Purifi Class D

[PYP]

7 minutes ago, barrows said:

IMO,  this test appears to be fine for a comparison within the given system context.  As the input buffers used on the Nilai are a discrete implementation, optimized for the Nilai, I would give the Nilai the theoretical edge there.  The difference with using discrete components vs. "using all in one" IC based circuits, is that a talented designer has much more flexibility in tuning the circuit for the task at hand.  In addition, Bruno Putzeys has mentioned in interviews that the Purifi Eval 1 input stage was not designed to be the best possible input stage for the Purifi module, and that he would do something different if were designing an input stage for the Purifi module if he were trying to make the "best" possible complete amplifier.

To get an idea what the "best" possible, Putzeys designed, input stage might look like, we could consider the input stage on the Mola Mola Kalugas (designed by Putzeys): this is an discrete based input stage, using his "single-ended/differential" circuit approach.  This design takes a balanced input, converts to single ended, and then back to differential to drive the module-in this process it also reduces overall input stage noise by 6 dB.  What approach does Hypex use with its discrete input stage on the Nilai... they do not really say: it might just be a discrete, single, opamp, style circuit, or it might be something else.

I find it a bit disappointing that more manufacturers are not getting a bit more creative with the commercial class D amps they design and sell.  I would like to see more Purifi based amps with unique input stage approaches, using discrete components, and even tubes.  I feel like there are a lot of cookie cutter builds out there, but few really well though out approaches.  It is clear that one can do better than just using a single opamp (circuit, IC or discrete) based approach, at least the DIY Neurochrome buffer is a bit better thought out than just a single IC, but where are the really cool, discrete input stage versions?  

On the Nilai's "newness", it is pretty clear if one believes Hypex's marketing materials on the Nilai, that it is indeed a new design-certainly based on what has gone before, but with refinements and improvements over Ncore.  What those improvements are... well we do not know.  But as with Purifi, it is likely that the improvements are in the control loop.  I am supposing that Hypex did not sit on their hands when the Purifi design was released.

I found the high frequencies are slightly more refined (more extended, and smoother) with Purifi vs Ncore-it is a small thing...  I wonder if Nilai has a similar improvement?

what he said.   My own assumption is that both companies have achieved a new level of lower distortion that is significant and can be heard WHEN the input stage is of a similar quality to the amp module.  

 

Since Bruno Putzeys has made the point that the input stage governs the sound, then differences should be in this implementation.   And, since the final sound is about personal preferences, there is not some kind of objective "best," that determination is made by the individual listener. 

 

As @barrows said, the consumer is best served by companies that do the extra work to design a discrete input stage (as one reviewer cautioned in the video, the amp modules are so good that the temptation will be to provide a box and a markup in price rather than further improvements).  

 

Having had two iterations of the original Ncore previous to the Kalugas, I was mystified by the size of the improvement from DIY, to NAD, to Mola Mola using very similar amp boards.  Until I understood the role of the input stage in the overall sound, it made no sense to me that this kind of improvement was possible (not saying it was the ONLY difference).    

 

This video explains a bit more about the Nilai:  https://www.youtube.com/watch?v=B1exMwmlvRg   

 

 

[ericuco]

For those looking for commercially available (vs DIY) options, there is the Rogue Audio Dragon stereo amp that has the Hypex NC500 modules with tube input stage and large power supply (weighs 38 lbs).

 

The Dragon is an improvement over my previous Nord mono block amps based on the same Ncore NC500 modules.

[Allan F]

4 hours ago, Jud said:

Yes, I understand the Nilai iteration of the Hypex design came later, but Putzeys designed Purifi after Hypex. So I suppose one could think of either as the latest technology.

 

But, Putzeys left Hypex before he designed the Purifi so, presumably, he did not participate in the design of the Nilai. If so, the latter would be the latest technology.

[mocenigo]

1 hour ago, Allan F said:

 

But, Putzeys left Hypex before he designed the Purifi so, presumably, he did not participate in the design of the Nilai. If so, the latter would be the latest technology.

He confirmed that he did not work on that design, and has also provided some criticism of it (of course)

[Jud]

1 hour ago, mocenigo said:

He confirmed that he did not work on that design, and has also provided some criticism of it (of course)

Can’t find the criticism. Link?

