Purifi Class D

[jaytor]

I built a pair of monoblocks with a (way overkill) linear power supplies incorporating a custom Toroidy 1500VA transformer, 134K uF caps for the high voltage rails, 54KuF for the low voltage rails. This is for each monoblock. I have experimented with a couple of different input buffers. I currently have the VTV tube input buffer installed which uses a single 6DJ8 and a pair of Weiss discrete op amps. 

 

The amp sounds very nice, but doesn't quite match either my Pass XA60.8s or my DIY PSET 300B monoblocks which use the Western Electric reissue 300B tubes. I've had the 300B amp in my system most of the time over the past year - definitely my favorite.

 

I have another Purifi stereo amp built with an SMPS and Neurochrome buffers. The monoblocks have a deeper sound stage, more natural decay, and a bit more meat on the bones in the upper bass (most obvious with male vocals, saxophone, etc.). 

[PYP]

NAD's C298 is based upon the Purifi module.  $2,399 online.  According to NAD:  "Our line inputs, both Balanced and Single-ended, can accommodate all kinds of analog source components by offering ideal input impedance characteristics with linear ultra-low-noise buffer amplifiers to prevent any sonic degradation caused by inappropriate loading of the source device. "

 

They also have the higher priced "Masters" amplifier.  Both amps have a bridged option so that the two stereo amplifiers can be used as mono amps.

 

NAD is clearly a fan of Bruno's designs.  Earlier Masters amps used the Hypex module (which I happily used for years) and at least one of their current DAC+Amp designs uses the Philips UcD module, which I believe Bruno designed when he worked there.    

[Allan F]

5 hours ago, Jud said:

 

Grateful thanks for this.  During the interview, as noted previously in the thread, Bruno says the TI OPA 1656 op amp will sound better than the TI OPA 1612 op amp he includes with his eval board (and that ships with various Purifi-based amps, including my Apollon).  Barrows tried the OPA 1656 and told me he liked it, so I got hold of a couple (at least for the Apollon, you want the DIP8 modules - readily available on eBay in the US for less than $20 the pair; don't know about availability in other countries).  Surprise, I think Bruno was right; I feel that I like the sound better.  Subjective impression (so to be taken with a grain of salt) is richer, more reverberant, more musical, sweeter, without being overly warm or less accurate.

 

I doubt that "a grain of salt" need be taken  Glad to hear that you prefer the OPA 1656 op amps and the reasons why. OTOH, I'm not sure what to make of your comment that their sound is not "overly warm". I can't recall anyone ever describing Purifi based Class D amps as being "warm" in nature. On the contrary, while they are generally praised for their extreme clarity and transparency, they have been criticized as lacking in warmth compared to solid state Class A or Class AB amplifiers.  

[Jud]

15 minutes ago, Allan F said:

OTOH, I'm not sure what to make of your comment that their sound is not "overly warm". I can't recall anyone ever describing Purifi based Class D amps as being "warm" in nature. On the contrary, while they are generally praised for their extreme clarity and transparency, they have been criticized as lacking in warmth compared to Class A or Class AB amplifiers.  

This should be read in the context of my remarks that the sound seemed to me richer, more musical, more reverberant, sweeter. I was saying it did not seem to me to cross the line into excessive warmth at the cost of accuracy (again, subjective impression). Vocals and instruments seem to me quite “present” and realistic, to have an “in the room with you” quality.

[57gold]

Who is producing high powered/high current Purifi amps?  

 

Have read that they require separate power supplies to deliver specified output/current.  

 

Also read that Hypex has/will introduce an updated high power/current amp board that may outperform the Purifi version.  Anyone heard or seen one of these units?

[barrows]

2 minutes ago, 57gold said:

Who is producing high powered/high current Purifi amps?

Appollon, VTV, and Nord do.  I suspect there are, or will be, others soon.  And yes, to achieve full output power a single Hypex SMPS1200 is inadequate, one would use two such power supplies, or equivalent alternatives.

 

Hypex already produces the higher power Ncore amplifier, are you suggesting they have newer model with an improved design?  Do you have any details?

[DuckToller]

14 minutes ago, 57gold said:

Also read that Hypex has/will introduce an updated high power/current amp board that may outperform the Purifi version.  Anyone heard or seen one of these units?

Sorry, but I have to ask:

Outperform in which qualities?

[Allan F]

2 hours ago, 57gold said:

Who is producing high powered/high current Purifi amps?  

 

In addition to the manufacturers mentioned by @barrows the following are also offering Class D amps based on the Purifi 1ET7040SA module:

boXem Audio of Europe: Arthur 4222/E1 mono amplifier - currently available on their website.

Rouge Audio of Italy: Studio N8 stereo amplifier - currently shown as "Out of Stock" on their website.

