Random bursts of high-pitched hum

Discussion in 'Audio Hardware' started by Mrtn77, Aug 8, 2014.

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  1. Mrtn77

    Mrtn77 Forum Resident Thread Starter

    Location:
    Paris
    Hello all,
    As the title states, I've been suffering from random bursts of hum.
    This hum is a high-pitched, fairly "pure" tone (it's more akin to tinnitus than amp hum from a garage band rehearsal) that's liable to ring out at any time, randomly it seems, whether the turntable is actually playing or not. I can spend hours without hearing it at all.
    I can make the hum vary in volume by putting my fingers on the cartridge or pushing the cables on the preamp. Especially when touching the cartridge.
    As far as I can tell (checked with a pair of tweezers), the arm's wires are securely attached to the cartridge.
    I have a ground wire running from the turntable to the preamp.

    Set-up is this
    Pro-ject Carbon Esprit
    Ortofon 2M Red
    Rega Fono Mini
    Atoll In30 amp to a pair of Dali Zensor speakers.

    I should add my previous turntable (a vintage ERA 444 with a Shure cart) never did this when hooked to the same preamp.
     
  2. Mrtn77

    Mrtn77 Forum Resident Thread Starter

    Location:
    Paris
    Anyone ?
    Any form of help would be appreciated, be it utter speculation. At this point, I'd be grateful for complete guesses.
    Could my cartridge somehow be at fault ? Unsufficiently shielded ?
    Am I wrong to believe that if my problem was due to the usual grounding problem, I'd get the hum constantly ?
    Again, I'd be grateful for some help.
     
  3. utahusker

    utahusker Senior Member

    If you have them, try a different set of cartridge leads. If not, disconnect, inspect and re-install.
     
  4. Mrtn77

    Mrtn77 Forum Resident Thread Starter

    Location:
    Paris
    Thanks for the suggestion. I only have the one set of leads. However, I'm not sure how I'd go about disconnecting them from both ends however, I can only get to them from the cartridge, the other end disappears into the tonearm.
    Still, I'll try that out when possible (no tweezers at hand).
     
  5. Mrtn77

    Mrtn77 Forum Resident Thread Starter

    Location:
    Paris
    Question : when I do disconnect the cartridge leads, what should I be watchful for ?
     
  6. utahusker

    utahusker Senior Member

    Sometimes they just need re-seated, but look for bare wires or loose connections.
     
  7. Mrtn77

    Mrtn77 Forum Resident Thread Starter

    Location:
    Paris
    Will do, thanks.
     
  8. Mrtn77

    Mrtn77 Forum Resident Thread Starter

    Location:
    Paris
    Since first posting here, I've tired doing a lot of things to solve my continuing problem (including writing to Pro-ject themselves, turns out they don't honour warranties for Amazon purchases !).
    I switched preamps, and still got the high-pitched, whistle-like, hum. I also switched turntables (borrowed my brother's Rega RP1), and, again, still got the hum.
    Tried turning off the wifi on my router, to see if that might be the cause, and, as ever, still got the hum.
    Tried putting ferrite chokes on my RCA cables, no luck. Tried looping them (the cables, not the ferrite chokes !), still no luck.
    People in my building have reported having the same problem. Something in the electricity network, perhaps ? We have a couple of cell-sites in the neighbourhood as well.
    Is there anything I could do to shut the hum once and for all ?
     
    Last edited: Sep 8, 2014
  9. Make sure everything is properly grounded
     
  10. Mrtn77

    Mrtn77 Forum Resident Thread Starter

    Location:
    Paris
    How can I tell when something isn't properly grounded ? (Please pardon my ignorance !)
     
  11. Colin M

    Colin M Forum Resident

    Your set up is so close to mine. I had no hum issues until I switched up from 2M Red to Bronze (got louder as the arm was moved towards the spindle). I switched from using the Fono Mini earth point to that on my amp, which cured the issue but I don't know your amp.
     
    Mr Bass likes this.
  12. Mrtn77

    Mrtn77 Forum Resident Thread Starter

    Location:
    Paris
    Didn't think to write it, but I did try grounding my turntable to one of my amp screws instead of the Rega Fono, and it made little difference.
    My hum, however, seems completely independant of tonearm position : I'm as liable to hear it when the arm is "at rest" as when it is moving.

    If I may ask, how do you like the Ortofon Bronze on your table and pre-amp ? And did you get rid of your own hum problem simply by grounding your table to your amp ?
     
  13. Upinsmoke

    Upinsmoke Well-Known Member

    Location:
    SE PA
    Maybe you have something plugged into that circuit that might be causing the problem? I had a water cooler at home than when the heater part of it kicked in I would get a hum. The long and technical solution to it was I turned the heater off. Problem solved.
     
