Saturday, 4 January 2020

An Inexpensive Hi-Fi Class-D Stereo Amp for the 2020's: Hypex nCore NC252MP (DIY Assembly)


Happy 2020 everyone!

A few months ago, I saw this video on YouTube that got me thinking about just putting together an amplifier to start off the decade of the 2020's. That project in the video involved the use of Bang & Olufsen's ICEPower 200ASC and 200AC modules, good Class D amps which I agree should sound great and certainly a worthy project!

But I wanted something potentially even better. Let's put together an amplifier that should perform with even less distortion, somewhat higher power, and this can be done even easier because you don't even need to string two boards together! "Better" does come with a little higher cost, but not that much more.

These days, many amplifier makers are assembling OEM modules of readily made components like the ICEpower. For example Emotiva's PA-1 is basically an ICEpower 300ASC in their enclosure. Not a surprise since this trend eventually happens with almost all commodity hi-tech products from CPUs (no practical desktop options beyond AMD and Intel these days), or motherboards (think ASUS, Gigabyte, MSI, ASRock, ...), or DAC chip (ESS, AKM, TI/BB, Realtek, Cirrus, Analog Devices...) coming from a select group of major manufacturers controlling the majority market share. This makes sense as a reflection of the maturity of products with increasing levels of engineered performance. At some point, the quality of the devices hits a threshold such that there really is no point devoting each company's own R&D dollars into something that can be obtained at a lower price with economies of scale from companies specialized in advanced design. While a company might put a significant spin on their device (like say throw in a tube input stage), the "heart" of the machine is based on the OEM specs. There is no need for a cottage industry of boutique companies making consumer CPUs that would never be able to compete in performance for example!

I'm guessing that's what we're seeing with Class D amplifier designs with Hypex, B&O/ICEpower, and the new Purifi Audio competing in the higher end, and the inexpensive chip amplifiers (like the old Tripath "Class T" or the TI TPA3116 device previously measured) targeting the lower end of price with generally lower performance as well.

[Having said this, on a side note, the fact that there are a number of boutique audiophile companies making things like resistor ladder DACs and old NOS DACs that objectively perform poorly, says something about the fact that much of audiophilia is NOT about actual engineered performance ("high fidelity"). IMO most of the chatter in magazines and various places is about supposedly-trustworthy gurus, their preferences, opinions and hype that builds from there. This is also demonstrated in the "fashionable" and meaningless audio trends over the decades. In the 2010's, one obvious example is the digital filter options offered by DACs culminating in the most silly of "formats" called MQA that used various weak filters to "render" final output with ultrasonic artifacts as if this represented actual decoded high samplerate content.]

The Hypex nCore NC252MP is one of these OEM modules available for builders to incorporate into and sell their own products with:


The amplifier module was announced back in 2016 and I believe became available in quantity starting in 2017. This single module contains everything in one place for a 2-channel dual-mono amplifier (rated 250W into 4Ω, 180W into 8Ω, at 1% THD, 1kHz signal) including input buffer and power supply. All you need to add is an enclosure with the proper input and output connectors, power switch, and power LED for basic functioning. Already, this component is at the heart of devices like the IOM NCore Pro (€550), the Nord One MP NC252 (£579), March Audio P252 (US$895), and Rouge Audio Studio N-4B (€655.00). The best deal I've seen is for the Audiophonics MPA-S252NC (€440); not sure how much more it would cost to ship to Canada though if I were to buy it from France and had to pay for border duties.

As we'll see, it's very easy if you're interested to assemble a device with the same sound quality yourself. The trick though is to find one of these OEM amplifier modules to buy! At this time, they're not widely available to DIY builders, unlike the ICEpower devices in the video above available from Parts Express or Hypex's own NC400 modules meant for the DIY market.

As I was wandering around looking at online sales in late October, I was able to find a seller on eBay who had 15 of these modules available at <US$300 each; I happily snatched one up. Then I went to Ghent Audio and picked up one of these "DIY Stereo Case-kit for Hypex NC252MP" enclosures. I went with the easiest install option - Type C with solderless parts (US$150, even less expensive if you want to do a bit of soldering):


Ghent Audio's kit as you can see above is quite simple. It consists of 4 main metal pieces for the top, bottom, back, and the front plate which can be of different colors. Good quality materials, nice connectors, professional workmanship with smooth rounded edges, and precise lettering. All the screws and cables you need. The enclosure feels robust, slightly wider than deep - I like this box!

