Hi, I am rewiring my power amp ground.
The IEC earth pin is connected to the chassis via a mains filter chassis. So there is no problem there.
I previously wired the amplifier PSU ground to the chassis. So there was no safety problem.
But now, I want to move that chassis connection point from the PSU ground to the signal ground. It has been said by many people in the forum that the amplifier ground point to connect to the chassis should be closer to the signal ground / RCA shield.
The problem is, the wire between the PSU ground and the signal ground is relatively thin, so I am not sure if in the case of a fault, the wire can stand the huge current. If the wire is broken first before the house safety switch, the internal components can develop a killing mains voltage.
From the PSU ground to signal ground, I have a 40mm long 1.5mm wide 2oz copper PCB track, and a soldered 12mm long and 0.6mm thick jumper. Would these be good enough to stand the current in a fault condition?
The IEC earth pin is connected to the chassis via a mains filter chassis. So there is no problem there.
I previously wired the amplifier PSU ground to the chassis. So there was no safety problem.
But now, I want to move that chassis connection point from the PSU ground to the signal ground. It has been said by many people in the forum that the amplifier ground point to connect to the chassis should be closer to the signal ground / RCA shield.
The problem is, the wire between the PSU ground and the signal ground is relatively thin, so I am not sure if in the case of a fault, the wire can stand the huge current. If the wire is broken first before the house safety switch, the internal components can develop a killing mains voltage.
From the PSU ground to signal ground, I have a 40mm long 1.5mm wide 2oz copper PCB track, and a soldered 12mm long and 0.6mm thick jumper. Would these be good enough to stand the current in a fault condition?
Explain this modification. note most consumer gear is not grounded. sometimes by introducing a 3 wire component in the chain can produce hum.
IMO moving SE around to solve noise problems is usually a lost cause and might be unsafe.
The most common or direct way is to float signal ground from chassis or PS ground using a small value resistor. The fault path to SE is at the transformer secondary. SE wiring gauge or the equivalent is based on the equipment fuse ratings.
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Thanks. I can try that. I previously had tried a 10nF connecting the RCA socket ground lug to the chassis next to it but the amplifier oscillated. But at that time, the point to connect to the chasses was in the PSU big capacitor ground which was far away from the RCA socket.
Thanks. I think the 40mm long 1.5mm wide 2oz copper track and the 12mm long .6mm diameter jumper should last longer than the fuse of the amplifier. So I have the answer - no safety issue.
Savvas, the amplifier ground is connected to the chassis via a 35A bridge rectifiers with a ground lift by 10R and .1u. However, I am moving the connection point from the PSU cap to the signal ground as experienced forum members said this is better.
Savvas, the amplifier ground is connected to the chassis via a 35A bridge rectifiers with a ground lift by 10R and .1u. However, I am moving the connection point from the PSU cap to the signal ground as experienced forum members said this is better.
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I am not sure about why.
The signal ground is considerably quieter than the PSU ground, that is for sure. If the connection point to the chassis is chosen to be the signal ground instead of PSU ground, perhaps it results in better shielding effects of the chassis on the sensitive part of the circuit?
The signal ground is considerably quieter than the PSU ground, that is for sure. If the connection point to the chassis is chosen to be the signal ground instead of PSU ground, perhaps it results in better shielding effects of the chassis on the sensitive part of the circuit?
Is it something like this you are thinking of, from Doug Self's book on amplifier design? Grounding System In Power Amplifiers - DIY AUDIO BLOG, AUDIO WORKSHOP
Protective earth should be connected at one point and not affect your circuit. However electrostatically induced currents between shields and signal ground can induce currents at some point worth noting with regard to the whole system.
The 'quietness' of the input ground point is not the relevant concern, but more the fact that it is your best available representation of signal ground and should be preserved that way. It should be connected to your best representation of ground for the supply section feeding the input. If the output is also taken from this point, the gain can work in your favour.
I also connect my PE to the signal zero volt line.
A side effect of this is almost zero hum. Without it I get some hum.
But I am careful about the mains side keeping it away from other the amplifier circuit.
I find none earthed equipment hums badly in my home.
I have an mp3 player into an amplifier and it hums like mad.
I think its capacitance across the mp3 player mains power supply.
If I run a PE to the power supply zero volt line it goes quiet.
A side effect of this is almost zero hum. Without it I get some hum.
But I am careful about the mains side keeping it away from other the amplifier circuit.
I find none earthed equipment hums badly in my home.
I have an mp3 player into an amplifier and it hums like mad.
I think its capacitance across the mp3 player mains power supply.
If I run a PE to the power supply zero volt line it goes quiet.
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