Finally, The Class D Holy Grail?

[Nordkapp]

Could this new class D module from Bruno be the one to finally silence all the naysayers?  The specs looks crazy. Any thoughts from the higher ups here? 

https://6moons.com/audioreview_articles/purifi/

https://www.purifi-audio.com/eigentakt/

[fas42]

What has been optimised is the global negative feedback to produce the excellent distortion figures, in conventional testing. Whether that translates to anomaly free sound in real world situations is the question mark; just saying " The module places no particular demands on the power supply quality." is a nice selling point, but I would want someone to try comparing using an excellent PS with a really crappy one, and tell me that they could hear zero difference in the SQ.

[Nordkapp]

8 minutes ago, fas42 said:

The module places no particular demands on the power supply quality." is a nice selling point, but I would want someone to try comparing using an excellent PS with a really crappy one, and tell me that they could hear zero difference in the SQ.

I am sure builders will want to optimize it with a kick ass LPS. It does look pretty impressive on paper. Those specs compete with the Benchmark AHB2. 

[Nordkapp]

Not to mention the people behind Purifi reads like an all star team.......

[fas42]

I'm certain that a well done implementation of the module in a finished component will produce sound second to none - now, just have to wait for a value for money unit with those qualities to come on the market ...

[audio.bill]

Didn't anyone else notice the high THD at its rated power? Output Power 450W @ 1% THD, 4Ω, yet they claim it sets a standard for power amplifiers of any class...

That's not very impressive from my perspective.

 

[Doak]

2 minutes ago, audio.bill said:

Didn't anyone else notice the high THD at its rated power? Output Power 450W @ 1% THD, 4Ω, yet they claim it sets a standard for power amplifiers of any class...

That's not very impressive from my perspective.

 

Shhhhh 🤫

We don’t want another round of the THD spec wars that we barely survived in the ‘70s .

[fas42]

32 minutes ago, audio.bill said:

Didn't anyone else notice the high THD at its rated power? Output Power 450W @ 1% THD, 4Ω, yet they claim it sets a standard for power amplifiers of any class...

That's not very impressive from my perspective.

 

 

Standard way of spec'ing, for engineers' benefit - it tells them how much power it can deliver at the onset of clipping, 1% means that you've reached the limit of the design.

 

The distortion just prior to that level tells the story - this is exactly how a good design should behave,

 

[Nordkapp]

7 minutes ago, fas42 said:

 

Standard way of spec'ing, for engineers' benefit - it tells them how much power it can deliver at the onset of clipping, 1% means that you've reached the limit of the design.

 

The distortion just prior to that level tells the story - this is exactly how a good design should behave,

 

Thanks Frank. I was just about to say that 1% is likely driven into clipping.

[Nordkapp]

My CIAUDIO monos use a custom UcD module, offered directly from Hypex. Dusty of CI goes to great lengths to insure he gets the max out of these modules. I am floored by the way these things sound. I can't even imagine the potential of these new units. 

[audio.bill]

24 minutes ago, fas42 said:

 

Standard way of spec'ing, for engineers' benefit - it tells them how much power it can deliver at the onset of clipping, 1% means that you've reached the limit of the design.

 

The distortion just prior to that level tells the story - this is exactly how a good design should behave,

 

In my opinion it would be more realistic and impressive to quote this amp at 300W into 4 ohms with <0.001% THD+N.

[Curio]

Hello Everyone from a newbie of this Forum,

The problem with these Class D amps is... due to the same Hypex Module ..could be  the same sonic result .. Channel Island , Bel Canto , Molla Mola Kaluga , Nord , Merrill... etc..etc.. between them .. or am I missing something with my question?

[firedog]

1 hour ago, Curio said:

Hello Everyone from a newbie of this Forum,

The problem with these Class D amps is... due to the same Hypex Module ..could be  the same sonic result .. Channel Island , Bel Canto , Molla Mola Kaluga , Nord , Merrill... etc..etc.. between them .. or am I missing something with my question?

The amps don't have all the same Hypex modules. Hypex makes several different models/lines of Class D boards. They don't sound exactly alike. Some amps based on them have home built input sections designed to give a certain sound.
Some like the NC 500 model allow for the addition of  "aftermarket" input boards. This can very much change the resulting sound. On some boards you can even "roll" op-amps on the input and get a different sound. 
And like all amps, the PS and the output section also make a difference in the final result. 

 

BTW, Bruno P, designer of NCore, has a new Class D amp design being  made by a new company. Supposedly even better than the best NCore amp board. 

[fas42]

13 hours ago, Curio said:

Hello Everyone from a newbie of this Forum,

The problem with these Class D amps is... due to the same Hypex Module ..could be  the same sonic result .. Channel Island , Bel Canto , Molla Mola Kaluga , Nord , Merrill... etc..etc.. between them .. or am I missing something with my question?

 

The basic rule for audio is, or should be, is that the closer one gets to optimum sound, the more the tiniest thing can make all the difference - the slightest variation in the implementation, the way a manufacturer builds in a module, could have a huge impact on the subjective SQ - there is a lot added by the "boxer", .

 

IOW, using a high performance core to a component increases the pressure to make sure every other part matches up to that quality - if one wants to get the best from the overall ... it doesn't get easier, it gets harder!

[Shadders]

8 hours ago, fas42 said:

 

The basic rule for audio is, or should be, is that the closer one gets to optimum sound, the more the tiniest thing can make all the difference - the slightest variation in the implementation, the way a manufacturer builds in a module, could have a huge impact on the subjective SQ - there is a lot added by the "boxer", .