In total then, before applicable taxes, we're looking at less than US$450 (around €400, £330) for this DIY kit.

Let's Put This Together...

Note that Ghent Audio sells a number of enclosures for different amplifier modules. These instructions might be useful for similar enclosures even if you don't have the Hypex nCore NC252MP as I have here.

DISCLAIMER: Shock hazard warning. We're assembling a device that plugs into your home wall outlet! Please make sure you understand what's going on, you're comfortable with doing this and use your own discretion. If you have any hesitation, just buy one of the pre-assembled units with service and warranty as well. I'm not responsible for any damage or injury that might occur in taking on the project...

1. Get the bits and pieces ready. You'll need a screw driver set with Philips heads (I think there were a couple screws with Torx head used) for the screws in the case kit and of course a comfortable work space. It should not take more than a couple hours. I used my silicone repair mat for these things. You'll also need something to cut wire insulation with and wire stripping tools (not shown):



2. Install the LED indicator light circuit board with some Philips screws in the kit:


Although you'll notice in the picture above, I have the footers attached, it's smoother to do this later in Step 5.

3. Stuff the rear panel with the 2 XLR connectors, IEC AC jack (basically pushed in and clicks into place), and speaker binding posts:


4. Secure the Hypex NC252MP amplifier module to the enclosure bottom plate:


Note that there are 11 screws to secure. Also, optionally, you might want to apply a thin layer of thermal compound (something like the Arctic MX-4 typically used between CPU and cooler) as an interface between the bottom of the amplifier board and the case which serves as heatsink. Don't apply too much; I probably covered <50% bottom surface of mine. Also, make sure not to get the paste inside the screw holes:

11 Philips screws to secure the amp to the enclosure. Again, I don't recommend putting the footers on yet unlike in this image until the next step!
5. Now it's time to put the footers on. Notice the longer silver screw included in the kit is used for the ground lug threaded through the right rear footer. Just use the nut to keep that footer loosely in place for now. We'll tighten that when we secure the ground connector cable in Step 9.


6. Strip back the XLR Input cable and connect the wires to the XLR connectors.


I removed back about 2cm of the thick insulator and about 5mm of exposed wire is enough for the connection. Also, there's quite a thick amount of ground copper strands; I cut off the excess and just inserted ~50% of those strands into the XLR connector.


Remember that this is the "non-solder" kit so it was easy to just tighten the screws to secure the conductors. Note the orientation of the wire colors; for my kit - blue = positive pin 2, clear = negative pin 3, and ground pin 1 by modern convention (some devices invert +/-).

7. Screw on the backplate.


8. Now we can attach the loudspeaker connectors, XLR input connectors, and the front LED connector to the amplifier module with the kit harness cables for the NC252MP. Should be self explanatory with this picture:


Have a peek at the PDF datasheet to look at the connector pinouts if you need to verify orientation.

9. Let's now connect up the power switch and safety ground. Remember, it's important to get this done right and especially make sure the ground lug is secure.

Let's start at the lowest connector and ensure that the ground is securely connected to the chassis:


Make sure the nut is tight! Remember, this is right over the longer silver screw used for that right rear footer in Step 5.

Now let's connect the IEC AC Neutral and Live connectors to the power switch:


And finally, connect the power switch to the amplifier module:


Double check to make sure the power connections are pushed in fully and the ground cable is secure. (Might want to use a multimeter to ensure continuity.)

10. Yippie... The electrical stuff is all done. What I did now was a test to make sure it turned on before putting the top and front panels in place to save the hassle in case I had to open it up again. Since the enclosure is still open, remember to be careful if you're going to plug it in like I did.


Turned the rear power switch to ON position and plugged it in without touching the case to make sure the front power LED lights up as it should.

First time turned on... It's alive...
If it looks good, then unplug from the wall and let's finish the case assembly. Otherwise double check the wiring if the power light doesn't turn on!

11. Now with the box unplugged of course, slide on the top cover and we can connect what looks like little silver bars to the front; these hold the faceplate in place:


Attach the front plate. You'll find a couple little screws and a small Allen key provided in the Ghent kit to secure the front plate from the bottom:


12. Congrats... Now you're free to hook this up to your system, perhaps open up some alcoholic beverage of your choice and enjoy some music :-).

