Geekzone: technology news, blogs, forums
Guest
Welcome Guest.
You haven't logged in yet. If you don't have an account you can register now.



5 posts

Wannabe Geek


Topic # 107079 6-Aug-2012 19:18 Send private message

Hi,

I am relatively new to the hobby of listening to Vinyl. I have got a record player and amp setup.

I am experiencing a lot of hum when I turn the amplifier on. I have done some research and the most common solution seems to be to add a grounding wire. I have tried this and no luck.

The turntable is an old one but still in good condition but it doesn't have a grounding point at the back??? so how do I ground it to the amp? I tried putting the wire on the screws at the back and nothing.

I am not running through a preamp, I have just got a Sony STR Amp that has phono inputs. I tried a mates turntable through it and it was fine, so its definately something to do with my turntable.

Any help would be appreciated! I am new to all this so not really sure what I am doing, would love to be able to listen to the old mans record collection.

Thanks













Create new topic
148 posts

Master Geek


  Reply # 668543 6-Aug-2012 19:52 Send private message

There will be a grounding point, you just may have to take the turntable apart to find it. The other (but more expensive) thing you can do is add an inline ground loop isolator.

148 posts

Master Geek


  Reply # 668544 6-Aug-2012 19:53 Send private message

Hmm, maybe not so bad. There is one on trademe for $15.



5 posts

Wannabe Geek


  Reply # 668583 6-Aug-2012 21:13 Send private message

Hey thanks for the quick reply.

Ground loop isolator looks like it could be a potential fix. Does this connect between the turntable and the amp???

148 posts

Master Geek


  Reply # 668607 6-Aug-2012 21:46 Send private message

Yup.

14 posts

Geek


  Reply # 668617 6-Aug-2012 22:03 Send private message

I spent a lot of time lookig after turntables in the past and even a bit now! These are a few things to check..

Turntable signal earth leads are connected to the metal parts of the tonearm, there will usually be an earth tag of some sort underneath where the signal leads are connected.
To test you can try touching a wire from the amp earth to a metal part of the arm. Or just try touching the arm and see if the level of hum changes.
The earth is needed as the signals are extremely low level and the circuit of moderately high impedance, so very good at picking up mains hum fields.
Fine unsheilded wires are used from the carrtridge/connector through the arm to the base to allow free rotation, so the whole system relies on the earthed metal tube to keep hum out.. very occasionally one of the wires may break, but this usually will affect only one channel.
There is also usually a connection from one of the Cartridge signal earth pins to any metal parts of the pickup cartridge itself. If the signal leads get reversed on the cartridge for some reason then there can be hum from that part too.
Sometimes the signal leads or connectors will get broken from being moved a lot, but usualy that's on DJ decks.

Line level isolating transformers will do horrible things to the phono level signals, being lower impedance devices. Besides that they are made for breaking an earth loop which you are highly unlikely to have there, especially since it doesn't look like a mains cable with an earth on the turntable.
There are a lot of small things that can break on older gear like that, but the good thing is they are usually pretty easy to fix..

1965 posts

Uber Geek

Subscriber

  Reply # 670187 9-Aug-2012 17:41 Send private message

Clamping a ferrite bead onto the wire(s) may help, not much if it is definitely an earthing issue, but can clean up other RF.




"You are" = "You're" - Not "Your".  "They are" = "They're" - Not "Their" or "There".  You probably mean "lose" not "loose".  There's no such word as "Alot".
 
On the internet, wasting time, since '89.

148 posts

Master Geek


  Reply # 671047 11-Aug-2012 15:02 Send private message

techricky:...
Line level isolating transformers will do horrible things to the phono level signals, being lower impedance devices. Besides that they are made for breaking an earth loop which you are highly unlikely to have there, especially since it doesn't look like a mains cable with an earth on the turntable.
There are a lot of small things that can break on older gear like that, but the good thing is they are usually pretty easy to fix..


Noted.

Create new topic



Twitter »
Follow us to receive Twitter updates when new discussions are posted in our forums:



Follow us to receive Twitter updates when news items and blogs are posted in our frontpage:



Follow us to receive Twitter updates when new jobs are posted to our jobs board:



Follow us to receive Twitter updates when tech item prices are listed in our price comparison site:




News »

Trending now »
Hot discussions in our forums right now:

Fecked up religious people strike again :-(
Created by Mark, last reply by BurningBeard on 25-May-2013 00:03 (84 replies)
Pages... 4 5 6


Cannabis is illegal yet we have really strong 'legal highs' ?
Created by qwerty7, last reply by freitasm on 23-May-2013 23:20 (74 replies)
Pages... 3 4 5


Xbox One
Created by DjShadow, last reply by Kingy on 24-May-2013 13:48 (68 replies)
Pages... 3 4 5


A new project coming to Geekzone
Created by freitasm, last reply by l43a2 on 24-May-2013 23:02 (342 replies)
Pages... 21 22 23


Troublesome transition to VDSL
Created by oseiler, last reply by michaelmurfy on 24-May-2013 13:57 (18 replies)
Pages... 2


HTC One (2013) owners' discussion
Created by Dingbatt, last reply by wlfkfgkwlaktka on 24-May-2013 15:49 (1564 replies)
Pages... 103 104 105


Monolithic Cement Sheet cladding mid 80s house - "leaky home" or not?
Created by joker97, last reply by mattwnz on 24-May-2013 23:46 (15 replies)

Warning - Users with Tenda ADSL modem
Created by Psi, last reply by Psi on 24-May-2013 22:01 (44 replies)
Pages... 2 3



Geekzone Jobs »
Most recent NZ jobs in technology:

Organisational Change Analyst
Posted 24-May-2013 19:28

Dedicated Java Developer/ Technical lead
Posted 24-May-2013 18:28

Account Manager - IT/Telco
Posted 24-May-2013 18:28

Commercial Java Developer
Posted 24-May-2013 18:28

Senior DB2 Database Administrator
Posted 24-May-2013 18:28

Technical BA
Posted 24-May-2013 18:28

OSS Systems Engineer
Posted 24-May-2013 18:28


Geekzone Live »
Try automatic live updates from Geekzone directly in your browser, without refreshing the page, with Geekzone Live now.

Are you subscribed to our RSS feed? You can download the latest headlines and summaries from our stories directly to your computer or smartphone by using a feed reader.

Alternatively, you can receive a daily email with Geekzone updates.