Strange noise...? - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 4th August 2007, 08:22 PM   #1
Skorpio is offline Skorpio  Denmark
diyAudio Member
 
Join Date: Mar 2004
Location: Denmark
Default Strange noise...?

I have build a pre-amplifier and it is very quiet, no hum or noise even with my ears close to the speakers.....but...

When I touch the volume control a buzzing sound comes in both speakers....and only when volume is turned up.....not in minimum.....

It is not very loud, but it puzzels me and is a little annoing.....
  Reply With Quote
Old 4th August 2007, 08:24 PM   #2
jaycee is offline jaycee  United Kingdom
diyAudio Member
 
Join Date: Apr 2004
Location: Norwich, UK
This is the 50hz field of power being picked up by your body and injected into the preamps inputs.

Is your case grounded to mains safety ground? If not, you should do this. If it is, you should have your house wiring checked in case you have a bad safety ground connection

Does the input stage of your preamp circuit include filtering?
  Reply With Quote
Old 5th August 2007, 10:21 AM   #3
Skorpio is offline Skorpio  Denmark
diyAudio Member
 
Join Date: Mar 2004
Location: Denmark
The baseplate is grounded but the front is not.....

There is no filtering on inputs.....
  Reply With Quote
Old 5th August 2007, 10:56 AM   #4
fotios is offline fotios  Greece
diyAudio Member
 
fotios's Avatar
 
Join Date: Feb 2007
Location: Δραμα - North Greece
Default Re: Strange noise...?

Quote:
Originally posted by Skorpio
I have build a pre-amplifier and it is very quiet, no hum or noise even with my ears close to the speakers.....but...

When I touch the volume control a buzzing sound comes in both speakers....and only when volume is turned up.....not in minimum.....

It is not very loud, but it puzzels me and is a little annoing.....
Have you checked if this noise heared also if you touch any other place on the metal case? Tell me this.
Fotios
  Reply With Quote
Old 5th August 2007, 11:00 AM   #5
diyAudio Member
 
Jan Dupont's Avatar
 
Join Date: Apr 2003
Location: Copenhagen, Denmark
Send a message via MSN to Jan Dupont
jaycee;
For your information, we do not have safety earth in our normal wall plugs here in Denmark

Skorpio;
What type of volume pot are you using ?
Have you tried to connect the pot/face plate to PSU Gnd ?
__________________
Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com
  Reply With Quote
Old 5th August 2007, 04:59 PM   #6
jaycee is offline jaycee  United Kingdom
diyAudio Member
 
Join Date: Apr 2004
Location: Norwich, UK
Quote:
Originally posted by ACD
jaycee;
For your information, we do not have safety earth in our normal wall plugs here in Denmark
  Reply With Quote
Old 5th August 2007, 05:05 PM   #7
diyAudio Member
 
Jan Dupont's Avatar
 
Join Date: Apr 2003
Location: Copenhagen, Denmark
Send a message via MSN to Jan Dupont
jaycee;
Thats right
Reel men doesn't take back-up or uses safety earth

We have safety earth for household machines like wasing machines, dish washers etc., but not in our standard wall plug for lamps, TV and audio etc....
__________________
Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com
  Reply With Quote
Old 5th August 2007, 05:07 PM   #8
diyAudio Member
 
Jan Dupont's Avatar
 
Join Date: Apr 2003
Location: Copenhagen, Denmark
Send a message via MSN to Jan Dupont
However....
Can't count the many times I have been exposed to 230VAC
Maybe thats why my brain works like it does
__________________
Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com
  Reply With Quote
Old 5th August 2007, 05:10 PM   #9
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
it's about time we did the humanitarian thing and moved the whole population out of Denmark.

The rules are very different here.
We have to ensure that all exposed conductive parts are connected to safety earth.
If you at least connect all the exposed conductive parts to audio ground then some measure of interference attenuation will accrue.
The metal case around the pot is probably electrically connected to the adjusting knob and to the front panel. Earthing the panel AND the pot case AND the adjusting knob will probably solve the problem.

The pot track and it's three/six terminals should be isolated from the pot casing.

BTW,
how do you make a 220Vac system safe to the user if there is normally no safety earth?
__________________
regards Andrew T.
  Reply With Quote
Old 5th August 2007, 05:19 PM   #10
diyAudio Member
 
Jan Dupont's Avatar
 
Join Date: Apr 2003
Location: Copenhagen, Denmark
Send a message via MSN to Jan Dupont
Quote:
BTW,
how do you make a 220Vac system safe to the user if there is normally no safety earth?
We don't... We are suposed to be wise people, that make our electric connection correct, so no safety earht are needed....

Or maybe it's a way to keep the population growh down
__________________
Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Strange noise coming from MTX Thunder1004 amplifier fastblackcar94 Car Audio 1 17th November 2006 10:17 PM
Quad 405 strange noise post upgrade lance_the_boil Solid State 1 14th October 2006 10:36 AM
strange noise from right channel keyser Everything Else 15 2nd May 2005 11:14 PM
Strange noise form lm3875 velikan Chip Amps 2 1st March 2005 05:45 PM
About strange noise from my amp! Otherwise Solid State 6 11th September 2003 01:12 PM


New To Site? Need Help?

All times are GMT. The time now is 09:00 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2