It's all much easier to understand if you remove the simple word 'ground' from the conversation.
Use concepts like:
chassis
circuit common
Safety Ground/Protective Earth
power supply common
input signal common
All class 2 equipment needs to be tested by a safety agency. It's not class 2 after you modify it.
Use concepts like:
chassis
circuit common
Safety Ground/Protective Earth
power supply common
input signal common
All class 2 equipment needs to be tested by a safety agency. It's not class 2 after you modify it.
SMPS600 G connection to chassis
It appears to me that the SMPS600 does not connect its G directly to the chassis on the metal standoff. Actually, the G is only connected at high frequencies (through a capacitor).
But, if we we wire NC-400 modules according to the data sheet, with the "shield" (which is also power supply G) of the input cable connected to chassis, then the chassis is at power supply G, and Nampon can connect to chassis as well.
One could also do a star ground, with Nampon(s), input cable shield(s), and perhaps optionally. AC ground all coming to a common point. Bruno points out that the star ground approach will not work at high frequencies though (too much impedance) and seems to believe it is of no value.
I have a stereo build in an aluminum chassis, and I followed the Hypex recommended way: Pin 1 of XLR to chassis, Shield connection of input cable to chassis at a different point (to pin 1). Two Nampon wires to one side of a switch, and the other side of the switch to chassis. Wiring/build is Class 2. Works fine with no noise.
It appears to me that the SMPS600 does not connect its G directly to the chassis on the metal standoff. Actually, the G is only connected at high frequencies (through a capacitor).
But, if we we wire NC-400 modules according to the data sheet, with the "shield" (which is also power supply G) of the input cable connected to chassis, then the chassis is at power supply G, and Nampon can connect to chassis as well.
One could also do a star ground, with Nampon(s), input cable shield(s), and perhaps optionally. AC ground all coming to a common point. Bruno points out that the star ground approach will not work at high frequencies though (too much impedance) and seems to believe it is of no value.
I have a stereo build in an aluminum chassis, and I followed the Hypex recommended way: Pin 1 of XLR to chassis, Shield connection of input cable to chassis at a different point (to pin 1). Two Nampon wires to one side of a switch, and the other side of the switch to chassis. Wiring/build is Class 2. Works fine with no noise.
From the SMPS600 datasheet:
and
How you choose to interpret that is entirely up to you, but maintaining the class 2 design criteria will, of course, maintain its conformance with class 2. And I see no modification to the equipment.
Thanks for your help guys.
I guess one of the problems (on my part) is that I don't actually have the NC400s and SMPS600s and associated cables/connectors in my hands yet to play with. Once I do, I suspect it will all become more clear.
That said, I have been reluctant to spend perhaps €1,300 on Hypex parts and maybe another €300 or €400 on case work, only to find I can't wire it all together!
I am sure I will manage
I guess one of the problems (on my part) is that I don't actually have the NC400s and SMPS600s and associated cables/connectors in my hands yet to play with. Once I do, I suspect it will all become more clear.
That said, I have been reluctant to spend perhaps €1,300 on Hypex parts and maybe another €300 or €400 on case work, only to find I can't wire it all together!
I am sure I will manage
Input shorted?
With the input open (nothing connected) the amp will probably pick up some noise from the air, and you will hear some hiss. With a source connected, you will hear some noise form the source, or from RF pick up on the cable.
To test for amp self noise, use a shorting plug between pin 2 and 3 of the XLR jack: I think you'll find the amp dead silent in this case.
With the input open (nothing connected) the amp will probably pick up some noise from the air, and you will hear some hiss. With a source connected, you will hear some noise form the source, or from RF pick up on the cable.
To test for amp self noise, use a shorting plug between pin 2 and 3 of the XLR jack: I think you'll find the amp dead silent in this case.
When you're doing your listening test, have you shorted the input?
Thanks for your help guys.
I guess one of the problems (on my part) is that I don't actually have the NC400s and SMPS600s and associated cables/connectors in my hands yet to play with. Once I do, I suspect it will all become more clear.
That said, I have been reluctant to spend perhaps €1,300 on Hypex parts and maybe another €300 or €400 on case work, only to find I can't wire it all together!
