I have the following schematic:
My XLR has the following connections:
Pin 1 = earth.
Pin 2 = hot
Pin 3 = cold
"lip (4)" = is connected directly to the connector case (shield)
I'm using a Neutrik NC3FD-LX which has a seperate 'lip (4)' so i can solder it to pin 1 as mentioned in the schematic.
To me it doesn't feel right because if lip (4) is connected to pin 1 all ground connections on the pcb board are also connected to earth through the xlr connector case. Also for RCA input because they are connected through the 9-pins connector (see schematic).
I have thought about some scenarios:
1) Only connect lip 4 with pin 1
2) disconnect lip (4) from pin 1 and connect lip (4) directly to my common earth point and leave pin 1 connected to the 9 pins connector,
3) disconnect lip (4) from pin 1 and leave lip (4) unconnected because lip (4) is also grounded through the connector case on the chassis case and leave pin 1 connected,
4) disconnect pin 1 and pin 4 completely from the 9 pins connector and connect both pin 1 and pin 4 to my common earth point ?
5) Other options ?
Anybody?
My XLR has the following connections:
Pin 1 = earth.
Pin 2 = hot
Pin 3 = cold
"lip (4)" = is connected directly to the connector case (shield)
I'm using a Neutrik NC3FD-LX which has a seperate 'lip (4)' so i can solder it to pin 1 as mentioned in the schematic.
To me it doesn't feel right because if lip (4) is connected to pin 1 all ground connections on the pcb board are also connected to earth through the xlr connector case. Also for RCA input because they are connected through the 9-pins connector (see schematic).
I have thought about some scenarios:
1) Only connect lip 4 with pin 1
2) disconnect lip (4) from pin 1 and connect lip (4) directly to my common earth point and leave pin 1 connected to the 9 pins connector,
3) disconnect lip (4) from pin 1 and leave lip (4) unconnected because lip (4) is also grounded through the connector case on the chassis case and leave pin 1 connected,
4) disconnect pin 1 and pin 4 completely from the 9 pins connector and connect both pin 1 and pin 4 to my common earth point ?
5) Other options ?
Anybody?
Last edited:
For balanced cables, pin 1 earth is for shielding.
Unlike unbalanced cabling it does not carry any signal.
If all your hi-fi equipment is metal cased and earthed then you have full metal shielding around all your cabling and circuitry to reduce pick up of external electromagnetic interference.
Whether your PCB ground should also be connected to the casing is a different matter.
You may want it connected at a single point or in practice it may not matter if there are multiple screws connecting the PCB to casework.
If it is a proprietary PCB then use what the designer has specified.
As you are screwing to a large sheet metal enclosure surface, it is unlikely to matter, unlike a PCB with thin traces where ground paths are more critical.
If you are still in doubt or you want some light reading try this -
Audio Component Grounding and Interconnection - diyAudio
Unlike unbalanced cabling it does not carry any signal.
If all your hi-fi equipment is metal cased and earthed then you have full metal shielding around all your cabling and circuitry to reduce pick up of external electromagnetic interference.
Whether your PCB ground should also be connected to the casing is a different matter.
You may want it connected at a single point or in practice it may not matter if there are multiple screws connecting the PCB to casework.
If it is a proprietary PCB then use what the designer has specified.
As you are screwing to a large sheet metal enclosure surface, it is unlikely to matter, unlike a PCB with thin traces where ground paths are more critical.
If you are still in doubt or you want some light reading try this -
Audio Component Grounding and Interconnection - diyAudio
Yep, XLR pin1 is just the shield, it's not part of the audio circuit common (aka ground).
Pin 1 should be attached to the chassis very near the connector.
Pin 1 should be attached to the chassis very near the connector.
... and if your input is balanced, no need to connect any audio ground to the case. In fact, that would be risky for hum & noise.
Jan
Jan
To rephrase the responses above:
1) Do connect xlr pin 1 to "lip" 4, making the pin 1/chassis connection at the xlr
2) Don't connect xlr pin 1 to the board. IE, leave pins 2 and 8 on your 9-pin connector unconnected.
1) Do connect xlr pin 1 to "lip" 4, making the pin 1/chassis connection at the xlr
2) Don't connect xlr pin 1 to the board. IE, leave pins 2 and 8 on your 9-pin connector unconnected.
Are You planning to use both connections ?
For RCA You have to short the inverting input to ground.
If it is permanently done, You'll loose the balanced connection.
Better use switched Neutrik sockets (Shorted when no XLR inserted) or a switch.
For RCA You have to short the inverting input to ground.
If it is permanently done, You'll loose the balanced connection.
Better use switched Neutrik sockets (Shorted when no XLR inserted) or a switch.
The pcb has two jumpers to select between ballanced and unbalanced, i replaced it with a switch.
Sadly i don't have a schematic of the pcb to see what's happend when i plug both XLR and RCA on it.