Yeah i understand that. But i was worried i would get ground loop becaouse everthing is one the same ground.
Balanced interconnects always have ground loops (ie, currents flowing in the shield). If the equipment at both ends is properly designed, this is not a problem. If it is not properly designed you get "pin 1 problem".
The correct solution is to connect the shields to chassis : shield currents flow in a big piece of metal at the back of the rack, and loop to safety earth. The incorrect solution is to connect the shields to a "GND" on a PCB, which makes the current flow in some sensitive GND nodes, and you get hum.
The correct solution is to connect the shields to chassis : shield currents flow in a big piece of metal at the back of the rack, and loop to safety earth. The incorrect solution is to connect the shields to a "GND" on a PCB, which makes the current flow in some sensitive GND nodes, and you get hum.
Hence...
Hence lots of confusion with the NC-400 modules. They have a ground wire (not to mention Nampon) which is attached to the PCB, and which must be grounded for the module to work. Recommended approach is to attach that wire to the chassis, hence it is connected to pin 1 via the chassis. This confuses me when everyone claims the NC-400 is not ground referenced, if not, how come that ground wire from the module must be connected to the circuit ground of the source for the NC-400 to work?
Hence lots of confusion with the NC-400 modules. They have a ground wire (not to mention Nampon) which is attached to the PCB, and which must be grounded for the module to work. Recommended approach is to attach that wire to the chassis, hence it is connected to pin 1 via the chassis. This confuses me when everyone claims the NC-400 is not ground referenced, if not, how come that ground wire from the module must be connected to the circuit ground of the source for the NC-400 to work?
Yes, that would make the pin 1 problem still a problem, when shield from XLR is grounded with the pcb-groun and nAMPON...?
I am going to have RCA on source end, converted to XLR. Hypex datasheet says this is a preferable connection. And i am going to use ground earth.
Pin1 is grounded to the chassi, the chassi is grounded to mains earth and the pcb should also be grounded to mains eart, and the nAMPON and the SMPS600. Everything on same earth, correct?
The PRE-AMP doesn't have and earth, but computer connected to preamps has grounded earth mains...
This is a correct installation i think.
I'm waiting for the parts to arrive on monday, we will see then.
Not quite
- Nampon must be attached to the PCB ground for the amp to work
- you don't have to connect the screen ground to ground for the module to work
- For best signal screening on its way to the amp, the screen should be connected to 'an earth point' - ie. Audio Input 'Ground'
- the amp has a 0V reference/rail
- for convenience the 0V rail is a convenient and controlled overall connection for the screen (Audio Input ground)
- since both the screen and the Nampon cable are run through the input lead it is convenient (and controlled) to have a single 0V (and screen) connection point on the back of the input connector
So we have
- a connection for Nampon - which must be connected to ground to turn the amp on
- a connection for the screen - which doesn't have to be connected to ground for the amp to work but will improve noise rejection if it is
The input signal is balanced and is not referenced to the amp's 0V. As long as you don't shift the balanced inputs out of their safe operating area, you can apply a DC offset - or any other non-DC common offset, for example due to noise - to the (two) input connections and it would be ignored
No, no problem
Make sure you maintain the apropriate air spacing around the components and then no mains earth is required and this is the recommended method of wiring
See http://www.hypex.nl/docs/NC400_datasheet.pdf section 12.3.1 figure 2
If you really want to connect the chassis to the mains earth then see 12.3.3 figure 5
Hey Chris...
I beg to differ...
"Not quite
- Nampon must be attached to the PCB ground for the amp to work
- you don't have to connect the screen ground to ground for the module to work
- For best signal screening on its way to the amp, the screen should be connected to 'an earth point' - ie. Audio Input 'Ground'
- the amp has a 0V reference/rail
- for convenience the 0V rail is a convenient and controlled overall connection for the screen (Audio Input ground)
- since both the screen and the Nampon cable are run through the input lead it is convenient (and controlled) to have a single 0V (and screen) connection point on the back of the input connector"
I own and use a NC-400 stereo amplifier, which I built. If I lift the ground (or shield if you prefer) connection, the modules will not work properly. My amp is built according to Hypex instruction: pin 1 direct to chassis, Nampon is connected to switch, and then to chassis as a mute (standby) feature. If the shield wire is lifted, the modules do not work, simple as that. The "shield" wire is indeed continuous with the 0 volt reference of both the Ncore modules and the SMPS600 (when plugged in).
