[Big Red Machine]

Right.  And I sold my $16k Class A mono blocks in favor of the NC400's.

I'm always perplexed by the comments you make about other's choices/opinions.

[I.Greyhound Fan]

Right.  And I sold my $16k Class A mono blocks in favor of the NC400's.

What ever!  The Ncores were dull and flat in comparison.  I have no interest in belittling Ncore amps but they did not cut the mustard in my system.  My Pass X250 was light years better.  The AVA 400R is also a huge step up so much so that my friend who is a member of AC bought the 400R to run with his Magnepan 1.7's and the ncores are sitting on a shelf waiting to be sold!

Maybe in your system the Ncores shine.

[DaveC113]

The one issue with class D is they can be "tweaky" and respond strongly to the rest of the system, including cables and AC power. The Crown amps specifically made efforts to address the sensitivity to AC power in their power supply design.

It does not surprise me one bit that the same class D amp would be great in one system and fall flat in another. This is one of the areas where D amps need improvements imo. When I sell cables to customers with D amps sometimes I get results that just don't make sense and don't match the experience of everyone else. They can react unpredictably to changes in a system.

[jtwrace]

What ever!  The Ncores were dull and flat in comparison.  I have no interest in belittling Ncore amps but they did not cut the mustard in my system.  My Pass X250 was light years better.  The AVA 400R is also a huge step up so much so that my friend who is a member of AC bought the 400R to run with his Magnepan 1.7's and the ncores are sitting on a shelf waiting to be sold!

Maybe in your system the Ncores shine.

Exactly my point.

[Occam]

Ncore amps are like a potentially perfect 'significant other'. Unless you, or your vendor, has devoted the requisite time playing 'slap and tickle' with her, she'll never provide your desired subjective responses.
Specifically, the ac and signal cabling internal (and external) to the amp can preserve and enhance the already excellent bass and treble behavior, while delivering much of that subjectively missing midrange density. Similarly, you've go to figure out how to mount her correctly. My Nc400 has responded with differing levels of enthusiasm to Stillpoints, Synergistic MIGs, and simple laminated bamboo footers, alone and in various combinations. It depends on how you've implemented her enclosure.

If you want to hear an Ncore implemented that IMO does it right, listen to one implemented by our own Mike Galusha.

[DaveC113]

Yeah, footers on class D amps (and power distribution) make a larger difference than I would have ever expected. Try Herbie's iso-cups with various balls, they beat out everything I've tried, but I'm not going NEAR stillpoints! 

[wushuliu]

I think the NCore has been well represented and discussed to death. I'd like to hear more about the Crown DriveCore. Most of what I've read about them has been positive but from the 'anti-audiophile' crowd.

[wushuliu]

From the What's Best forum 2011:

The Harman Drive Core amplifier chip is a completely in-house design done through Crown engineering. The only thing we used TI for was their expertise in IC Chip manufacturing. There are several patents on the chip design, although the basic topology is a Class D output stage. The Drive Core technology is used in several places, including the Lexicon DD-8, and several Crown amplifiers. There are 2 chips, one is a complete amp on a chip that includes an output stage that is capable of delivering 75 - 150 watts into 8ohms (depending on power supply and application requirements) and is table to 2 ohms, and the only thing that is really needed is a power supply and an input stage. The first use of the technology was in the Lexus LFA supercar. The requirements were high output, small size, high efficiency (greater then 90%), and great sound. Moving the input and output stages onto a single IC allowed much tiger tolerances of the clock and triangle wave form generator that is the heart of all digital amp designs, and often the cause of the "Class D" sound some people don't like. There is also a version that is everything without the high output stage (the input, waveform generator, feedback circuit, etc...) that can me used to drive higher output stages either Class D or our patented Class I, where more then 150 watts is needed.

thanks for the interest,
Todd Packer
Harman Luxury Audio Group
Field Application Engineer

[/i]

Also very lengthy thread on DriveCore here:

http://www.hometheaterequipment.com/mono-stereo-amps-59/crown-audio-xls-drivecore-series-amplifier-official-thread-1319/

Seems the XLS 2000 has a lower noise floor so should be the base model for audiophiles...