[mocenigo]

8 hours ago, davide256 said:

I'm getting the impression that you do not play/esteem any sort of wind or string instrument. Which escalate in price based on the strength of that warmth/timbre depth you are eschewing as much as technical capability.

I am not sure what this has to do with the subject at hand (also, I think you are misusing the verb “to eschew”, which means “to deliberately avoid using”). Any I do play a few instruments, including woodwinds and strings. Soooooooo, what are you trying to say? 

[fas42]

7 hours ago, PYP said:

Having had two iterations of the original Ncore previous to the Kalugas, I was mystified by the size of the improvement from DIY, to NAD, to Mola Mola using very similar amp boards.  Until I understood the role of the input stage in the overall sound, it made no sense to me that this kind of improvement was possible (not saying it was the ONLY difference).    

 

 

In any audio reproduction chain, any 'character' you hear is due to those parts which are the "worst" in the chain - the point of the exercise is, or should be, is to steadily improve those parts - you end up with, nothing but the sound of the recording itself.

 

The hardest belief for audiophiles to break, it seems, is that getting better sound is an additive process - the reality is, that one subtracts the aspects which degrade the SQ - all fully competent rigs will sound, subjectively, effectively identical ...

[PYP]

6 minutes ago, fas42 said:

 

In any audio reproduction chain, any 'character' you hear is due to those parts which are the "worst" in the chain - the point of the exercise is, or should be, is to steadily improve those parts - you end up with, nothing but the sound of the recording itself.

 

The hardest belief for audiophiles to break, it seems, is that getting better sound is an additive process - the reality is, that one subtracts the aspects which degrade the SQ - all fully competent rigs will sound, subjectively, effectively identical ...

My assumption is that even identical equipment (including the same speakers) will sound different in different rooms.   I don't believe there is a way to remove the room entirely from the sound of the overall setup.   

[Jud]

14 minutes ago, fas42 said:

all fully competent rigs will sound, subjectively, effectively identical ...

So if tube electronics sound different from solid state, which are “fully competent”?

 

If two components sound alike, is that a sign they are “fully competent,” and anything that sounds different is bad?

 

 If two components sound alike on one track but different on another, has one or both become less than fully competent?

 

Just trying to figure out how to parse this in practicality.

[fas42]

12 minutes ago, PYP said:

My assumption is that even identical equipment (including the same speakers) will sound different in different rooms.   I don't believe there is a way to remove the room entirely from the sound of the overall setup.   

 

Yes, there will always be measurable differences. And audible ones that matter, for people who are sensitive to such; people who have to sit in exactly "the right seat" for a live orchestral performance would fit into this category.

 

Let's say you have world class string quartet visit your home, for real. And they play for you in various rooms of your home. Which would be more important to you, the fact that they sound a bit different in each of these spaces, or being blown away by the intensity, drive and energy of them performing? I fit in the latter category, and so strive to achieve that, for an audio setup.

[Allan F]

22 minutes ago, Jud said:

So if tube electronics sound different from solid state, which are “fully competent”?

 

If two components sound alike, is that a sign they are “fully competent,” and anything that sounds different is bad?

 

 If two components sound alike on one track but different on another, has one or both become less than fully competent?

 

Just trying to figure out how to parse this in practicality.

 

A sound application of the Socratic method!

[kumakuma]

22 minutes ago, Jud said:

So if tube electronics sound different from solid state, which are “fully competent”?

 

If two components sound alike, is that a sign they are “fully competent,” and anything that sounds different is bad?

 

 If two components sound alike on one track but different on another, has one or both become less than fully competent?

 

Just trying to figure out how to parse this in practicality.

 

For some reason, Frank's thinking often reminds me of this image from Monty Python...

 

 

 

[barrows]

37 minutes ago, PYP said:

My assumption is that even identical equipment (including the same speakers) will sound different in different rooms.   I don't believe there is a way to remove the room entirely from the sound of the overall setup.   