 

IOW, using a high performance core to a component increases the pressure to make sure every other part matches up to that quality - if one wants to get the best from the overall ... it doesn't get easier, it gets harder!

Hi,

I do not think you can say what an optimum sound is - it is meaningless. Please see the following URL :

"www.slideshare.net/shenpei/class-d-and-linear-power-amplifier-testing"

 

Examine slide 11 and 12. Slide 11 shows the spectral output from a class D amplifier, and slide 12 has typical class D output for a low level signal. It is a shame the signal level is not given in the slide.

 

How can the tiniest thing make all the difference, when you cannot hear the effect of the noise that is permanently on the signal ???

 

If you examine a class A/B signal, it is vastly more cleaner than the class D signal. Also, class D is an approximation to the signal which is filtered/averaged using a filter.

 

The real issue is that your hearing is not as good as you believe it is. You either have to agree that you cannot hear above 20kHz, and any information above 20kHz has no effect on what you hear, or if you agree that 20kHz+ signals make a difference, then why can you not hear the effect of the "mush" on class D amplifiers ?

 

Regards,

Shadders.

[The Computer Audiophile]

Hi Guys - Stay tuned for much more information about Purifi from us. We are putting together notes and videos from a private demo in Munich.

[Nordkapp]

3 minutes ago, The Computer Audiophile said:

Hi Guys - Stay tuned for much more information about Purifi from us. We are putting together notes and videos from a private demo in Munich.

Excellent!

[psjug]

6 hours ago, Shadders said:

 

If you examine a class A/B signal, it is vastly more cleaner than the class D signal. Also, class D is an approximation to the signal which is filtered/averaged using a filter.

 

The real issue is that your hearing is not as good as you believe it is. You either have to agree that you cannot hear above 20kHz, and any information above 20kHz has no effect on what you hear, or if you agree that 20kHz+ signals make a difference, then why can you not hear the effect of the "mush" on class D amplifiers ?

 

Any amplifier output is a scaled approximation of the input.  If it is the modulation in Class D that bothers you, I wonder if you feel the same about sigma delta converters, DSD, etc.

 

I think I share your general point of view, though.  If the best Class AB amplifiers (e.g. AHB2) can provide comparable or better performance than the best Class D amplifiers, then I'd rather not have the switching noise even if it is not causing a problem.  Especially if the Class AB amplifier provides this excellent performance while also including Class H efficiency.

 

Rather than chase after lower and lower THD+N, I would rather see Class D advancements where the switching noise is made significantly lower.

 

[gdpr]

29 minutes ago, psjug said:

Any amplifier output is a scaled approximation of the input.  If it is the modulation in Class D that bothers you, I wonder if you feel the same about sigma delta converters, DSD, etc.

 

I think I share your general point of view, though.  If the best Class AB amplifiers (e.g. AHB2) can provide comparable or better performance than the best Class D amplifiers, then I'd rather not have the switching noise even if it is not causing a problem.  Especially if the Class AB amplifier provides this excellent performance while also including Class H efficiency.

 

Rather than chase after lower and lower THD+N, I would rather see Class D advancements where the switching noise is made significantly lower.

 

Any real life examples?

 

Dirk

[Curio]

On 5/13/2019 at 1:06 PM, firedog said:

The amps don't have all the same Hypex modules. Hypex makes several different models/lines of Class D boards. They don't sound exactly alike.

It seems you were right .. I have found this comment by a Stereophile reviewer

 

"Why should various amps based on circuit boards of the same technology (NCore) and made by the same company (Hypex) sound different? I don't know, but the amplifier boards aside, I could see physical differences inside these three amps. The big Theta uses a big linear power supply or two, while the more compact Bel Canto and NAD use a Hypex SMPS. Theta and NAD use the input circuit on the NCore amp board, while Bel Canto supplements it with a proprietary circuit. These differences must affect the sound quality, but to link them with what I heard will take testing procedures that control more variables than I can."
Read more at :

https://www.stereophile.com/content/bel-canto-eone-ref600m-power-amplifier

[psjug]

15 minutes ago, ddetaey said:

Any real life examples?

 

Dirk

Sorry, I don't follow you.  Examples of what?

[Shadders]

38 minutes ago, psjug said:

Any amplifier output is a scaled approximation of the input.  If it is the modulation in Class D that bothers you, I wonder if you feel the same about sigma delta converters, DSD, etc.

Hi,

The class A/B amplifier is a continuous function, and the output is exactly the same as the input with added noise, whether harmonically related or not. It is not an approximation.

 

A class D amplifier is discrete time and discontinuous before the output filter. It can only be an approximation of the original signal.

 

Regards,

Shadders.

[psjug]

1 minute ago, Shadders said:

Hi,

The class A/B amplifier is a continuous function, and the output is exactly the same as the input with added noise, whether harmonically related or not. It is not an approximation.

 

A class D amplifier is discrete time and discontinuous before the output filter. It can only be an approximation of the original signal.

 

Regards,

Shadders.

If the amplifier has any noise or distortion then I would say its output is an approximation, whether modulation is used to get there or not.  So a good Class D amplifier provides a better approximation than a bad Class AB amplifier.

[gdpr]

10 minutes ago, psjug said:

Sorry, I don't follow you.  Examples of what?

Examples of Class AB amplifiers with Class H efficiency.

[psjug]

2 minutes ago, ddetaey said:

Examples of Class AB amplifiers with Class H efficiency.

Oh, I should have been more clear.  I was referring to the the Benchmark AHB2 that I mentioned.