Some input on my sub

Discussion in 'Speakers & Subwoofers' started by Chris Gunn, Nov 3, 2005.

  1. Chris Gunn

    Chris Gunn Extra

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    I just got my BFD and I spent a day on getting my 15" BluePrint SonoTube sub as flat as I can here are the results.

    This is with the JBL E100 set to small.

    ://camaroman.redirectme.net/Sub.jpg
    (Just add the http to the link above)


    I think it came out great I used the BFD Guide to get started.

    There are Two things I don't like....
    1. I had to boost 20hz +13
    2. Had to boost 70hz +16 and it still has a bad dip....

    I don't know if I have the filters set up right I just did small changes at a time till it came out as flat as I could get it.


    Is there any Ideas on how to get rid of that dip @ 70hz?

    Any input would be great

    Thanks,
    Chris
     
  2. ScottCHI

    ScottCHI Screenwriter

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    Well, why do you use a 120Hz xover with those speakers? Did you try 80Hz?
     
  3. Chris Gunn

    Chris Gunn Extra

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    I did try it at 60 and 80 did not seem much diffrent. But I will give it another try.

    Thanks
     
  4. John S

    John S Producer

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    I'd give it another try. 120hz is way to high in my opinion, unless you have a compelling reason to run it that high.
     
  5. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    This is just asking for trouble. Do you have any idea the sort of demands that puts on the woofer and amplifier?

    You're boosting +13dB at 20Hz and only realizing a 2 or 3dB gain. Is it really worth risking the integrity of your woofer for that? The curve really didn't look too bad down there. I think this is a case where you're working way to hard to achieve perfect flatness. Its not necessary and at any other listening position, you're probably just introducing new peaks and dips. Plus your Radio Shack meter isn't nearly that accurate down there anyway. Try only correcting to within +/- 3dB. This way you'll spend much less boost.

    The 70Hz dip looks like a big null. Before EQ, your response ranges from 62dB to 98dB. That's really wide. If there's any other possible sub locations, I'd give them a try.
     
  6. Victor Ferguson

    Victor Ferguson Stunt Coordinator

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    I agree with the above poster. You are not supposed to use the BFD that way, it is used to make cuts to peaks in your FR not boost low areas (more on that below). The largest boost you should make is 3db but IMHO don't even do that. Now the reason why you have nulls is the interactions in your room are cancelling those frequencies boosting them is not going to help. Room treatments or better sub location is all you can do.
     
  7. Chris Gunn

    Chris Gunn Extra

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    Thanks for the replies. I'm going to start over and try to get it better without all the boost.

    I have tried different locations for the sub and my curent location is the spot that gave me the flattest curve before EQ.

    I will get this done this weekend and will post a new curve.

    Again,
    Thank you
     
  8. MikeNg

    MikeNg Second Unit

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    Chris, what does your FR look like pre-BFD?
     
  9. Chris Gunn

    Chris Gunn Extra

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    OK, I have redone things and here they are....

    Without BFD Sub Alone

    Sub Alone No EQ

    Here is Sub w/BFD

    Sub w/BFD

    Here is sub w/BFD & Mains JBL E100

    Sub w/BFD and JBL E100 Mains

    Now with my mains as you can see It has raised 45hz to 63hz almost 5 dbl's Now do I bring down some of the filter gains to bring it back in line?
     
  10. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    This looks much, much better. Especially in terms of the amount of boost you're using. Some comments:

    You could probably eliminate filter #4 by tweaking filter #3 a little bit. Like maybe
    Filter 3 = +5dB @ 20Hz, BW=7
    You might also have to push filter #5 around a little to make it work. But it just doesn't seem like #4 is doing much when you've got it surrounded closely by 3 and 5.

    I can't really figure out how you fixed the peak at 32Hz. You're using filter #1 set to -4dB, but somehow that dropped the peak by 8dB!!! None of the other filters seem close enough to help out. Strange.

    You could certainly cut the 45-63Hz down a little if you want. That might de-emphasize the null at 70Hz. But be careful with center frequency and bandwidth so that the cut does not extend above 64Hz or so.

    Good work. I just finished EQ-ing my infinite baffle sub today.
    [​IMG]
     
  11. MikeNg

    MikeNg Second Unit

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    Hey Ryan, what are you running on your IB? Specifically drivers and amps?
     
  12. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    4 Ascendant Audio Atlas 15's powered by a single 250 watt plate amp.
     
  13. MikeNg

    MikeNg Second Unit

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    Mmmmmmmm, tasty.

    Is that going to be enough juice?
     
  14. Wayne Ernst

    Wayne Ernst Cinematographer

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    Keep in mind I.B. subs don't need a whole lot of juice to get fired up. [​IMG] [​IMG]

    Here was my IB readings before any EQ effects applied. Well, actually ... things were disassembled before and EQ was added. Instead, I'm going nuts and adding an IB setup in my zone 2 (the living room). It'll be a "10" when it comes to WAF. [​IMG]



    http://members.cox.net/wjepics/sinesweep.jpg
     
  15. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    The plate amp wouldn't have been my 1st choice except for the fact that I already had it lying around. Wayne is correct - I get +6dB sensitivity from running 4 drivers instead of one. It's the equivalent of a single Atlas powered by 1000 watts, if the Atlas could take that much. So far it seems to be sufficient, though the amp does get warm during aggressive material and sound levels.
     
  16. MikeNg

    MikeNg Second Unit

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    What's the impedance on each of those Atlas'? Can the amp take the ohm load you're giving it? It might be working too hard.
     
  17. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    In order to prevent this thread from straying too far off topic, I'm starting a new thread in the DIY area about my IB. I'll answer your question there, Mike.
     

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