How much do EQ filters change the Qtc?

Discussion in 'Archived Threads 2001-2004' started by Greg P, Apr 6, 2002.

  1. Greg P

    Greg P Stunt Coordinator

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    Yesterday I did a shoot from the hip EQ from the graphing results from Unibox on my 1503. I know I flattened it a bit but I definately noticed it seemed boomier, and the transient responce was not as good. I did have 11 filters though. How much is lets say 3 or 4 filters going to change the QTC?
     
  2. Wayne A. Pflughaupt

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    Greg,

    Equalization makes electronic correction to compensate for shortcoming in a speaker system’s natural or room-induced response characteristics.

    Equalizers don’t change a driver’s Thiele-Small parameters.

    Regards,

    Wayne A. Pflughaupt
     
  3. Greg P

    Greg P Stunt Coordinator

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    Hi Wayne,

    Thomas is an authority on diy as you are and he wrote in my other thread:

    "Using EQ changes the Qtc of the system, it makes it higher. So the fewer filters used the better." (Thomas W)

    So I am confused now? Can someone explain this?
     
  4. Wayne A. Pflughaupt

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    Greg,

    I’m no expert on the ins and outs of Thiele-Small; however, Thomas was speaking of changes in Qtc to the system, not the driver itself; therefore we are probably both correct.

    Of course, it is always best to use as few filters as possible, as Thomas mentioned. However you typically use as many filters as you need to achieve smooth in-room response. I don’t see Qtc issues as a reason to limit the number of filters if it means you have to live with less-than desirable response.

    But rather than try to second-guess Thomas, it would probably be best if he explains what he means by this.

    Regards,

    Wayne A. Pflughaupt

    PS, Greg, it probably would have been best to continue your first thread, instead of starting a new one.
     
  5. ThomasW

    ThomasW Cinematographer

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    Wayne

    You got it right, my reference was the "Q" of the system. Sorry for any confusion.

    I've seen people fixate on getting a sub flat within 1 db using all 12 filters in a DSP1100P/DSP1124P and wonder if they couldn't do better by ganging in another 12. The results had a negative impact on the detail and clarity. With judicious use of the controls we were able to obtain 90% of his original curve with only 5 filters. Overall it was a much better sounding option.
     
  6. Wayne A. Pflughaupt

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    Thanks for “weighing in,” Thomas.

    You’re right: People can get carried away with equalization. What’s best is what sounds best.

    Greg, hope all this gets you pointed in the right direction.

    Regards,

    Wayne A. Pflughaupt
     
  7. Greg P

    Greg P Stunt Coordinator

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    Thanks guys,

    Ya, my next channel filter is only gonna use about 5 filters. I used 12 on the quick one I did, and I did notice less "clarity" or the bass being a tad bit muddy.
     

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