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Old 12th November 2011, 04:03 PM   #411
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Not sure that we have an exact answer here but at present my star gound is from the output ground of the main power supply and everything sounds good. That is connected to the chassis via a thermistor, as Nelson suggested, for safety (mains outage possibility from the circuit) and to eliminate hum (thermistor). That is my understanding.

I may not connect the BiB reg yet as it is running too hot at present for two of the heatsinks. This could be due to the voltage diff between the transformer and the output being too high. The current mosfets on the BiB are running just fine with respect to temp.
Chris
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Old 12th November 2011, 04:30 PM   #412
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hmm, I would consider connecting frontend ground to power amp board
and then only there, ofcourse

genuine star ground is a special 'theory' where every ground connection goes directly to the same point, thus called star ground

its just not very practical

look at your ground connections like branches on a tree

so, what you have in reality is multiple star grounds, connected to each other
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Old 12th November 2011, 04:40 PM   #413
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Quote:
Originally Posted by tinitus View Post
hmm, I would consider connecting frontend ground to power amp board
and then only there, ofcourse
The front end has to have a connection with the ground of the regulated power supply. This leaves (looking at the BA-3 circuit board) a ground connection for the signal input (I assume). This leaves the ground of the power supply for the power output section not connected to the BA-3 front end at all. This is why I wanted to connect the regulated ground to the main power supply ground.
Chris
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Old 12th November 2011, 05:43 PM   #414
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depends on where and how you connect signal ground

thicker wire may be needed

I choose the shorter more convenient route

like Andrew suggested, it is also possible to make practical use of the the 'negative' speaker terminal
either by a snall copper plate mounted, etc
or just using a thick solid core wire between the speaker terminal and one other point
and place every other needed ground connects along this thick copper wire

one 'could' connect all grounds to amp board ground, but it tends to get messy, and not very practical

personally I choose the shorter and least noise plagued route fore the ground wire
in the old days the midpoint of big power supply caps was often used
but not done that way so much anymore

like said, if taken all parts of the whole setup and their individul ground connections into consideration, it looks like this anyway

basicly, the biggest issue is to determine where you need heavy ground connection, meaning thick wire
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Old 12th November 2011, 05:45 PM   #415
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Star grounding is always practical and preferable. This is a dual mono Hiraga 30W Class A. It has one central zero point per channel, where all grounds meet except of the the input grounds. Both star groundings are connected to the chassis via thermistors.

It is dead silent.




Quote:
Originally Posted by tinitus View Post
hmm, I would consider connecting frontend ground to power amp board
and then only there, ofcourse

genuine star ground is a special 'theory' where every ground connection goes directly to the same point, thus called star ground

its just not very practical

look at your ground connections like branches on a tree

so, what you have in reality is multiple star grounds, connected to each other
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Old 12th November 2011, 05:52 PM   #416
tinitus is offline tinitus  Europe
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nice one

you still have two star grounds in each channel
one on amp board, and one on power supply

with this especially short distance between power supply ground and amp board ground like yours, I don't think it matters much how you do it
its basicly similar to a very big 'on-board' supply
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Old 12th November 2011, 06:26 PM   #417
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Quote:
Originally Posted by Backbones View Post
The front end has to have a connection with the ground of the regulated power supply.
Chris
hmm, are you taking power from output amp trafo, or using smaller seperate trafo fore regulated frontend supply ?

but basicly, its a relation of how much current the actual curcuit draws, and how thick the wire is

multiple units could cause problems tho
I would claim that if connection between negative speaker terminal and amp board ground is used fore all ground connections, then it would be very safe, and hard to mess up

preferably placing the connecting grounds closer to amp board rather than speaker terminal, ofcourse

in other words
you have two possible BIG 'ground strings'
either the one between big power supply and amp board
or the 'ground string' between amp board and speaker terminal
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Old 12th November 2011, 06:30 PM   #418
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Don't understand what you mean. There is only one star grounding per amp at the power supply. Only the input grounds pass the amp boards. I do practice this since about thirty years in all my audio equipment - preamps, filters, power amps - and it has always been working perfectly.



Quote:
Originally Posted by tinitus View Post
nice one

you still have two star grounds in each channel
one on amp board, and one on power supply

with this especially short distance between power supply ground and amp board ground like yours, I don't think it matters much how you do it
its basicly similar to a very big 'on-board' supply
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Old 12th November 2011, 06:53 PM   #419
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Quote:
Originally Posted by permaneder View Post
I do practice this since about thirty years in all my audio equipment - preamps, filters, power amps - and it has always been working perfectly.
ofcourse it works
I have built all older amps this way too

but when you start to build two different amps into one box, and each having their own seperate supply, the it could get a bit more tricky

btw, genuine star ground means that every gound connection in the whole amp curcuit all meet in one and the same point, on the amp board

the way you show it has always been common practice, and used fore ages, long before the word star ground was invented
essentially 'star ground' relates to how the amp board layout and its curcuit is designed

as far as I know, but maybe I'm wrong

like I said, it will always be multiple star grounds connected to one string, no matter what
the only choise you have is to choose which goes where
and each can have only one connection
but if you begin to look at it like one single star ground, that's where the trouble starts
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Old 12th November 2011, 07:10 PM   #420
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I still don't understand. There are two separate amps in one box with separate supplies each = dual mono.



Quote:
Originally Posted by tinitus View Post
ofcourse it works
I have built all older amps this way too

but when you start to build two different amps into one box, and each having their own seperate supply, the it could get a bit more tricky

btw, genuine star ground means that every gound connection in the whole amp curcuit all meet in one and the same point, on the amp board

the way you show it has always been common practice, and used fore ages, long before the word star ground was invented
essentially 'star ground' relates to how the amp board layout and its curcuit is designed

as far as I know, but maybe I'm wrong

like I said, it will always be multiple star grounds connected to one string, no matter what
but if you begin to look at it like one single star ground, that's where the trouble starts
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