#1
hello, I am having some trouble understanding the different grounds in an amp(or preamp). I do understand how grounds in general work, but not in these audio applications.

right now I am building a soldano x88r lead channel(preamp) and I have a pretty good idea of how I am supposed to ground it. I will use a "galactic ground" approach I found on slocloneforums which is basically just all the gain stages grounded across a buss wire to a single point on the chassis(if I understood it correctly).

here are my doubts/questions.
should the buss wire be grounded to the shield of the input jack which should be grounded to the chassis?

how long is too long for a ground wire?

how does a floating ground work? I saw a video on youtube saying the transformer primary center tap should be connected to a floating ground as a common. I dont quite understand this since I thought the center tap had to be grounded to earth.

in the video("power supply wiring 1" by soundgaragetales) he uses a terminal strip for the common. doesnt soldering the center tap to a terminal strip just make an open wire?

if i solder one end of my buss ground to a terminal strip and the other end to the input jack, would this create a ground loop(dont quite understand how floating grounds work)?

until now, thats all the questions I can think of.
Marty Friedman is GOD!

curently in a SEX MACHINEGUNS and X JAPAN phase AND Galneryus AND Anthem phase

damn J-Metal, why you so awesome

My Gear:

Schecter Hellraiser V-1 fr
Ibanez RG321mh
Fender GDC-200sce
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#3
pardon the late reply. I just read the article and tried to analyze my doubts. so to my understanding:

1) the buss should connect to the shied of the input jack, and NOT grounded to the chassis.

i also read Aiken's star grounding article, and he also "Do not ground the input jacks, and be sure to use isolated input jacks. Run the input jack ground to the local ground of the first stage, which then goes to the star point." i dont quite understand where Im supposed to ground it. does the shield act as a ground?

I am using a switchcraft switching jack(from hoffmanamps) and Im sure if I should wire its ground pin together with the shield at the first star point. heres a quick-n-dirty sketch of the layout I think would be right.




as for the other questions, I guess Ill just wire the center tap to the first filter cap. Id still like to know about floating grounds though.
Marty Friedman is GOD!

curently in a SEX MACHINEGUNS and X JAPAN phase AND Galneryus AND Anthem phase

damn J-Metal, why you so awesome

My Gear:

Schecter Hellraiser V-1 fr
Ibanez RG321mh
Fender GDC-200sce
Peavey Vypyr 30 w/ sanpera 1
#4
1- Correct. The chassis is just a shield against noise and other junk in the airwaves. Having said that, 99% of the time they use it as a giant ground wire just because it is convenient.

2- what they were trying to say was you should use isolated jacks so that their ground lugs (sleeves) won't connect to the chassis and muck up your star grounding scheme by having multiple ground points connected to the chassis. You ground the input (or other jacks) to their associated stages just like R.G. Keen was talking about in his article.

A floating ground is just a common circuit return that is NOT connected to earth (i.e. the terra firma we are standing on). The word "ground" has become a catch-all for any common circuit return...

The neutral and ground wires of house wiring (at least in the US, unsure about foreign wiring) are seperate wires at the outlet but are connected together inside the breaker panel (as of 2009 all new-construction has them connected at the kW/hr meter instead). So since the neutral and ground are connected, they are not isolated from Earth. Running the hot and neutral wires through a transformer will isolate the neutral from the ground, providing a floating ground unless you connect the amp chassis to the ground prong of the line cord while also grounding the amp circuitry to the chassis, which all factories do.

It's really hard to explain.

Idk about your diagram. It doesn't look right. The R.G. Keen article has example diagrams of how it should be.