Well, lockdown is driving me to tinker with my system in an unplanned manner! I have LP12, CDX2 and ND5 XS2 sources, an 82 with Olive Hicap, a 250DR and PMC Twenty 24. Just bought a fraim too but they sent the wrong stuff so this is all currently sitting on a blokstax.
I got a bit enthusiastic the other night and bought a 2006\7 300 (non DRed) on eBay. I’ve just always fancied a 300 even though it takes me close to mullet territory! It has arrived and is in beautiful condition but the 300PS hums! Not very loud and it isn’t audible through the signal path, just the unit itself, but it’s quite noticeable. Is this normal? My 250DR was silent on the same mains connection.
At its age (24**** serials) it is probably in need of a service and I had factored that in but would need of service possibly cause the hum?
I’ve been very lucky over the years with Naim kit. The only item I did have mechanical hum with was a 300PS which would hum when Mrs n used a hairdryer and used to make a grunting noise every Sunday morning for 30 mins or so (local sewage lift pump). @GadgetMan wrote a very useful guide which may help you track down issues within your house that could be causing the 300PS hum.
Getting my Olive boxes on Fraim reduced the buzzing/humming, but not entirely. So when you get yours sorted out, that might help. Also getting a dedicated mains installed helped a lot too.
Now, most of the time they are pretty much silent. However, if someone in my neighbourhood uses something that dumps DC on the mains, they can hum like crazy for the few minutes whatever it is, is on. Then silence again.
What power cable do you use? I have an XPSDR attached to a Powerline and had rather much buzzing compared to my 300PS with Audioquest. I did some careful cable dressing and it seems to have lowered the hum. Since the Powerline is not shielded I believe it is much more sensitive to get contaminated creating buzz. It’s free to try it out at least
PS. I have all Naim after a Supra DC Blocker but still different amount of hum between devices. Will try a well shielded PC replacing the Powerline tomorrow to see if hum is reduced even further.
Thanks for all the helpful advice. I’ve read GadgetMans article now, which really helpful and I’ll try some of the ideas in it,
I agree that waiting til my Fraim situation is sorted might well help. The design of the blokstax includes hollow sides that I’m sure aren’t helping! I guess I’m still surprised at the difference with my 250DR as that doesn’t hum at all.
Regarding cables I’m using a Graham Hydra with all 5 heads in use. It’s the same as I used with the 250. However, I’ll certainly try some other cables. Indeed can do that right now…
Try and listen for the hum at different times of the day. If it changes then it’s likely not the unit per se but something on the mains that is causing it. Obviously try and reduce it following the thread tips but the main thing is to provide a dedicated power supply.
I had two 300s for about 2.5 years (actually the first one a couple of years longer). Both were dr’d and serviced at the factory two years ago. One of them hummed almost permanently. Not diminished by the service or dr. And that was ok a dedicated hifi spur. The new 500dr I have doesn’t hum but that upgrade is not a cost effective one
Out of 3 Nap250DRs and 2 Supercap DRs and one non DR Supercap, only the latter has an occasional buzz. Actually thinking about it, of all the equipment I have owned over the years that’s the only one with that issue and recently I’ve not noticed it as much. It seems that occasionally a transformer is particularly prone and it’s not model dependant and you will find that other equipment on the same mains circuit is unaffected. Not very helpful I’m afraid, just my two cents.
Thanks for this chaps. I’m pretty sure it’s the amp and not my mains as the hum is constant all times of the day. Also I live a place with pretty clean mains - very little noise and < 0.5v DC offset. I’ll get it serviced and mention the hum - maybe I’ll get lucky like mickdale
In the meantime, it’s hardly terrible and I’m sure will be even better when the Fraim arrives!
I have two PS to date for a Nac552 DR (2015) and Nap500 DR (2018) both hum very noticeably. I’ve mentioned this to my dealer who has suggested opening up the PS and fitting some pads under the transformers. This free of charge service has apparently worked previously. My boxes are on a Naim Fraim and their own dedicated spur.
I’ve a new PS555 DR turning up later today for a NDX2, hum city here we come.
I did it by measuring the DC voltage between the neutral and earth on the plug that’s feeding the device. I got the method from another post on this forum, so I’m hoping it’s okay. You just need a decent multimeter. HTH