Hypex NC1200: Quality of the implementations

[wynpalmer]

BTW, one thing I don't understand is that lm4562 is almost half price of lme49720. I heard there are some protection circuit or biasing difference between the two. Idk if that's true or not.

Nope, no difference as far as specs etc. is concerned. The consensus is that it's the same part.

https://www.diyaudio.com/forums/chip-amps/107344-lme49720-vs-lm4562.html
The part no. difference appears to be a marketing ploy. The above thread discusses the "evidence".

 

[Thomas savage]

Nothing says Class D efficiency like the Krell logo..

 

[maty]

Cheap or inexpensive, they are just objects. At least I used italics.

 

[maty]

NCORE-MX Mono Case-Kit from ghentaudio

https://www.ghentaudio.com/kit/ncore-mx.html

Brief Specifications

• Internal size: 193 mm(W) x 58 mm(H) x 265 mm(D)
• Color: 1) Full Black (Default); 2) Silver Face-plate & Black case;
• Face-Plate: 8 mm thickness & NCORE logo (Option: Blank face-plate without logo is available)
• Top-Cover: 3 mm thickness, with standard venting holes (Option: Blank top-cover without holes is available)
• Bottom-Plate: 3 mm thickness, pre-drilled holes for Hypex/NCORE modules (Free drilling for other modules)
• Rear-Plate: 3 mm thickness, one XLR socket, pair of Binding Posts, IEC socket with power button
• DC Supply for LED Dimmer: DC +10v ~~~ +26

But, like Hypex NC500, NC1200 is only OEM.

 

[maty]

More unexpensive and beautiful the enclosure of my gadget, I think. And you can also build a dual mono system in one box, with internal steel compartments -> you save money.

An example, Akitika GT-102 made by Dan Joffe.

https://www.akitika.com/GT102.html

BTW: notice that he moved the circuitry away from the black coated steel walls. You know, at least 6 mm. Better more, 10 mm, if there are components below the PCB, now or in the future.


Updated with new picture from:

 

[DonH56]

Looks like a nice amp but is not dual-mono. Single power transformer, single power supply.

 

[Matias]

@maty I understand that inner compartments isolating the power supply from the amplifier board is more important in large linear transformers than small switching power supplies, no?

 

[maty]

It is obvious. What I wanted to review was the use of steel separators, so it is unnecessary to have the power supply in another box, with the consequent savings. And the separation to the steel walls. And so you can lower the cost of the kit without compromising the sound quality.

At most, I could add the option of a thick aluminum front, more beautiful and more friendly...

 

[maty]

SMPS are very RF/EMI noisy. But Hypex presumes that their expensive SMPS emit very little radiation, so keeping the proper distance from the SMPS coils to the audio module will suffice.

 

[maty]

An obvious implementation error that was/is incomprehensible. Left channel.

Nord One NC500, stereo

https://www.audiosciencereview.com/...-and-measurements-of-nord-one-nc500-amp.7704/

Which was later solved in the mono amps.

NORD One SE NC500

 

[maty]

I think I had never seen the bottom of the Hypex modules. The NC1200:

https://www.hypex.nl/product/nc1200-oem/1

 

[maty]

Hypex NC1200 v6

Curious: the six small Wima capacitors (red) are glued together. Striking because the ones that are usually fixed very well are the BIG electrolytics.

 

[maty]

To finish, a different view of the Hypex SMPS1200A400

https://www.hypex.nl/product/smps1200a400/10

 

[maty]

https://www.acoustic-technology.com/en/blog-atm-en/buffer-for-hypex-nc1200-v1-part-i

BUFFER FOR HYPEX NC1200 MODULES

We have developed, in collaboration with Richard Doporto, a specific buffer for the Hypex NCORE NC1200 power module. This buffer is adapted on top of the NC1200 module. It is prepared to use several very low noise operational amplifiers such as Sonic Imagery SIL990 and SIL994 Ehn Ticha and Sparkoslabs SS3602 and SS2590. You can also use the instrumentation, medical line and traditional operational amplifiers.

 

[maty]

Compare with the buffer incorporated in the Purifi 1ET400A connection board. With OPA1612.

 

[maty]

Some posts ago, in the first page, I upload the picture of the amr buffer with Sparkos.

 

[headshake]

@maty ever use Interference-Shielding Wrap-Around Sleeving?

https://www.mcmaster.com/catalog/125/886

 

[Matias]

@maty
As far as magnetic shielding, aluminum is not the way to go, even thick chassis walls. Yes, CNC chassis look nice and work great for heat dissipation, but the magnetic permeability is not good at all.

Relative magnetic permeability
Vacuum: 1 perfect
Air: 1.0
Aluminum: 1.0
Carbon steel: 100
Iron: 5,000
Mu-metal: 20,000 to 50,000.
https://en.wikipedia.org/wiki/Permeability_(electromagnetism)#Values_for_some_common_materials

So applying mu-metal around big transformers of linear power supplies is going to shield it a lot more than thick aluminum chassis walls. Mu-metal shielding is already used by some high-end audio manufacturers.

And mu-metal sheets are cheap, about $20 per sheet on eBay. Using scissors, just cut strips of the sheet with width the same height of the transformer, and install a couple of circles around it. Some sheets have self adhesive, so it is possible to stick it to itself, so that it is easy to install and remove and compare.

In other words, a 0.004" (0,10 mm) thick mu-metal sheet has the same magnetic permeability as 78" (2 meters) of aluminum, worst case (20,000 relative permeability).

 

[maty]

With interference you have several ways of dealing. One is the use of a shield and another is to keep the proper distance. Better use both ways.

Like force at Newton's gravity law, energy depends on the inverse of the squared distance, that is, it falls exponentially.

About mu-metal, Cu, Alu, stainless steel... I wrote three very instructive posts in Diyaudio.com. First Watt M2 from Nelson Pass. Somewhere in the thread: https://www.diyaudio.com/forums/pass-labs/321925-diyaudio-watt-m2x.html

https://www.google.com/search?q=diyaudio-watt-m2x+mu-metal+cu+maty+tinman

 

[Matias]

Yes, and as seen on the permeability table, distance (air) is almost equal to aluminum, both vastly inferior to sheets of iron, steel or mu-metal.