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
156 posts

Master Geek
+1 received by user: 1


  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.

156 posts

Master Geek
+1 received by user: 1


  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???

156 posts

Master Geek
+1 received by user: 1


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

Yup.

16 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..

Watchmaker Wizard
2395 posts

Uber Geek
+1 received by user: 56

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.




156 posts

Master Geek
+1 received by user: 1


  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 tech item prices are listed in our price comparison site:




News »

Trending now »
Hot discussions in our forums right now:

Hierarchy of a mistake: Gerry Brownlee
Created by joker97, last reply by nathan on 26-Jul-2014 04:30 (68 replies)
Pages... 3 4 5


Logitech K400r HTPC Cordless Keyboard Half Price
Created by Dynamic, last reply by Blanch on 28-Jul-2014 22:16 (25 replies)
Pages... 2


Checking UHF aerial is working
Created by OnceBitten, last reply by B1GGLZ on 28-Jul-2014 21:49 (21 replies)
Pages... 2


Bridge Work - Auckland
Created by networkn, last reply by jeffnz on 28-Jul-2014 21:18 (19 replies)
Pages... 2


Dick Smith in Continual Sale Mode
Created by Dynamic, last reply by eracode on 29-Jul-2014 01:42 (56 replies)
Pages... 2 3 4


Is chorus going to deliberately slow adsl internet down
Created by rugrat, last reply by juha on 26-Jul-2014 14:25 (54 replies)
Pages... 2 3 4


What Size iphone 6 will you be buying?
Created by mattbush, last reply by myopinion on 26-Jul-2014 20:19 (35 replies)
Pages... 2 3


Geekzone giveaway: Thecus N2310 NAS
Created by freitasm, last reply by BlakJak on 28-Jul-2014 11:39 (99 replies)
Pages... 5 6 7



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.