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digi01 18th January 2008 02:21 AM

understanding star grounding
 
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I would like to give you some impressions about star grounding.I hope the topic will help you avoid grounding issue.
1,star grounding is not problem with mono system,as a result it can avoid inner ground loops.surely it is not problem with dual mono stereo amp.
Ok then how about when the equipments are interconnected?
Notice,there are two way to make interconnector cables,connect the cable shield on both ends or connect the cable shield only at one end.whatever there are still no loops between the source and power amp.

Zang

digi01 18th January 2008 02:22 AM

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2,be careful star grounding the integrated stereo amp and multi channel amp.
example:
when you install two power units in a single chassis.there are two common ground on each power unit.if you do star grounding,there are latent loops.

gainphile 18th January 2008 02:35 AM

Interesting. I am currently fighting this ground hum. If I put a pair of amp (L+R) no hum. But once I put additional pair (to make it 4-channel) I hear hum.

At the end I had "all grounds connected everywhere" to obtain minimal hum - still audible on very quiet night.

What is the correct grounding for stereo amps then ?

digi01 18th January 2008 02:46 AM

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continue the case 2,
when the equipments are interconnected,whatever what kinds of the cable shield way you are using.there a big loop between the source and power stage.the interconnector is a pair of antenna:xeye:
this can explain why you amp is quiet but when connected the source,the hum coming.

digi01 18th January 2008 06:37 AM

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to prevent ground loops,i do works below:
connect all signal grounds (RCA plate terminal) to one common point,
choice one power unit's ground as common ground.the common may be a wire,a track on a pcb,
assemblied the power units as compact as possible.


P.S.
when do air wring,use strong wire or big copper as common ground.
when you design a pcb board,you have to be smart address the specific factual situations of grounding.lay out enough grounding pads on your board.
to design a circuit board for integrated amp,layout multi-channel amp in one board with star ground concept.
star ground is talk about pcb layout technology.star grounding is talk about wire connecting technology.do not mix up.

the attached is a example of grounding 3 channel amp in a single chassis.

Zang

sukyone 18th January 2008 06:40 AM

thank you very much.
:)

digi01 18th January 2008 07:03 AM

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the attached is another idea.
it is useful when you build an integrated amp with pieces single channel pcbs.
connecting all pcb's ground track via a strong wire.i use 4mm diameter copper wire.this wire is your amp's common ground.then connecting all RCA plate together to this common ground.

again,
assemblied the amp units as compact as possible.

Zang

Paswa 18th January 2008 07:42 AM

Why need the break resistor of 6 ohm??

gainphile 18th January 2008 07:42 AM

Thank you....thank you... :)

I think one of my mistake is not isolating the input RCA grounds. They are connected to the chassis!

defect9 18th January 2008 08:03 AM

Wow, I think I finally understand what I've been doing wrong. Thanks a lot!

-Jared


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