Thanks again. I never knew about nCore output. Sounds like my REL will be fine then.
I think i will order the bits and get started
If i may ask one more stupid question, i am puzzled by the whole ground vs signal ground issue.
I plan on making the amps double insulated, so i won't be connecting the mains earth lead to the chasis. (Which is OK I believe?)
Should I connect XLR pin 1 to the chasis, or not?
If i do not, how and where do I pull nampon low? With no mains earth and no signal ground, what do you connect nampon to?
What's the recommended approach to all of this?
Thanks
I plan on making the amps double insulated, so i won't be connecting the mains earth lead to the chasis. (Which is OK I believe?)
Should I connect XLR pin 1 to the chasis, or not?
If i do not, how and where do I pull nampon low? With no mains earth and no signal ground, what do you connect nampon to?
What's the recommended approach to all of this?
Thanks
Sorry to be stupid, but you mean mains outlet ground? I am not planning on connecting the mains earth to anything, so I cannot connect nampon to it.
Or by "power supply", do you mean SMPS600?
Perhaps you can paraphrase for me?
Yes, the SMPS600 is the power supply, and there is a ground connection between the SMPS and the NC400.
Thanks again.
This whole "ground" thing really confuses me. For example, I note that the SMPS600 J3 connector for mains input has live and neutral input, and ground is NC - not connected. So if the whole of the SMPS600 is not grounded, how can you ground the NC400 nampon line by connecting to an ungrounded SMPS600?
I am sorry, I am not trying to be difficult, or stupid, just genuinely trying to understand this stuff. If anyone could be kind enough to spell out the basics of this kind of thing, it would be really helpful. Or course I can google (and have done) but it's difficult to find material that explains things at the right sort of level without getting too technical and losing me.
Presumably I could attach nampon to the chassis instead? (Since the chassis is attached to XLR signal ground at least.)
Mains earth is different from circuit ground. Mains earth is mainly an electrical safety issue.
The power supply still has a circuit reference earth. This is what the various supply voltages are referenced to, and this is what nampon connects to.
But mains earth and circuit ground would be the same if the chassis is earthed, right?
And can I connect nampon to the chassis? The chassis will be at circuit ground, since the 4th mounting hole is conductive, yes?
If circuit ground is connected (using 4th mounting hole or by other means) to the chassis, and the chassis is connected to mains earth, then yes.
If your nc400 is bolted directly to the chassis, then yes, but I would try to avoid long loops.
Balanced (differential input) signals are nice, but the nAMPON input isn't differential. I would prefer to do the nAMPON switching directly between the nAMPON input and circuit/power supply ground, and not use the chassis as one leg.
Thank you once again - you have been most helpful.
My FINAL question, I promise ;-)
Do the NC400 and SMPS600 come with any sort of build instructions, or is the only thing the data sheets on Hypex.com. Those seem quite clear about what all the connections actually ARE. But there doesn't seem to be anything that tells you what you should actually DO.
Step 1. Connect A to B.
Step 2. Connect C to D.
Step 3. ....
That sorts of stuff. Do you get any of that with it?
My FINAL question, I promise ;-)
Do the NC400 and SMPS600 come with any sort of build instructions, or is the only thing the data sheets on Hypex.com. Those seem quite clear about what all the connections actually ARE. But there doesn't seem to be anything that tells you what you should actually DO.
Step 1. Connect A to B.
Step 2. Connect C to D.
Step 3. ....
That sorts of stuff. Do you get any of that with it?
True, but long loops are only a problem if they are part of the signal path, and if you use balance signals / separate audio ground they aren't.
No. The assumption is that the data sheets contain all the information you need.
If you need more detailed information, feel free to ask here!
My point is that ground loops might still be an issue for the nAMPON signal itself, not the audio signal.
You can have ground loop issues even with "digital" control signals.
To be clear, am I OK to connect mains earth to the metal chassis (for safety reasons) AND signal ground to the chassis? (The SMPS600 will be connected to the chassis by the 4th, conducting, standoff.)
I don't want ground loops, but I don't want death by electrocution (or invalidated house fire insurance) either!
The hypex stuff, ie the SMP600, is built to class 2 - doesn't need a mains earth - just ensure there's enough of an air gap around all the components and the case, or if you really want to make things tight, some alternative form of insulation instead of the air gap.
The datasheet shows that it's not recommended to use a mains earth
Most builds won't have a mains earth (well, mine doesn't )
The datasheet shows that it's not recommended to use a mains earth
Most builds won't have a mains earth (well, mine doesn't
)Yes, it is ok. If ground loops are an issue then you can go Nelson Pass's method and put a thermistor, say a CL60 that connects earth to signal ground. That should reduce the hum, hopefully enough that it isn't an issue anymore.
ADDITION: While the SMPS should probably not have earth connection or other hypex stuff that are class 2 it is never a bad idea to connect the chassi to earth. Doing this will not impact the signal path unless you use RCA plugs where the shield is the return signal and you connect it to chassi. But this can be solved by just using a dual conductor cable with a separate shield, and wire it like it is balanced but where just one of the internal cables have signal ground instead of negative signal.
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The module itself is built to class 2, but to comply with class 2 requirements, your enclosure and everything else needs to be compliant too. No problem if you know what you are doing and are familiar with class 2 requirements - but if not, I would definitely recommend earthing the enclosure/chassis to mains earth.
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