Choppy playback - dodgy desk lamp?

[danielbriggs]

Hi,
I know this is a bit of an oddball question to ask, but I'm sure someone will know the answer and will be able to explain it to me..

I've recently purchased a set of Z-5500 speakers and have the control unit to my left. I also have my desk lamp to the left, close, behind the control unit. Recently I've noticed my music will "mute" itself for about 1 second at a time every 10-30 seconds or so. The penny finally dropped that this only happens at night when I had the desk lamp switched on - doh!

OK, so I thought it was some sort of spike / EM field on the cable? However the audio feed in is a toslink optical cable! So how can this spike affect the optical signal?

It will 'mute' whenever I switch the light on or off, but why does the 'muting' occur constantly when the light is on, even if not touched?

The light and the speakers are plugged into two separate surge protectors on different sockets.
I moved the light to the other end of the room on a different mains socket and it works fine i.e. no muting. As the light is a halogen 12V lamp, there is a transformer in the base. The only sensible thing I can think of is could the lamp transformer be interfering with control centre?

BTW: The PC is NOT the problem, I've tested it with my Shure SE530-PTH's and the playback is flawless, as it always was...

Any ideas?
How can I sort this? (apart from getting rid of the lamp! )

Thanks,
Dan

[bik2101]

I might be wrong but it still is possible for your PC to be the problem. I had a similar issue with my EMU0404 USB dac. Playback plugging headphones directly into audio out from my PC was no problem. But, playback through my emu' was choppy when my dvd drive was in use. So, while you have perfect playback through your audio out on the PC, there might be an issue with the signal going from PC to the 5500 control center since your toslink isn't plugged into the audio out of your PC. Don't know if this makes any sense or not..

[Uncle Erik]

It's probably the lamp putting out some RFI.

RFI is a radio signal, so using optical cable doesn't matter. The radio waves go right through the plastic cabinets of the speakers and right into the internal amp.

That interference only comes through a power cord or interconnect is a complete myth. Radio waves can go right through cases and enclosures.

[danielbriggs]

Thank you both for your replies.
It turns out I seriously got the wrong end of the stick with this issue. It was a flaky micro switch on the optical port of the computer. All sorted now thought

Also: I think the lamp is dying; every time I switch it on now I get a loud crackling sound (not from the speakers). So it's clearly not safe, and I'm going to replace it.

Talk about coincidences!
As soon as I fix one item, another breaks!
Thanks for your help,
Dan