hypex ncore

[Bruno Putzeys]

Originally Posted by noah katz

Care to comment on this, Bruno? Seems a bit doctrinaire, which doesn't sound like you.

It doesn't sound like someone who uses IC op amps as much as I do. The reason for the discrete buffer has to do with something I posted earlier on page 26.
Based on what I know about IC processing, getting round the non-linear capacitance from the inputs to the rails would require an SOI process. For an op amp manufacturer this is not enough reason to do so. This is pretty much the only serious drawback I can name for IC op amps. This issue causes exactly no problem at all when you balance the impedances at both op amp inputs. Unfortunately there's just no way you can do this in a follower stage because the impedance at the inverting input is fixed (the feedback network) and at the noninverting input it's whatever the source throws at it.
The closest you can get to having no problem is by keeping both impedances low. Now, if there's one thing you can't count on when selling amplifiers into the consumer audiophile market it's the output impedance of the preamplifier. Just think about passive controllers.
Under those circumstances having a discrete input stage definitely helps. The NC400 is intended as a no holds barred design so discrete is what it became. Now, adding cascoded emitter followers in front of an ordinary IC op amp equally does the trick but once you've done that you've already built half an op amp. That and the fact that you don't add the input noise of the IC.

Originally Posted by Trevor White

This sounds a bit pretentious and dismissive of others work in the field

Originally Posted by ChrisPa

I've never known a journalist to report what actually happened/was said - take it as interpretation by the authors

That was a bit of creative quoting of my own just now :P

The snippet you're referring to is a heavily condensed version of my answer to the question who I thought was equally working to push the bounds of audio performance and theoretical insight in class D. In that case indeed Lars, Sören and the rest of the TI crew come to mind. I think what they're doing in silicon terms is pretty trailblazing. The guys who did the original Mueta design are also still actively researching modulation theory but not doing any practical audio work (on account of being too busy making rather amazing sensorless motor drives).

M&H's interpretation sounds a bit crass but I can't help noticing a certain paucity in the number of published class D measurements approaching those of Ncore. That could either mean nobody's doing it or there's suddenly going to be an Ncore killer from a hitherto unknown designer. The former makes people uneasy because it's simply not on to say (or even think) you're ahead of the game, the latter makes me uneasy because I have no idea what or who I'm racing against. But the least you can say is that I'm not doing too badly. Of course there is the occasional outburst from those who advance philosophical arguments to excuse less than stellar results ("it's more digital!" "measured results matter only until they're as good as mine", "the stuff you hear is something different altogether" etc) but I don't think it would be pretentious to suggest that they're in an entirely different game.

[earflappin]

Bruno,

I have a pair of nCore 400's arriving tomorrow. Looking forward to auditioning them.

Question. And please just direct me if this has already been addressed elsewhere in this or another thread.

For those with digital sources the nCore requires an upstream DAC and PRE (unless a digital attenuator is used). Do you believe it is feasible to design a commercially viable integrated device which could substantially improve sound quality of a DAC/PRE/nCore signal chain? This device would input a PCM signal via USB or SPDIF which would then be converted to Pulse Width Modulation, reclocked via a high quality clock, amplified in the digital domain, reclocked again, and then demodulated at the output of the amplifier to drive a speaker directly using some form of volume control (e.g. a voltage controlled attenuator that resides outside the signal path)?

Supposedly, Core Audio Technology in California is offering a product like this under the name Kratos. Currently it only outputs 20wpc so it is rather limited to high efficiency speakers.

Thanks for your perspective on this.

[Bruno Putzeys]

It's been discussed earlier in the thread (I'm sure someone will post a link). In short, you're at the mercy of the switching speed of the FETs, the quality of the power supply and the load-dependent frequency response of the output filter when you do such a thing. Not a good idea.

[Speedskater]

Did any manufactures display models at the recent CES show?

[Bruno Putzeys]

Yes.

[mr_push_pull]

Originally Posted by FloridaBear

so they could do ABX testing...

ABX what???

[pieter t]

Originally Posted by Bruno Putzeys

Yes.

Theta Prometheus....................................6000 dollars for one mono amplifier featuring ncore....and linear power supplies....
Gallery: Audio Electronics at CES 2012 | Sound and Vision Magazine

[Jan-Peter]

Originally Posted by pieter t

Theta Prometheus....................................6000 dollars for one mono amplifier featuring ncore....and linear power supplies....
Gallery: Audio Electronics at CES 2012 | Sound and Vision Magazine

Yep...that's correct...

Cheers,

Jan-Peter

[pieter t]

For that price it had to be big'n heavy, so no SMPS.....

[ro9397]

Originally Posted by earflappin

"The end of January passed, are there any modules shipped?"

Mine shipped on Monday and I expect them to arrive tomorrow or Thursday latest. I got a shipment confirmation and tracking number from Hypex.

Unlike the rest of the DIY williewankers who have received the nCores but not posted reviews, I will definitely be posting my observations on their sound quality.

Thank you for that promise. Very much looking forward to reading your feedback. ETA? If not this thread, where?

Your comment reminds of the one of Zaph Audio's better DIY monitor designs...searched forever and could hardly find a couple sentences of feedback.