Transistor hum? + Unit isolation

Hi All & Happy New Year,

I know I am breaking all set-up rules with my “stacked” system but I’m currently rather tight on space. Could the hum I am experiencing be interference between units sitting on top of each other? All cables are Naim.

NAP 250 DR/Flatcap2/NAC-N 272/Stageline N with 5" to spare underneath my shelf. Any unit isolation suggestions would be greatly appreciated.

On another note, my speakers are Linn Kan MkII. My ears prefer deeper bass, any “bookshelf” sized speaker upgrades would also be greatly appreciated. (E.G. Harbeth P3ESR / Dynaudio S40?)

Many thanks for looking.

Hi, that is almost certainly a compromised setup, especially with a phono stage stacked like that, and most likely the cables are not separated and well dressed either! But you already know that.
If you can’t change the shelf they sit on for a dedicated HiFi rack, perhaps some sort of isolation shelves to sit the boxes on would help.
Something like this, recently posted by Neil0001 in the System Pics thread, might work, as it would put some distance between the boxes as well as providing mechanical isolation:

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Thanks ChrisSU, that shelving system looks very neat indeed. I will contact Neil0001 to find out what it is. All the Best, Rob.

You could do a lot worse but better support and separation will help. You’ve got the transformers in the Naim kit as far away from the TT as you can which is good. I’d try and move the Stageline though as Chris mentions.

Is the hum on all the inputs etc. I take it you mean hum that’s audible from the speakers rather than hum from the kit itself ?

One simple thing to try (if the hum is audible at the speakers) would be to flip the ground switch on the 272 (as you have an LP12 in the system) to see if that makes any difference to your hum.

Thanks James, the “hum” description in my post was rubbish. The hum is more like a buzz, it is audible from the kit as opposed to through the speakers and to be more specific is coming from my NAP 250. When I press the power button, it goes “ping” and then buzzes … with all other Naim equipment turned off. I should have been more specific. Could it be mains interference?

The following article will probably get you started


Ah ok - yes some naim kit can hum. Mechanical noise from the transformer. A search on hum will find quite a few threads…(edit as just posted above)

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When powering on my xpsdr, it always comes in with a thump, then the ping from the casing. Its pretty quiet after that.
Noisiest transformer I have is the cd5xs. The cd5si was also noisy. Strangely the ndx2 is silent.
The NAP140 has its moments, but silent compared to the cd5si.
All normal. Someone will pipe up about DC offset, mains smoothers etc. Good luck with all that.

My NAP140 is virtually silent but my olive HiCap (recently put in) is much louder, unfortunately.

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