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  #16  
Old 22-04-17, 10:10 AM
Tony L Tony L is offline
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Quote:
Originally Posted by matt j View Post
It's an internal one in the amp.

How should it be grounded? it currently goes from a tonearm ground wire to a screw on the turntable chassis, the same screw then has the ground wire that goes to the amp with the RCAs.
Personally I'd not ground the tonearm to the turntable, only to the ground post on the back of the amp or preamp. That means the turntable can be grounded independently via its mains plug with no risk of a earth loop, this being very beneficial from a static perspective.

I remember when you called round with the CDs the other day you commented that your 3009 had been rewired or at least looked different to a proper SME lead I showed you. This is the area I'd look at first. The four pin sockets on the SME arm base are the four cartridge pins, the raised washer thingy at one side is the arm earth and should correspond with a clip, i.e. you should have at the other end of the arm connector two RCA leads (left and right) and the arm earth lead, which should be taken to the preamp's earth terminal on the rear panel. A multimeter with a continuity setting is a very useful thing to have for diagnostics as if all is correct you should have earth continuity from the headshell right to the preamp earth (try sticking a probe on the headshel collar as it is bare metal). If you do not something is wrong.
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  #17  
Old 22-04-17, 05:32 PM
matt j matt j is offline
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I'll do some more investigating and testing when I get chance, cheers chaps.

Tony, the TT doesn't have a mains earth, just a live and neutral, but I'll look into the arm as you say. No doubt there'll be more questions soon enough!
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  #18  
Old 27-04-17, 08:34 AM
matt j matt j is offline
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Not got anywhere with this.

I've separated the grounds, the arm is now grounded direct to the amp earth post, the TT is earthed via the chassis. It's very slightly better but not by much, still very audible.

Not sure what else to try.
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  #19  
Old 27-04-17, 09:35 AM
sq225917 sq225917 is offline
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crocodile clip and 1m lengths are wire are your friend, just mess about until you get it quiet, then rebuild in the system wires.
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  #20  
Old 27-04-17, 09:43 AM
matt j matt j is offline
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Don't really have the time TBH, will be ages before I can sit down and look at it.

Plus I've no idea what else to try.
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  #21  
Old 27-04-17, 10:28 AM
oldius oldius is offline
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I recently had a similar noise coming through and I could not fathom it. I disconnected everything, re routed cables and disconnected all components one by one.

It turned out to be an ethernet mains plug on the opposite side of the room and I only turned it off by chance. In my old house they gave me no problems whatsoever but they are problematic in this and I have no idea why that may be.
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  #22  
Old 27-04-17, 10:46 AM
Julf Julf is offline
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Quote:
Originally Posted by oldius View Post
It turned out to be an ethernet mains plug on the opposite side of the room.
Ethernet or mains?
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  #23  
Old 27-04-17, 10:50 AM
matt j matt j is offline
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I have homeplugs but I've already tried them, plus they didn't effect the TT previously.

It can only be TT/arm related because nothing else has changed, it's just a case of finding it, which I don't have the time or patience for at the present.
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  #24  
Old 27-04-17, 10:58 AM
oldius oldius is offline
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Quote:
Originally Posted by Julf View Post
Ethernet or mains?
Homeplugs that create an ethernet through the mains.
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  #25  
Old 27-04-17, 11:55 AM
mercalia mercalia is offline
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see my reply #6 here
http://www.pinkfishmedia.net/forum/s...d.php?t=201248

or here

http://www.pinkfishmedia.net/forum/s...d.php?t=200891
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  #26  
Old 27-04-17, 12:20 PM
Julf Julf is offline
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Quote:
Originally Posted by oldius View Post
Homeplugs that create an ethernet through the mains.
Ah, OK, yes, ethernet-over-mains stuff generates nasty stuff over the mains (that's how they work).
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  #27  
Old 27-04-17, 03:18 PM
oldius oldius is offline
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I never had a problem with them previously but all sorts of fluttering fax like noises this time. Immediately stopped when I took them out.
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  #28  
Old 28-04-17, 01:43 AM
Jim Audiomisc Jim Audiomisc is offline
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One of the problems with the 'ethernet over mains' systems is that they're tested on the assumption that nothing much but a length of wire is connected to them. i.e. No concern for the effect of the RF encountering nonlinear loadings. Fortunately, no one would dream of ever connecting, say, diodes, or switches, to the mains, would they?... 8-/ And of course, all connetions will be perfectly Ohmic in every home.

OfCom define them as 'not transmitters' because - when not connected to anything - they don't radiate RF.
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  #29  
Old 04-05-17, 12:08 PM
matt j matt j is offline
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Just an update - This issue has magically vanished and left me scratching my head.

I haven't listened to any vinyl since my last go at curing the problem, the noise was too annoying during quieter passages and certainly too noisy at anything above low level listening.

So I've just fired it up and switched over to the phono stage input on the amp and it's silent, and I've no idea why as I'm struggling to think what has changed and I can't think of anything.

Hopefully it stays gone.
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  #30  
Old 04-05-17, 12:39 PM
mercalia mercalia is offline
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the hum pixie has decided to visit some one else - hope he stays away
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