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Humming along with Rega

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hedgehog@35 View Drop Down
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    Posted: 17 Jan 2018 at 8:39pm
I have been happily living for several years with my Michell, SME M2 and Goldring feeding my Reflex M.
Recently my friendly local dealer offered me a loan of the new Rega planar 6 so I could discover if all the great reviews were correct.
Plugged everything in and switched on - and there is was: the dreaded mains hum that I vaguely remembered from years ago when I had a planar 3 in the 1990's.
I then recalled that Rega have this weird system of providing the earth connection through the left ground wire (is that correct?). Anyway Rega arms still don't have a ground wire to connect to the Reflex which is humming merrily away.
My usual set up will show mains hum, which disappears when I connect the earth tonearm wire from the SME to my Reflex.
My question is this - and I apologise if this has come up hundreds of times before: is there a solution to this. I obviously can't rewire the arm (it's not mine), but I would like to try and sort the problem so I can give the deck a proper evaluation. Also the hum does get louder as I increase volume and is still there with the turntable switched off. 
Any Rega owners out there who have an easy(!) fix for this?
Thanks
Russell
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BAK View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BAK Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jan 2018 at 8:50pm
Have you unplugged the Reflex input cables to see if the hum goes away?

If so, and you are sure the hum is coming from the cartridge to the Reflex input,
 then try taking a piece of wire and touching it to the Reflex input shield (outside part of the plug),
while all is connected, and touch the other end of the same wire to the tonearm or head-shell.
Of course, do this while not playing an LP and at just enough volume so as to hear the problem hum.



Edited by BAK - 17 Jan 2018 at 9:21pm
Bruce
AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jan 2018 at 9:50pm
Maybe the left channel ground isn't actually making contact with the arm metalwork?

We try all sorts of things here - it's our job to do so - I wired a Technics so the ground runs in both left and right shields/screens and it works a treat and just as good as the separate earth wire. There is nothing inherently wrong in doing it this way. However, the Technics earth wire is bonded to the arm tube, and with most hi-fi arms it is bonded to the arm base, which means if the bearings don't conduct the micro earth current because of the light coating of lubricant, there is no earth.

Even ancient HMV and Dansette record players got that right...

Try running a wire from a headshell screw to the Reflex ground post, that's assuming it will make contact with the arm. Usually the anodising won't let it.

Oh, and if the turntable is switched off and even unplugged if there is no ground it will still do the same.

Sometimes if the cartridge pins have been mixed up: right signal with left ground etc, that can sometimes do the same.

Otherwise I'm stuck for an answer. Sorry.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fatmangolf Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jan 2018 at 8:48pm
Please tTry Graham's advice first. If the hum persists I think the Goldring is a moving iron like mine and I found that grounding the Rega P3-24's spindle (bit of wire clamped with jubilee clip) and motor casing (more involved) helped reduce mains hum. You could do a quick test by running a ground wire from the preamp earth terminal and touching the metal bits to see if the hum reduces.

Jon

Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.
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hedgehog@35 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote hedgehog@35 Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jan 2018 at 9:16pm
Just out of interest I decided to play a classic Miles Davis lp so switched to mono on the back of the reflex and the hum disappeared! Has this got something to do with adding the left and right signal inputs together?
I have now tried (at shop's suggestion), a wire from outside of phono input plug to ground post - didn't work. They also soldered a wire from the turntable psu unit which I connected to ground on reflex - still no joy.
Will try your other suggestions - many thanks
Russell
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fatmangolf Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jan 2018 at 11:26pm
That is interesting Russell. It makes we wonder about polarity of wiring so to eliminate that I would double check the RG/WB wires are all correctly connected up.

Then, following Graham's suggestion find a longer wire, run it from the Reflex ground and touch it against one of the metal screws holding the cartridge in the headhell, probably no effect but if the hum disappears the arm grounding wire has probably come away from its connection at one end or simply broken.

My last suggestion at this point is about the Goldring cartridge. When I had the metal bodied 2500 I think one of its ground pins (Green?) was bonded to the metal body which was then electrically connected to the headshell and arm by the mounting screws. That meant the arm had two groundlines and I got hum soI unplugged the tonearm wire from that pin.

Jon

Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote properlydeafened Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jan 2018 at 10:52pm
It is correct that the Rega is grounded through the RCA shielding.  I have an RP6 and have never had any issues with hum.  I have read an instance where grounding the TT-PSU solved a hum but it doesn't seem to be a commonly discussed solution.  
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