World-Designs-Forum  

Go Back   World-Designs-Forum > World Designs > WD Amplifiers
Register FAQ Members List Calendar Gallery Today's Posts Search Today's Posts Mark Forums Read

WD Amplifiers For discusson of World Designs Amplifiers

Reply
 
Thread Tools Display Modes
  #1  
Old 16th January 2017, 04:36 PM
pager8 pager8 is offline
Junior Member
 
Join Date: Mar 2013
Location: Bristol
Posts: 16
Default Annoying Hum

Hi all,
I have just got hold of a WAD 300b Clone and upon swapping it with my WD88VA connected to a Pre3/Psu3 have the most awful hum. I have tried removing the earth from the Psu3 ( No joy) and replaced it. I have also tried different interconnects and they make it sound worse. I realise that this is likely to be the dreaded Earth loop so any help in this matter will as always be gratefully appreciated. The source is a CD Player which has no Earth ( Twin wire only) It also hums when the CD is connected to the 300b directly using the CDs variable output, and yet all worked perfectly with the WD88VA

Thanks in anticipation

pager8 (Geoff)
Reply With Quote
  #2  
Old 16th January 2017, 07:47 PM
Phil Y's Avatar
Phil Y Phil Y is offline
Senior Member
 
Join Date: Jul 2006
Location: Bristol, UK
Posts: 576
Default Re: Annoying Hum

Hello Geoff,

What you need to do is put your '88 back into the system using all the same cables (including mains) and confirm things still work. You could have caused or aggravated a bad connection somewhere when swapping the amps over.

If all is well, plug a pair of shorted phono plugs and speakers into the 300b and switch on. If it is quiet, it is probably an earth loop. If humming, the amp has a problem.

Do this then report back and we can go from there.

Phil.
__________________
Commission for Dark Skies (CfDS)
Reply With Quote
  #3  
Old 17th January 2017, 05:20 PM
John Caswell John Caswell is offline
Super Moderator
 
Join Date: Dec 2005
Location: Wokingham, Berkshire
Posts: 1,397
Default Re: Annoying Hum

Hi Geoff,
I assume that with the inputs shorted out you have adjusted the hum bucking pots for minimum hum.
If it hums with both the CD cables connected, try with one cable only and then the other only to see if the hum lessens. As the CD is double insulated (ie no earth) you cannot get an earth loop via the mains. It sounds more like an input earth loop to me.

John
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT +1. The time now is 09:12 AM.


Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright World Designs