Of course one cannot remove the room, not only that, one would not want to.  A system would not sound good, for example, in the outdoors on a quiet day, with no room sound.  Neither would a system sound good in a fully deadened anechoic chamber.  The loudspeakers and the room work together to create the sound field one hears (or they work at odds with each other).  But one should not assume that the room is evil, it may not be at all.  Just depends on the room.

[fas42]

42 minutes ago, Jud said:

So if tube electronics sound different from solid state, which are “fully competent”?

 

Probably neither ... . IME, ordinary tube stuff gets some things right, and ordinary solid state gets other things right; I couldn't live with either in a sub-optimal state - it has regularly been said that that top class tube "sounds virtually the same" as top class solid state, and I agree.

 

42 minutes ago, Jud said:

 

If two components sound alike, is that a sign they are “fully competent,” and anything that sounds different is bad?

 

Highly unlikely that two below par rigs will sound exactly alike - the chances of them having identical weaknesses is so low, unless they are made up of exactly the same model components, that one should be able to safely discount it. The way I deal with it is, I use as a reference the best I have ever heard a variety of 'difficult' recordings sound - the closer I get to that, the closer I am to "full competency".

 

42 minutes ago, Jud said:

 

 If two components sound alike on one track but different on another, has one or both become less than fully competent?

 

It's not really about individual components I find - rather, it's about whether the combination of components, at that particular moment, have adequate integrity as a chain to do their job properly. "Easy" tracks can often sound the same; it's how they react to the 'testing' ones that will then separate "the men from the boys". The intrinsic weaknesses of setups will differ; meaning one rig will do poorly on some track, and the other rig on a completely different piece of music - neither is fully optimised.

 

42 minutes ago, Jud said:

Just trying to figure out how to parse this in practicality.

 

As above. Use recordings which can sound awful, or pretty damn good, depending upon everything, as a guide - the closer you get to the most recordings moving to the "pretty damn good" basket, the closer one is to achieving, best sound.

[mocenigo]

2 hours ago, Jud said:

Can’t find the criticism. Link?

He spoke about it at private conversations, and the criticism had been also mentioned to me by some folks at Purifi. It was about the shape of the distortion curve that in their opinion showed that they were optimised by trial and error instead of using a mathematical frameworks. In other words, it was only to make numbers better, not to solve a specific problem (which, in Bruno’s approach, is hysteresis distortion). So it is a criticism of the methods and goals, not of the results.

[fas42]

Appropriate for what has just occurred, a test CD of mine is a $1 from a charity shop album of Ike and Tina Turner tracks - some recorded live in some club environment. "Rough as guts!!" is probably too generous a term to use for some of these - the sharpness and aggressiveness of the sound can tear your head off, very easily; which is probably why it ended up in that shop, . But get it right, and it becomes, "entertainment magic" ...

[Jud]

17 minutes ago, fas42 said:

Use recordings which can sound awful, or pretty damn good, depending upon everything, as a guide

Fortunately or unfortunately, the good recordings and less good recordings (can’t think of any really bad ones) have seemed to stay quite consistent over the few times I’ve changed equipment.

[PYP]

30 minutes ago, mocenigo said:

 In other words, it was only to make numbers better, not to solve a specific problem (which, in Bruno’s approach, is hysteresis distortion). 

Is the "in other words" part what they said?  I ask because the "only to make the numbers better" hypothesis seems silly to me.  The distortion was already so low that anyone could question whether better numbers = better sound.  And subjectivists use their ears, not the measurements (to the dismay of objectivists).  

 

One could just as likely interpret this theory as -- Mola Mola did less math but a lot more listening and finalized the result based upon listening rather than math.  I'm not saying that I believe that, but theories about intentions are just that.   Maybe both parties wanted to make the best product they could and found ways to improve upon the original design.  The world is surely large enough to accommodate two excellent companies innovating to improve the listening experience.  Some folks seem to want to turn lemonade into lemons.   

[fas42]

32 minutes ago, Jud said:

Fortunately or unfortunately, the good recordings and less good recordings (can’t think of any really bad ones) have seemed to stay quite consistent over the few times I’ve changed equipment.

 

Which is a good sign. Does the "worst of your less good" recordings always sound the same, as you change equipment - or what alters, when things sound different on some track, as you mentioned above?

