SuperCap transformer swap!

Slow day on my day off, so I’m entertaining silly ideas about my SC2 and SCDR:

SC2 - no transformer hum
SCDR - humming like a bee
Both connected to Musicworks powerboard.

Thus - if I were to have the transformers swapped over (!) would the hum situation be reversed?

Just curious…like I said, slow day :slight_smile:

First worth switching over the mains cables, then also physically swapping their position to ensure the hum stays with the same SC

Possibly. However, you need to be careful as if the Supercap is pre ROHS then the transformers could not be swapped over. Also, on a different mains installation the hum situation might be quite different, or even the opposite.

Thanks @Richard.Dane and @GadgetMan

Was only an idle thought, must admit. Though a tempting one!

I will try swapping rack positions etc, cheers.

What is ROHS, Richard?

ROHS is the Restriction Of Hazardous Substances Directive that was implemented in 2004 and came into force in 2006.

My SC2 is 2008, so I’d guess OK in that regard.

Yup, should be ROHS compliant.

Cheers Richard… I’ll see what happens between the 282 with 2 HCDR vs the SC2 when the 250 arrives (ie whether the SC2 stays or not). If not…hmm, lol :slight_smile:

My experience of Naim transformers generally is that more recent ones seem to hum less than older ones. That’s not based on a large sample of units, I admit, but if a newer one is louder than an old one I would be talking to my dealer about the possibility that it needs a bit of attention. Maybe the mounting needs to be adjusted a bit.

Thanks @ChrisSU
I had wondered if perhaps the mounting could be a factor. I remember reading one recommendation re using a rubber mallet (not here). Not going that route! But I presume opening it up (completely powered down etc!) wouldn’t tell me anything (I’m certainly no techie)?

A friend of mine had terrible hum from his Supercap. The city recently serviced the power transformers next to his house and the hum is gone. I have no idea what was changed out but the hum is no longer a problem.

It could well be because of an over voltage issue. I’m having that currently, and they have already reduced my average from 255V to 249V, but still in progress to see if it can be lowered further. When they temporarily dropped it to 240V it made a big difference but not perfect. Problem can also be who else is on their substation causing issues, and they may have just put them on a different circuit.

Higher voltage is not likely to cause hum in itself. In the UK mains electricity is nominally 230 V, with a tolerance of –6% +10%, i.e 216.2-253V. If not in that range (if measured, that includes allowing for the accuracy of the meter) they are not complying with the supply regulations. If it is in that range then it is deemed to be satisfactory. Voltage will often vary depending on demand,

If the hum comes and goes it is most likely to be DC imposed on the AC.

1 Like

Absolutely correct with the range, and the fact that they are not complying with the regs, however surprisingly they dont measure the voltage at the substation end, and in my case the substation was on the wrong tapping, and had been like that for probably 25 years. I could certainly prove that (thanks to charts from my Solar Panels) we have had values way above 253V for over 1 year. They have since dropped the tapping, and have a meter on my house and the substation, and so far are still getting a few spikes above 253V, so waiting to see what they will do next. I can say for certain that the hum did drop when they dropped the Voltage from 254V to 240V on their first visit. Once I conclude this journey, I was intending to write it up in a new Topic.

DC Offset as you say is often more likely to cause Humm which can come from your own house appliances, or other properties nearby apparently, but not easy to measure. Over Voltage is a simple one to test, and eliminate.

Sadly, @Innocent_Bystander, the hum is always present. Most of the time, I don’t notice it - just fades into the background as it were. Noticeable if I sit in the chair next to the Fraim, and louder at the sides and back of the rack. Luckily, it does not intrude when listening to music so that is a blessing… I’d rather the SCDR was quiet, but at least it’s livable with.

Why not buy a dc blocker?
A lot hear with similar problem are very satisfied.

Tried two, @frenchrooster, hum only marginally lessened, if at all.

Maybe that rubber mallet will come in handy after all!

(Just kidding)

It’s not a huge problem, but is a little annoying that it’s the later DR SC that has it while the 2 is quieter than a mute mouse.

I’d send it for a service and use the 2 in the meantime but AFAIK transformers aren’t included, and lockdown would mean next year in any case.

I can live with it :smiley: I guess.

1 Like

This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.