Distortion on hi frequencies but only certain times of day

Discussion in 'Hi-Fi and General Audio' started by bass58, May 8, 2021.

  1. bass58

    bass58

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    I've tried three different CD players, three different amps and three different sets of speakers. I'm using a dedicated fused circuit and tried an ifi filter but I'm still getting nowhere. Any ideas?
     
    bass58, May 8, 2021
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  2. bass58

    Sergeauckland

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    I presume you've tried different CDs and they're OK some times of the day and not at others.

    What I would do here is to try and eliminate all common factors. So far you're tried different sources, amplifiers and 'speakers so we can assume it's not one of those. What about the cabling? Are those the same or have you changed interconnects and 'speaker cables? Unlikely as it may seem, it's possible I suppose for there to be an intermittent break/damage to the cabling that causes distortion rather than complete silence.

    Once the entire system including cabling has been checked, the only thing remaining that I can think of is mains. I did think of external RF interference, but eliminated that as you've changed sources and amplifiers several times, and it's pretty unlikely for RF to affect three different amps (unless they are three examples of the same amplifier) .

    Does this happen at specific times of the day, or is it random?

    For mains, can you try running an extension cable from another ring in your house? If that's still a problem, is it possible to run a mains cable from a next door neighbour, as they may be on a separate phase of the mains. (Be careful with mains, especially over two phases.)

    Finally, you may be in need of some mains filtration. I am very sceptical of any mains filter that's sold for HiFi, they are mostly overpriced and underperforming. Something like this might be more suitable.
    schaffner - Search Results | CPC (farnell.com)

    Schaffner are specialists in proper mains filtration, none of the audiophile bullshit that accompanies so much sold for HiFi.

    Hope some of this helps. I can well understand how maddening this sort of thing can be.
    S.
     
    Sergeauckland, May 8, 2021
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  3. bass58

    bass58

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    Hi, Thanks for the reply. I wired in a dedicated socket from the fuse box of 10mm cable and found this did not help with the problem but I could now use my coaxial input without other appliances interfering when they were switched on and off.

    I Have tried the other circuit option and I also took out all the other fuses or tripped the trips so only the dedicated circuit was on.

    The afi filter did nothing for the audio but works fantastic for improving quality of streamed TV audio and picture so not a total waste.

    The problem is at is more likely to happen at peak electricity periods and always between 18.00 and 20.30.

    My next door neighbor is on the same phase but my other neighbor is probably not but quite a distance away so a lengthy extension may have to be bought to test that.

    I went to CPC(farnell.com) and think I will try that route when I can work out the best option they have. Do you have any thoughts on this.
    Thanks for your help. all the best T.
     
    bass58, May 10, 2021
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  4. bass58

    Sergeauckland

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    I think that may be significant.
    Couple of suggestions:-
    Are you using any appliances like a microwave oven or induction hob when the problem happens?

    Anything with a motor in it, like a hair dryer?

    It's really hard to think of a cause, but it's looking increasingly likely it's something on the mains. Odd that it should happen with three different sources and amplifiers, as I would expect that different equipments have different mains power supply arrangements, so wouldn't all be giving the same results.

    As to a suitable filter, I would try this one
    Filter, 16A, Multi Stage, Chassis (farnell.com)

    It's more expensive, but as we don't know what's causing your problems, this one offers two-stage filtering, both common-mode and differential. One of those in a box and put it in the mains feed to all your hifi.

    If you use a metal box, then make sure the box metalwork is well earthed.

    Sorry I can't offer any better suggestions, but trying to diagnose problems like this at long-range is difficult.

    Good luck with the quest.
    S.
     
    Sergeauckland, May 10, 2021
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  5. bass58

    bass58

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    Hi. I wired in the filter and I did get a slightly improved general sound but no real improvement with the distortion.

    Over the weekend I observed when my nearest neighbours were in and out of the house and found that when they were out, the sound was fine! I also noticed that the improvement, when it happened seemed to be on the hour or the half hour. I'm guising it has something to do with tv program times so could it be a satellite wireless repeater signal straying into our property?

    I have aluminium foil around one of the speakers at the moment and dragged to see what hapens.

    I feel I'm getting closer. T.
     
    bass58, May 24, 2021
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  6. bass58

    Sergeauckland

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    A foil hat?;)

    S
     
    Sergeauckland, May 24, 2021
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