Connect up your speakers, XLR cables to preamp, favourite IEC power cable, and have a listen!


When I ordered the enclosure from Ghent, I actually asked for a gold/"champagne" faceplate to make the amp look a little more like some of the "classic" audio products of yesteryear as I wanted to change up the look of my system a bit. It has been the black motif for a few too many years ;-).

As you can see, Ghent Audio mistakenly sent me the all-black kit above, but quickly remedied the issue by sending me this front plate:


Cosmetic color change of course. Notice that with the "champagne" / gold faceplate, the "nCore" text shows up more distinctly.

And here she is with the gold faceplate on:


It looks pretty nice to me in real life, especially when the white LED is turned on. It's small compared to my much larger Emotiva XPA-1L monoblocks so the color will stand out in my system but not too "in your face". Dimensions: 21cm x 19cm x 8cm, only 5.8lbs.

Here's a size comparison with my Emotiva monoblocks stacked to the right:



So how does this thing sound???

The Hypex Class D amps have generally been well regarded for their sound quality. Likewise, for more objective folks, measurements are generally excellent and this specific amplifier module performed quite well on the Audio Science Review testbench. Of course I'll run my own tests to see what I get from this specific module and enclosure build.

Subjectively, let's be clear... This does not sound like the inexpensive Class D Yeeco TPA3116 "chip" amp. It's not "airy", the noise floor clearly is much better with essentially no hiss coming from the speakers with volume turned way up. It sounds more authoritative with more "oomph" behind the bass and clearer treble.

Does it sound much different than the Class AB Emotiva XPA-1L monoblocks? No. They seem to sound about the same and can both push the volume of my speakers beyond comfort. Without a proper switch, I would not be able to perform an instantaneous A/B comparison of the amps. Remember I have a powered sub so what differences I might hear would be mostly the quality of the upper bass, midrange and treble. The impression I have is that the Hypex achieves a "sweet" treble that's detailed but not harsh. I was listening to the Wicked (2003 Broadway Cast) (album DR9) recording the other day and really enjoyed the clarity of the beautifully done duet between Kristin Chenoweth and Idina Menzel in "For Good". Like what I find typical of low distortion amplifiers, I can pump up the volume without feeling dysphoric or fatigued. A track like Breakage / Jess Mill's "Fighting Fire" (Loadstar Remix) off Getdarker Presents: This Is Dubstep 2011 with its deep, tight propulsive drive even with the subwoofer turned off is a nice demonstration of subjective "speed" and control the amp has over the speakers - no "flabby" bass. By the way, notice the excellent "surround" effect as well sitting in the sweet spot on this track (especially with the room correction DSP turned on in my system).

I have not noticed any amplifier "break in" period or change over the weeks (some people have expressed that Hypex amps improve over 50 hours). This is solid state technology after all and I expect any significant "break in" to be done within a few hours and changes after that might actually be "break down". If I did hear a change, it's much more likely to do with my own psychological expectations - the brain is certainly not solid state technology :-). [Would be nice if certain reviewers like this might consider this likelihood.]

Bruno Putzeys in his 2011 whitepaper on the nCore technology stated that: "If you want to wax lyrically about all the different sonic colours and textures amplifiers can add to the listening experience, there’s not much to say." Agreed. This is high-fidelity. There should not be much to speak of when a device is simply sounding "transparent" operating within technical limits; better to just spend time listening, enjoying the music than trying to poetically make up stuff about tonal textures and the like unless you're purposely seeking some form of coloration. Quality of textures, timbres, dynamics, "speed", sense of clarity these days should be the result of the artist's creativity, decisions made by the production team, and skills of the recording engineer rather than any additive effect from an otherwise good DAC or amplifier unless one chooses to do so (eg. EQ, DSP, non-linear possibly tube amp/preamp/DAC). Obviously speakers and rooms make a huge difference.

As you can imagine, at <$300 for the stereo module, this is not the top-of-the-line Hypex amplifier. If you're looking for more power out of 2 channels, consider building with the Hypex nCore NC502MP module rated as 2 x 500Wpc into 4Ω. Again, this is an OEM module so not easy to find but I've seen it on eBay for <US$375, Ghent Audio doesn't have a pre-built case for that module at this time so you'll have to look around.

