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Review and Measurements of Hypex NC400 DIY Amp

Nathan_A

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Ask Hypex :)
These red LEDs are installed on all Hypex low noise voltage regulators. I personally always considered them as an indication of "looks like there is juice inside"
As a matter of "human factors engineering" they should be either banal (e.g. blue or white) or affirmative (e.g. green), and absent that they should be documented clearly (or more clearly, it's possible I just couldn't find the reference).

:shrug:

That said, I'm happy to know those blazing red lights lighting up those little round modules is normal.
 

Nathan_A

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The guidance is that the output wires should be inserted the same direction into each terminal. In your unit the negative wire is inserted into the negative terminal approaching from the opposite direction as the positiver wire is inserted into the positive terminal. Folks say that this creates a loop that can pick up interference. The cleaner method is to insert the negative terminal wire into the negative terminal approaching from the same direction that the positive wire is inserted into the positive post. Doing that is challenging with these thicker wires. I can't imagine that it will sound any different but it's better cable dressing.
Ah, gotcha. That's easy enough to do with a little effort. I'll pop the lids today and reroute them.

So far, I gotta say... can't really tell a difference between these NC400s and the Icepower 1200AS2 amp they've been swapped in for. Other than I just happen to have always wanted monoblocks, so I prefer them on nothing but inane vanity reasons. The Yamaha MX-1 seems to have a little more "oomph" in the bass, but honestly that could just be looser cone control masquerading as psychoacoustically satisfying bloom in the bass?

The biggest difference in sound, by far, comes from the upstream components. The best combo seems to be the SONCOZ SGD1 fed into the Parasound P5. Feeding the SGD1 directly using digital volume control sounds "thin" and "flat" no matter what amp is hanging off of it. Oddly when I used my Topping D50s straight into the MX-1, it didn't exhibit this. The P5 DAC itself sounds pretty good, even though I know it doesn't measure well. :shrug:

I fully expected the NC400s driven straight off the SGD1 to be my "end game" based on the measurements, but I guess it turns out I like a little color to my music. Now if I could just isolate which kind of color that is, I could optimize for that. Time to break out some DSP. :)
 

Julf

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I fully expected the NC400s driven straight off the SGD1 to be my "end game" based on the measurements, but I guess it turns out I like a little color to my music. Now if I could just isolate which kind of color that is, I could optimize for that. Time to break out some DSP. :)

Indeed. DSP is the best tool for that.
 

PaulD

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As a matter of "human factors engineering" they should be either banal (e.g. blue or white) or affirmative (e.g. green), and absent that they should be documented clearly (or more clearly, it's possible I just couldn't find the reference).

:shrug:

That said, I'm happy to know those blazing red lights lighting up those little round modules is normal.
No, red is the quietest LED - it is a noise issue, a technical issue. Low noise is needed for the voltage reference. If you do not like the colour do not look! They are not meant to be seen, they are a very low noise voltage reference.
 
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firedog

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Indeed. DSP is the best tool for that.
fully expected the NC400s driven straight off the SGD1 to be my "end game" based on the measurements, but I guess it turns out I like a little color to my music. Now if I could just isolate which kind of color that is, I could optimize for that. Time to break out some DSP.

IME, most people like a slight boost (1/2 db or 1db) in the 100-400hz or 200-400 hz range. Works well for most people with most speakers. Try it and see if you like it.
 

Herbert

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Could the the Hypex modules and power supply
being placed into the same chassis
with a DAC board, i.e Khadas?
Or a nogo because of the HF-noise emitted?
 

Matias

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pedrob

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My subjective opinion when I had nc400 was that they were not perfect in the treble region. But damn perfect in bass region. Subjectively.
Maybe this is confirmed now then here with the rising distortion in higher frequencies?

Amir, will you do subjective listening test?
Here's an interesting thread on performance of the amps.
https://www.stereo.net.au/forums/topic/100666-hypex-nc400s-are-they-musical/

I believe the upper register is fine but certainly nowhere as spectacular as the bass, and I wondered if my Denon AVR-X4300H was the limiting factor? I should mention I am using it as a PRE/PRO configured at 5.2.4.

After reading literally every thing I could find, I came to the conclusion the current batch do not provide the level of improvement I was after.

Amir has said the ability to switch off amps can turn recent AVRs in to excellent processors.

Mine doesn't have that option but I discovered turning ECO on can reduce the voltage to the amps by around 30%.
https://www.avsforum.com/threads/denons-eco-mode-what-does-it-do-exactly.2089586/

It helped and there was only a slight improvement, nothing like I hoped for.

Now the interesting part.

I opened up the case of my 4300 and physically disconnected the inputs to the power boards. The improvement was simply amazing and upper frequencies are now as stunning as the bass.

The only conclusion I can draw is that surround processing demands stunningly perfect, stable and clean power supplies and the inclusion of extra features and channels puts additional stresses on more compact power supplies.

I hope other members might be willing to do the same and have the results tested.

