Cable Hum

[NDA]

Bit of a numpty question I guess....

I have a pair of decent studio audio cables (mono) and they hum when plugged into my patchbay - I have looked in the jacks and all looks well. Other cables of the same length seem absolutely fine - have overlooked something obvious?

[tubbystu]

Are the a true mono 1/4" jack ? With a sharp pointed tip ? If they are rounded tip they are a GPO jack as used in studios a while back...........and are not interchangable with 1/4".

[timbob]

You're not plugging them into something which needs a balanced jack are you?

[NDA]

No, just a regular patchbay.

Here's a shot of the offending lead - the cable next to it (green) is an identical tip. It hums on all inputs with or without anything connected to the other end.

[telecat]

Sounds like the earth has gone. If not at the plug ends then it may well be in the cable.

[tubbystu]

NDA said:

Genuine Neutrix 1/4" jacks, which the barrel should easily unscrew and you can visually check the soldering - you may have a poor / dry joint on the ground/shield side.

See here http://www.neutrik.com/uk/en/audio/210_214010859/N...

If I'm teaching you how to suck eggs I apologise in advance........

[NDA]

I'll resolder them and see - seems odd that both cables do it.

Anyhoo, thanks for the advice, appreciated.

[Graham E]

hum = bad ground 99% of the time. Could be a break in the cable / impedance mismatch.

[dumbfunk]

If it's the green or yellow cable playing up then I think it could just be a knackered joint inside them. I've had what seems like hundreds of these little patch cords over the years and they all seem to have a very finite lifespan.

Failing that check the mains connections of the unit they're plugged into - I used to get mains hum if a terminal screw was loose within the plug even!


dumbfunk