For the "high end" which will provide more power and even lower levels of distortion, building an amplifier using a couple of Hypex NC400 DIY modules plus switching power supply and enclosure will generally run you ~US$1000+. There's also the Hypex NC500 module for OEM builds such as in the recent ATI AT54XNC amplifiers. In 2019, we also saw the release of Purifi Audio's "Eigentakt" 1ET400A amp module for consideration. These can be bought online for ~US$300 x 2 for stereo pair plus you'll need to add a power supply and case; similar price point to Hypex NC400's (check out Mitch's article on some Purifi goodies recently).

As someone who believes that there is such a thing as a "good enough" level of fidelity, it's quite possible that a ~US$450 amplifier like this that is fanless, power efficient idling at <15W (based on my Kill-A-Watt meter, compared to something like 50W idle for my Emotiva XPA-1L single channel monoblock), runs very cool, and in typical use only sucks up ~25W at the SPL I listen to, could very well be my "reference" amplifier for much of the 2020's! I think it's quite a good deal. Let's see what my measurements show, but I don't think this amplifier would be the weakest link in the sound system (speakers and room more than likely as usual).

At some point, as much as some audiophiles want to believe that they're always hearing better and better sound (ironic because as we get older past our prime, our ears get worse!), we need to contend with the idea that technology has already matured to the point where there really is no further audible fidelity to achieve. Beyond the point of transparency, we're simply left with subjective idiosyncratic preferences. Assuming the objective measurements are better than my Class AB Emotiva XPA-1L amps, this little amp is a nice reminder of what technological progress looks like. Smaller, lighter, more efficient, less expensive to purchase and run; and sounds just as good if not better.

One feature that I would have liked is a 12V trigger in the case kit to turn the amp on like I have with the Emotiva XPA-1L monoblocks. No worries, a simple substitute is this US$25 Iot Relay Power Switch which I'm using currently. Just connect up the trigger output from my preamp to the +/- green connector and plug the amp into one of the "Normally OFF" receptacles:

Iot Relay Power Switch - trigger connected to turn on amplifier when preamp activated with remote.
Ohhh... Look, an "audiophile" thick power cable for the amplifier - might be worth a measure with amplifiers ;-).

I think this is a nice start to the 2020's. We'll certainly talk more about this amplifier with measurements and such in the days ahead.

Have a great January everyone!


Measurements now published.

49 comments:

  1. Hi Arch, happy 2020!
    I see the Audiophonics assembly is down to 391 Euros (no VAT)... very tempting.
    Looking forward to your measurements (although Amir's are a pretty good selling point.)
    I'm currently running 2 relatively dated (and hungry) power amps by Quad and Hafler for my MCH setup, and Class D looks like a very interesting alternative. Might even pay for itself.
    Mitchco's project looked a bit daunting, and the Hypex 400s are a bit pricey, so I'll be watching this space as always for your measurements and observations.
    All the best
    Phil

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    1. Hey PhilFromTO,
      Great deal on that Audiophonics at <400€! Obviously will need to look into shipping and applicable taxes (TO = Toronto?).

      Yeah, I've done a little bit on the measurement side already and what I'm seeing correlates nicely with Amir's IOM unit (including the ~420kHz ultrasonic switching noise which I'll show). In fact, preliminary results show that this build on my testbench has lower 60Hz hum and harmonics so my SINAD is slightly better at 5W into 4Ω.

      Of course, as reasonable people, I hope most of us appreciate that when we're looking at SINAD values >90dB, other than bragging rights, it's gonna be hard justifying that such levels of THD+N will result in appreciably higher levels of "joy" when listening to music ;-).

      Yeah, I would certainly consider looking at Class D these days for the size, price, and power utilization. Depending on electricity costs, it could take awhile to pay for itself of course. Overall good not to waste energy...

      I know Mitch is quite impressed by what he heard with the Purifi and I'm definitely intrigued by what he's hearing/measuring with those mid/bass drivers. Great to see guys like Purifi pushing the envelope of no-nonsense engineering and increasing performance at reasonable costs... Ultimately advancements in technology brings real value for all of us.

      Delete
  2. 43 EUR to Toronto... what the heck, I'm in.
    I'll keep you posted, might even try some PA measurements myself.
    P

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    1. Ohhh...

      Not bad at all man! Lemme know how it goes and taxes and such coming into Canada. I've not personally purchased anything big from Europe sent here to Vancouver, so would very much be interested in your result. (I think the largest purchase was the Linear Audio Autoranger kit.)

