Hello... and a question about humming.

[PenguinTunes]

Hi there.

So I have been lurking around these pages for some time, and am the proud owner of a pair of NVA A40’s and various lengths of cable. I have enjoyed reading various discussions over the time, yet here I wonder if someone may be able to assist me in a humming problem that I have acquired. I’m not sure how this has come about - everything was fine until about a month ago.
I use the NVA A40s with LS5 and some SSC interconnects (one new to check the connections of the older), an Icon Audio pre, and mainly an M-DAC attached to a Sonos Connect. (Also have a Rega turntable and phono amp, but this is somewhat a bit of a dabble in vinyl really.)
The humming is to both channels (although I think it started with only one), and is there whether the Icon is in the line or the amps are just connected to the DAC. Very, very weirdly however the humming disappears when the DAC is powered up in the latter scenario. If the Icon is in the chain, the humming increases in volume with a turn off the volume knob. I have tried unplugging everything from my extension block, and the humming is evident with nothing powered up apart from the A40s when they are connected to the Icon with nothing else attached. I have also tried another power socket in case there was something up there. No change.
Flummoxed. Any ideas?

Thanks!
Jonathan

[jammy395]

Im a Scot ...fuked if I know....Only the English hum.......

[Dr Bunsen Honeydew]

Might be the system needs a mains earth. Take a lead from the Icon Audio connected to the neg side of a phono plug and plugged in a spare (any) socket on the Icon. Other end wired to the earth pin on a mains plug, plug in mains socket and see if that solves it. Other suggestion move things around and see if the hum changes.

[Dr Bunsen Honeydew]

I ought to add that I am presuming you are using their passive pre not the valve one.

[Fretless]

I had this problem when running my A40's directly from my Hegel DAC. When the output section was off I got a severe hum through the amps.

Problem was resolved by inserting an NVA passive pre-amp that earthed the connections. No hum at all now.

Edit: the P50Sa with SSP sounded better than a direct link to the DAC.

[PenguinTunes]

I ought to add that I am presuming you are using their passive pre not the valve one.

Yup. Ok, thanks very much, I will try the earthing tomorrow.

[PenguinTunes]

I ought to add that I am presuming you are using their passive pre not the valve one.

Yup. Ok, thanks very much, I will try the earthing tomorrow.

Might be the system needs a mains earth. Take a lead from the Icon Audio connected to the neg side of a phono plug and plugged in a spare (any) socket on the Icon. Other end wired to the earth pin on a mains plug, plug in mains socket and see if that solves it. Other suggestion move things around and see if the hum changes.

Got 'round to doing this this morning. Bit nervous about wiring up to a mains plug (even if earth) but it seems to have done the trick. Beyond my electrical understanding! Hum took a few minutes to completely disappear.

[Dr Bunsen Honeydew]

It means what is before the amps doesn't have an earth reference and is floating. It is obviously relying on the amp to provide the earth. NVA being built to ClassII double insulated regs doesn't have that earth, it is designed to float (off the earth) so your source not being ClassII didn't like it and hummed. All you have done is give the system an earth reference point.