A common ground between preamp and amp - 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 1st November 2007, 05:38 PM   #1
diyAudio Member
 
Join Date: Aug 2007
Default A common ground between preamp and amp

I'm about to build a pre-amp to connect to my amp (Velleman 4004B) and need to know if there are any problems in grounds between different sources (the amps and the audio input and output).

For example, my battery operated pre-amp (I could make one powered by a plug-in transformer) will have a common ground with my audio input and audio output. The output of the pre-amp will then become the audio input of the next stage, the power amp. This amp also has a common ground between audio input, the amp itself and then audio output.

Should I have any concern that two different amps (pre-amp and amp), powered from two different power supplies [one possibly a battery where (-) is ground] is also tied to audio in and audio out with a common ground? Will that create any problems? If so, what are the solutions?
  Reply With Quote
Old 3rd November 2007, 12:22 PM   #2
Gordy is offline Gordy  United Kingdom
diyAudio Member
 
Join Date: Nov 2006
It's difficult to comment without seeing the circuit, however in general there should be no problems with a 'ground' formed from a battery being tied to mains ground. In effect the mains ground becomes the reference point and the battery ' + ' supplies a voltage relative to the mains ground.

Grounding is not an easy subject, so best advice is to indulge in a little background reading...

http://www.gbaudio.co.uk/data/ground.htm
(Ground loops...)

http://rane.com/note151.html
(Grounding and shielding notes from Rane)

http://www.tcaas.btinternet.co.uk/jlhearthing.htm
and
http://sound.westhost.com/earthing.htm
(Grounding basics)
  Reply With Quote
Old 3rd November 2007, 03:36 PM   #3
diyAudio Member
 
Join Date: Aug 2007
Thanks. Yikes....it's complicated.

Indeed, I had two concerns in an audio circuit: ground loops and audio hum. The references authoritatively talk about those subjects.
  Reply With Quote
Old 3rd November 2007, 04:03 PM   #4
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
I suggested in another thread that the pre-amp grounds for each channel be kept separate for best immunity to loops and hum.
The consensus was this should not be necessary.
__________________
regards Andrew T.
  Reply With Quote
Old 3rd November 2007, 09:00 PM   #5
Gordy is offline Gordy  United Kingdom
diyAudio Member
 
Join Date: Nov 2006
Quote:
Originally posted by AndrewT
Hi,
I suggested in another thread that the pre-amp grounds for each channel be kept separate for best immunity to loops and hum.
The consensus was this should not be necessary.
If taking things to extremes I would look at separating them as you suggest. However in practice it's more a case of separating the signal (i.e. current) return loop flow paths. If done with consideration this can be done well while still using a single overall ground plane (...assuming that a pcb is used).
  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
Adcom...common ground amp?? Heiney9 Solid State 60 30th July 2012 03:56 AM
common ground or not? Mordor Car Audio 5 7th October 2008 12:08 PM
Phono stage common ground hum!! ungie Analogue Source 11 2nd January 2008 11:01 PM
Common Ground layout on Eagle -_nando-_ Everything Else 18 17th December 2007 03:03 PM


New To Site? Need Help?

All times are GMT. The time now is 08:41 PM.


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