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Thread: Rega P6 getting hum

  1. #1
    Join Date: Mar 2017

    Location: East Sussex

    Posts: 35
    I'm Bruce.

    Default Rega P6 getting hum

    I recently bought a P6 with Exact MM cart and Elex-R amp.

    I am really happy with it and the sound is great.

    However... a couple of weeks ago, I was moving the arm over with the volume a little higher and noticed a hum. After playing around for a bit, the hum is coming from the motor and when the arm gets nearer the spindle the hum starts to be audible between tracks where the volume is a bit high. I would be lying if I said I could hear it on normal play but I now know it is there and didn't expect it.
    I searched on the web and there are a few remarks about this but not much really to go on. There is no earth from the P6 to the amp, something I have found out that Rega do not bother with. My old SL-BD20 was quiet as a church mouse and I am a bit disappointed that I am getting hum from the P6.

    I have gone back to the dealer and waiting for them to comment on whether the shop one did the same. They said that they had never heard of this before.

    I have moved the NEO PSU as far as the lead will allow, about 1.5m away but it makes no difference.

    Is this a trait of Rega decks or do I have a rogue specimen?


    Any comments would be much appreciated.

    Thanks
    Bruce

  2. #2
    Join Date: May 2008

    Location: A Strangely Isolated Place in Suffolk with far away trains passing by...

    Posts: 14,559
    I'm David.

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    That's a Rega for you!!!!!

    The top model(s) do have some extra motor shielding, but the main range models have never had this - ever - and some cartridges, especially their own MM's and Grado's I remember, are sensitive to this, as fully shielding the cartridge all round would reduce it's output (I was told by Roy Gandy when discussing the Bias, Elys and Exact models in particular).

    One thing regarding equipment racks if you use one... Can I ask you to lift the deck off its support and see if some of the hum reduces? Roy G was adamant that hum is additive, and a nearby transformer hum field can add to the field from the motor and make a tiny issue into a problem.

    You could get in touch with your local dealer, take the deck there and see how it compares to their demo one in a different system.

    Usually, careful cartridge choice renders this a pretty well non-issue, but it does rear its ugly head from time to time.
    Tear down these walls; Cut the ties that held me
    Crying out at the top of my voice; Tell me now if you can hear me

  3. #3
    Join Date: Oct 2017

    Location: Ontario, Canada

    Posts: 792
    I'm Svend.

    Default

    Hi Bruce,

    This video was extremely useful in helping me solve a hum in my Heybrook: https://www.psaudio.com/askpaul/find...turntable-hum/

    At 4:45 he starts to talk about the different kinds of hum or buzz and their causes. In my case -- and this is where Paul was spot on -- I had mismatched ground potential between the preamp and the TT power supply. My TT-PSU was plugged into a simple 6-outlet power bar, and from there into the wall socket; whereas the preamp went straight to the wall. As soon as I unplugged the TT-PSU from the power bar and into the wall the hum disappeared. Simplest fix ever. So if either your PSU or preamp are on a power bar, and the other is not, this may be the same issue for you. If not, he gives other basic fixes for you to investigate. Worth checking out....

    Hope this helps.

    Svend

  4. #4
    Join Date: Apr 2012

    Location: Southall, West London

    Posts: 40,507
    I'm Geoff.

    Default

    Quote Originally Posted by DSJR View Post
    That's a Rega for you!!!!!
    Yup. "they all do that sir"

    Good reason to not use a Grado or Decca in one.

  5. #5
    Join Date: Apr 2012

    Location: Southall, West London

    Posts: 40,507
    I'm Geoff.

    Default

    Maybe find a vintage Shure M55E cart, bung a Jico stylus on it and stick it in the Rega arm. It won't hum and it will sound punchier than any Rega cartridge.

  6. #6
    Join Date: May 2008

    Location: Reading, UK

    Posts: 303

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    Bruce,

    I had the same experience - I once had an Exact on an RP8 and the hum as the cartridge approached the centre was, quite frankly, intolerable. The RP6 was better.

    I think it's a problem with the Exact not being well screened. Quite frankly, I must have tried 3 or 4 Exacts and they did not last long. Cartridges are a personal thing but I always found the Exact very unexciting.

    The latest Planar 6 is made for the Ania if you can afford one and have MC capability. MCs also seem much less prone to hum.

    Cheers

    Phil

  7. #7
    Join Date: Oct 2017

    Location: Ontario, Canada

    Posts: 792
    I'm Svend.

    Default

    Quote Originally Posted by RothwellAudio View Post
    The OP states that the hum gets worse as the cartridge gets nearer the spindle - ie, nearer the motor - so the cause is induction from the motor's magnetic field, not a ground loop.
    A sheet of earthed steel on the bottom of the turntable might deflect the magnetic field enough to reduce the hum. Maybe worth experimenting with.
    Does the turntable have a piece of steel with three large holes in it going from the arm base to the bearing? Maybe earthing that would help.
    Andrew, mine showed the same behaviour -- hum got louder as tonearm moved to spindle. Connecting the PSU to an outlet with better ground fixed the problem. Not trying to be contrary here, just sharing my observations. BTW, as mentioned in the PS Audio video, the hum was as described for ground loop -- a higher-pitched buzz.

  8. #8
    Join Date: Oct 2017

    Location: Ontario, Canada

    Posts: 792
    I'm Svend.

    Default

    Quote Originally Posted by RothwellAudio View Post
    Yes, I may have misinterpreted the symptoms and maybe plugging into a different mains outlet will cure the problem. It's certainly worth a try.
    Yes, definitely worth trying. TBH, I was quite surprised that the fix was so easy. I was expecting to fuss over this for days trying to track down the problem in tonearm wiring, etc.... It was a revelation when I watched that video...I had never heard or read anything describing "ground potential" in those simple terms.

    Cheers,
    Svend

  9. #9
    Join Date: Mar 2017

    Location: East Sussex

    Posts: 35
    I'm Bruce.

    Default

    Thanks everyone for the replies, some things to try this evening and i'll report back.

  10. #10
    Join Date: Mar 2017

    Location: East Sussex

    Posts: 35
    I'm Bruce.

    Default

    Thank you for your suggestions and comments, here is what I have tried so far...

    Connected the TT PSU direct to the wall socket along with the amp - no difference
    Lifted the TT well above the rack - no difference
    Connected an earth the motor shell - no difference
    Connected an earth to the metal plate from arm to the spindle - no difference
    Placed a piece of steel of about 7 inches with a hole in the middle around the motor spindle, between the top of the plinth and the platter, unearthed - reduced the hum, earthing it probably made it worse


    I am still waiting for the dealer to try on the one they have in the store but as mentioned by Phil, perhaps the way to go is MC.

    I will have a look at Shure.

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