Show Us Your Core-NCore!

Julf · « **Reply #480 on:** 1 Apr 2015, 03:04 pm »

Quote from: dan1502 on 1 Apr 2015, 02:48 pm

http://www.diyaudio.com/forums/vendors-bazaar/190434-hypex-ncore-286.html#post2937571

The above is the post I refer to. My setup in balanced. I would not use them in an unbalanced setup.

Right. In that posting, Bruno states the same thing as I have - the filters capacitively couple the mains to chassis. I agree that it shouldn't be an issue in a balanced system, but as Bruno stated, you should try to minimize their use, and they are not needed with the Hypex SMPS. I also agree that as your setup is balanced, it doesn't make much of a difference in your setup.

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On a similar subject I have been meaning to find out more about whether or not to connect the XLR chassis to earth and, if so whether or not to connect the housing tab on the XLR plugs to ground. As it stands I have connected neither to ground.

I would connect the XLR chassis to ground (either directly or through the housing tab), as the XLR housing/chassis should (electrically) be part of the enclosure to minimize HF ingress/egress.

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I will probably take you comment about the cables on board. The cables are twisted tighter than I have seen any others twisted. The cable I used turned out to be unexpectedly good in that regard for quite thick cable. However I did not think of soldering them in a different orientation at the time.

Yes, the twisting in your pic is nicely tight - but it is equally important that it is as symmetric as possible (having one lead straight and the other twisted around it is no good), and the main priority is minimizing the area of any possible untwisted loops.

dan1502 · « **Reply #481 on:** 1 Apr 2015, 03:16 pm »

Thanks. The wires are twisted symmetrically. I was careful about that. I will change the orientation. I just hope I manage to de-solder and re-solder neatly.

Connecting the chassis to ground using the tabs is easy enough though if I had known before I would have not needed another ring terminal to do so. Connecting directly is harder due to how tough the anodising is so I'd rather avoid that.

What about the case tabs on the XLR interconnects? Should I connect these to ground? I've heard this can increase the risk of ground loop issues and is best avoided but that could be the wrong opinion.

Julf · « **Reply #482 on:** 1 Apr 2015, 03:23 pm »

Quote from: dan1502 on 1 Apr 2015, 03:16 pm

Thanks. The wires are twisted symmetrically. I was careful about that. I will change the orientation. I just hope I manage to de-solder and re-solder neatly.

Should be reasonably straightforward - at least you have lots of space around the terminals. Desoldering the feedback resistors was trickier

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What about the case tabs on the XLR interconnects? Should I connect these to ground? I've heard this can increase the risk of ground loop issues and is best avoided but that could be the wrong opinion.

Should not be any ground loop issues as long as the wires are kept short. The cases of the XLR connectors should be connected to the main chassis somehow, and I agree dealing with the anodising is tricky.

dan1502 · « **Reply #483 on:** 1 Apr 2015, 03:33 pm »

I'm pretty sure the Neutrik XLR plug cases connect to the Neutrik XLR sockets by design. So if I connect the socket earth tab to the cases they would be grounded at that end. The question then is whether or not I should connect the interconnect cable shielding to the plug earth tab or not if you know what I mean. Currently I just have the signal pins connected (of course) and the ground pin to cable shield but have not connected the ground tabs. This would be a bit of a pain to do retrospectively as I've twisted and soldered the shielding to the ground pin but I could just solder a tiny bit of wire from the ground pin to the earth tab but I'm not sure whether it's worth the bother if the shells are earthed via their connection to the socket which itself would be earthed if I proceed as advised.

Julf · « **Reply #484 on:** 1 Apr 2015, 03:49 pm »

If the socket earth tab is connected to the case, then that is more than enough - no need to worry about the plugs.

dan1502 · « **Reply #485 on:** 1 Apr 2015, 04:21 pm »

I thought so but thanks for confirming. That would have been a fiddly job.

dan1502 · « **Reply #486 on:** 2 Apr 2015, 07:13 am »

Looking at this before going ahead, presumable I just solder a very short wire between the xlr socket shell tab and Pin 1 which is next to it? Pin 1 is then wired to the chassis earth point visible in my picture.

Julf · « **Reply #487 on:** 2 Apr 2015, 07:21 am »

Quote from: dan1502 on 2 Apr 2015, 07:13 am

Looking at this before going ahead, presumable I just solder a very short wire between the xlr socket shell tab and Pin 1 which is next to it? Pin 1 is then wired to the chassis earth poing visible in my picture.

Yes, that would do it.

dan1502 · « **Reply #488 on:** 2 Apr 2015, 07:43 am »

Thanks. I do try and read up on this but most of what I read in terms of technical papers and discussions goes way over my head leaving me without a straight answer as to what's best for my situation.

Julf · « **Reply #489 on:** 2 Apr 2015, 07:50 am »

Quote from: dan1502 on 2 Apr 2015, 07:43 am

Thanks. I do try and read up on this but most of what I read in terms of technical papers and discussions goes way over my head leaving me without a straight answer as to what's best for my situation.

