I got my XPS (DR) however.........

Weather or not a Naim box is going to hum does seem to be a bit hit-and-miss, and I can only assume this is the result of variation in hand assembled products. To help eliminate any external factors, you can try turning off all other appliances in your house, by unplugging them, or turning off whole circuits at the consumer unit. Turn things back on one by one to see if there are any individual culprits. These might include fridges, some light fittings, anything with a SMPS. There's a good chance this will not solve your problem, but it's worth checking anyway in case you have any rogue appliances.

Putting your HiFi on a dedicated circuit may also not solve your problem, but for many people it's a good sound quality upgrade at relatively low cost, so well worth doing in my opinion, even if the hum persists.

Thank you Guys,

I've spent ages exploring the forum threads on this topic and I'm really surprised how many people have experienced mains (Naim's) hum . 

The feedback is really appreciated - apart from the Puccini - I just can't get it out of my head.............or is that Kylie?.

I'm taking a break for a couple of weeks and will return to this issue (problem) then. 

Should I leave the kit switched on or off?

 

Steve

 

 

 

 

 

 

An interesting thread for me as XPS is the next step for my 272/250. In fact I am hopeful that one day I will have two with the other one powering the CdX2.

Have those further up the road found hum problems when you have two PS's? Secondly, on a five shelf full fat Fraim would I best have the CD player on top and Ps below then 272 with Ps and finally 250 on the bottom? Yes I know another Fraim would be better but no room for that, let alone the cash!

i currently do not have a dedicated mains supply which I know would be better but practical considerations make it difficult to install. The good news is that I currently have no hum

I am having a dedicated supply installed as part of an extension. Still a month or so from completion  - so will be interested to hear the result SQ and hum wise. As it happens my experience is that the DR models (SC, XPS and 250 in my case) have all been less prone to hum than their predecessors. Still had their moments though. Worst identifiable offender was my wife's hairdryer by a country mile. Other moments seemed to be unconnected to appliances such as fridge, boiler, etc. use / switch cycles.

Steve gtx....Why don't you try the xppsdr in a family members house or friends homes and see if it hums? that way you may eliminate the cause of the hum, " before anyone else asks " once tried don't forget to bring it back home and connect to your nac n272,

This may eliminate the need for a dedicated power supply...although no harm in having one anyway, or simply ask Naim for another as yours isn't fit for purpose, sorry Naim but if as you say you quality match components then one xppsdr shouldn't be any different to another, ( as graemeh pointed out ) or should it? 

Does your local dealer have a dedicated spur, does it buzz on his/her premises 

Just a thought 

Alan Willby posted:

Worst identifiable offender was my wife's hairdryer by a country mile. Other moments seemed to be unconnected to appliances such as fridge, boiler, etc. use / switch cycles.

Some more basic hair dryer designs are notorious for asymmetric mains loading, causing a DC offset, and ultimately causing efficient transformers to saturate and clip and therefore loudly hum or buzz. Often the half heat setting works by taking current from just one side of the mains cycle as this is very easy and cheap to implement and thereby creating the mains offset.

Alan Willby posted:

As it happens my experience is that the DR models (SC, XPS and 250 in my case) have all been less prone to hum than their predecessors. Still had their moments though. Worst identifiable offender was my wife's hairdryer by a country mile. Other moments seemed to be unconnected to appliances such as fridge, boiler, etc. use / switch cycles.

You seem to have pretty well ID'd that you have a real problem with the other units with variable hum.   Plus "Other moments seemed to be unconnected to appliances such as fridge, boiler, etc. use / switch cycles."  None of the appliances you list have half wave speed controls these days & any speed controls are a bit more sophisticated.   It probably means the problem is coming from your local (neighbourhood) supply & in this case I agree with Huge that a dedicated radial is not going to do much.  However it will be worthwhile explaining the problem to your electrician & ask him to assess your installation from incoming main to the CU.  He might be aware of nearby installations,  farms, industrial units etc on the same supply line (not much comfort or solution for you other than there is a reason)   

Mike-B is absolutely correct.

My home network is in a similar position - due to certain limitations is shares one of the phases with some heating pumps in the basement. Occasionally (there is no pattern though) those would cause a certain assymetry / distrotion in the power supply, which feeds back to my dedicated circuits and manifests itself as a slight hum from transformers. (at least that is how I understood the explamation - if I twisted some facts, that's becasue I know nothing about electricity ).

Adam

My Nap300 hummed way too much - enough that it shook. Had to ship it back to Naim, and they replaced the transformer. 0 hum after that.

I did try the Isotek Synchro trick, but that did nothing.

To test whether it's really related to smps, just switch everything else in the house off from the mains panel - everything except the line to the system. If the system still hums, getting an synchro won't  help. Neither will a dedicated circuit.

 

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