XO experts: what the heck is this??

Discussion in 'Archived Threads 2001-2004' started by Dave Milne, Mar 17, 2003.

  1. Dave Milne

    Dave Milne Supporting Actor

    Joined:
    Jul 2, 2001
    Messages:
    568
    Likes Received:
    0
    Trophy Points:
    0
    I'm looking at a schematic for a crossover designed by Dynaudio (shown below, hopefully) and there are a bunch of parts on the right side just hanging off the input. If the amp source impedance is really zero (or darn close)... what could these parts possibly do?

    http://www.azstarnet.com/~dmilne/rev...eral005002.jpg

    Text from Dynaudio states:
    "The circuit following the tweeter area is no conventional circuit but it improves the electrical impedance of the loudspeaker and the electrical phase response of the filter until nearly ideal values are achieved. These additional filters produce an extraordinarily flat impedance response which reliably prevents reflections caused by cables up to a frequency of 500 KHz."

    I built these and tried them with and without the "extra" network and didn't hear a significant difference. Is this snake oil?

    Dave
     
  2. Brian-K-Owens

    Brian-K-Owens Stunt Coordinator

    Joined:
    Feb 6, 2003
    Messages:
    194
    Likes Received:
    0
    Trophy Points:
    0
    Additional branches like that could be used for many things, like:

    Resonant frequency traps for the tweeters Fs.
    Getting rid of peaks in the tweeter's frequency response.
    Controlling rising frequency response of a tweeter.
    Changing phase response of the tweeter.

    Brian
     
  3. Mark_E_Smith

    Mark_E_Smith Second Unit

    Joined:
    Jan 10, 2002
    Messages:
    275
    Likes Received:
    0
    Trophy Points:
    0
    The complexity of the 3 way! Ditto what Brian said
     
  4. Dan Wesnor

    Dan Wesnor Second Unit

    Joined:
    Apr 28, 1999
    Messages:
    389
    Likes Received:
    0
    Trophy Points:
    0
    Impedance compensation circuits (like that one) are intended for use with amplifiers that have problems with reactive loads - i.e., tube amps. If you are using a quality solid state amp, I doubt you would hear much difference. Usually, most designers will mark impedance compensation circuits as "optional".
     
  5. Brian-K-Owens

    Brian-K-Owens Stunt Coordinator

    Joined:
    Feb 6, 2003
    Messages:
    194
    Likes Received:
    0
    Trophy Points:
    0
    Good call Dan. My bad, as I should have looked closer at the diagram. I just glanced at it and after reading "circuit following the tweeter area" and "up to a frequency of 500 KHz.", I thought all of the additional network was in parallel with just the tweeter. I now see it is in parallel with the entire network.

    I agree with Dan's post. . .

    Brian
     
  6. Dave Milne

    Dave Milne Supporting Actor

    Joined:
    Jul 2, 2001
    Messages:
    568
    Likes Received:
    0
    Trophy Points:
    0
    Brian,
    It didn't sink in with me at first either, until I started building them and noticed that this network is straight across the amp terminals. What could possibly be the effect? But Dan's post makes sense. In my case, I've got a solid-state amp (Bryston 4BST) with only about 18" of 12ga wire to the crossovers. Yes, that's inches. I put the crossovers in separate boxes in my equipment closet so I could "tweak". Three separate 12ga runs connect the crossovers to each speaker. So I probably wasted my money on the Solen coils and caps (ouch) for these networks.

    I guess the Dynaudio engineers were in one of those "cost is not object" moods. Oh well, maybe I can use the parts in the next projext...
     

Share This Page