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Mounting crossovers in trunk
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<blockquote data-quote="Hoot" data-source="post: 1007799" data-attributes="member: 559411"><p>What do you these comments lifted from the ICIXSound.com forum in the CDT section? (In answer to the same question posed, here.)</p><p></p><p>"A passive network has problems that has to do with their impedance. Impedance restricts power transfer; it's like resistance, only frequency sensitive. In order for the passive network to work exactly right, the source impedance (the amplifier's output plus the wiring impedance) must be as close to zero as possible and not frequency-dependent, and the load impedance (the loudspeaker's characteristics) must be fixed and not frequency-dependent (sorry -- not in this universe; only on Star Trek). Since these things are not possible, the passive network must be (at best), a simplified and compromised solution to a very complex problem. Consequently, the crossover's behavior changes with frequency -- not something you want for a good sounding system.</p><p></p><p>One last thing to make matters worse. There is something called back-emf (back-electromotive force: literally, back-voltage) which further contributes to poor sounding speaker systems. This is the phenomena where, after the signal stops, the speaker cone continues moving, causing the voice coil to move through the magnetic field (now acting like a microphone), creating a new voltage that tries to drive the cable back to the amplifier's output. If the speaker is allowed to do this, the cone flops around like a dying fish. It does not sound good. The only way to stop back-emf is to make the loudspeaker "see"a dead short, i.e., zero ohms looking backward, or as close to it as possible -- something that's not gonna happen with a passive network slung between it and the power amp, and if the crossover is closer to the amp the impedance can't be zero ohms, but will be closer when the crossover is closer to the speaker, maybe not still exactly zero but better since the speaker cable distance has been eliminated. Now what about phase, impedance/inductance, frequency response slope, damping factor, transient response, attenuation due to distance of the capacitors, amplitude, etc. as other factors? (Man I'm getting a head ache-why did you ask this question of me?).</p><p></p><p>In other words to make it a little more visual:</p><p></p><p>A. Speaker X-Over</p><p></p><p>( o )------------------------------------------------------------------------------[__]-----AMP</p><p></p><p>B. Speaker X-Over</p><p></p><p>( o )------[__]-----------------------------------------------------------------------------AMP</p><p></p><p>In the A. scenario it exhibits what occurs in the above description. I'd rather have the amp be the workhorse.</p><p></p><p>In the B. scenario as the crossover does not have to deal with any loss of frequency or phasing or loss of slope or any extra impedance issues to have to push the frequency over a distance. Maybe in a lab there is an effect like I said but my electronics gut seems to tell me B. is a better approach."</p></blockquote><p></p>
[QUOTE="Hoot, post: 1007799, member: 559411"] What do you these comments lifted from the ICIXSound.com forum in the CDT section? (In answer to the same question posed, here.) "A passive network has problems that has to do with their impedance. Impedance restricts power transfer; it's like resistance, only frequency sensitive. In order for the passive network to work exactly right, the source impedance (the amplifier's output plus the wiring impedance) must be as close to zero as possible and not frequency-dependent, and the load impedance (the loudspeaker's characteristics) must be fixed and not frequency-dependent (sorry -- not in this universe; only on Star Trek). Since these things are not possible, the passive network must be (at best), a simplified and compromised solution to a very complex problem. Consequently, the crossover's behavior changes with frequency -- not something you want for a good sounding system. One last thing to make matters worse. There is something called back-emf (back-electromotive force: literally, back-voltage) which further contributes to poor sounding speaker systems. This is the phenomena where, after the signal stops, the speaker cone continues moving, causing the voice coil to move through the magnetic field (now acting like a microphone), creating a new voltage that tries to drive the cable back to the amplifier's output. If the speaker is allowed to do this, the cone flops around like a dying fish. It does not sound good. The only way to stop back-emf is to make the loudspeaker "see"a dead short, i.e., zero ohms looking backward, or as close to it as possible -- something that's not gonna happen with a passive network slung between it and the power amp, and if the crossover is closer to the amp the impedance can't be zero ohms, but will be closer when the crossover is closer to the speaker, maybe not still exactly zero but better since the speaker cable distance has been eliminated. Now what about phase, impedance/inductance, frequency response slope, damping factor, transient response, attenuation due to distance of the capacitors, amplitude, etc. as other factors? (Man I'm getting a head ache-why did you ask this question of me?). In other words to make it a little more visual: A. Speaker X-Over ( o )------------------------------------------------------------------------------[__]-----AMP B. Speaker X-Over ( o )------[__]-----------------------------------------------------------------------------AMP In the A. scenario it exhibits what occurs in the above description. I'd rather have the amp be the workhorse. In the B. scenario as the crossover does not have to deal with any loss of frequency or phasing or loss of slope or any extra impedance issues to have to push the frequency over a distance. Maybe in a lab there is an effect like I said but my electronics gut seems to tell me B. is a better approach." [/QUOTE]
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