HiCap DR Noise

Oh, and I guess I should add, this is not the normal large transformer hum, I get that. This one was so loud I had initially thought someone was running something outside in the back yard. 

It could well be something outside in the back yard.  This used to happen whenever my wife (now ex) turned on her hairdryer.  The fact that the music system was out in the barn across the courtyard and fed from it's own separate meter and CU made no difference.  I eventually figured out the cause... Also the Smithy down the road had a certain ancient welder that would do similar things to the transformers in the Naim kit (as well as some other bits of kit).  It was loud! Like a diesel engine had just started up inside the box.  No harm done though, so rest easy there.

Richard Dane posted:

It could well be something outside in the back yard.  This used to happen whenever my wife (now ex) turned on her hairdryer.  

That's dedication to quiet power supplies !

James, where to start...

My daughter's hairdryer does same even though on a separate mains ring

Hairdryers are terrible for some reason. When my wife or girls use one the interference pattern on the TV gives a visual clue as to how it is bu**ering up  the audio signal.

G

Hairdryers typically use half wave rectification, which puts a lof of DC back on the mains. This results in the  mechnical noise from the transformer.

There is a more technical description available as a case study on the Fluke website, googling for "hair dryer half wave rectification" will get you there.

Same here but with my CDX2. Hairdryer, straighteners, Christmas decorations. All terrible.

I've come to the conclusion that if I can hear the transformer buzzing, the music isn't loud enough! 

Thanks for all the replies! .. It was definitely not something outside in the yard, all the noise was coming from the HICAP. It has now been powered on all day and it is still dead silent as it was prior to this. It is good to know that something else in the house may have caused it though. 

If it was triggered by something someone may have turned on elsewhere in the house, would it continue making noise even after that device had been turned off? I am asking this as a simple power cycle to the HICAP fixed the noise issue. 

More then likely some other device in your home (or possibly in a neighbours) was the cause & it so happened that by the time you turned the HICAP back on, the source was no longer running.  Like others have mentioned, it was likely transformer hum caused by DC offset, & when it happens, yes it can get rather loud.  It will go away as soon as the source is turned off again.  No need to worry about turning the HICAP on & off.  

I have the same issue with hair dryers, both the HICAP DR & previous 200 would get major transformer hum.  I would also get some when bright scenes happened on the Panasonic Plasma that was on the same circuit. 

I did have to turn the HC off/on, that was the only way to kill the noise, I had only turned it off for a few seconds, then back on. It wasn't the source that cause it to stop, It was turning the HC off/on that stopped it.  That was why I had asked if the HC could continue making noise, even after whatever may have caused it had been turned off, assuming this was the cause.