moray james Posted February 2, 2012 Share Posted February 2, 2012 Don: if youtook Bob's example what kind of ripple would you be looking at? Quote Link to comment Share on other sites More sharing options...
djk Posted February 3, 2012 Share Posted February 3, 2012 The change in output level is trivial, the change in Qts is not. Read the Loudspeaker Design Cookbook for how to calculate the effect on Qes and Qts. Quote Link to comment Share on other sites More sharing options...
Don Richard Posted February 3, 2012 Share Posted February 3, 2012 Don: if youtook Bob's example what kind of ripple would you be looking at? It is not possible to accurately determine response irregularities from the information he presented because the inductance of the hypothetical coils was not given. That data would be needed, along with the crossover's design and the loudspeaker's driver characteristics. I can estimate (guess) that if one changed a LP filter alignment from Butterworth to Linkwitz-Riley and left the HP portion of the crossover alone a change of 3 dB could result in the crossover overlap region. That's if the original crossover had a maximally flat summation to begin with. Quote Link to comment Share on other sites More sharing options...
John Warren Posted February 4, 2012 Share Posted February 4, 2012 Don: if youtook Bob's example what kind of ripple would you be looking at? It is not possible to accurately determine response irregularities from the information he presented because the inductance of the hypothetical coils was not given. Actually, an approximation can be had rather easily. If you consider the equivilent circuit for the vented assy and consider the volume velocity of the diaphragm and duct independently the effect of inductor DCR of, say a 2.2mH inductor in series with the woofer can be examined. The plot below shows simulated volume velocity of the port and diaphragm of a vented system as a function of three inductor DCR values. The phasor sum of the combined outputs is also shown. The purple is DCR = 0, the blue is DCR = 0.2 and the mustard is DCR = 0.5 Ohms. As evidenced in the plot, the output is altered in the 1-2dB range. Only the DCR was changed. Quote Link to comment Share on other sites More sharing options...
moray james Posted February 4, 2012 Share Posted February 4, 2012 Thanks John for the plot the visual is helpful. The shift in response is not huge so perhaps there are other components to the difference heard when large low dcr value inductors are substituted into a network? Best regards Moray James. Quote Link to comment Share on other sites More sharing options...
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