Here's images of the connecters I disconnected. Without removing any components, it is a delicate operation as space is tight. Front and Rear has been written on the images to help locate the position of the connectors.

I should mention that disconnecting the power supply connectors does not work as the Denon quickly shuts down.
 

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doug2761

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Here's an interesting thread on performance of the amps.
https://www.stereo.net.au/forums/topic/100666-hypex-nc400s-are-they-musical/

I believe the upper register is fine but certainly nowhere as spectacular as the bass, and I wondered if my Denon AVR-X4300H was the limiting factor? I should mention I am using it as a PRE/PRO configured at 5.2.4.

After reading literally every thing I could find, I came to the conclusion the current batch do not provide the level of improvement I was after.

I built NC400 monoblocks from the Hypex DIY kits and listening to these in comparison to my McIntosh MC402. My experience is that the Hypex amps are incredibly clear and precise. With the Hypex amps I'm confident that I'm hearing what the source is sending. For source I'm swapping between Chord Qutest or HiFiBerry DAC 2 HD. Sources are connected directly to the amplifier of choice when listening. My McIntosh is also clear and precise and I doubt I could pick one over the other with normalized listening volumes.

I built the Hypex amps based on the measured performance in the review on this site to see how an objectively outstanding amp would sound compared to my McIntosh. Well I think that they sound subjectively outstanding. Objectively there's nothing to worry about from a performance perspective.

I read a few pages of that thread you shared on the performance of these amps. I understand that folks prefer the euphoric of tubes or other set ups but that's just not for me anymore. I was listening to, "Beethoven Trios", Daniel Barenboim, Michael Barenboim, and Kian Soltani on the Deutch Gramaphone label from Qobuz over Roon in 48/24 and the clarity of the piano is stunning with the Hypex setup or McIntosh. To me that's a beautiful recording and the Hypex amps convey it truthfully.
 

pedrob

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I fully agree and I can't imagine ever replacing my NC400s.

BTW I've seen concerns the SMPS600N400 power supplies overheat. I had that issue and it was so sever they cut out. My solution was attaching finned heatsinks to the flat heatsinks, massively improving air flow ability and attaching externals fans to keep the air flowing. Perfect and the supplies never get too hot to touch no matter how hard and long the amps are driven. Long term reliability is virtually assured. Plus I believe the power supplies are more stable and the amps sound better.
 

PaulD

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No, that site is not interesting, it is subjective nonsense.

Now the interesting part.

I opened up the case of my 4300 and physically disconnected the inputs to the power boards. The improvement was simply amazing and upper frequencies are now as stunning as the bass.

The only conclusion I can draw is that surround processing demands stunningly perfect, stable and clean power supplies and the inclusion of extra features and channels puts additional stresses on more compact power supplies.

No, I think the conclusion that you should draw from this is that a double-blind test is required to verify that these effects actually exist rather than being the effects of bias. This is the standard of evidence ASR promotes, not casual listening tests.

I would point you to this post for reference https://www.audiosciencereview.com/...aphic-dac-available.17062/page-17#post-556223
When people do a blind test suddenly all of the "obvious differences" between the amplifiers disappear. It is a very sobering experience to be part of and I HIGHLY recommend taking the time to do it. Also worth reading is the PDF from that post https://linearaudio.nl/sites/linearaudio.net/files/Valves versus Transistors DCD.pdf

This has been proved so many times I am sorry to keep repeating that double-blind and level matched tests are needed to verify audible differences. Casual listening tests, particularly with amplifiers (and DACs), tell us basically nothing. What audible differences actually exist between amplifiers can be readily explained by their measurements (frequency response, distortion, output impedance, and so on).
 
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pedrob

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Well you're not going to like this, but too bad.

I guess it's like criticising a book or movie without having read it or seen it. Telling me I'm fooling myself is the height of arrogance.

To say subjective assessments are useless is simply bizarre.

Why would anyone need to be blindfolded? The only reason I can think of is their emotions are overbearing and influencing.

Perhaps the difference is I have developed to ability to shut off my beliefs/feelings/expectations and make logical decisions based on what I hear and not what I read.

Physically disconnecting the amps is only following Amir's observations. Why shouldn't I report on the difference?

Edit.

Perhaps this is easier to comprehend.

I have been listening to my unchanged system for months. If I make a change, I can easily tell if if the same, worse or better.
 
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restorer-john

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Well you're not going to like this, but too bad.

I guess it's like criticising a book or movie without having read it or seen it. Telling me I'm fooling myself is the height of arrogance.

To say subjective assessments are useless is simply bizarre.

Why would anyone need to be blindfolded? The only reason I can think of is their emotions are overbearing and influencing.

Perhaps the difference is I have developed to ability to shut off my beliefs/feelings/expectations and make logical decisions based on what I hear and not what I read.

Physically disconnecting the amps is only following Amir's observations. Why shouldn't I report on the difference?

People around here tend to use the call to the DBT as a way to lord their imagined superiority over other peoples' first hand experience, knowing full well the rigours of a properly conducted DBT are unavailable to all but a few folks out there.

