[Qucs-help] 1st order crossover model errors

[Robert C. <rsc...@be...>]

Hi Claudio,

Thanks for this. I’m attaching the text of the .sch and .dpl files.

rob

<Qucs Schematic 0.0.18>
<Properties>
  <View=0,-25,800,800,1,0,0>
  <Grid=10,10,1>
  <DataSet=Cross over 1.dat>
  <DataDisplay=Cross over 1.dpl>
  <OpenDisplay=1>
  <Script=Cross over 1.m>
  <RunScript=0>
  <showFrame=0>
  <FrameText0=Title>
  <FrameText1=Drawn By:>
  <FrameText2=Date:>
  <FrameText3=Revision:>
</Properties>
<Symbol>
</Symbol>
<Components>
  <GND * 1 160 440 0 0 0 0>
  <Vac V1 1 160 360 18 -26 0 1 "1 V" 1 "1 GHz" 0 "0" 0 "0" 0>
  <GND * 1 540 420 0 0 0 0>
  <L L1 1 300 320 -26 10 0 0 ".44 mH" 1 "" 0>
  <.AC AC1 1 140 530 0 33 0 0 "lin" 1 "0" 1 "20 kHz" 1 "20001" 1 "no" 0>
  <C C1 1 300 130 -26 17 0 0 "14 uF" 1 "" 0 "neutral" 0>
  <R R1 1 440 320 -26 15 0 0 "5.5 Ohm" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
  <GND * 1 540 230 0 0 0 0>
  <R R2 1 440 130 -26 15 0 0 "5.5 Ohm" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
  <Eqn Eqn1 1 370 540 -25 13 0 0 "Lo_pass_dB=dB(LoPassVout.v)" 1 "Lo_pass_F3=xvalue(Lo_pass_dB, -3)" 1 "Lo_pass_F9=xvalue(Lo_pass_dB, -9)" 1 "Hi_pass_F3=xvalue(Hi_pass_dB, -3)" 1 "Hi_pass_F9=xvalue(Hi_pass_dB, -9)" 1 "Summed_dB=dB(LoPassVout.v + HiPassVout.v)" 1 "Hi_pass_dB=dB(HiPassVout.v)" 1 "Hi_pass_phase=rad2deg(unwrap(arg(HiPassVout.v)))" 1 "Lo_pass_phase=rad2deg(unwrap(arg(LoPassVout.v)))" 1 "yes" 0>
</Components>
<Wires>
  <160 320 160 330 "" 0 0 0 "">
  <160 320 240 320 "Vin" 210 290 16 "">
  <160 390 160 440 "" 0 0 0 "">
  <540 320 540 420 "" 0 0 0 "">
  <470 320 540 320 "" 0 0 0 "">
  <330 320 410 320 "LoPassVout" 400 290 43 "">
  <540 130 540 230 "" 0 0 0 "">
  <470 130 540 130 "" 0 0 0 "">
  <240 320 270 320 "" 0 0 0 "">
  <240 130 240 320 "" 0 0 0 "">
  <240 130 270 130 "" 0 0 0 "">
  <330 130 410 130 "HiPassVout" 410 100 45 "">
</Wires>
<Diagrams>
</Diagrams>
<Paintings>
  <Text 180 30 12 #000000 0 "Simple 1st order 2 way cross over, -3 db at approx. 2000 hz">
</Paintings>


<Qucs Schematic 0.0.18>
<Properties>
  <View=0,0,957,800,1,0,0>
  <Grid=10,10,0>
  <DataSet=Cross over 1.dat>
  <DataDisplay=Cross over 1.sch>
  <OpenDisplay=1>
  <Script=Cross over 1.m>
  <RunScript=0>
  <showFrame=0>
  <FrameText0=Title>
  <FrameText1=Drawn By:>
  <FrameText2=Date:>
  <FrameText3=Revision:>
</Properties>
<Symbol>
</Symbol>
<Components>
</Components>
<Wires>
</Wires>
<Diagrams>
  <Tab 50 487 454 197 3 #c0c0c0 1 00 1 0 1 1 1 0 1 1 1 0 1 1 315 0 225 "" "" "">
	<"Lo_pass_F3" #0000ff 0 3 1 0 0>
	<"Lo_pass_F9" #0000ff 0 3 1 0 0>
	<"Hi_pass_F3" #0000ff 0 3 1 0 0>
	<"Hi_pass_F9" #0000ff 0 3 1 0 0>
  </Tab>
  <Rect 670 480 240 160 3 #c0c0c0 1 00 0 0 1000 5000 0 -25 5 10 1 -1 1 1 315 0 225 "" "" "">
	<"Hi_pass_dB" #0000ff 0 3 0 0 0>
	<"Lo_pass_dB" #ff0000 0 3 0 0 0>
	<"Summed_dB" #ff00ff 0 3 0 0 0>
  </Rect>
</Diagrams>
<Paintings>
</Paintings>


> Hello Rob,
> no need to apologize,  the qucs-help mailing list is the right place to ask questions about how to use Qucs.
> 
> Note
>  that the attachment did not pass thru the list, it was probably too 
> big. Since the .sch and .dpl files are actually text, you can paste them
>  in the body of your message or use a (free) sharing site like 
> pastebin.com . 
> 
> I think there might be nothing fundamentally 
> wrong in your design: the messages appearing in the "Errors:" window are
>  actually "WARNINGS:", so just a suggestion that something might not be 
> as expected. In this case it is likely that the nodes mentioned below do
>  not have a DC connection to ground thru some resistance, so the 
> simulator complains that it cannot calculate their DC value and 
> internally builds a path to ground thru a very high resistance to ground
>  to fix their voltage. This is a "problem" common to all circuit 
> simulators, they do not like to have nodes with an undefined voltage.
> 
> Regarding the AC response, I'll need the schematic to check, might be a measurement error or anything else...
> 
> Regards,
>   Claudio