I am sure I will manage
They come with complete cable sets. Unless you think you need to shorten the cables, you simply
- plug the PSU cable between the SMPS600 and the nCore
- wire up the input cable to the back of your input socket; decide what you're doing with the nampon signal; and plug the other end into the nCore
- wire up the (2 core) mains cable to the back of your mains inlet and plug the other end into the SMPS
I also mounted a 2 pole double-throw switch with inbuilt bicolour LED on the front panel. I wired 1 pole to my nampon signal as a 'mute' switch (useful when swapping cables etc.. And I used the aux supply (cable provided) on the SMPS to power a bicolour LED via the other pole on the switch
Thanks Chris. Re the switch / LED, sounds like a nice solution. Can you remember which one you used? Did you need a series resistor to drop the aux voltage down a bit?
If you follow all the instructions exactly, then you are not modifying the equipment. So what's the problem?
I think it was this - it was convenient and comparatively cheap
MCM2122TCFW01 - MULTICOMP - SWITCH, TOGGLE DP BI-COL LED | CPC
Multicomp MCM2122TCFW01
Yes you need a resistor - calculate based on the lowest forward voltage drop of the two LEDs, the lowest max current of the two LEDs and the value for the aux voltage
Considering getting a pair of ncores and corresponding SMPSs for use as bass amps.
Do they have to be enclosed in a metal box?
I was considering mounting each module and supply on a rectangular copper plate which would be open on the top and sides.
Seems there is not much radiated noise from the specifications but then I could be missing something. The amps would be away from the source components at the woofer boxes.
I am cheap and have no desire to buy boxes if they are not needed. I have the copper plate on hand.
Considering replacing a CROWN K2 and would appreciate any comments by those familiar with both amplifiers.
I would appreciate advice!
Thanks,
Do they have to be enclosed in a metal box?
I was considering mounting each module and supply on a rectangular copper plate which would be open on the top and sides.
Seems there is not much radiated noise from the specifications but then I could be missing something. The amps would be away from the source components at the woofer boxes.
I am cheap and have no desire to buy boxes if they are not needed. I have the copper plate on hand.
Considering replacing a CROWN K2 and would appreciate any comments by those familiar with both amplifiers.
I would appreciate advice!
Thanks,
If I remember correctly they don't strictly need a box as they are Class II compliant, or if you have a box it doesn't have to be conductive. The modules have lethal voltages so personally I would enclose it anyway. You can get decent boxes form ebay for 50$ or less including shipping, you can't be too cheap for that. But for me it is mostly that I promised myself I will never compromise on safety, which is why I also always connect earth to the chassi even if I don't have to.
ADDITION: The Hypex Plate amps for example are only a metal plate, but in this case the speaker box hides it form roaming fingers =)
Second addition: The NCore is overkill in the bass, it shines in the mid-high frequencies so as you are cheap the UcD is good enough in the bass and much cheaper. The designer of the NCore, Bruno has said this earlier in the thread ( that the advantage of the NCore is not in the bass, he didn't mention the pricing
).
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The smps has mains voltages. I'm sure it's intended to be enclosed, as ollboll has indicated.
And I'd rather there was something to nominally prevent stuff from accidentally falling on the circuit
I don't believe they need cases for screening. Bruno has been quite adamant about low rfi being an inherent part of the circuit design and not the packaging
And I'd rather there was something to nominally prevent stuff from accidentally falling on the circuit
I don't believe they need cases for screening. Bruno has been quite adamant about low rfi being an inherent part of the circuit design and not the packaging
I'm running the ncore mounted vertical under the SMPS 600 on a thick piece of aluminum in wooden boxes, open top and bottom for ventilation, like to keep temperature down for electronics, would never use a closed box anyway, but the Crown K2 gets so much more hot of course ( never made comparison soundwise )
never had any problems with noise, dead silent, full range with my 108db/w horns and different sources close to ncores
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To start with, it is definitely not a good idea to ground the negative speaker output, but it is also not a great idea to burn away all your output power in those resistors. Playing at full volume would probably result in smoke from the resistors.
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