Questions on Shiva EBS Alignment

Discussion in 'Home Theater Projects' started by Russell R, Aug 28, 2003.

  1. Russell R

    Russell R Stunt Coordinator

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    Hello,
    I am in motion on this project and have a few questions.

    I am using a PE250 plate amp without the bass boost. How will the 19hz rumble filter work with the 18.1hz port tune? Will the the lower than 19hz information be present or does the filter remove this information? I have the 142.5 liter tube cut and will finish up the end caps this weekend. With this given volume, what would be the benefit of increasing or decreasing the port tune? I will play with the numbers in WinISD, but would like your opinions.

    Thanks,
    Russell
     
  2. AndersP

    AndersP Stunt Coordinator

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    The filter will dampen a 19 Hz tone 3 - 6 dB. The fact that the sub has its tuning in this area is nothing to loose sleep over, taking your room modes in to account.

    You can always remove/tweak the rumble filter at some later time.

    Stick with the given alignment. You will need some measurements to point you in the right direction if you start tampering with it. I think eq is the way to go if you want to optimize the sub.
     
  3. CarlDais

    CarlDais Stunt Coordinator

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    Gee doesn't the SVS-01 outboard subsonic filter have 3 differnt filter settings 15Hz---20Hz---25Hz? I think
    Tom had these points chosen to correspond with the tuning points of his SVS subs 16--20--25. Didn't give him any second thoughts or undue concerns.

    I'd be willing to bet your tuning and subsonic filter points will be OK. And after, all filters & rooms aren't always exactly predictable.

    Next variable would be what do you listen to most often and is it always at or near reference level?
     
  4. Jack Gilvey

    Jack Gilvey Producer

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  5. Russell R

    Russell R Stunt Coordinator

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    Hello,
    Thanks for the replys. I am intending to build the Adire Shiva EBS Alignment as is, but will allow for tuning capabilities later on. Jack, why did you recommend a higher tune than the 18.1hz? Just wondering. This will reside in a small room (12x13) possibly moving to larger room later.

    On a side note, has anyone here used a DBX 120? It is supposed to create sub-harmonics based on a family of low frequencies.

    Thanks for you help.

    Russ
     
  6. Russell R

    Russell R Stunt Coordinator

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    I ran the tuning through WinISD and with the 142.5 liter enclosure, the 20 to 22hz appears to be flatter down to 20hz than the original 18.1hz tune. This is without the additional room gain though. So, will the additional room gain be a bad thing? This is for a dedicated HT room, but I do listen to music. Your thoughts?

    Thanks,
    Russell
     
  7. Jason_Me

    Jason_Me Stunt Coordinator

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    I say stick with the 18hz tune and 19hz filter. The EBS alignment is designed for flat in room response. Starting the roll-off at 19hz will give you better protection below tuning, where the woofer is uncontrolled.
     
  8. Greg Monfort

    Greg Monfort Supporting Actor

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    Assuming the latest version of the Shiva is as robust as the original, disabling the rumble filter and tuning to 16Hz for organ music/the few movies with really low special effects should work well.

    FWIW, I put two in a stuffed 8ft^3 (acoustically ~10ft^3, or roughly 2x what you're building) tuned to 16Hz with dual 15" PRs. Stuck in a corner and driven with 300W/driver, it popped drywall nails out on organ notes and could hit DD reference at 14ft, so when you become jaded and start thinking new sub, just double up. [​IMG]

    GM
     
  9. Russell R

    Russell R Stunt Coordinator

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    Hello,
    Yes, all of the comments make sense. I plan on tuning to 18hz with intentions to modify and test later on. On that note, I am using the PE Flare port. Will duct tape or a light film of silicone seal be a problem with holding the port together? I want to make this a variable that can be changed later.

    Eventually, the PE amp will be replaced by a larger Pro amp. So, with that in mind, I want to have the flexibility of tuning.

    I listen to some pipe organ, but not all of the time. My room is small and dedicated to a front projector setup. So, movies are the big thing for me.

    Thank you all,

    Russell
     
  10. Jason_Me

    Jason_Me Stunt Coordinator

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  11. Greg Monfort

    Greg Monfort Supporting Actor

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    >I wouldn't bother with that sub, that amp is more than capable of bottoming a Shiva with modern LFE content in just about any alignment, but especially an EBS.
    ====
    Oh really?! With 300W/driver and tuned to 16Hz I never came close to bottoming the original Shivas, though I could easily clip the amp on organ music. Are there movies with significant LFE below 16Hz?

    GM
     
  12. Jack Gilvey

    Jack Gilvey Producer

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  13. Greg Monfort

    Greg Monfort Supporting Actor

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    Something's not right. Of these I only have SWE1, and don't have the Shiva sub/amp combo anymore for a direct comparison, but driven with 110W/chnl, I can't bottom my 5mm Xmax extreme EBS fullrange mains (four drivers = 20mm Xmax/+6dB eff. gain/220W) with this one at 10dB below reference.

    GM
     
  14. Brian Bunge

    Brian Bunge Producer

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    Greg,

    IIRC, The Haunting has info. down to, and possibly below, 10Hz.
     
  15. Scott Simonian

    Scott Simonian Screenwriter

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    The Adire Tempest that I have is vented @ about 15hz. When I first got AOTC the opening recked hell on it. The low tuning put the most excursion in the 30-35hz area. I had to turn down the gain on the receiver from now on.
     
  16. Greg Monfort

    Greg Monfort Supporting Actor

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    >IIRC, The Haunting has info. down to, and possibly below, 10Hz.

    ====

    Interesting that they would go this low knowing that few receivers, amps, much less subs, can handle it. I assume it's at a very low amplitude.

    ====

    >The Adire Tempest that I have is vented @ about 15hz. When I first got AOTC the opening recked hell on it. The low tuning put the most excursion in the 30-35hz area.

    ====

    Interesting, since the BW of max excursion above Fb in a BR is the first octave, or up to 30Hz in this case. Do you have the bass boosted at all?

    GM
     

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