins Second Unit

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    Shouldn't have a problem with a flared 3" port; if you're worried about it, use a full-length 4" flared port and have zero issues.

    Note that even with the vented box, you can still push past the linear limits of the driver between 30 and 45 Hz. And make sure your amp does NOT have any EQ in it - that will really screw things up, too.

    Dan Wiggins
    Adire Audio
     
  5. BryanDO

    BryanDO Stunt Coordinator

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    Thanks, I ordered the 4FP. I found out my amp has a 4 dB boost at 25Hz. Not sure what to make out of that? Any tips due to the boost?
     
  6. Allen Ross

    Allen Ross Supporting Actor

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    just tossing out an idea, have you tried moving the sub around the room? It might just be that you have a nasty null in the spot that you have it. If you find that it still sounds horrible then my best guess is go ported like my man Dan mentioned.
     
  7. James W. Johnson

    James W. Johnson Screenwriter

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    Id wager that you just did not buy enough bass for your tastes.

    Sell the Shiva and buy a pair of Tempests if you want some truly killer bass.
     
  8. KyleGS

    KyleGS Second Unit

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    I would suggest simply selling the Shiva and getting a Tempest. You could run it in a fairly small 3.5cf to 4cf box with heavy stuffing and run that same amp. You would probably have more than enough output.

    I'm running a sealed 100L (3.6cf) Tempest with a clean 450watts and it more than fills my auditorium sized room with amazingly deep and loud bass.
     
  9. BryanDO

    BryanDO Stunt Coordinator

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    The shiva right now sounds great and blends very well with the rest of my system. My first passion before home theatre was car audio so maybe I am looking for more. I will try out the ported Shiva, if it's not enough I'll look into a tempest. Such a shame though, I haven't had the Shiva for a week [​IMG]
     
  10. BryanDO

    BryanDO Stunt Coordinator

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    Just thought I'd update. I put the 4" flared port firing rear and wow, huge difference! it seems like 24hz and under just hammer you in the chest. No problems bottoming out at all NO port noise. Thanks Dan for making me love my Shiva [​IMG]
     
  11. Kyle Richardson

    Kyle Richardson Screenwriter

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    Good to hear Bryan!
     
  12. Dan_Gtp

    Dan_Gtp Extra

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    Bryan, I come from the same kinda thing, car audio. We are spoiled with much more ease in getting loud bass. Getting something in your HT to blow your socks off will be difficult, and possibly structurally dangerous [​IMG]

    I have a 240L Tempest sonosub ported to ~17hz. It's in a pretty big basement (24x24) as well, so no I don't get the "kicked in the chest" feeling, but that's because of 2 things. 1)The size of the room compared to a car, and 2)These HT subs we build are tuned flat, and don't have the big hump in the midbass that adds tot he "kick" feeling. I love the Tempest, it is still fairly loud and impressive, and it goes so deep, you will have to give whatever you end up with a chance to enjoy that part of it. Unfortunately though even I have thought about upgrading, sometime. So before you jump on the idea of getting a Tempest, make sure that will be enough. Don't get me wrong, I can shake ductwork like mad, and give you a massage by laying on the floor above my HT room, it's just I know where you're coming from [​IMG]

    I just finished a 142L Shiva sonosub ported to ~18hz for a friend tonight. I'll be testing it tomorow, but I expect the same as my Tempest, just a little less output.
     
  13. BryanDO

    BryanDO Stunt Coordinator

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    After spending a little more time with the ported Shiva, I've learned to accept the fact that I'm not going to get 140dB's like in the car. I've decided to concentrate on the sound quality, how it hits those low notes and has a very flat response. That made me apprecaite it more. Right when I was feeling good about my Shiva, I found out were moving [​IMG] The basement at the new house is massive and has hardwood floors. How my HT is going to sound I have no idea. I'm going to keep the Shiva, I can't afford another sub at the moment, I'll shoot some pics of the new house, maybe you guys can help me get it ready for a theatre.
     

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