This is topic Sound problem with light switches. in forum General Yak at 8mm Forum.

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Posted by David Park (Member # 123) on March 30, 2006, 03:33 AM:
When playing the digital sound from a DVD through my multi channel AV amp. if a light is switched off there is a dip in sound for a moment, anything I can do?
Posted by John Clancy (Member # 49) on March 30, 2006, 07:57 AM:
Don't switch the light off.

Sorry. Can't help myself sometimes. There must be a bad earth somewhere so perhaps an electrical check on the house would be worthwhile.
Posted by David Park (Member # 123) on March 30, 2006, 08:09 AM:
I have had the suggestion that it might be the fact of useing co-ax digital connection, or poor quaulity lead.
One of the 2 DVD players has optical output, so will get an optical lead, as I'm told these do not suffer interferrence from electrical sources.
For the other I will try a better quaulity lead.
Posted by Jan Bister (Member # 332) on March 30, 2006, 09:49 AM:
I can't help but ask... What happens when you turn the light on?
Posted by David Park (Member # 123) on March 30, 2006, 09:54 AM:
I won't say it does not happen, but I'm faily sure only when switching off.
I will have to check.

Some switches off only.
Others on and off
Posted by Jan Bister (Member # 332) on March 30, 2006, 10:16 PM:
(And you use incandescent bulbs, right?)

I dunno, the whole thing seems very unusual to me. I've never heard of such a thing happening, and you might be better served trying to get an answer around a forum dedicated to hi-fi and home theater setups.

Posted by David Park (Member # 123) on March 31, 2006, 07:58 AM:
One of the DVD players has an optical output, so today have bought an optical lead.
This appears to have solved the problem.
Posted by Rob Young. (Member # 131) on March 31, 2006, 09:48 AM:
David, glad you have found a fix.

Strange stuff electricity.

I used to have a problem with my Elmo ST when I connected the sound to an external amp using the headphone outputs. Although this provided great stereo, everytime someone in the house switched something else on there was a loud pop or bang from the speakers! The oven was the worst offender; everytime the thermostat kicked in there was a huge bang from the speakers, so watching a film whilst dinner cooked was right out!

I fixed it with a 240v to 240v mains transformer that an electrician friend of mine got cheap for me. I'm no expert but he told me this cleans up the mains supply to whatever you plug into it and acts as though they have their own separate supply. You just plug it into the mains and then plug all the projectors and amps, etc. into it. Hey-presto!

I believe you can buy similar things from hi-fi specialists which do the same thing but last time I looked they cost a few hundred pounds believe it or not (mine was 20 quid!)

Other than that, years back when I sold hi-fi gear, I remember some fanatics went so far as wiring a separate circuit from the mains supply to the house just for their hi-fi gear to stop all interference and "improve" the sound; a step too far me-thinks [Wink]
Posted by Jan Bister (Member # 332) on March 31, 2006, 06:41 PM:
Hmmm.... one possible solution (other than a transformer to create a separate circuit) might be the use of an uninterruptible power supply like the ones they sell for personal computers. The idea would be for the UPS to correct both spikes and brownouts (voltage dips) caused by spikes in the home wiring's current load.

And if all else fails, get yourself a car battery and a 12VDC-to-240VAC converter [Big Grin]
Posted by Stuart Mercer Thorburn (Member # 574) on April 01, 2006, 02:08 AM:
You don't half like to over complicate things!

Try this -®ion=UK¤cy=GBP&pf_id=5785&customer_id=PAA0109040306329BFQUEKOUDSJLOQVG

This small kit will take out all the pops plus you should think about a 'superclamp' or a mains conditioner. This will take out all the background fuzz from ALL your hi-fi, tv and projector circuits plus improve your playback quality. Mmm nice bass!

Turn up your gear to 10 and listen to all the noise [Eek!]

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