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<blockquote data-quote="John Roberts" data-source="post: 130297" data-attributes="member: 126">Re: XLR cable passes signal but ~20db lowerWhile generally we expect a neat 6dB drop or perhaps complete loss if one leg is open, but I can imagine another hypothetical. Imagine if there is a resistor termination inside the receiving input circuitry directly between pins 2 and 3. When both 2 and 3 are connected and driven from low impedance all is well, but now if one or the other leg is open we get a single legged full input on the connected input, but now the opposite polarity input is being fed through the input termination. In general there will be another resistance to ground on both inputs, so this opposite polarity signal is slightly padded down so it doesn&#039;t subtract completely. A 1 dB loss to the subtracted opposite signal will give about -20 dB result. Caveat lector... this is just a WAG hypothetical.&nbsp; but it could happen. A cable tester should reveal the issue... Note: Pin 2 and 3 shorted should give complete cancellation, but in an imperfect world, it could also just attenuate the signal a bunch. Fix the cable with an axe... JR</blockquote>

[QUOTE="John Roberts, post: 130297, member: 126"] Re: XLR cable passes signal but ~20db lower While generally we expect a neat 6dB drop or perhaps complete loss if one leg is open, but I can imagine another hypothetical. Imagine if there is a resistor termination inside the receiving input circuitry directly between pins 2 and 3. When both 2 and 3 are connected and driven from low impedance all is well, but now if one or the other leg is open we get a single legged full input on the connected input, but now the opposite polarity input is being fed through the input termination. In general there will be another resistance to ground on both inputs, so this opposite polarity signal is slightly padded down so it doesn't subtract completely. A 1 dB loss to the subtracted opposite signal will give about -20 dB result. Caveat lector... this is just a WAG hypothetical. but it could happen. A cable tester should reveal the issue... Note: Pin 2 and 3 shorted should give complete cancellation, but in an imperfect world, it could also just attenuate the signal a bunch. Fix the cable with an axe... JR [/QUOTE]

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