Hi, I designed a 2 way series crossover speaker system a while back (Fig 1 based on System 7's concept giving very good phase alignment) and was just going back over the design trying to determine the power that the drivers and resistors will see. Original design was with Vision's BOXSIM program. I replicated the crossover in 5SPICE (Fig 2) and took in the BOXSIM equivalent circuit for the drivers. Using that equivalent circuit gave a pretty good match of the calculated impedance curves between BOXSIM and 5SPICE (Figs 3 and 4). Based on BOXSIM the woofer SPL looks to be more than 4dB attenuated in crossover/box (Fig3) based on raw output of driver being 87db but seeing ~83dB or less in the box. Using 5 spice I calculated PwrDiss (Speaker Driver V, Driver Current) divided by PwrDiss(System Input V, Input Current)(Fig 5). This shows much less attenuation - more like 1.5 to 2 dB for a good part of the range. (I also ran the calculation just multiplying V and Current rather than using the PwrDiss function in 5SPICE and got similar results)
Why the large discrepancy? For this 40W rated woofer can I put in 100W like BOXSIM implies or only 50W like 5SPICE implies?
Then for the resistors - I used 5 spice to calculate the power dissipated as for the driver. For the 6 Ohm resistor in the woofer circuit (R12) it sees a peak of -4.7 dB or about one third of the input power at around 2.3kHz (Fig 6). Do I have to size this resistor to handle 1/3rd of the input power even if it is not over a broad frequency range? Should I even believe this calculation based on the discrepancy between BOXSIM and 5SPICE on the Woofer driver above?
Thanks in advance for any help!
Fig1
Fig2:
Fig3:
:
Fig4:
Fig5
Fig6
Why the large discrepancy? For this 40W rated woofer can I put in 100W like BOXSIM implies or only 50W like 5SPICE implies?
Then for the resistors - I used 5 spice to calculate the power dissipated as for the driver. For the 6 Ohm resistor in the woofer circuit (R12) it sees a peak of -4.7 dB or about one third of the input power at around 2.3kHz (Fig 6). Do I have to size this resistor to handle 1/3rd of the input power even if it is not over a broad frequency range? Should I even believe this calculation based on the discrepancy between BOXSIM and 5SPICE on the Woofer driver above?
Thanks in advance for any help!
Fig1
Fig2:
Fig3:
:
Fig4:
Fig5
Fig6