And unfortunately a lot of the electrotrickery is counterintuitive. Took me a long time to learn to trust the science and maths instead of what seemed to make intuitive sense. A solid theoretical background combined with practical experience helps, but still - every day is (hopefuly) a learning day.

dan1502 · « **Reply #490 on:** 2 Apr 2015, 11:29 am »

One of the problems for me is I intend to read up on a topic to a point I have a reasonable understanding for a particular project then don't have need to apply the knowledge again for a long time by which time I've forgotten it. I read all the DIYAudio thread about three years ago when I bought the units and built them into mock-ups but am now a little rusty.

dan1502 · « **Reply #491 on:** 3 Apr 2015, 11:25 am »

Improved output connection orientation to reduce or eliminate loops and connected xlr shell to chassis ground as per Julf's recommendations. Thanks for the constructive criticism.

Julf · « **Reply #492 on:** 3 Apr 2015, 11:59 am »

very neat!

dan1502 · « **Reply #493 on:** 3 Apr 2015, 02:34 pm »

Now I'm getting a static like popping but strangeley it only seems to be when using the USB input to my Benchmark DAC2 HGC not the coax or optical inputs (but I haven't listened to them for long enough to be certain). I'm now thinking I should remove the XLR shell to ground pin links I just connected. Any thoughts as I really want them to be finished and just enjoyed from today?

In case it helps, the USB is connected to a silent HTPC with Paul Pang card and two separate linear power supplies.

Julf · « **Reply #494 on:** 3 Apr 2015, 02:38 pm »

Quote from: dan1502 on 3 Apr 2015, 02:34 pm

Now I'm getting a static like popping but strangeley it only seems to be when using the USB input to my Benchmark DAC2 HGC not the coax or optical inputs (but I haven't listened to them for long enough to be certain). I'm now thinking I should remove the XLR shell to ground pin links I just connected. Any thoughts as I really want them to be finished and just enjoyed from today?

In case it helps, the USB is connected to a silent HTPC with Paul Pang card and two separate linear power supplies.

Whenever I have problems like that, I remove any sort of esoterica from my system. Can you try with just a regular laptop feeding the DAC?

dan1502 · « **Reply #495 on:** 3 Apr 2015, 02:43 pm »

Yes, I can do. It's just strange how that hasn't happened until today when I connected the shell earth tab to ground pin.

Julf · « **Reply #496 on:** 3 Apr 2015, 02:56 pm »

Quote from: dan1502 on 3 Apr 2015, 02:43 pm

Yes, I can do. It's just strange how that hasn't happened until today when I connected the shell earth tab to ground pin.

So just to check, you have the inputs of the nc400's connected to pins 2 and 3 on the XLR's, pin 1 and XLR connector chassis tab soldered together and connected to chassis/ground via short lead? And the only difference to the earlier situation (with no popping noises) was that the connector chassis tab wasn't connected anywhere?

dan1502 · « **Reply #497 on:** 3 Apr 2015, 03:21 pm »

Yes. But rather oddly I have just tried the HTPC connected via the onboard card (not the Paul Pang with separate Swenson supply) and no popping. However we have been using the HTPC to watch DVDs via the Paul Pang USB out for a week or so with no popping. It just seems unlikely to be a coincidence that this has only happended since connecting the shell ground tab to pin 1. You can see in the abov picture where the ring tabs connect to chassis ground (under the heatshrink of the signal cable).

Julf · « **Reply #498 on:** 3 Apr 2015, 03:54 pm »

Quote from: dan1502 on 3 Apr 2015, 03:21 pm

Yes. But rather oddly I have just tried the HTPC connected via the onboard card (not the Paul Pang with separate Swenson supply) and no popping. However we have been using the HTPC to watch DVDs via the Paul Pang USB out for a week or so with no popping. It just seems unlikely to be a coincidence that this has only happended since connecting the shell ground tab to pin 1. You can see in the abov picture where the ring tabs connect to chassis ground (under the heatshrink of the signal cable).

I agree it is an unlikely coincidence. Unfortunately the only way to verify would be by disconnecting the shell ground tab again. Do you have a cheap extra XLR cable where it would be easy to disconnect the plug chassis connection?

dan1502 · « **Reply #499 on:** 3 Apr 2015, 04:02 pm »

It's an unlikely coincidence but still odd that it doesn't happen with the other USB output or other sources. Plus the Paul Pang card only has two power inputs i.e. +5v and ground with no earth. I'm just going to take the cover off the HTPC and have a look as there have been reports of issues with Paul Pang cards. All my XLR connections are cheap but I do have some used spares and cable. My current cables just have the 3 pins connected though without the tab from plug shell to ground (shielding) connected. Do you mean try with just signal pins connected? If so I could but it's a bit of a faff.