Ok, fixed BFD and replotted

Discussion in 'Speakers' started by MikeyWeitz, Mar 12, 2005.

  1. MikeyWeitz

    MikeyWeitz Supporting Actor

    Joined:
    Feb 10, 2002
    Messages:
    939
    Likes Received:
    0
    Fixed ground hum with cheater plug as many suggested.
    Re-Plotted my sub + mains
    Pio 1014 set to -15

    Now could use some filter advice from the gurus.

    Thanks

    Dayton 10" + main BFD passthru
     
  2. Wayne A. Pflughaupt

    Joined:
    Aug 5, 1999
    Messages:
    6,098
    Likes Received:
    32
    Location:
    Katy, TX
    Real Name:
    Wayne
    No, what you did there was avoid fixing the hum.

    As far as filters, start with 1/4-octave at 71 Hz, boosted about 12 dB. If you see your readings at 63 and 80 Hz increase, make the filter tighter.

    Then try a 1/3-octave filter at 25 Hz boosted 10 dB. After that, take new readings between 16-45 Hz and we’ll see what we need to clean up that area.

    We’re going to end up with flat response, so you might want to use a shelving filter to achieve a house curve.

    Regards,
    Wayne A. Pflughaupt
     
  3. MikeyWeitz

    MikeyWeitz Supporting Actor

    Joined:
    Feb 10, 2002
    Messages:
    939
    Likes Received:
    0
    Thanks Wayne, yeah I avoided it for now. Wil fix this weekend.


    I will try them now.
     
  4. MikeyWeitz

    MikeyWeitz Supporting Actor

    Joined:
    Feb 10, 2002
    Messages:
    939
    Likes Received:
    0
    Ok, here it is after applying those 2 filters. Weird to my untrained eye:

    1st 2 filters
     
  5. Max F

    Max F Second Unit

    Joined:
    Jun 26, 2004
    Messages:
    250
    Likes Received:
    0
    Man, why is everyone testing their subs so loud! Turn it down and save your ears, subs, pets from damage.

    70s and 80 db are more than enough for testing room response.
     
  6. MikeyWeitz

    MikeyWeitz Supporting Actor

    Joined:
    Feb 10, 2002
    Messages:
    939
    Likes Received:
    0
    Ok, here it is after creating some filters. I guess it is a bit better.after filters
     
  7. PatrickS

    PatrickS Stunt Coordinator

    Joined:
    Jul 31, 2002
    Messages:
    58
    Likes Received:
    0
    Wayne,

    From what I've heard, wouldn't boosting freq. (especially lower ones)be requiring way to much power from the sub amplifier? Potenially damaging it?
    From all I've read about applying EQ, the usual rule is to cut Freq. (and usally not more than 6dB if you can help it), and not to boost any freq. (inparticular low frequencies).

    Is there something I'm missing about this, or is that rule just a very "paranoid" one![​IMG]

    Best Regards,
    Patrick
     
  8. JasonCI

    JasonCI Stunt Coordinator

    Joined:
    Dec 29, 2004
    Messages:
    59
    Likes Received:
    0
    Great Job Mikey,

    Now I'd try a 1/6th octave-wide 5 dB cut centered at 36 Hz.
     
  9. Lewis Besze

    Lewis Besze Producer

    Joined:
    Jul 28, 1999
    Messages:
    3,134
    Likes Received:
    0
    all I see is theater photos....
     
  10. Greg Bright

    Greg Bright Second Unit

    Joined:
    Feb 24, 2000
    Messages:
    265
    Likes Received:
    2
    Real Name:
    Gregory Bright


    Right. Hovering over the link shows the correct URL, but clicking on it just takes us to a big gallery.
     
  11. MikeyWeitz

    MikeyWeitz Supporting Actor

    Joined:
    Feb 10, 2002
    Messages:
    939
    Likes Received:
    0
    Sorry, they must ahve removed the chart.
    Here it is:

    FR chart w/ BFD

    Added the 36hz cut, but won't be able to re plot it for a while.
     
  12. Wayne A. Pflughaupt

    Joined:
    Aug 5, 1999
    Messages:
    6,098
    Likes Received:
    32
    Location:
    Katy, TX
    Real Name:
    Wayne
    Patrick,
    I wouldn’t call that advice “paranoid,” it just hasn’t been thought through. The fact is, any sub equalizing places demands on both the amplifier and driver.

    Let’s take Mickey’s situation, for instance. The original graph is no longer up for reference, but his main problem was two fairly narrow low spots at about 71 and 25 Hz.

    If you follow the “cut only” advice from the folks you’ve been reading, you would have had to apply numerous filters to bring down the rest of his response curve to match those two narrow low points.

    What do you have when you’re finished? Well, your overall sub level is now 10-12 dB lower than it was before you started. So you have to increase the sub’s gain at least that much to get it back to a usable level.

    You might think, “No big deal, you’re only driving the sub as hard as you were before,” right? Nope. The situation now is that you now have much flatter response. This means the frequencies that were underrepresented before (25 Hz and 71 Hz) are now being driven harder than they were before equalizing. That’s right – you’ve succeeded in boosting those low areas, whether you intended to or not.

