Preamp Grounding Question

Davec113 · 18th July 2012, 02:25 AM

I have a question about wiring the ground for the preamp I'm working on, it is using an Aikido all in one octal pcb. I am using an input selector switch that switches grounds and have isolated the RCA jacks. The chassis is wood with a .125" aluminum top plate which the PCB is attached to. RCA jacks are on a separate aluminum plate on the rear of the chassis, input and volume are in the wood front panel.

I am considering wiring the safety ground from the mains input jack and the ground from the PCB to the same point on the top plate, along with the ground outputs of the selector switch. Will this work or can anyone suggest an improved scheme? Thanks!

DF96 · 18th July 2012, 10:21 AM

Safety ground should be used for safety alone. All external metalwork should be connected to it. Signal ground is different as it provided the reference voltage for signals. There must be one and only one connection between these two different grounds. The selector switch handles signal ground. The plate with the RCA sockets should connect to safety ground.

Davec113 · 18th July 2012, 05:09 PM

OK, in that case maybe I need to ground the selector switch to the PCB's ground, then the PCB to the top plate where the safety ground attaches to. That will provide one path to ground for the signal.

DF96 · 18th July 2012, 05:11 PM

Yes, for the signal ground there must be one and only one path between any two grounded points. None of these paths should carry any PSU ripple.

Chris Hornbeck · 18th July 2012, 08:08 PM

And the power supply ripple is the important part. Modern systems with multiple safety grounds are riddled with ground loops; keeping power supply currents away from signal is the best that's possible (without transformers or balancing). And signal ground must be considered to include safety grounds.

All good fortune,
Chris

18th July 2012, 02:25 AM	#1
Davec113 diyAudio Member Join Date: Jul 2007	Preamp Grounding Question I have a question about wiring the ground for the preamp I'm working on, it is using an Aikido all in one octal pcb. I am using an input selector switch that switches grounds and have isolated the RCA jacks. The chassis is wood with a .125" aluminum top plate which the PCB is attached to. RCA jacks are on a separate aluminum plate on the rear of the chassis, input and volume are in the wood front panel. I am considering wiring the safety ground from the mains input jack and the ground from the PCB to the same point on the top plate, along with the ground outputs of the selector switch. Will this work or can anyone suggest an improved scheme? Thanks!

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Passive Preamp - Grounding plan	The Boz	Analog Line Level	33	31st March 2011 09:16 AM
B1 Preamp Grounding Question	jonsmith	Pass Labs	8	18th November 2009 11:49 AM
diy phono preamp grounding ?	basil	Solid State	5	20th November 2007 12:30 PM
Simple passive preamp. Neen some help in grounding.	FaTTy	Solid State	32	20th July 2007 06:10 AM
Preamp grounding	nlinus	Solid State	1	15th January 2004 07:21 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	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

18th July 2012, 10:21 AM	#2
DF96 diyAudio Member Join Date: May 2007	Safety ground should be used for safety alone. All external metalwork should be connected to it. Signal ground is different as it provided the reference voltage for signals. There must be one and only one connection between these two different grounds. The selector switch handles signal ground. The plate with the RCA sockets should connect to safety ground.

18th July 2012, 05:09 PM	#3
Davec113 diyAudio Member Join Date: Jul 2007	OK, in that case maybe I need to ground the selector switch to the PCB's ground, then the PCB to the top plate where the safety ground attaches to. That will provide one path to ground for the signal.

18th July 2012, 05:11 PM	#4
DF96 diyAudio Member Join Date: May 2007	Yes, for the signal ground there must be one and only one path between any two grounded points. None of these paths should carry any PSU ripple.

18th July 2012, 08:08 PM	#5
Chris Hornbeck diyAudio Member Join Date: May 2011 Location: Little Rock	And the power supply ripple is the important part. Modern systems with multiple safety grounds are riddled with ground loops; keeping power supply currents away from signal is the best that's possible (without transformers or balancing). And signal ground must be considered to include safety grounds. All good fortune, Chris