On Sat, 5 Oct 2019 18:03:33 -0400, MLewis wrote:
Snip >An engineer told me what was up, and I cut open some connections that >seemed solid to check. In each case there was a gob of solder at the >end, but only some trace solder within the first part of the strands, >with minimal contact between the wire and the crimp. I've cut one open a >number of times over the years since, to show such to people. The engineer failed to explain why this is an electrical problem. (Note: >NASA will not accept crimped connections of tinned stranded or tinned >solid wire. I've no idea why, but I figure it's a given that they know a >lot more about terminations and connections than I ever will.) I know why.... They don't like diodes/rectifiers in connections. Crimped connections can produce point contact junctions thru the tinning layer resulting in rectification. Snip >I've heard a lot of speculation over the years as to why this difference >in clarity, but nothing that seems completely credible. The closest to >credible speculation I've heard is: >- a poor connection results in multiple signal paths resulting in a >sightly overlapped signal so the signal is no longer clear, or To create a multipath error of 1 electrical degree at 20KHz (inaudible) requires a path error of about 30m. Not going to happen in a cm connector. >- a poor connection has multiple connections and combined with eddy No eddy currents >currents in the connector you can get tiny RC paths instead of a single >long connection, so you've got multiple re-injections of a delayed >signal that smooths tiny changes in voltage, which is your signal. For R<~1ohm, C<~1pF the time constant is <~10e-12sec. Not in the audio domain. >Causation is clear. Not clear! >The explanation? No idea. The explination: A poor connection rectifies. For 1% difference between forward and reverse conduction expect to hear about 1% THD. To make matters worse the rectification will likely be nonlinear with current thru the connection further increasing THD. Snip Regards Bill Beam NL7F _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
