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circuit design issue / question

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  • Raw drivers on baffle


    tajanes
     John H, btw forum has decided I don't get emails
  • that looks spot on
  • Well looks like you can cross higher with the right curves.




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  • edited March 2020

    jhollander

    Interestingly here is your designed Xover measured traces (~red) vs. what I had worked into prior (~blue).  I had to adjust the tw’s level (up significantly) to get it to match up with the mid’s level of your design.  (I ran w/o baffle step compensation circuit, as I’m mostly interested in mid/tw, as I’ll be using dsp for Xover and eq btwn woofer and coax).  

    FYI (per your crossover layout) for my tw filter I had; R1 3.0, R2 5.0, C2 2.2uF, C4 6.0uF, and L2 0.085mH



    I’m clearly liking your mid trace (over what I had), and preferring my tw trace.  Now I’ll play around a bit to work out a smooth transition.  Pic 2 is the initial look of the re-matching.



    Thx

  • edited March 2020

    Actually, looking at my inputs I had finally measured (w/o baffle circuit); L3 at .15 (only off by a factor of 10, geeze) and progressively moved C1 to 5.2 for the Red trace in the above pic (sorry, my bad).  But those values ~lined up (must be a mis-match in impedance values?)

    I’ve been trying to back into your values, all day changing values and measuring, but no luck.  If you get a chance can you let me know what impedance values you had modeled for the mid and tw- thx (w/o the baffle step)

  • You know if you can measure we could use real FRDs. Your curves look like they have a ton of smoothing

    Anywho the impedance curves were botched as well, lets try that again
    dcibel
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  • Interesting that most of my issues come from tracing graphs while drinking.

    Traced tweeter imp traced, mid imp from Response modeler



    jr@macbrek81
     John H, btw forum has decided I don't get emails
  • edited March 2020

    Yes, I did over-smooth each to the same degree, to try to compare the filters, and trying to back into impedance (through trying to target component values and Xover points via a crossover calculator, but couldn’t get to a point that seemed close).

    I could get you raw frequency curves (through REW), but I actually think you have nailed the freq charts.  If you can get similarly close on impedance for the drivers that would be great- I’m not (unfortunately) set up to generate impedance curves (most driver’s data / charts are fairly detailed, the beyma is not all that clear, but even trying ranges of their stated lows 5.7, 5.0 LF, HF to approx's per their chart at/around 4-8kHz, backing in to estimates has been illusive). 

  • Not much change.  I think there is a bunch of optimization that could be done. 

    With some diligence and ability to read logarithmic graphs you can do some tracing to get your designs closer.  Personally it's way easier for me to measure and spend time creating an x-o the measures the same as the simulation.

    This is a long way from the RC/ RL question but the point I guess was without decent FR and Imp data the textbook answer may not be correct





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  • edited March 2020
    looks like, @5kHz ~8ohm for mid, and ~4.8 for the tw (I'll probably push the tw up a bit to say ~5.2ohm as it appears to be off its low as a reference- which beyma states is 5.0ohm)

    and work into backing into your values for the filters- thx
  • edited March 2020
    thx, will get a fresh start
  • This no baffle over baffle step with no change in x-o.  Typical baffle step is going to impact 1K and below, so no impact on L3 and C1 as that is the mid roll off at 6K.


     John H, btw forum has decided I don't get emails
  • thx, really appreciate it
  • Interesting that most of my issues come from tracing graphs while drinking.



    John, you shouldn't drink and trace, its for your own good. Everyone knows that... ;)
  • edited April 2020
    think I'm just about there... (the green is with a 300Hz 2nd order LR HP filter)
    thx John

  • Audibility is debatable, but if you notice how above and below the XO point, there is considerable divergence? This usually indicates phase issues. 
    I have a signature.
  • edited April 2020
    As is the issue in multiple driver designs...
     
    This is in-room actual (20 inches at 15 degrees). The horizontal spacing is 5db, so 'considerable' here is what ~+/- 0.35dB (say at 1g and 15g).  Or likely as a contributor the affects of the active HP filter for the green trace. (the crossover at 5.8g is passive)

    here is an example with and w/o an active ~300Hz LR HP in place (check 1 to 2g, HP affect) and there is some divergence in measurement

    But yes, phase issue probably so around 8+g.

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