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<blockquote data-quote="helotaxi" data-source="post: 2770884" data-attributes="member: 550915">&quot;i&quot; is the same as sqrt(-1).&nbsp; Take an algebra or calc class.&nbsp; He didn&#039;t say the same thing you did and if you comprehended what he said you would quicly realize that.&nbsp; You can&#039;t measure impedance using DC because impedance is a value related to AC and it varies with frequency, if the frequency is 0 (DC) the inductance portion of impedance is going to be 0 and DCR is the result.&nbsp; The &quot;nominal&quot; impedance is just that, nominal.&nbsp; The min impedance will usually be even higher than the nominal depending on enclosure.&nbsp; Sometimes it will be lower, but not usually.There are no &quot;industry standards.&quot;&nbsp; Even if there were and the tolerance was 20% and all of them were that low, the actual impedance would still be higher.&nbsp; But guess what, a speaker builder will know the DCR (Re) almost exactly because the voicecoil is made with an exact length of wire of an exact diameter.&nbsp; The DCR of a piece of wire is not going to vary measurably between samples.Actually the JL amps continuously monitor the output current vs. the output vlotage and adjust the max rail voltage accordingly.&nbsp; It isn&#039;t just a one time thing at power up.&nbsp; If the amp is shutting down at high volume and it&#039;s because of a low impedance load, it&#039;s probably because you wired the subs wrong.</blockquote>

[QUOTE="helotaxi, post: 2770884, member: 550915"] "i" is the same as sqrt(-1). Take an algebra or calc class. He didn't say the same thing you did and if you comprehended what he said you would quicly realize that. You can't measure impedance using DC because impedance is a value related to AC and it varies with frequency, if the frequency is 0 (DC) the inductance portion of impedance is going to be 0 and DCR is the result. The "nominal" impedance is just that, nominal. The min impedance will usually be even higher than the nominal depending on enclosure. Sometimes it will be lower, but not usually. There are no "industry standards." Even if there were and the tolerance was 20% and all of them were that low, the actual impedance would still be higher. But guess what, a speaker builder will know the DCR (Re) almost exactly because the voicecoil is made with an exact length of wire of an exact diameter. The DCR of a piece of wire is not going to vary measurably between samples.Actually the JL amps continuously monitor the output current vs. the output vlotage and adjust the max rail voltage accordingly. It isn't just a one time thing at power up. If the amp is shutting down at high volume and it's because of a low impedance load, it's probably because you wired the subs wrong. [/QUOTE]

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