 

[57gold]

5 hours ago, barrows said:

Appollon, VTV, and Nord do.  I suspect there are, or will be, others soon.  And yes, to achieve full output power a single Hypex SMPS1200 is inadequate, one would use two such power supplies, or equivalent alternatives.

 

Hypex already produces the higher power Ncore amplifier, are you suggesting they have newer model with an improved design?  Do you have any details?

 

Introduced for DYI crowd, OEM versions are supposed to be in the works.

 

Nilai® Class D technology is here!

We have taken our existing control-loop topology to a whole new level resulting in an immense performance upgrade compared to NCORE®. The overall performance has increased by not less than 10 times!

This massive performance boost results in distortion figures that are 10 times lower, a power supply noise rejection that is 10 times higher and a reduced output impedance that has dropped by a factor 10. These figures may already sound incredible, wait until you hear them come alive through your speakers!

 

HIGHLIGHTS:

• 500W / 4 ohm
• THD+N: 0,00015% (-116dB) @ 100W / 4 Ohm / 20 – 20.000 Hz
• Output noise: 9,5µV @ 11,8dB gain
• Gain adjust in 3 steps (11,8 - 21,8 - 27,8)
• High fidelity components
• Discrete buffer stage and regulators
• Dedicated high-end power supply
• Available in mono & stereo kits
• 100 x 100 x 40mm and 355g

 

Found a link to OEM version intro:

 

Hypex Announces New and Improved NCOREx Class-D Amplifier Technology

 April 21 2022, 08:10

Hypex Electronics announced a new and improved iteration of its popular NCORE Class-D amplifier technology and unveiled the NCx500 OEM, the first of a new NCOREx family of modules to be launched. According to the Dutch company, the new technology will afford at least 2x better performance compared to original NCORE products — the reason for the x designation, as in eXceptional! Hypex will introduce the new NCOREx technology at the ISE and High End shows in May 2022, paving the way for future OEM products.

 

I do not know what all this means, but here is a link to more:

https://audioxpress.com/news/hypex-announces-new-and-improved-ncorex-class-d-amplifier-technology

 

 

[John Hughes]

Wow! that some impressive specs improvements!  I don't doubt that it will be an improvement!

[barrows]

Yeah, really cool to see that Hypex has developed the new Nilai amp for DIY, with a matching improved SMPS to replace the NC400 and SMPS 600.  Also really cool that they incorporated discrete circuitry for the input buffer and onboard regulators, which is a similar approach to what the NC-400 used.  Keeping a single board design with the dedicated onboard input stage is really cool as well.  I suspect they will be able to sell a whole lot of these.  I am looking forward to hearing them!

[Allan F]

7 hours ago, 57gold said:

We have taken our existing control-loop topology to a whole new level resulting in an immense performance upgrade compared to NCORE®. The overall performance has increased by not less than 10 times!

 

7 hours ago, 57gold said:

Hypex Electronics announced a new and improved iteration of its popular NCORE Class-D amplifier technology and unveiled the NCx500 OEM, the first of a new NCOREx family of modules to be launched. According to the Dutch company, the new technology will afford at least 2x better performance compared to original NCORE

 

 A rather significant difference in the description of the performance improvement of the NCOREx compared to the original NCORE. And I very sincerely doubt that the difference can be attributed to semantics, i.e. that, technically, one could argue that an increase of not less than 10 times is at least 2x better. 🙂

[57gold]

Who knows what all the promotional language (what my real estate financier friend calls NYC developer speak, versus lies and misleading statements) means.  Not sure which prior amps and power supplies are being compared to the new units.

 

Was trying to find third party data on these new products, and this is what's out there, so far.   There is some chatter that the Hypex NCOREx "leapfrogs" (whatever that means) the new high powered Purifi amps...

 

Watching these developments for a high current version as my DNA-500 is nearing 20 years in service and I need that kind of power to light up my beloved Aerial 10Ts, which still sound pretty fine. 

[mocenigo]

3 hours ago, Allan F said:

 

 

 A rather significant difference in the description of the performance improvement of the NCOREx compared to the original NCORE. And I very sincerely doubt that the difference can be attributed to semantics, i.e. that, technically, one could argue that an increase of not less than 10 times is at least 2x better. 🙂

it may also be that in one case they measured the power of the residual noise (which is measured in V but assume constant I…) and the corresponding subjective intensity change. Then 10=2.

 

 Roberto 

[barrows]

The claims are a bit confusing.  The introduction of Ncorex and Nilai, at nearly the same time is also confusing.  According to Hypex, Ncorex is an improved version of NCore, and Nilai (for now DIY only) is something more, with a bit of a new approach and a larger improvement over NCore than Ncorex.