      Delete
  3. You'd never make it as an audiophile reviewer

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    1. LOL. Thank Heavens AJ that my income isn't derived as part of the purely subjective audiophile advertorial mechanism :-).

      This also brings up a thought I had a few months ago when I was reading this book. Obviously I'm not saying this applies to all since I have met and spoken to thoughtful and insightful writers over the years. Definitely worth sitting back and pondering though...

      Delete
  4. Awww, him dont like MQA. Waaaaaaaaaa

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    1. As you know, me dont like MQA longtime!

      https://audiophilestyle.com/ca/reviews/mqa-a-review-of-controversies-concerns-and-cautions-r701/

      No need to cry! It's great that this abomination has not taken hold and will be a joyous occasion when audiophiles and music lovers can finally say goodbye to something so unnecessarily ugly, I trust at some point in this new decade! ;-)

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  5. Interesting little device. Considering how economy of scale works, one can hope that eventually the higher power modules will become more affordable and we'll see more class D equipment with exceptional performance at well under the $1000 price point. Prices for the cases seem highly variable too; seems like they should be much cheaper, especially when you have just a kit. It would be nice if there's eventually enough competition to bring the price for a complete unit down to the ballpark of some typical ready-to-play devices of comparable performance; I have no problem soldering and assembling a unit if it's a good value.

    I'm totally not buying into any "break-in" philosophy, though. The only thing that could possibly affect the performance of a properly-designed amplifier is the need to form the electrolytic caps when you initially power it up. If the manufacturer has at least run the module for a few minutes to verify that it's assembled properly, then the only thing you need to worry about is infant mortality of the parts which would probably be decisive and permanent.

    The listener can certainly become accustomed to a system as they listen for an extended period of time, but as you note, that's psychology issue, not a real change in performance. ;-) Also, unless they level match, the perception of louder=better will overpower any possible true sonic differences; I've proved to myself via ABX testing that it's possible to hear level differences of <1 dB as sound quality rather than loudness. Stereo salesmen have known this trick for decades.

    Looking forward to seeing the measurements for this amp!

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    1. Thanks for the note Greg,

      Just like the advent of high resolution and jitter-free asynchronous interfaces in DAC technology that over time eventually infiltrated into the sub-$100 market in the 2010's, if I were to guess, I see these Class D amplifiers of high quality expanding and taking on a huge chunk of the audiophile amp market this decade.

      With a price point like this Hypex module already very much affordable, it would be silly I think for enterprising companies not to take that leap and raise the level of overall quality for all audiophiles to enjoy! For me, the need for "high end" (aka high priced) DAC or a "high end" luxury digital streamer is dead as it applies to sound quality. A good quality Class D amp with all its positive benefits and objective levels of engineered performance hitting price points where essentially anyone who desires one can afford should do the same for the amplifier market I think.

      Class D has been with us for quite awhile now. But seeing the level of performance enhance in the last decade I think should definitely put it on the radar for audiophiles and music lovers to take notice. And especially start shedding off some of those preconceived notions of the past about this technology...

      Delete
  6. This annotation has served as motivation to create a thread where I comment on different amplification possibilities for the GR-Research Studio Monitor speaker (Danny Richie).

    https://www.audiocircle.com/index.php?topic=167210.msg1775096#msg1775096

    - maty -

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  7. There are power strips that have 1 master outlet and several slave outlets. The strip senses when the master is turned on and powers the slave ones with no trigger cables needed. Plus a few always on outlets. Makes for a very simple and cheap home theater automation. :)

    Example
    https://www.amazon.com/Tripp-Lite-Protector-Protection-AV88SATG/dp/B0084PKCGA/

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    1. Thanks Matias!

      Had not seen these around over the years but will definitely keep my eye out on situations where these will help save energy and allow "master" control!

      Delete
  8. Archimago, good to see a common sense take on Class D amplification. I'm currently using my 1987 vintage Yamaha receiver for my little bookshelf speaker system that I have set up on a credenza. I have been researching the different Class D amplifiers available as I would like a smaller footprint component purely for aesthetics. And as you would expect in the audiophile community I have found there are some very strong opinions on Class D amplification. The most prevalent opinion amongst ardent subjectivists seems to be that all Class D amps sound sterile and harsh. I recently read one forum thread in which the purchaser of a Hypex NCore 125 amplifier claimed the only way to reduce the “brightness” of the amp was to use his “warmest” RCA interconnect cable. And on the objectivist side I have read endless debates about SINAD and THD measurements and what is audible to a listener. I look forward to the measurements and more of your opinion on the sound of the amp.

