once again, proper grounding of balanced ins and outs

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Axelerator

Well-known member
Joined
Jul 28, 2006
Messages
176
Location
Ruhrpott (north-west-germoney)
I asked this qestion over at the m/s pultec post :
i have this clone with in and output transformer.In his pictures, igor grounded all pin 1 of the xlr´s in and outs to chassis ground, as i also did .
Now(thinking after doing..) i remember several discussions about just grounding the ins? and after reading the rane notes, this seems not to be the right way. i am confused. Pin1 to chassis ground on all ins and outs ? my signal ground is also grounded to chassis at the ac inlet , so i get some parasitic elctricity floating through all my units? totally confused.
by the way, all my diy is transformer coupled on out and most on the ins .
if somebody has the patience to clear some misunderstandings up, please chime in !
thank you,
axel
 
Axelerator said:
I asked this qestion over at the m/s pultec post :
i have this clone with in and output transformer.In his pictures, igor grounded all pin 1 of the xlr´s in and outs to chassis ground, as i also did .
That's the AES recommandation. The only problem with it is when there is a large voltage difference between chassis - this can happen in several circumstances, including, among others,  large radiated electromagnetic field or large leakage in one or several units. That's the reason why some have advocated lifting pin 1 on one side; this is not the best option IMO. I think inserting a parallel RC circuit between pin 1 and chassis provides a better all-round solution, but in most instances the Pin 1-to-chassis arrangement works well.
my signal ground is also grounded to chassis at the ac inlet , so i get some parasitic elctricity floating through all my units? totally confused.
I seriously doubt this explanation. Electricity doesn't "float".
by the way, all my diy is transformer coupled on out and most on the ins .
"most" is probably the reason...are those inputs without transformer balanced or not? Typically, well balanced units can ignore quite large common-mode voltages. Areall these units powered from the same outlet? Can you determine which combinations are quiet and which ones are not?
 
ok, thank you, john!
that was a good starting point,something like star ground for information !;)
i am still confused with the way transformers react for bal/unbal current wise but i i am getting there slowly !
axel
 
ok thanks to everybody so far !
i have encountered no hum and buzz in my diy so far..
i did read only the old rane doc, and that left many questions.
the new one i found via pin1 problem was much better !
 
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