  14. Mr Bass

    Mr Bass Chevelle Ma Belle

    Location:
    Mid Atlantic
    Since there is greater gain (amplification) in the phono circuit than the linestage (preamp) the cartridge/tonearm can be more revealing of hum (ground loop) issues. Since it is occurring when moving preamp cables or when the TT is at rest it probably is Not originating there though. Do you have any hum when you change to playing a CD? Do you have everything connected through one wall outlet? Using 2 or more outlets can cause problems. Are the cables touching each other? Do you have power cables sitting next to interconnects?
     
  15. Colin M

    Colin M Forum Resident

    Yes my hum was cured, using the amp earth... to do this I had to use a separate lead to that in the supplied cable . How often do you power down the fono mini? I've found mine could misbehave if left on continuously.

    The Bronze was a serious jump in quality and works well with the fono mini
     
  16. Mrtn77

    Mrtn77 Forum Resident Thread Starter

    Location:
    Paris
    No hum when using the DAC on the exact same set-up.
    The table is connected to a Belkin surge protector, along with a bunch of other stuff : the Rega Fono Mini pre-amp, the Atoll In30 amp, a Nuforce Icon HDP DAC, a Blu-ray player, a PC (hooked to the DAC by optical cable) and a monitor. That surge protector is hooked to a wall outlet by itself.
    All this stuff is, of necessity, bundled closely together and it is, indeed, highly possible that power cables might both be touching each other AND be sitting next to interconnects.
    I'll give the cable a thorough sorting out, but the space is so limited, I'm not sure I'll be able to keep them at a great distance.
     
  17. BuddhaBob

    BuddhaBob Forum Resident

    Location:
    Erie, PA, USA
    Could it be a faulty dimmer in your home or nearby? LED dimmers can throw off all kinds of noise, but any dimmer is suspect.

    You might be able to use a portable radio on AM or SW and track the source based on the strength or loudness of the signal, if you can pick it up.
     
    Analogman and Vidiot like this.
  18. Mrtn77

    Mrtn77 Forum Resident Thread Starter

    Location:
    Paris
    Actually, no, I've never thought to power down the preamp. I would if it had a power button ! I'll unhook the power supply when the table is not in play from now on. It can only save on electricity !

    Why did you feel the need to use a separate ground lead ? Was there anything wrong with it ?
     
  19. Mrtn77

    Mrtn77 Forum Resident Thread Starter

    Location:
    Paris
    No dimmer in the flat, no. And I doubt the neighbours use them. Now that I think about it, I don't think I've ever seen a dimmer used in France.

    I'll give the AM radio a try.
     
  20. Colin M

    Colin M Forum Resident

    Well yes there was something wrong with it... too short. :D
     
  21. Mr Bass

    Mr Bass Chevelle Ma Belle

    Location:
    Mid Atlantic
    Use cable ties. It is OK to bundle power cables together as long as they are not resting against interconnects. The computer / monitor is another issue. Do you have hum when those are turned off?
     
  22. Mrtn77

    Mrtn77 Forum Resident Thread Starter

    Location:
    Paris
    Ah, yes. I can see how that could be a major shortcoming (pardon the pun).
    I asked because my own ground wire has a sort of coppery coloration that seems odd :
    [​IMG]
     
  23. Mrtn77

    Mrtn77 Forum Resident Thread Starter

    Location:
    Paris
    I'll give cable ties a try. Is it OK to bundle RCA interconnects together as well ?

    I do get the bursts of hum with the PC and monitor off. But, like so many modern day appliances, the monitor doesn't shut off completely unless it's unplugged, which I've yet to try. Will do so.
     
  24. BuddhaBob

    BuddhaBob Forum Resident

    Location:
    Erie, PA, USA
    That darker color is residue from the solder flux, that's rosin. Completely normal for it to surround the edges of a solder connection and wouldn't be the source of a problem in the connection shown in your picture.
     
  25. Mrtn77

    Mrtn77 Forum Resident Thread Starter

    Location:
    Paris
    A month later, still struggling with my hum problem, I've managed to catch it on video hoping it'd help to troubleshoot :

    Bear in mind that the hum isn't triggered by my fingers, it had started ringing prior to filming, my fingers only "spurred it on", so to speak.
    I'd also like to remind my kind readers that I've gotten this hum with my both own Orotofon 2M Red equipped Pro-ject Carbon and my brother's Ortofon OM5E equipped Rega RP1, but never had it when using an older ERA 444 with a P-Mount Shure cartridge.
    Could Ortofon cartridges be unsufficiently shielded ?
     
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