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    1. Thanks Joe,
      Will do what I can ;-).

      I've seen that word "sterile" come up countless times all over the place. It almost seems like a catchphrase for anything resembling "digital". CD's were "sterile", no matter how good hi-res digital is, it's still "sterile" to those who never got past LP or reel-2-reel levels of resolution (not all but much of which to my ears sound "dirty"/noisy as I mentioned back in September when I visited RMAF 2019 and those rooms with mainly vinyl playback). I seriously don't know what to think anymore when I read articles and editorials from older folks who never got past the idea that audio reproduction fidelity (not to mention convenience and reliability) has way surpassed their tubes and turntables.

      Look, I don't mind that some writers look back on their childhoods and early adulthoods to relive experiences, memories, and exploits, but surely as a hobby we also need to look forward. To explore and advocate for ways to bring quality to new generations of music lovers because ultimately it is the music itself which gives us joy and fulfillment. As a hobby, if "we" see it as our mission to introduce real performance and value to newcomers and the younger generations, we will have contributed in a good way.

      Subjective ruminations and sentimentality towards expensive old stuff, or veneration of overpriced, even snake oil goods created mainly for the purpose of "financial extraction" because someone subjectively said it's "good" is simply the wrong way to go with this hobby IMO.

      Delete
    2. They aren't wrong.

      sterile == lacking noise and harmonic distortion

      Sure, it's ironic they use sterile as a pejorative, but they are referring to a real phenomenon.

      The "UD" in "FUD" comes in when they use "warm" as the opposite of sterile, ie. the presence of noise and distortion. Obviously warm has nothing to do with sterile. Grungy, septic, purulent are correct. Ok, ok... musky.

      "This new tube amp and turntable pair have the musk of a Parisian beatnik after he pushed his comrade's Citroen 12 blocks home in the rain. If you like that sort of thing."

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    3. Allan, this may be the best thing I've read so far on this blog!

      Delete
    4. LOL. I agree with Greg... Well said Allan.

      The choice of the word "sterile" is a subjective one to try to inject a pejorative spin on what's more properly described as "clean". As if the device's noise floor can be "too low" - a ridiculous idea!

      Obviously for those interested in high fidelity, one must start with a clean slate. And the cleaner (down to audible thresholds), the better. From there, allow the music itself to impart whatever warmth, grunge, and "musk" one wants the equipment to reproduce...

      Delete
    5. It's probably been mentioned on this blog before, but it sort of meshes with the unwillingness of "audiophiles" to suffer tone controls in their system - choosing instead to impart the desired tonality by exchanging amplifiers, phono cartridges and DACs. ;-)

      I recall Bob Carver's Amplifier Challenge, where he emulated the sound of a very expensive Conrad-Johnson amplifier by introducing deviations in the frequency response of his M-1.0 amp.

      Delete
    6. Thank you! I'll be here all week!

      Tip your servers.

      Delete
    7. gregdunn, my old Yamaha receiver has both tone controls and a variable loudness control, both of which I use. In my search for an affordable Class D integrated amp, I am not finding too many options (beyond the really inexpensive Chinese amps) that include tone controls.

      Delete
  9. What a great project. I'm happy to see my video helped influence you to do a project like this. Looks like a fantastic build!

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    1. Thanks man,
      Nice project with the ICEpower and great blog as well!

      Delete
  10. I have a small class D amp I've been using on my desk paired with a set of modified Sony MH-150 bookshelf speakers that I installed a proper crossovers into. I enjoy listening to my music with it as it has less distortion and noise than my old class AB pioneer amp that I gave away.

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  11. Very nice review and DIY work.
    I own the 8 channel NC502MP x 4 from Apollon which runs pretty well for more than a year.
    Looking forward to your measurement !

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    1. Yup Dust,
      Should be able to get those measurements up this weekend ;-).

      Delete
  12. Did they miss the decimal point of the THD? Idk if the human ear can tell I want 0.1 or 0.01 THD at full power.

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    1. This too is an important question, right Fanplant?

      How much THD do we really need? In the days ahead, I have plans to explore this question...

      Delete
  13. Yep, electronics knowledge never stops improving even if some people believe that the 'old way' is the only way to go.

