Strange Issue....any ideas

I have a issue around my system sounding different on different days
I live near a industrial estate and suspect the issue may arise from the estate
My systems nearly always sounds very good sometimes it sounds freaking awesome but betwen once a week to once every two weeks the sound becomes slightly muffled. Ideally I like freaking Awesome every day.
I think its RFI but have balanced mains that make a huge difference to everything; cables and everything work well
Its like a itch I cannot scratch:scratch:
Any thoughts

I have noticed that... But there is no pattern... I have put it down to ears/mood

I know the brain tricksy but nahh think its something else

Hi John, sorry to hear this as i can imagine it must be very frustrating :rolleyes:

I'd suggest you find out exactly what these businesses on the industrial estate near you actually do. You possibly have a couple of choices in reality, either very heavy mains born interference or RFI as you point out.

Do you have any radio amateurs living near you? Look round for unusual aerials, might also be interference from taxi firms (if local) or a CB radio entusiast.

If you can find out what the firms are doing it might narrow things down a bit, heavy mains interference will likely be down to something using very heavy current which has possibly been rectified. Think something like electroplater.

It's a pity you don't have an oscilloscope kicking about as when the sound isn't good you could take a look at the incoming mains waveform to your house & possibly narrow it down to EMI or RFI ;)

Is there a pattern to it?
Id start by taking note of when the problem happens and doesn't, see if that gives any clues

no real pattern but think Mark on the right path I was wondering about getting a noise sniffer to see if its RFI It seems like it might be something i just have to accept
As i said it does not happen to often so I suspect it might be machinery

It's heavy machinery used in the trading estate. I too live close to a trading estate and have found out that equipment in the estate are affecting the power supply. One is noise and the other is actual fluctuation in the mains level. The audio stuff with switched mode power supplies would be largely unaffected, but amplifier outputs with unregulated power supplies are mutually tied to the mains power supply level. So a decrease in the mains will cause a decrease in the amp output, but more importantly, the bias voltage of the amp outputs stage would also be affected, unless it is using auto biasing.

Cheers Stan
Seem to effect sub plates more than power amp The sub plates are moset valve whilst the power amp is tube

John, can i ask you how your balanced mains is made? Are you using a transformer/s out of interest? This isn't off topic by the way ;)

I find Mondays are the worst for me here, but it could easily be me and my mood at present... On bad days the Spendors sound like they have a severe cold, better with the crowns driving them and worse with both the Quads. By Wednesday the system seems to sound totally different and not at all congested. I'm sure it's more me though.....

Its mainly one huge transformer weighs nearly 26kg on its own The sub plates go through the transformer but power amp has diiferent feed also my DAC goes through the balanced transformer

I'm just wondering if your system is suffering due to DC on the mains line :scratch: I know it sounds crazy but take it from me, it can & does happen.

I'd suggest if you happen to have a multimeter you check the mains for DC prior to the transformer when this problem occurs. If you get a DC reading (AC will be rejected when set to DC) then there is a possible cure :)

No point in going into it now though as we still have no idea what the problem is.

Keep us informed though ;)

Ok I buy a multimeter and report back

I seemed to have solved the issue (fingers crossed)
One of the wires from the crossover to the mid driver was touching the magnetic driver I re-routed and last few days no issues

Good stuff John,hope that's the problem solved.