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Thread: Speaker noise in time with revs

  1. #1
    Helpful Club Member Scooter's Avatar
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    Speaker noise in time with revs

    OK, I have had a low pitch whine from my car stereo that was only really noticeable with the volume down and I noted it was in time/tune to the revs.

    This morning I was in traffic on the way to work and it suddenly changed to being very loud, so loud that initially I thought the car had an issue to the point I'm pulled over in the engine bay blipping the throttle etc trying to see if the alternator or fan were whining. I heard nothing and sitting back in the car it was as loud as ever and I thought this isn't right as normally worrying noises inside are louder when out of the car/nearer the source. Anyway the penny dropped and I tried switching the stereo off and all was good (should never have doubted the old girl!)

    Anyway some google research gives the following. Now since I've not heard of issues before on here and the fact that it's got worse over time is there anything specific I can look at re the alternator, wiring grounding etc? any simple tests? My plan was to try the car without the belt or with the alternator disconnected to verify it is the culprit.

    Any advice if it is?

    "Speaker Whine From Alternators

    One of the most common causes of speaker whine comes from the vehicle’s alternator. If the noise changes in pitch or intensity when the engine RPM changes, then it’s a safe bet that you’re dealing with some type of engine noise, and interference from the alternator output is a likely source.

    "The issue at hand is that noise from the alternator is getting into your head unit via the power cables. You can deal with the problem in one of two ways:

    Install a noise filter between the alternator and the battery
    Install an inline noise filter in the head unit power cable


    In either case, the alternator will still be "generating noise" but it won’t be able to get into your head unit and cause the speakers to whine."
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  2. #2
    Did somebody say carbon? Club Member Ric's Avatar
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    Bad grounds usually.

  3. #3
    Helpful Club Member Scooter's Avatar
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    Cheers, fits with getting worse if the corrosion/connection has gone worse in time? just for a numpty we are talking the engine bay ones, or could it be behind the dash/stereo?
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    Did somebody say carbon? Club Member Ric's Avatar
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    Quote Originally Posted by Scooter View Post
    Cheers, fits with getting worse if the corrosion/connection has gone worse in time? just for a numpty we are talking the engine bay ones, or could it be behind the dash/stereo?
    Ground for the alternator, battery, and stereo are where i would start but I've never experienced the problem myself on the supra.

  5. #5
    Helpful Club Member Scooter's Avatar
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    No worries, I'll start in the engine bay where I'm more familiar and hope that sorts it, thanks for the input.
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  6. #6
    I'm part of the furniture Events Organiser Al Massey's Avatar
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    Do you have an amp fitted?
    TRD widebody in need of carbon

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    Helpful Club Member Scooter's Avatar
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    No, but the noise was definitely from the alternator as it failed on the way home from work tonight! AA to the rescue, my first ever Supra call out, so listen out for that in the future everyone.
    Number 8 ...........doing my best to keep
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  8. #8
    I'm part of the furniture Events Organiser Al Massey's Avatar
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    I was just wondering as you can also get these symptoms if an amp power cable is too close to speaker wires, it will cause an interference.
    TRD widebody in need of carbon

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    Helpful Club Member Scooter's Avatar
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    Ta, it seems like the alternator has been dying a slow death for some time as the interference has been there for a while (wish I'd googled it back then) but didn't bother me, then on the way to work it literally jumped in volume (so much so at first I thought something on the car had broke/seized etc) which must be when it completely gave up, from then on I was simply draining the juice from the battery until breakdown.
    Number 8 ...........doing my best to keep
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  10. #10
    Helpful Club Member Scooter's Avatar
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    Ok inspired by this video I am going to try and replace my bushes, given the seemingly gradual demise of my (25 year old) alternator I'm suspecting the brushes?

    https://www.youtube.com/watch?v=I1vcdoP3PRQ
    Number 8 ...........doing my best to keep
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    Number 10 ........on its way

  11. #11
    Helpful Club Member Scooter's Avatar
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    Just to conclude I got some bushes and a regulator for £35 to repair mine but then saw and got a refurbed alternator from Germany eBay seller woospa for about £100. That's now on and a trip to Poole and back completed fine this weekend. I will attempt the refurb now on the original one, I may need a rectifier too which seem to be available from America only, this will be another £60 or so.
    Number 8 ...........doing my best to keep
    Number 9 ........been and gone!
    Number 10 ........on its way

  12. #12
    I'm addicted now! Club Member Harrypm82's Avatar
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    Let us know. Mine does this with the alarm siren in the engine bay but only when the window buttons are pressed or the rear window heater is turned on. Strange

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