ATC said it's best not to put signal and mains next to each other but don't worry about doing it if you have to. Seriously though I don't think that whatever is getting in is doing it via the signal cables.Dunno if one or more of these will help, but might be worth a try ..
http://www.mains-cables-r-us.co.uk/mains-filters/509-optimus-in-line-mains-filter.html
And it should be simple to mess around with some temporary, separated cabling to see if there are issues with the stuff buried in your conduit. Something in the back of my mind tells me you aren't supposed to mix signal and mains anyway from a regulations pov.
Also worth phoning ATC - they're always very helpful ime.
That would be my luckMy impression is that you're dimmer is injecting RF back into the mains circuit. Having a 'screened' mains cable running to the speaker won't necessarily fix that as the crap is already being guided by the wiring. Indeed, a screen might help keep the RFI running along the wires. Its an example of the 'Russ Andrews flaw'.
Do you think there is any chance that the noise is being transmitted through the air rather than through the main. I am puzzled at why it affects one speaker more than the other, although I appreciate that it's possible- they do seem to have the same cable type and lengthIf trying either RF filters and/or a ferrite 'block' it is usually best to try these near the source end.
ATC said it's best not to put signal and mains next to each other but don't worry about doing it if you have to. Seriously though I don't think that whatever is getting in is doing it via the signal cables.
Yes. Good idea. In fact I think the first I'll do is to take out that particular bulb (there are others on the same switch circuit) to see whether it makes any differenceAnd as others said: even sooner try an ordinary incandescent lamp in the same fixture.
I quite agree. But unfortunately others differ on the need for dimmer switches. Fortunately the switches themselves are getting a bit sticky and may "need replacing".Temporarily change the dimmer for a normal switch. 10 to 1 its the problem. they are evil when it comes to sending noise down the mains.
Don't get me wrong. I would not be doing it except thatIt is not always good to belive experts, ATC generally is great engineering (I have Atc 100A,s) and they sound superb; quite envy your 40's from a domestic viewpoint. I would not dismiss the mains/signal cable completly though, although a very different environment in industry we did not run control/signal cables in the same trunking and even now when sorting out the rats nest I try and keep signal cables separate from mains. There was phrase 'avoid the need' when approaching problems. Anyway hope you sort out the problem
No worries. I'm very happy with the ATCs. This is only minor.Pity you're having this hassle, getting a pair of ATCs is one of the best moments in hifi.
That would be my luck
Do you think there is any chance that the noise is being transmitted through the air rather than through the main. I am puzzled at why it affects one speaker more than the other, although I appreciate that it's possible- they do seem to have the same cable type and length
No worries. I'm very happy with the ATCs. This is only minor.
Good idea, although tricky to execute as they are quite heavy and spiked into shoes. Then again I rarely get the chance for a danceIts possible it is being radiated or coupled via the 'air'. However I think you said you'd disconnected the signal input and that didn't get rid of it. So I'm assuming it isn't getting in via the signal terminals/cable.
It *could* be being picked up by the power amp(s) in the speakers. Indeed, voice coils can act as effective 'loop antennas' if not well sheilded. You can check that by rotating the speaker slowly about 90 deg around its vertical axis whist listening with your ear against the tweeter. (Hey! Dancing with you speaker. You must love them. )
I only worked out what the problem was last night. I will begin messing about this eveningDid you swap the speakers over so each one was moved to where the other had been? If so, did the noise follow the speaker?
Don't worry my F-dac will be here any minute.All you need now is a nice Chord Hugo TT to do them justice. One of the other best moments in hifi.
If it's a multigang dimmer and more than a couple of years old it is entirely possible that whatever suppression cap is in there on the affected 'way' (probably something miniscule, yellow, perhaps 0.047- 0.1uF / X1 and very cheap) has gradually lost its metallisation and is now doing nothing useful - IOW, it can appear perfectly functional, with no discolourd components , and yet noisier than its new replacement*.
Mains suppression caps don't last forever: it is part of a key design approach for safety (internal arcs or temporary overvoltage punches holes in the insulating layers, and the energy is dissipated in vaporising the very thin (tens of nm) metal film 'plates' into non-conductance locally - rather than causing internal shorts)
(*Which should be a 3-gang switch ; )