To be perfectly clear: if I lift the shield wire from its connection to chassis, the modules do not work.
I beg to differ...
"Not quite
- Nampon must be attached to the PCB ground for the amp to work
- you don't have to connect the screen ground to ground for the module to work
- For best signal screening on its way to the amp, the screen should be connected to 'an earth point' - ie. Audio Input 'Ground'
- the amp has a 0V reference/rail
- for convenience the 0V rail is a convenient and controlled overall connection for the screen (Audio Input ground)
- since both the screen and the Nampon cable are run through the input lead it is convenient (and controlled) to have a single 0V (and screen) connection point on the back of the input connector"
I own and use a NC-400 stereo amplifier, which I built. If I lift the ground (or shield if you prefer) connection, the modules will not work properly. My amp is built according to Hypex instruction: pin 1 direct to chassis, Nampon is connected to switch, and then to chassis as a mute (standby) feature. If the shield wire is lifted, the modules do not work, simple as that. The "shield" wire is indeed continuous with the 0 volt reference of both the Ncore modules and the SMPS600 (when plugged in).
To be perfectly clear: if I lift the shield wire from its connection to chassis, the modules do not work.
So that we all understand what's going on:
Where is your nampon wire connected to? (Audio input pin 3)
Where is your ground wire connected to? (Audio input pin 4)
Apart from the PSU, what else is connected to the Amp's 0V?
Apart from the amp. what else is connected to the PSU's 0V?
Where are you lifting the ground connection?
When you lift your ground connection what is nampon connected to?
and how does nampon then make connection to the amp's 0V?
How does your wiring compare to any of Hypex's figures 2, 4 or 5?
Thanks
If you're wiring according to any of Hypex's figures, then if you lift the ground at (either end of the input cable) then nampon is floating - there is no connection between nampon and any part of the amplifier; ie. it's not connected to amplifier 0V and so the amp won't turn on
Edit: for clarification:
From what I understand of your description above - because your nampon goes to the chassis, unless you have also independently made a connection between 0V on the amp or PSU, then if you lift the ground on the input connector, then the chassis is no longer connected to 0V and therefore nampon is no longer connected to 0V and so the amp will remain turned off
PS. my nampon is connected (also via a switch) to the 0V pin on the auxiliary supply connector on the smps600
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Chris, answers...
So that we all understand what's going on:
"Where is your nampon wire connected to? (Audio input pin 3)"
Through switch, to chassis for mute function
"Where is your ground wire connected to? (Audio input pin 4)"
Shield/ground is connected to chassis
"Apart from the PSU, what else is connected to the Amp's 0V?"
Nampon (when switch is closed), Shield (to chassis)
"Apart from the amp. what else is connected to the PSU's 0V?"
DAC, via XLR pin 1 (again to chassis)
"Where are you lifting the ground connection?"
Lift the shield wire from its connection to chassis
"When you lift your ground connection what is nampon connected to?"
When I lift the shield connection, Nampon is still connected to chassis, and to DAC G via pin 1 XLR.
"and how does nampon then make connection to the amp's 0V?"
It does not. But it is still pulled (generally) to 0 VDC via DAC G. Note that during testing of modules, before putting everything in the chassis, connecting the shield/G directly to nAmpon does not allow the modules to work unless the shield is also connected to a G (either DAC G or AC G)
"How does your wiring compare to any of Hypex's figures 2, 4 or 5?
Thanks
If you're wiring according to any of Hypex's figures, then if you lift the ground at (either end of the input cable) then nampon is floating - there is no connection between nampon and any part of the amplifier; ie. it's not connected to amplifier 0V and so the amp won't turn on"
Actually not true. Nampon is still grounded via DAC ground, pin 1:
Nampon-chassis-XLR pin 1-XLR cable-pin 1-DAC ground.
BTW, the module does turn on with shield lifted, there is noise at the output, so it is not muted as is the case when Nampon is "off" i.e. not grounded.
This is why I am confused. For example, if I disconnect pin 1 at the DAC, the amp also does not work, while Nampon and shield are both connected to the amp chassis, G.