So far there appears to be no third party listening tests, or measurements of either Ncorex or Nilai, so we will have to be a little patient.

For me, I think I will get my hands on the Nilai stuff, and fire them into the chassis which now houses my NC400 amp, and then listen test vs my DIY Purifi amp (recently changed to OPA 1656 in the input stage).

[57gold]

Be interested in your listening tests.  

 

Though, DYI is NCD (no can do) for me.  I burn myself every time I try to use a soldering iron.

[mocenigo]

3 hours ago, 57gold said:

Be interested in your listening tests.  

 

Though, DYI is NCD (no can do) for me.  I burn myself every time I try to use a soldering iron.

Well, these amps sound incredibly neutral and especially the Purifi ones have very smooth treble, with an absence of grain that I heard before only with small power DHTs.

 

They are also the most silent and clean amps I have ever heard, even with very sensitive speakers. Details and dynamics are just right.

 

They are also brutal - no defect in a recording will be masked, which I consider a good thing. 

[PYP]

1 hour ago, mocenigo said:

They are also brutal - no defect in a recording will be masked, which I consider a good thing. 

They also reveal whatever feeds them.  Reducing the noise in the components that are upstream is worthwhile, as is reducing the noise from the electrical system.   

[Miska]

On 11/23/2022 at 4:37 PM, 57gold said:

Who is producing high powered/high current Purifi amps?

 

I believe latest NAD M-series?

 

[Allan F]

1 hour ago, Miska said:

I believe latest NAD M-series?

I am pretty sure that the NAD M-series is based on the original Purifi 1ET400A module, not the newer high current 1ET7040SA that is the subject of this discussion.

[PYP]

24 minutes ago, Allan F said:

I am pretty sure that the NAD M-series is based on the original Purifi 1ET400A module, not the newer high current 1ET7040SA that is the subject of this discussion.

It appears to be some variation of the 1ET400A -- from the NAD website (bolding added):  "NAD’s renowned designers worked closely with Purifi Audio to customise the Eigentakt implementation to ensure every product featuring the technology would meet the high standards NAD is known for. For this reason, NAD manufactures its own Eigentakt modules rather than buy off-the-shelf."

[mocenigo]

15 hours ago, PYP said:

They also reveal whatever feeds them.  Reducing the noise in the components that are upstream is worthwhile, as is reducing the noise from the electrical system.   

 

My approach is mixed objectivist/subjectivist in the following sense: the sound is fundamentally characterised by the speakers and the listening environment – and these two are so fundamentally imperfect, that, within the best we can afford to purchase or build ourselves, we have to pick by necessity what we like most.  But electronics are a solved problem, so by picking them intentionally components that reproduce the signal as perfectly as today's technology can do (which is achievable at modest expenses, and after that there are differences that are either deviations from fidelity or indistinguishable – of course provided that the measurement set is complete as of today's tech, not according to the marketing of the 80s) I remove them from the equation, provided of course that electric matching is appropriate. At this point, to finish setting up the system I only have to play with the speakers and the room.

(As for the electronics: even TAS, when they listened to the Topping D90SE, had to admit https://www.theabsolutesound.com/articles/topping-d90se-digital-to-analog-converter/ that "What I heard was reference-level digital reproduction without any sonic bromides." Reference level. Other DACs may be able to drive amplifiers that require stronger output circuitry from their sources, or a lower output impedance (the D90SE is not perfect from these points of view) to avoid either distortion or uneven frequency response, but if the electrical matching is correct, this is reference. That's why I use a D90 to drive the Neurochrome Buffer and the latter drives the Purifis.)

[mocenigo]

8 hours ago, PYP said:

It appears to be some variation of the 1ET400A -- from the NAD website (bolding added):  "NAD’s renowned designers worked closely with Purifi Audio to customise the Eigentakt implementation to ensure every product featuring the technology would meet the high standards NAD is known for. For this reason, NAD manufactures its own Eigentakt modules rather than buy off-the-shelf."

 

The modules they use are indeed 1ET400A's. They look mostly the same and I cannot tell where the differences in the circuits are, if any, but the modulator boards appears to have a little shielding of their own.

[57gold]

Over at ASR (the test/no listen crowd) they tested the various NAD amps and found them noisier than other implementations of Purifi amps, but with an enhanced power supply that generates more output than Purifi/Hypex combinations.  

 

Purifi announced a while back that they were developing their own power supply(s), but do not believe they are yet available.  

 

Guessing that all this Class D new product has been greatly slowed down by the mess in China over COVID and supply chain issues.

[GerFod]

I found it interesting that the reviewer gave a higher rating of the adcom gfa-565 se over the NAD. I currently have the original 565 and love it.