Hey, my mains cable's microphonic!

Honest! Just fiddling behind the system, and (volume on zero) as I inadvertantly knocked the mains cable going to the pre-amp, there was a thump through the speakers. It's repeatable, and nothing to do with the physical connection, for if I hold the IEC plug in place, but tap the cable, the thump's still there.
Now interconnects I can sort of see why, as they're directly in the amplified signal path, but mains cables?


(Please note, I haven't done a double blind test on this, nor did I get the wife in to listen, although I'm sure she would have noticed the difference.)

 

loose connection or fuse inside the cable, it's more likely to be where you pre and power are plugged into, than the pre cable per se.

when i turn my phono stage on, even unconnected to the pre, my speakers thump, it's the power surge in the 6 way.

 

Do you have a tube pre amp?

 

No. Tag AV32R

It's not a power surge. The thing's already switched on, but when I tap the cable, I can hear it through the speakers. No switching on of anything, not doing anything else, just tapping the cable!

 

so you believe the power cable is microphonicly modulating the ouput at the your speaker terminals.

is it volume level dependant, if so then you are right.

but it's a very strange state of affairs. could be an earth issue inside the pre, faulty iec socket?

 

mains cables

most wise manufacturers of most cables would ensure to run a ferrite strand allthe way through;
nando

 

Please explain further... I do not see the benefit in this...

 

Ferrite

MOST CABLES SUFFER FROM RF INTERFERANCE, FERRITE CANCELS THOSE FREQUENCIES, IS A LONG PROCESS TO EXPLAIN,
NANDO.

 

I still have trouble understanding your posts nando.

Also.... most manufacturers would not have a ferrite strand all the way through a cable, they would use a ferrite ring around one point of the cable if they wanted to use it that is.

 

DOM, I ALSO MAKE CABLES WITH A COLEGUE AND SELL THEM, I CAN NOT TELL YOU HOW WE DOIT FOR OBIOUS REASONS, SORRY BUT I HAVE DOING ELECTRONICS SINCE 1973 AND CBLES ARE A PAIN IN THE BUT TO GET RIGHT OR ALMOST AS CABLES ARE ALWAYS SYSTEM DEPENDANT, BUT 9/10 YOU CAN GET IT RIGHT, A FERRITE RING IS A CHEAP WAY OF TRANSFERRING A NO-NO GOOD LOOKING CABLE ON TO ........££££££££££'S

 

what is microphony and how do we deal with it? microphony is an interference voltage induced into a component or circuit due to vivration, regrettably, these rogue voltages cause distortion that creates damage to the integrity of the audio signal being passed through the circuit of any audio or audio visual component,
enough said, oh it's late
regards, NANDO.

 

nah, bollocks, he just has a cold weld or bad connection somewhere and it's arcing casuing the thump.

there's nowt in his tag amp that even throwing against the wall would induce an output at the speaker pins

 

not necessarily but it is a possibility.....

if the connections are tight and its still doing it ...then its possibly microphonic. I've seen speaker cable demo's that do the same tap the cable with a reasonable volume and you hear a pop.

But don't forget according to some luminaries on here your all barking as cables Quote "Can't possibly make a difference"... - Who let the dogs out - [sung to that well known tune]

 

microphonic

are bollocks microphonic?
nando.

 

There must be a fault in the power amp section or box if you hear it when volume is set to zero, e.g., a fault along the lines that sq suggested.

 

Yes definitely. Try giving someone's bollocks a good hard flick, and I'm almost certain that you'll hear some sort of audible response.

 

Thank you LT. I was cringing at the thought of possible responses that Nando might receive (he does walk into situations, doesn't he?).

 

Glad to be of service Dev; it was begging for some sort of childish response and there are few who are more childish than me .

 

if volume is zero I concur....

 

solid state gear, cables make a noise, soemthing is broken, or loose. end of....