So that we all understand what's going on:
"Where is your nampon wire connected to? (Audio input pin 3)"
Through switch, to chassis for mute function
"Where is your ground wire connected to? (Audio input pin 4)"
Shield/ground is connected to chassis
"Apart from the PSU, what else is connected to the Amp's 0V?"
Nampon (when switch is closed), Shield (to chassis)
"Apart from the amp. what else is connected to the PSU's 0V?"
DAC, via XLR pin 1 (again to chassis)
"Where are you lifting the ground connection?"
Lift the shield wire from its connection to chassis
"When you lift your ground connection what is nampon connected to?"
When I lift the shield connection, Nampon is still connected to chassis, and to DAC G via pin 1 XLR.
"and how does nampon then make connection to the amp's 0V?"
It does not. But it is still pulled (generally) to 0 VDC via DAC G. Note that during testing of modules, before putting everything in the chassis, connecting the shield/G directly to nAmpon does not allow the modules to work unless the shield is also connected to a G (either DAC G or AC G)
"How does your wiring compare to any of Hypex's figures 2, 4 or 5?
Thanks
If you're wiring according to any of Hypex's figures, then if you lift the ground at (either end of the input cable) then nampon is floating - there is no connection between nampon and any part of the amplifier; ie. it's not connected to amplifier 0V and so the amp won't turn on"
Actually not true. Nampon is still grounded via DAC ground, pin 1:
Nampon-chassis-XLR pin 1-XLR cable-pin 1-DAC ground.
BTW, the module does turn on with shield lifted, there is noise at the output, so it is not muted as is the case when Nampon is "off" i.e. not grounded.
This is why I am confused. For example, if I disconnect pin 1 at the DAC, the amp also does not work, while Nampon and shield are both connected to the amp chassis, G.
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Answers...
DAC is based on a Twisted Pear Audio B-IIIse/Legato 3 combo with Salas regulators and Sonore async DSD/DXD interface. Balanced outputs only, capacitor coupled, pin 1 to chassis, and circuit ground to chassis. Note that the USB interface is totally isolated from the server, no ground connection to server (and server is powered via battery supply, no connection to home AC wiring at all).
Interconnect twisted pair for pin 2 and 3, shield connected to pin 1 both ends.
DAC is based on a Twisted Pear Audio B-IIIse/Legato 3 combo with Salas regulators and Sonore async DSD/DXD interface. Balanced outputs only, capacitor coupled, pin 1 to chassis, and circuit ground to chassis. Note that the USB interface is totally isolated from the server, no ground connection to server (and server is powered via battery supply, no connection to home AC wiring at all).
Interconnect twisted pair for pin 2 and 3, shield connected to pin 1 both ends.
This is getting a bit out of hand.
I'm going to connect pin 1 to the chassis as in the hypex manual.
But im also going to ground the mains for safety. My only question about that is, do i need the 47k, im going to use RCA-XLA cables. In XLR - XLR you dont need the 47k i take it, but do i need it? THe PRE AMP is NOT grounded, but the computer wich is connected to pre-amp is.
I'm going to connect pin 1 to the chassis as in the hypex manual.
But im also going to ground the mains for safety. My only question about that is, do i need the 47k, im going to use RCA-XLA cables. In XLR - XLR you dont need the 47k i take it, but do i need it? THe PRE AMP is NOT grounded, but the computer wich is connected to pre-amp is.
Depends on your earth/ground strategy, but in almost all cases, yes. Are you also using the standby mode?
No. nAmpon is permanently soldered to XLR audio ground.
See RCA holes, vertical pair located between horizontal L/R XLR holes:
An externally hosted image should be here but it was not working when we last tested it.
I desire to install AC Mains toggle switch in the top RCA hole. I must check SMPS1200A400 maximum current for AC Mains. The two OEM Mains wires look like 18AWG, possibly 19AWG, indicating low to moderate current. Hoping but not sure switch with suitable current rating fits the RCA hole. If I interrupt only one leg of Mains, what about shorting two switch contacts of DP switch to double the current capacity?
Critical: How do you quantify risk of potential performance impact with one AC Mains wire proximity to speaker posts ,speaker cables, and XLR cables in chassis?
Interrupt Line or Neutral wire? I'm thinking N but not clear if this makes difference.
Thanks Julf for you kind help, as usual.
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