Thanks for responding - good, you folks know what your're talking about at a fair expert level.

It's all above my head, I've never managed to retain any understanding of impedance, capacitance, ohms and such like.

So, I'll now expand on why I opened this thread.

[cable wired the wrong way at one end was just one possible idea that occured to me]

I've just bought a new mail order mass produced premium 'standard jack to jack' guitar lead [one of the big brand names]

There's definitely something amiss with it, but no obvious faults like crackle
or intermitent signal brak up and loss if I wiggle the jacks in their sockets,
or waive the cable around.

Compared to all my other decent quality guitar leads,
this new one has a very weak signal level and dark tone.
Similar to what you'd hear with an electric guitar's vol and tone knobs rolled right down. Very severe vol and treble cut-off !!!

I've tested with a couple of guitars and amps.
eg, 4 watt Vox combo valve amp - all knobs on 12 oclock / strat type guitar - tone & vol knobs on 10.

Normally this would be anti social bedroom practice vol level.
At this setting, the new lead is barely audible.
But as I said, no crackles or signal break up ?

I phoned the manufacturer's helpline, and they said this isn't right,
so they're sending another so I can compare for them
to help investigate - very positive result - good customer service..

But this is where it get's interesting, because as this 'faulty' lead is acting as some kind of vol & tone attenuator,
I can now push the amp to full volume,
and get a pleasing smooth vintage tone without any ice pick treble,
at a sensible home practice level ???

So even if it is a 'dud' - it's a keeper.

It'd even be interesting to know how to replicate this 'fault' deliberately ?

Also of relevance, if the dodgy new lead is plugged between electric guitar and a true bypass overdrive pedal
[ and a good working lead from pedal to amp]
the signal hitting the amp is still weak and dark.
However if the the leads are reversed. Good lead now from guitar to pedal,
and dodgy new lead from pedal output to amp.
The signal is now mysteriously restored to near normal level ???

Hope this is an interesting enough problem for you folks to get your teeth into...
cheers...