Purifi Class D

[57gold]

Have read that the stock input buffer is a weak link, on the VTV and other builders like Nord or Apollon, which offer several upgrade options.  Additionally, the VTV is value oriented versus some of the other builders that have spent more efforts on layout, wiring choices, parts upgrades, and power supply enhancements.  

 

This one even uses what appears to be LPS (3 toroids) to drive input and output of amp, if I understand this correctly ($10K, hardly a bargain):  

https://www.stereophile.com/content/lkv-veros-pwr-power-amplifier

 

Run Aerial 10Ts, which are power/current hungry beast, and sent a note to Purifi to see if they intended to produce a double power amp, like 400 watts into 8 ohms, which had been rumored.  Response was no, just a rumor.  Bridged monos, they said wouldn't help with these speakers, as power goes up but current capabilities wouldn't increase in that configuration.  Sticking with the McCormack DNA-500, even checked on SMc upgrades described here in CA, though $5K cost, which is more than I paid for the amp.

 

 

[57gold]

1 hour ago, RickyV said:

I wondering about transformer based class-d amps. So not only for the input stages but also for power. Is somebody doing that? 600va transformer, rectifier and big capacitance. 

And the question would be if that would be better then the smps?

 

 

That's what the LKV one I linked above utilizes, the reviewer was smitten.  Can't be a big magazine advertiser based upon the size of the company.  Here is what the pointed out on its site:

 

Transformers: Three separate toroidal power transformers are employed in the PWR+: (a) One large 1KV transformer weighing over 12 pounds supplies high current for the Class D output stage. (b) A second serves as a floating, +15 volt supply for the driver circuitry in the Purifi module. (c) A third feeds the power supply for the LKV Class A input/gain/driver stages.

 

High Current Supply: This power supply employs almost 40KuF of capacitance and is specifically designed to meet the demands imposed by Class D amplification circuits. Most importantly, it copes quite effectively with “power pumping,” a problem unique to Class D amps.

 

Line Level Supply: To assure the very accurate, low noise/distortion performance for which the LKV Class A circuits are known, each power rail in this supply has two stages of power regulation, a capacitance multiplier, and 40KuF of capacitance.

[57gold]

 

17 hours ago, GUTB said:

I thought the LKV was a custom GaNFET design. Is it a Purifi? I put the VTV back in, currently playing CDs.

 

 

 

"LKV Research founder Bill Hutchins uses Purifi Audio's 1ET400A class-D power amplifier modules" clipped from review.

[57gold]

On 2/2/2021 at 3:14 PM, Matias said:

I am just waiting for Bruno to finish his new more powerful Purifi modules.

 

A few months back, contacted Purifi and they stated that they had no immediate plans for a release of more powerful modules.

 

Has that changed?

[57gold]

Matias - Thanks for the heads up.

 

Wonder what kind of power supply will be required to supply the juice to output 40 amps of current?

 

I guess there is the one that is used to power the Hypex Ncore NC1200.

[57gold]

Haven't seen anything more on this new unit.

 

Given its capabilities, you'd think amp builders would be jumping on board, scrambling to announce a new unit?

[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?

[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

 

 

[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. 

[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.

[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.

[57gold]

The GAN amp in link above looks to be a module, like the Purifi ones.

 

Are there any amp builders who are making amps out of them?  Imagine they will need a pretty serious power supply and decent input stage.

[57gold]

What caught my eye was the spec of this amp module's ability to deliver 1,000 watts into 2 ohms.  

 

The Orchard Audio amps are lower output/current designs.