    Thus, in Mickey’s case it makes much more sense to use a couple of filters to boost the low spots instead of multiple filters to lower everything else.

    Now let’s consider the opposite situation, where instead of a couple of low points in response you have a couple of “hot spots”. A 6-12 dB or more standing wave at say, somewhere between 40 and 80 Hz will make everything sound boomy with a “one-note” quality. What happens is, since that hot frequency dominates your sub’s response, and because it’s so annoying, that’s what determines your subwoofer setting. You’re forced to set it artificially low.

    What happens when you eliminate that response peak? The natural tendency is to think you’ve picked up some “free” headroom. But as was the case above, you now find that the sub’s volume is too low. So you boost it back up, and the “free” headroom is gone. And as it was in the first situation, you now have flat response, which means you’re driving everything across the board harder than you were before. Thus even cutting a hot spot or two will end up in a net loss of headroom.

    So as you can see, boosting or cutting is usually academic and gets the same results in the end. It’s unavoidable that just about any subwoofer equalizing places increased demands on the amplifier and driver, so practically speaking you have to have enough headroom going in. If not you shouldn’t attempt it.

    Regards,
    Wayne A. Pflughaupt
     
  13. Greg Bright

    Greg Bright Second Unit

    Joined:
    Feb 24, 2000
    Messages:
    265
    Likes Received:
    2
    Real Name:
    Gregory Bright
    But by boosting certain bands by 10-12dB isn't one making the BFD more susceptible to overload? Unless one also lowers the LFE channel output at the receiver? Things do tend to get more and more complicated... and more fun.
     
  14. MikeyWeitz

    MikeyWeitz Supporting Actor

    Joined:
    Feb 10, 2002
    Messages:
    939
    Likes Received:
    0
    I am going to have to re plot it @ a lower level. I was @ -15 on my 1014, but never listen to it @ that, so I am going to try @ -25 or -30 next time.
    I am not real happy with how it sounds, so going to try again in few weeks when I can.
     
  15. PatrickS

    PatrickS Stunt Coordinator

    Joined:
    Jul 31, 2002
    Messages:
    58
    Likes Received:
    0
    Interesting Points Wayne. Thanks for the insight!

    Best regards,
    Patrick
     
  16. DevinJC

    DevinJC Stunt Coordinator

    Joined:
    Nov 4, 2004
    Messages:
    65
    Likes Received:
    0
    Bah Wayne you convinced me. I've been fighting mine trying to not boost, or just a little boost, and one good kick up in the right spot would solve the last of my problems.

    And if I blow the Dayton, I needed a better sub anyway. [​IMG]
     
  17. Joe Mihok

    Joe Mihok Second Unit

    Joined:
    Dec 14, 2003
    Messages:
    265
    Likes Received:
    0

    On my 1014 I calibrate my sub at -27. After creating a flat response with the BFD, the sub sits at 83db @ -27 on the 1014. 83db's should be okay but I wouldn't go louder when playing those tones.
     
  18. MikeyWeitz

    MikeyWeitz Supporting Actor

    Joined:
    Feb 10, 2002
    Messages:
    939
    Likes Received:
    0
    Yeah, I am going to do it again @ -30 as I rarely listen to it any louder then that.

    I tweaked it some more by ear last night. I am happier with the sub sound now, but still notice a slight boominess.

    I will be able to even it out in a few weeks :)
     
  19. Wayne A. Pflughaupt

    Joined:
    Aug 5, 1999
    Messages:
    6,098
    Likes Received:
    32
    Location:
    Katy, TX
    Real Name:
    Wayne
    Greg,
    This isn’t a problem, as the BFD was designed for professional use (albeit low-end professional use). Pro audio protocol uses much hotter signal levels than home equipment does, so it’s virtually impossible to overload the BFD. I’ve been following these BFD threads for 5-6 years now, and I’ve rarely seen anyone run into this problem. If it does prove to be the case, you can simply lower your receiver’s sub output level to compensate.

    What I have seen on at least one occasion was just the opposite: Some poor fellow who had a response curve similar to Mickey’s and went wild cutting everything in site to bring it all down to a couple of low spots. What he ended up with was a signal so weak that the BFD wouldn’t even pass it out the other end.

    Regards,
    Wayne A. Pflughaupt
     
  20. Greg Bright

    Greg Bright Second Unit

    Joined:
    Feb 24, 2000
    Messages:
    265
    Likes Received:
    2
    Real Name:
    Gregory Bright
    Wayne,
    Maybe overload wasn't the right term. I was referring to those times when those dreaded red lights come on, and digital distortion occurs. Dialing back the receiver's sub out, as you stated, would solve that. In any event this type of balancing act would put an expert juggler to shame, considering that the levels of three separate devices (sub, BFD, receiver) must all be set independently, yet in perfect symbiosis. Not a task for the faint of heart.

    Greg
     

Share This Page