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understanding star grounding
understanding star grounding
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Old 28th March 2019, 07:39 PM   #661
Bicicletta is offline Bicicletta  Europe
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Quote:
Originally Posted by andyr View Post
Wrong - you don't want chassis ground (ie. mains earth) to connect to signal ground ... which is the central ground star.

Andy
However, there are many double-insulated commercial equipment, and desperate audiophiles who sever the earth connection ...
How we can build a safe and earthless device?
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Old 28th March 2019, 07:59 PM   #662
MalleMike is offline MalleMike  Spain
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I think that is exactly what I am doing. Two active speakerboxes which contain the powersupply plus amplifiers plus a wireless reception module each and no other connection except the mains cable.
All of this and some more in a wooden enclosure with walls of an inch thickness. So no chance of any accidental contact as long as it is closed. There is an automatic circuit for standby if no signal is received within 3 to 5 minutes , adjustable. The audio signal is received by wlan connection with a real bandwidth greater than 3000kbps (Audio) so is transmitted uncompressed and lossless. Since there is no compression transmitting and receiving the delay is minimal.The wlan itself has a bandwidth of 1200 mbit/s.
No ground connection there as its wireless so the grounding and its problems are confined to within each box alone.
No wiring at all except mains cable-

In part I am doing this just to prove I can do it , and for fun of course. I love good music and good sound.

Last edited by MalleMike; 28th March 2019 at 08:06 PM.
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Old 28th March 2019, 08:32 PM   #663
mchambin is online now mchambin  France
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Originally Posted by Bicicletta View Post
However, there are many double-insulated commercial equipment, and desperate audiophiles who sever the earth connection ...
How we can build a safe and earthless device?
Using a resistor and diodes able to large current.
This is not legally aprouved safety, but in fact excellent safety.
See: Earthing (Grounding) Your Hi-Fi - Tricks and Techniques
Figure 4
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Old 28th March 2019, 08:35 PM   #664
brian92fs is online now brian92fs  United States
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understanding star grounding
Quote:
Originally Posted by Bicicletta View Post
How we can build a safe and earthless device?
You're describing a "Class II" device. There are many requirements (from a regulatory view) to building this type of device. I suspect this is typically beyond the skill set of the typical DIYer. And from a safety perspective, most DIYers would probably advise against pursing it. Just my 2 cents.
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Old 28th March 2019, 09:13 PM   #665
Bicicletta is offline Bicicletta  Europe
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much more. We would forget the absence of earth connection working on open box, and we would use cardboard or wood as electrical insulator.
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Old 29th March 2019, 02:26 AM   #666
BigE is offline BigE  Canada
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Quote:
Originally Posted by mchambin View Post
Using a resistor and diodes able to large current.
This is not legally aprouved safety, but in fact excellent safety.
See: Earthing (Grounding) Your Hi-Fi - Tricks and Techniques
Figure 4
Excellent. Same as what Nelson Pass says.

Except, NP does not include the 100 nF cap in parallel with the resistance.

Last edited by BigE; 29th March 2019 at 02:37 AM.
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Old 25th March 2020, 06:35 PM   #667
Bensen is offline Bensen  Belgium
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understanding star grounding
Default Preamp grounding scheme

Hello,

I would like to ask for advice if below sheme is best practice on how to do the grounding.
I'm doing the concept of a preamp with 3 transformers, where each xfmr has double secondary windings and where each secondary has it's own bridge rectifier. This is visible by the two black lines (0's) at the output of psu PCB.
The actual buffers (preamp without gain) will have Jung-Didden superregulators.

The grounding scheme has impact on the PCB design, which is also work in progress.


Hope the picture is clear enough for you all. At the left you can also find the earth ground loop breaker. This preamp will drive two monoblock amps.

Regards
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Last edited by Bensen; 25th March 2020 at 06:41 PM.
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Old 26th March 2020, 05:52 AM   #668
Mark Whitney is online now Mark Whitney  Netherlands
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Each transformer/PSU should have it's own ground loop breaker.
All high impedance signal wiring should be coax and laid out with minimal loop area.
Use hum breaking resistors in your amp design.
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Old 26th March 2020, 06:13 AM   #669
scottjoplin is offline scottjoplin  Wales
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Do you mean cross-channel hum breaking resistors Mark?
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Old 26th March 2020, 08:55 AM   #670
Bensen is offline Bensen  Belgium
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understanding star grounding
Quote:
Originally Posted by Mark Whitney View Post
Each transformer/PSU should have it's own ground loop breaker.
All high impedance signal wiring should be coax and laid out with minimal loop area.
Use hum breaking resistors in your amp design.
Hi Mark,

Each xfmr a ground loop breaker? This would mean there are 3 ground loop breakers in parallel, while at the end there is on star ground, not?

My amp has indeed 10R + 2 antiparallel hum breaking resistors between signal input ground and power ground.


Is the way I routed the gnd lines correct? All to start ground, made between 0V's of the two PSU's for the buffers?
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