Ground LM3886 chipamps

[chevy2410]

Hello,

I was wondering when grounding the LM3886 amps, is it better to use one wire run from each amp to star ground or what I want to do is use one long wire to span all amp chips and then "T" into the long wire from each amp and then connect that long wire to star ground? It seems it would just save from trying 4 wires, in my case, to star ground. Doing the latter I would only need to do 2 wires. Btw I'm doing 3 monoblocks in one chassis and all with their own PSU and tranny.


Thanks,
Chevy

[janneman]

Originally posted by chevy2410
Hello,

I was wondering when grounding the LM3886 amps, is it better to use one wire run from each amp to star ground or what I want to do is use one long wire to span all amp chips and then "T" into the long wire from each amp and then connect that long wire to star ground? It seems it would just save from trying 4 wires, in my case, to star ground. Doing the latter I would only need to do 2 wires. Btw I'm doing 3 monoblocks in one chassis and all with their own PSU and tranny.


Thanks,
Chevy

If you do the T stuff, you no longer have star ground. That means, that earth currents from one chip set up error voltages across the parts of the T wiring. That means that not all chip earths are at earth, but that some float on error voltages above ground. That means that this error voltage ends up as input to the chip. You don't want that, I guess.

Once you understand the reason for star ground, you would no longer entertain this type of ideas

If you draw it out, with currents shown, and show voltages in the wire impedances resulting from these currents, it will be much clearer.

Jan Didden

[chevy2410]

If you do the T stuff, you no longer have star ground. That means, that earth currents from one chip set up error voltages across the parts of the T wiring. That means that not all chip earths are at earth, but that some float on error voltages above ground. That means that this error voltage ends up as input to the chip. You don't want that, I guess.

Once you understand the reason for star ground, you would no longer entertain this type of ideas

If you draw it out, with currents shown, and show voltages in the wire impedances resulting from these currents, it will be much clearer.

Jan Didden

Ok, I won't do the "T" stuff. I will run separate wire from each chip right to star ground.

Thanks,
Chevy