[Rclark]

What ever!  The Ncores were dull and flat in comparison.  I have no interest in belittling Ncore amps but they did not cut the mustard in my system.  My Pass X250 was light years better.  The AVA 400R is also a huge step up so much so that my friend who is a member of AC bought the 400R to run with his Magnepan 1.7's and the ncores are sitting on a shelf waiting to be sold!

Uh huh. 

[werd]

From the What's Best forum 2011:



Also very lengthy thread on DriveCore here:

http://www.hometheaterequipment.com/mono-stereo-amps-59/crown-audio-xls-drivecore-series-amplifier-official-thread-1319/

Seems the XLS 2000 has a lower noise floor so should be the base model for audiophiles...

Noise is the bane of Class D. It needs to be extremely low or it's no good.

[DaveC113]

Noise is the bane of Class D. It needs to be extremely low or it's no good.

It can be. Or just a mismatch in cables and components can make them perform well below expectation. That's why I wanted an AB amp for speaker testing but I think I'll pick up a Crown XLS 1500, the guy who owned the 2000s talked to Harman and they recommend the 1500 for more sensitive speakers. Noise was an extremely minor issue with the Crown 2000 / Pipedreams, only audible from an inch or two from the cones, and could be due to other factors. I've heard NCores be completely silent.

[Freo-1]

Right.  And I sold my $16k Class A mono blocks in favor of the NC400's.

So what does that prove?  The speakers are VERY different.  Measuring amps into resistors will not tell one much about the sonic attributes of the amp into any given speaker load. 

So, if you like the Ncore better with your speakers, that's cool.  It's also cool that someone else was not happy with NCore on their speakers. 

[jtwrace]

So what does that prove?  The speakers are VERY different.  Measuring amps into resistors will not tell one much about the sonic attributes of the amp into any given speaker load. 

So, if you like the Ncore better with your speakers, that's cool.  It's also cool that someone else was not happy with NCore on their speakers.

I'm not trying to prove anything.  It's strictly saying that what works for one might not work for another. 

[I.Greyhound Fan]

I'm not trying to prove anything.  It's strictly saying that what works for one might not work for another.

This is universal for every system.

[playntheblues]

Amen 

[DS-21]

The one issue with class D is they can be "tweaky" and respond strongly to the rest of the system, including cables and AC power.***

Gee I wonder where that came from.

***When I sell cables***

Oh, that explains it. Salesmen like their tall tales.

[DaveC113]

That was an incredibly rude personal attack DS-21. But if you want to read that into it, have fun...   

Sorry to be here sharing my experience with class D amps, what is it you're doing here exactly?

[rodge827]

Yeah, footers on class D amps (and power distribution) make a larger difference than I would have ever expected.

Dave could you elaborate on the type of power distribution you are referring to?

Thanks,

Chris

[DaveC113]

Dave could you elaborate on the type of power distribution you are referring to?

Thanks,

Chris

I was trying the SurgeX I'm refurbing/modding at a friend's place and I stuck 30 duro (very soft) Sorbothane hemisphere footers on it. This produced a sound with a sense of ease and refinement with a very quiet background, but it's a little on the dark side, which works great with my system but was a little too dark in my friend's system. It made things sound a little less exciting on some tracks. He suggested trying some different footers and had Black Diamond Racing cones and pucks, and they both changed the character of the system quite a bit vs Sorbothane. They both made the sound more vibrant and exciting, the cones were a bit thin and the pucks were just about perfect in his system. As a result I plan on shipping them with the Sorbothane as well as another alternative.. the BDR pucks are a little pricey but I'll be trying some of Herbie's products, wood blocks, as well as a wood stand to hold the unit vertically instead of horizontally.

I have tried Herbie's isocups and various balls that pair with them on my amp, preamp and DAC with great success but the changes I heard with the power distribution system are far greater that with my other components. The results definitely took me by surprise!

Class D amp also respond strongly to different footers, on the level of the power distribution in many cases.

*I do not sell footers or any sort of vibration control devices  *

[OzarkTom]

If anyone is interested in what is under the hood on these Crown amps,watch this youtube video. There looks like plenty of room for the DIY'ers to do their stuff.

https://www.youtube.com/watch?v=b_F749Ngzc0

What is also special on the Crown amp is the high pass and low pass filters. The mids and highs should sound better if you are using the high pass EQ on your main speakers and using a powered sub for the lows. The Virtue amp I use to own sounded much better hooked this way.