[undertow]

Hello,

Okay here it goes, I received the units, I am running a dual Mono so dual power supplies and dual Ncores. I am looking for a few simple answers.

I am running 100% XLR with true balanced preamp and all associated equipment. worrying about adding RCA jacks to jump this and convert is not an issue for me.

However, first I looked at some of the built photos and my observations are...

1- Is it suggested to take the ground pin on the IEC jack and just go direct to the chassis screw? Or leave the IEC earth ground off completely? Hard to tell in most of the photos.

2- It looks like most just took the XLR body pin and also connected to the same chassis screw(or another screw same thing direct to chassis) They DID NOT put the pin #1 to the Chassis which is fine. However, in the instructions from Hypex it looks as if they are connecting pin #1 direct to the chassis, I will check, but I assume the XLR jacks I bought ground pin #1 automatically thru the body once bolted in anyway not 100% sure. Is there any reason to consider doing this a different way or more added grounds should not be an issue?

3-  The Ncore wire harness comes with the XLR standard 3 pin wires and an added 4th wire which I assume is just for grounding at the chassis screw or XLR body as well because pin #1 will be on the shield wire?

4- The SMPS power supply has just a 2 pin power harness. However, it then has a what is in the instructions described as "J1 Vaux & Control"? Not sure what this is, as it looks like a 7 pin ground wire harness, its all black wires, but in the photos I see so far nobody is using this harness or hooking it up.

5- Finally there is a 4 pin harness that looks un-used as well on the NC400? I don't see it anywhere listed in the instructions, nor do I see anybody using it in the photos.

**So to keep this simple I assume I can simply take the:

1- IEC direct to chassis ground

2- 4th wire on the XLR input harness direct to chassis ground

3- XLR connector housing direct to chassis ground leaving pin #1 just on the shield

4- Power switch direct to chassis ground(yes I am adding a power switch on mine just because its easy)

**Basically having a total of 4 earth ground connections direct to a chassis screw for ground?

??There is no wire for earth ground on the SMPS power supply directly, I believe one of the Screw down standoffs is metal and probably grounds it while it is directly bolted to the chassis? Which would be the fifth ground??

I just want to make sure I will not be fighting with noise for some stupid reason not adding a ground somewhere or removing it from the 100 different ways it looks like you can ground this thing ultimately.

Thanks

[bhakti]

I will try giving some free advice here (just remember it is worth every penny  )

Item #1:
 Yes to the mains ground - this is your safety ground.  Trips the breaker if the case goes 'hot'. 

Item #2:
 (from the datasheet)
 7.3 J9 Audio input Connector type: 2x2 pin Molex Microfit header type 43045-0412, Mates with 43025-0400 cable part. Pin Type Function 1 Analogue in INH: non-inverting audio input 2 Analogue in INC: inverting audio input 3 in, wpu nAMPON 4 passive Ground. Notes: wpu=weakly pulled up to 3.3V, not to be driven above 3.3V. The audio input is differential. This means that ground is not part of the audio signal. When connecting an unbalanced source, treat pins 1 and 2 as a floating input with pin 2 being the “audio ground” of the source. Pin 4 may be used to attach the shield of a shielded twisted pair cable, but the “audio ground” connection of an unbalanced source should never connect here.

I read this as pin 4 only being needed if you want to ground the shield on a shielded input cable.  Maybe you haven't seen many people doing this because they either aren't using shielded cable or they are not concerned about grounding the shield on a short run.  Not even sure if this is needed or an issue with a balance input as any noise will be cancelled out.

Item #4: Did you mean the nampon muting function?  If so, yes you need to ground that to take the amp out of mute.

[undertow]

Thanks, but not sure I follow?

Problem is the overall is not clear, I am not even sure what a :
"nampon muting function" is?

It would be best if somebody can just tell me how many grounding points they used, and from what?

such as:

1- XLR body ground pin to chassis? #1 pin to shield on NC400 cable not to chassis?

2- IEC earth ground to chassis?

3- PIN #4 on XLR harness to chassis?

4- SMPS no wire ground but is already ground to chassis with metal standoff?

[bhakti]

Meant to say that - IMHO the designers are attempting to make it clear that the audio ground is isolated from the safety ground.  Most of the components will have a safety ground, but this is not tied to the audio ground in any way.

Not sure I'm answering your questions, but it helps me clarify the build as I am waiting for parts to assemble my amps as well.

[Steidl Guitars]

Problem is the overall is not clear, I am not even sure what a :
"nampon muting function" is?

On the set of input cables, there is a single black wire; that is the nAMPON line which has to be grounded for the amp to work.  Therefore, lifting it from ground can function as a mute.  If you don't need or want a mute, just ground it somewhere. 

1- XLR body ground pin to chassis? #1 pin to shield on NC400 cable not to chassis?

2- IEC earth ground to chassis?

3- PIN #4 on XLR harness to chassis?

4- SMPS no wire ground but is already ground to chassis with metal standoff?

What you describe is exactly what I did and I have no hum, though I use an RCA-XLR adapter (don't know if that matters). 

[undertow]

Steidl Guitars,

Got ya!

Thanks, makes total sense. I saw some people using a small switch for the ground wire off the input, now I know why. Not a bad idea, same time don't think its necessary for me to have the mute. I actually thought people were adding that switch to the little black #4 wire in order to have a "Ground Lift" for possible noise which is why I asked the question in the first place if this for some reason was due to people getting possible noise, now I understand its a mute function so not worried that wire will bring in any hum now.

Beyond that RCA conversion cable is no issue with XLR on the chassis only as your doing.

I was just saying I am not going get into adding the extra capacitor and RCA's on the chassis for now.

Again just not necessary accept for Re-sale if it came to it. I could add later, but the conversion cable is easiest like your doing, but only downfall most people would want RCA at the chassis to use any cable they want without hacking up a 1000 dollar pair of whatever I am sure to make a hybrid XLR / RCA. Or due to they don't even know how to make a conversion cable, or just buy an XLR to RCA adapter which kinda is a waste.

[undertow]

bhakti,

As to your point, I think there is only one live "Audio" ground being used in this unit which would be the shield on the XLR input cable. So it seems this is not hooked directly to the Earth ground as you state. But I am not so sure as most XLR Jacks might have continuity from the #1 pin to the body of the XLR, but it might be isolated I am not 100% sure.

Thanks

[Emile]

I dont have it connected to earth ground at all, the ncore has a floating differential input, I just use pin 1 (signal ground) on my xlr lead to switch nampon, works like a charm