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<blockquote data-quote="azazel" data-source="post: 1292506" data-attributes="member: 559376">My Xover frequency is at about 2.5KHz 4th order with a Zobel network.Don&#039;t worry too much about the wattage hit that you will take.&nbsp; Even at 37 watts you are only 3dB down from 75 watts.&nbsp; That should be plenty.&nbsp; If you&#039;ve ever measured the actual wattage that you&#039;re sending your speakers, you&#039;d be amazed at how little power you&#039;re actually sending them to get quite a bit of volume.&nbsp; I measured a 4 ohm speaker on my home system at normal listening levels and I wasn&#039;t even giving it 1 watt!Also remember that the power that your amp puts out is not necessarily cut in half when the impedance doubles.&nbsp; It will be less, yes (P = V²/R) but at the same time, a higher impedance (say, P = V²/2R) will often result in slightly higher voltages (it now becomes P = (V + x)²/2R) across the speaker, which means that the power will be reduced, but not necessarily by a factor of 2.I guess what I&#039;m trying to say is you should be fine.&nbsp; If you find that it&#039;s not loud enough for you, you can get a bigger amp.&nbsp; If this setup is all you have in your car, I doubt that your alternator will have a problem with it.&nbsp; I have one of the smallest cars on the road (with a proportional alternator) and I have a 100Wx2 @4 ohm amp in it with no electrical problems at all.</blockquote>

[QUOTE="azazel, post: 1292506, member: 559376"] My Xover frequency is at about 2.5KHz 4th order with a Zobel network. Don't worry too much about the wattage hit that you will take. Even at 37 watts you are only 3dB down from 75 watts. That should be plenty. If you've ever measured the actual wattage that you're sending your speakers, you'd be amazed at how little power you're actually sending them to get quite a bit of volume. I measured a 4 ohm speaker on my home system at normal listening levels and I wasn't even giving it 1 watt! Also remember that the power that your amp puts out is not necessarily cut in half when the impedance doubles. It will be less, yes (P = V²/R) but at the same time, a higher impedance (say, P = V²/2R) will often result in slightly higher voltages (it now becomes P = (V + x)²/2R) across the speaker, which means that the power will be reduced, but not necessarily by a factor of 2. I guess what I'm trying to say is you should be fine. If you find that it's not loud enough for you, you can get a bigger amp. If this setup is all you have in your car, I doubt that your alternator will have a problem with it. I have one of the smallest cars on the road (with a proportional alternator) and I have a 100Wx2 @4 ohm amp in it with no electrical problems at all. [/QUOTE]

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