    Those Hypex nCore amplifiers are just pushing the old paradigm that only 200 pounds megabucks amplifiers can be great. I bought a NAD M27 built on Hypex modules because I need 6 channels of amplification for my active 3 way speakers system and because I wanted to get out of the pain of having 3 big stereo black boxes. Never regret it, even if it is "officially" a home theater amplifier, it sounds absolutely great ! Seven 180 watts channels packed in a box size of a 20W class A, thanks to class D, and no more ground loops problems ! It is also interesting to read John Atkinson comments and measurements of the NAD M10 integrated amplifier (also built on nCore) that he compared to a $16K Vandersteen amplifier with no that much difference... More than ever, megabucks amplifiers are for those who wants to show how deep are pockets, but it is certainly no longer absolutely required to have high end audio.

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  14. A question on how you can connect these to Speakers.
    Source -> NC252MP -> Preamp/Receiver with preout? -> speakers?

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    1. Pretty straight forward... So for me it looks like this - I use Roon to stream to my Oppo UDP-205:

      Computer (Roon) --> ethernet --> Oppo UDP-205 --> XLR out --> Emotiva XSP-1 preamp --> XLR out --> NC252MP build (see the back panel) --> banana plug speaker cables --> speakers

      If you look at the back panel picture, the Ghent enclosure uses standard binding posts so I like using locking banana plugs. You're free to even just attach bare wire if you want.

      https://blog.kantoaudio.com/tech-tuesday-how-to-connect-speaker-wire-to-a-binding-post/

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    2. Oh yeah, one more thing. Feel free to use female RCA --> male XLR adaptors if you need like these from your pre-amp:
      https://amzn.to/2N5dDx6

      Remember, this is a power amp so you'll need something to attenuate your volume! Don't directly send a line level signal straight from a CD player/source without attenuation.

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    3. What can I use to attenatuate the volume? I am thinking of buying the ghentaudio kit and the NC252MP amp. I plan to buy and power the Dynaudio Emit m20 with this.

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    4. Why the preamp, Arch?

      Oppo and Roon both offer volume control.

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    5. Most people use a preamp because they have multiple sources they want to switch between, along with the volume control.

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    6. OK yeah, that turn-table... I keep forgetting about analogue sources. :)

      OTOH, if one has gone full digital, it's amazing (well, to me) how Oppo is essentially a modern-day integrated receiver. They're like the Smart Phone of hifi... one device replacing a cabinet-full of kit.

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    7. rance, as Allan noted, you could just use volume attenuation with your digital source. Just make sure it doesn't reset to 100% and you blow the speakers at full volume!

      Speaking to the need for a pre-amp in my system, other than having multiple sources for switching, remember that my 2-channel system is part of my multichannel setup as well.

      The preamp has a HT-bypass function that allows me to route the 2 front channels of my surround output from the AV receiver to the amp and speakers.

      The Hypex amp sounds great with movies as expected.

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  15. Some really interesting gems in there...

    Nice silicon repair mat.

    2 channels at typical listening levels uses 1/2 the power of one monoblock at idle? Wow.

    On the enclosures, I wonder how hard (which probably means it's already been done and a half dozen YouTube how-to's made :)) to mod a used enclosure. I remember that was a thing with iPods & furniture-size console stereos for about a hot minute. I don't think it took that long to soak up what was left of the nation's stock of 60 yo console radios. Some 70's wood grain and gold lettering with a pair of VU meters... I could get into that. :)

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    1. Seriously, can you imagine it.

      Right in my neighborhood, even. But 200 bones. And the guy used "rare" in the title so forget about him dropping the price 50%. Not that I'd be able to bring myself to butcher it even if he did.

      For any late comers, here's a more permanent link. But photos don't do it justice like the guy's at the first link.

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    2. Hey Allan, that would look awesome to gut out an old (ideally broken!) 70's receiver, drill a few holes, make sure there's enough contact with metal for heat dissipation. Use the old VU meter to make it dance with the music :-).

      Even if the front looks old-skool, make sure to get some updated XLR connectors and speaker binding posts out back... No fan of the old 70's speaker wire clips.

      I'm sure someone, somewhere has done it. And let's just say, this should sound better than anything from that era. As usual, "better" must be evaluated through a person's subjective lenses ;-).

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    3. New idea. Cassette recorder. Line-level VU meters, guilt-free butchery, better visual match with the Oppo 105 I already have.