Don't worry about it. It's unlikely simply unplugging the inputs to the power amp stages did anything audible at all. But that's not to say it isn't impossible. Unloaded (no speakers) power amp stages pull the same current regardless of whether there are signals running through the stages or not. Without speakers attached, there is no return path to PSU/GND/0V. That said, at certain high levels when amplifiers run into the supply rails, things can go awry and noise/PSU modulation/fluctuations can find their way into the front end supplies on averagely designed gear.
 

pedrob

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You could be right, but going on Amir's recommendation to turn amps off when used as a pre/pro I concluded the drain on the power supply would be greatly reduced resulting in a far cleaner and more stable power supply = less noise introduced into the processor/DACs. Power supplies are always going to be a compromise as available space diminishes with ever increasing features. Less stress on the supply is going to be highly valuable, since the cleaner a supply the better.

More features, more amps and higher amplifier wattage means a bigger power supply is required, but sadly the more features the less space is available. That probably explains why quality is diminishing not improving.

My view is the processor circuit needs a perfectly clean stable voltage, while amps need high current which can cause voltage drop and noise, especially with multiple channels. Hmm, maybe that suggests two power supplies are best.

I'm starting to think a shielded and isolated power supply in an external case is the next step to obtaining better results. Not sure they'd be accepted.

It could be that to get the best out of the NC400s, the processor needs to be as close as possible in THD+N, etc.
 

Sal1950

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Well you're not going to like this, but too bad.
I guess it's like criticising a book or movie without having read it or seen it. Telling me I'm fooling myself is the height of arrogance.
To say subjective assessments are useless is simply bizarre.
Why would anyone need to be blindfolded? The only reason I can think of is their emotions are overbearing and influencing.
Perhaps the difference is I have developed to ability to shut off my beliefs/feelings/expectations and make logical decisions based on what I hear and not what I read.
Poppycock
Sorry but this is a 'science' based site, not one of imaginary flights of fancy. You're not a super-human, able to shut-off the normal reactions to the mental bias we all are suspect to. You will hear what you expect or want to hear just like the rest of us.
What if I told you I heard a fuzzy top end and soft mushy bass in a comparison to amplifier X, who is right and who is wrong?
The only way to determine that would be using a DBT to first determine if they really sounded different at all. If there were repeatedly identifiable differences in the files, a close examination of the measurements of both amps will in almost all cases identify the inaccurate device.
Yes "a properly conducted DBT" demands a rigorous adhesion to the procedures that will result in repeatable, accurate results. This fact is true of any scientific testing, sloppy procedures will return sloppy answers. Garbage in, garbage out they say in computer science. But if your quest is to find the truth and not the answer you desire, you need to follow the science.
 

pedrob

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Well then, I guess you're accusing Amir of giving out false advice. At the moment I can't locate the link, so maybe you should ask if it exists.

If you don't appear to understand power supplies, so listen and learn. That's the real science.

In any case, all I'm saying is it worked for me, so why not give it a try. You just might be surprised. If not, no harm done.

Surely the ability to shut out prejudices is a skill that can be developed. Without even knowing me you shouldn't be jumping to ill-founded fake assumptions.

Who knows, maybe you are accusing me of being so stupid I can't tell when my system sounds better.
 
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PaulD

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People around here tend to use the call to the DBT as a way to lord their imagined superiority over other peoples' first hand experience, knowing full well the rigours of a properly conducted DBT are unavailable to all but a few folks out there.

No, it's about education, and acknowledging how we work.

Surely the ability to shut out prejudices is a skill that can be developed. Without even knowing me you shouldn't be jumping to ill-founded fake assumptions.

That refutes how our minds work. Sal is right, without a proper test this is MUCH more likely imaginary than factual.
 

Julf

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Telling me I'm fooling myself is the height of arrogance.

No. Not acknowledging the effects of expectation bias and the fallibility of your senses, and taking your subjective perceptions as objective truth is the height of arrogance.
 

Sal1950

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No. Not acknowledging the effects of expectation bias and the fallibility of your senses, and taking your subjective perceptions as objective truth is the height of arrogance.
AMEN.
In any case, all I'm saying is it worked for me, so why not give it a try. You just might be surprised. If not, no harm done.
Have you given your super-human hearing a test and listened to level equalized, bias controled DBT's to see if you could tell one amp from the next?
Everyone I know who have, has cast their subjective beliefs to the wind, so why not give it a try?
 

restorer-john

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My view is the processor circuit needs a perfectly clean stable voltage, while amps need high current which can cause voltage drop and noise, especially with multiple channels. Hmm, maybe that suggests two power supplies are best.

AVR manufacturers may skimp a bit, but low level circuitry and processing on all classes of product, even inexpensive ones, have separate PT tappings, rectification, regulated supplies and decoupling from the main HV amp rails.

The only time you'd see serious degradation in front end/processing performance is an amplifier running right at the edge into difficult loads. Idling along with no speakers/loads attached you will see no ill effects.
 
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