 

Next step, can you go to any gain level within the sensible limits of the equipment, without flinching, or feeling uncomfortable, during some passages?

[fas42]

Chris nailed what competent playback is like to experience, in his just posted Munich wrap up,
 

Quote

 

Finishing my listening session in this room, I really went for it. I played a track that can only be played at the very end of a listening session. Similar to how bands never wanted Rage Against The Machine as their opening, it's tough to follow The Raconteurs' title track from the Consoler of the Lonely album. Especially when I have control of the volume. 

 

I cranked it up and let the kick drum hit me in the chest. Jack White's dirty guitar sounded like it was coming straight from his amp, rather than through a high end audio system. It was in my face, just as it should be! My feet were tapping and my head was bobbing during this track, and I could see some others in the room were also getting into it in their own way. This isn't a typical audiophile standard at audio shows, but I think even the traditionalists enjoyed it.

 

 

That's what it's about. Evolving a system to this standard means you get to enjoy this level of intensity and 'meatiness', on just about anything you choose to put on - if you're not getting this, then there's room for improvement ...

[Allan F]

46 minutes ago, PYP said:

One could just as likely interpret this theory as -- Mola Mola did less math but a lot more listening and finalized the result based upon listening rather than math.

 

That would not appear to be consistent with Bruno Putzeys approach to design, as gleaned from his many interviews that can be found online.

[Jud]

52 minutes ago, fas42 said:

 

Which is a good sign. Does the "worst of your less good" recordings always sound the same, as you change equipment - or what alters, when things sound different on some track, as you mentioned above?

 

There are differences when components change, but they are consistent across recordings rather than being concentrated on “less good” ones. For example a more powerful amp provided more “physical” and tighter low bass on tracks with low bass.

 

52 minutes ago, fas42 said:

Next step, can you go to any gain level within the sensible limits of the equipment, without flinching, or feeling uncomfortable, during some passages?

 

Some days I feel like turning it up, yes. I also agree with one of the YouTube amp evaluators earlier in the thread that it’s important to have components that provide musical involvement and the emotional satisfaction that comes from it at low volume.

[fas42]

38 minutes ago, Jud said:

 

There are differences when components change, but they are consistent across recordings rather than being concentrated on “less good” ones. For example a more powerful amp provided more “physical” and tighter low bass on tracks with low bass.

 

Sounds like things are in good shape . That more powerful amp experience is because low bass requires a lot of energy, to drive the woofer; a less capable amp has a power supply with lower reserves of energy, and hence must draw mains current with a more 'spikey' waveform, to maintain voltage rails. This can easily add distortion, and the sense of a "tight bass" is reduced.

 

38 minutes ago, Jud said:

 

Some days I feel like turning it up, yes. I also agree with one of the YouTube amp evaluators earlier in the thread that it’s important to have components that provide musical involvement and the emotional satisfaction that comes from it at low volume.

 

Yes. One reason that I bought my current active speakers is that reviews especially noted that they still sounded fine at low volume; and that showed that the engineering in a key area was "good enough". This translates, currently, to being able to drop the (digital) level to one step above muting; and with ear close to a speaker, you still get the same presentation ...

[Allan F]

58 minutes ago, Jud said:

I also agree with one of the YouTube amp evaluators earlier in the thread that it’s important to have components that provide musical involvement and the emotional satisfaction that comes from it at low volume.

 

You might recall that is why some preamps years ago, such as Dynaco's PAS 3 and PAT 4, were equipped with a "loudness" control to compensate for that deficiency at low volume.

[mocenigo]

7 hours ago, PYP said:

Is the "in other words" part what they said?  I ask because the "only to make the numbers better" hypothesis seems silly to me.  The distortion was already so low that anyone could question whether better numbers = better sound.  And subjectivists use their ears, not the measurements (to the dismay of objectivists).  

 

They said both things, actually. And it is obvious that they cater to objectivists as well.

 

7 hours ago, PYP said:

One could just as likely interpret this theory as -- Mola Mola did less math but a lot more listening and finalized the result based upon listening rather than math. 

You mean Hypex, not Mola Mola. Well, they used measurements, and trial and error, not listening.