      Hmm, or maybe reel to reel!?! (Could one of those ever be guilt-free?)

      Help me out bros. Seeking peer-group approval. :)

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    4. Alright bros, wish me luck. Pioneer CT-F700. She's much bigger than I expected. But hey, $20 off eBay from a person that lives in my own neighborhood. What are the chances of that!

      Now for the baddish news. VU-meters just sit there until you move either of the input or output knobs, then they all peg at once. But as you can see I'll have plenty of room to play with.

      Initial thought Chromecast Audio -> JDS Atom -> selectable between Line Outs or Headphone jack (won't really need an amplifier for a while as I have self-powered monitors.)

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  16. I have a March Audio p252 (Pi streamer & Chromecast-->RME->p252->Harbeth SHL5+). It replaced a huuuge Adcom 5802 that I had for years. With my son's help, I A/B'd them. Results described here:

    https://www.audiosciencereview.com/forum/index.php?threads/best-class-d-or-cool-running-amplifier-to-try.8110/page-8#post-213633

    As I said there, ultimately I found I couldn't tell the difference, even though I thought I perceived something initially, something that corresponded to all the words I'd been reading, of course.

    I don't know why people are so focused on the higher power units. This is quite a bit of power for most home set-ups. I don't see any problem with headroom. Harbeths are medium-to-easy load, for sure, but less efficient than, say, Revel F208. And I love that it doesn't heat up the room.

    IMO, engineering class D to powerful, full-band, transparent, efficient, and inexpensive units like this is one of the few really significant innovations in audio in the last decade.

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    1. Thanks for the note and link, Andrew,

      Great to hear from someone who has actually taken the time to do an A/B comparison rather than the typical audiophile reviewer comment/opinion/testimony of being able to hear the difference as if one has the auditory acuity, much less memory to be able to reliably evaluate the sound of what should be already high fidelity products like this and the 300W Nelson Pass designed Adcom GFA-5802 monster! (As usual, I'm sure some people would object to me saying so...)

      I agree, the amount of power on tap here with this little Class D unit is quite a bit already and likely more than enough for the vast majority of 2-channel music lovers.

      Speaking of running cool and not needing A/C running as per your post, I hope things are OK where you are in Australia.

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    2. Glad to see others doing A/B testing on amps. It's possible for amps with poor damping factor to show audible differences with difficult speaker loads and that of course should be measurable too. There used to be a switch box (expensive but well-made) which let people do a full ABX test on electronics, but not many were built. These days, something like it would be really helpful to help us know the real state of affairs. A/B testing preamps, DACs, and such is not as challenging from a mechanical standpoint but switching the amp/speaker interface is a lot of effort, especially when matching levels which is critical.

      Bob Carver wrote an article for AUDIO Magazine in Feb. 1972 about the utility of high power amplifiers for the home. True, he was hoping to breed interest in his new Phase Linear amps, but he showed some good info about how much power is really needed for clip-free reproduction of music at even moderate levels. The necessary voltages to avoid clipping (audible or not) were pretty high with even normal acoustic suspension speakers of the era.

      The real advantage of high power amps at home is not the ability to play loudly, but the ability to play at decent, non-damaging levels without constraining peaks. I have a pair of older Magneplanars which are certainly not efficient. I've found (via monitoring with scope and peak meters) that at a very restrained listening level I'm still asking the amps to provide 50-100 Watt peaks. At normal levels, they frequently show momentary voltages which translate to nearly 300W (the amp's rating). The speakers are almost perfectly resistive in the audio band so this is real.

      Would I notice the infrequent clipping of a smaller amp? I don't know. I do like knowing that I have as much power as I need and can run the amps at a comfortable level where they are very clean and don't clip. I have heard some speakers, including mine, get really unpleasant at higher levels using smaller amps and I can't say for sure where the issue lies; but the fact that they sound cleaner with a larger amp indicates to me that there was clipping or something amplifier-related at the root of it.

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  17. Great writeup! I did this exact same build about a month ago and I love the little amp. I wish a similar build existed for an XLR out dAC/Peamp. Or I may just have to get a SMSLSU-8 to pair with it.

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  18. I bought one. US$483 delivered. Took a week to arrive (totally on-schedule). Came with a European power cord (there was not an option to select a North American one). Not a big deal; I have plenty of IEC power cords.

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