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<blockquote data-quote="helotaxi" data-source="post: 3077800" data-attributes="member: 550915">In a set where both the mid and tweet are 4 ohm, the amp sees a 4 ohm load.&nbsp; The 4 and 8 ohm crossovers determine what impedance the crossover circuit needs to have on it for the crossover to work right.&nbsp; Use any filter calculator and it will ask you the driver impedance.&nbsp; Change the impedance and the component values in the resultant design change as well.&nbsp; Also if you consider a simple second order filter, the cap and the coil change in opposite directions with a change in impedance.&nbsp; If you were to wire a 4 ohm driver to a filter meant for a 8 ohm driver, you end up with a staggered filter, the filter will begin to roll off higher than designed (for a low pass filter) at 6 dB/oct and then will turn into a 12dB/oct filter at a freq lower than designed.&nbsp; The driver imp determines the freq at which the different components in the filter begin to have their effect.The way a crossover works is that the low pass portion of the crossover increases the resultant impedance of its branch of the circuit above the crossover freq and the high pass portion increases below the crossover freq.&nbsp; The result is that the overall impedance of the network as a whole is the same as the given drivers for their portion of the frequency spectrum&nbsp; Above the crossover freq, the impedance that the amp &quot;sees&quot; is that of the high freq driver and below that it&#039;s the impedance of the low freq driver.</blockquote>

[QUOTE="helotaxi, post: 3077800, member: 550915"] In a set where both the mid and tweet are 4 ohm, the amp sees a 4 ohm load. The 4 and 8 ohm crossovers determine what impedance the crossover circuit needs to have on it for the crossover to work right. Use any filter calculator and it will ask you the driver impedance. Change the impedance and the component values in the resultant design change as well. Also if you consider a simple second order filter, the cap and the coil change in opposite directions with a change in impedance. If you were to wire a 4 ohm driver to a filter meant for a 8 ohm driver, you end up with a staggered filter, the filter will begin to roll off higher than designed (for a low pass filter) at 6 dB/oct and then will turn into a 12dB/oct filter at a freq lower than designed. The driver imp determines the freq at which the different components in the filter begin to have their effect. The way a crossover works is that the low pass portion of the crossover increases the resultant impedance of its branch of the circuit above the crossover freq and the high pass portion increases below the crossover freq. The result is that the overall impedance of the network as a whole is the same as the given drivers for their portion of the frequency spectrum Above the crossover freq, the impedance that the amp "sees" is that of the high freq driver and below that it's the impedance of the low freq driver. [/QUOTE]

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