Phono questions

[AntIbbots]

Hello
Had a Phono 1 for a couple of weeks now and pleased with it, except that I am now picking up mobile phone type bippity bip noises. I am running the phono stage into an ADC then DAC and headphone amp. It's barely audible on silent passages so not really a problem and only an occasional irritant for general listening however I also use this set up for archiving vinyl and it's a bit of a fag to have to find and edit out. This has not happened with previous phono stages and I wonder if it is something the NVA amp is prone to, and any way to stop it?

[Dr Bunsen Honeydew]

Sorry but NVA is prone to it. We use a Perspex / acrylic case deliberately to not block field from either direction. One of the big problems with phono stages is within a metal case the field emitted by components pcb's and wiring is contained, reflected, and bounces around mucking up musical time signatures (phase) and creating other pollution. So the NVA case lets it out. Inversly it will let strong outside signals in to be picked up by the circuit.

The answer is keep all mobile devices away from it in another room or switched off, as it is only things in close proximity that give off the strong enough signal to be picked up.

[AntIbbots]

The phones are in the room below but at least I know the cause and it is not unusual to my set up, and I can now deal with it when it matters. Thanks.

[guydarryl]

possibly a daft suggestion, but as the 'phones are in the room below would a sheet of aluminium foil under the carpet (if fitted) act as a shield for components above it, without keeping the amp's stray fields within the case?

Guy.

[Dr Bunsen Honeydew]

Not a clue. Sounds a bit like this

http://en.wikipedia.org/wiki/Tin_foil_hat

[AntIbbots]

No dear, that's not a new gimp hutch in the corner of the bedroom it's me Faraday cage.

[terrybooth]

I keep my phone in my shirt pocket. But the Phono 2 reminds me about it when I turn to that source. My listening room has a corridor outside and family wandering along that with phones turned on can be picked up. Having said all that, my PC speakers also pick up the phone signal.

[Dr Bunsen Honeydew]

The worst case scenario I came across was a dealer in Stafford back in the late '80's. He was moaning about he couldn't use any Phono Stage especially ours. Back in those days some cab companies still had old AM radios for cabs. I visited to see the problem, he had a cab company a couple of shops down. When they switched on their transmitter it nearly blew the speakers out of the cabinets and you could hear every message as clear as a bell.