Class D is just Dandy!

As I read more and more about Class D amps, one thing stood out to me is the power supply. There are quite a few Class D amps out there that are being put together with DIY kits from Hypex. No doubt that these amps with DIY kits does a good 'job' on most systems and afford us the opportunity to stretch our hard earned dollars on rest of the components in the system.

But if you want the very best in Class D, consider auditioning the amps with NC-500 or NC-1200 module and SMPS1200A700 power supply. I think you will be pleasantly surprised!

@jrunr, I don’t have any direct experience with 7B’s but I was in similar situation as you. I own a pair of B&W 800’s and they are quite power hungry. After sticking with Class A/B amps for couple of years I begin experimenting with Class D amps.

If you’re looking for multi-channel amp, I would give it a serious consideration to ATI 500NC series amps. I have been listening to 544NC amp for a week now and couldn’t be any happier. While amp is still settling, the amp got gobs of power and finesse to drive my 800’s with ease. Most dealers have 30 days return policy minus the shipping so you can audition this amazing and fairly inexpensive amp risk free.

I’ll probably order their 543NC - 3 channel amp soon to complete my 7.1 HT setup.

http://ati-amp.com/AT52XNC.php

PS: I have also heard high praises for Bel Canto REF600M’s.

@guidocorona,

I believe Bel Canto's REF600M is based on Hypex’s NC500 OEM module and SMPS1200 power supply.  They do not use the NC1200 Hypex module.  

I am hoping to try the 600's in next couple of weeks. It would be interesting to see how these mono's stack against the ATI's 544NC which is using the same NC500 module in bridge mode per channel.  

@kdude66,

"I have a new Red Dragon S500....

Kenny, I tried this amp recently with my B&W 800D2’s. While it sounded wonderfully adequate in low end and detailed in mid’s /high’s, it didn’t quite push the 800’s the way my current amp does from ATI 544NC. In addition to being detailed, the 544NC drives the low end with such brute force that I have not felt the need to use my JL sub.

I would have been more than content with S500 if I owned the B&W 802’s. When I spoke to Ryan Tew of RDA, he recommended using a pair of S500 in bridge mode to drive my 800D2’s.

Got one more amp on my list of audition before I happily settle with my choice of class D amp.  Getting closer to sit back and enjoy the music :-) 

@kdude66 

That's quite a coincidence...I just ordered a pair of Bel Canto's REF600M's to try them out. The ATI 544NC amp is equipped with dual NC-500 modules in bridge mode per channel, so plenty of power (900W in 4 ohms load) to drive any speaker out there. 

I didn't want to end my quest for a 'perfect' Class D amp without auditioning the REF600's. 

PS: I did find @georgehifi comment about REF600's little discouraging.  

Cheers! 

@merrillaudio,

Thank you you for taking the time to share great insight on Class D amplification. A bit of clarification on couple of things, in your comments, 

"Class D tends to be fast, unless slowed intentionally or with a tube"  - Are you referring to mating Class D with a tube preamp/Linestage?

In reference to above comment, the end user should be able to reduce "Coherency Distortion" issues with a tube pre as pointed out in your Synergy 2 paragraph, right? 

I have been experimenting with Tube/Class D amps in a bi-amping setup with Tube preamp. It hasn't been easy as I intentionally chose not to add any external crossover or gain switch in the signal path.

I do feel I am very close to the attaining that perfect synergy of Tube's lush mid range and Class D's prodigious slam in the low end.

Cheers!  

@toddverrone, You may be confusing 'Active' bi-amping with bi-amping. 

Bi-Amp - 2 amps wired to the speakers LF and MF/HF binding posts using the internal passive crossover.

Active Bi-Amp - Putting an active crossover in between the amps and the preamp. In this case, it's highly recommended to remove the crossover in the speaker and wire the drivers directly to the binding posts. This adds a level of complexity you may or may not like because you have to know crossover point of the MF/HF and LF drivers. 

Fortunately, my VT-80 outputs equal watts in 4 and 8 ohms load with 26dB gain which made it bit easy to coordinate. I tried few Class D amps that had very high damping factor or high gain settings (obviously they didn't quite gel as they over-powered the tube amp). While it's only been couple of days with THOR mono's in my system, I am throughly enjoying their more than adequate bass slam. In my system, the key was to attain just the right amount of low end without overwhelming the mid's and high's. So far I have not notice any coherence or speed mis-match issues.  

PS: I am glad to hear that you're enjoying your setup. 

@georgehifi 

Just by reading your posts, I am convinced that you are stuck in Class A/B la la land. Since you're struck there that can only mean one thing: not being firmly in the present.

Through either anxiously living in an anticipated future or stuck in the habitual past, we cut ourselves off from the inspiration and creativity that exists when we are fully present.

The following five steps may help you clear away the mental cobwebs, swiftly returning you back to the creative flow where you belong.

1. Hit the Shower
2. Seek out Sweat Sessions
3. Change the Channel
4. Change the Environment 
5. Still stuck, seek professional help. 

Class D is here and contending head and shoulders with Class A/B. 

I have compared amps side by side with older Hypex Ucd and Hypex NC500 and I could not discern any major audible differences. As others have pointed out, It's all in the design implementation and most importantly the power supply.

To 'kuribo' point, I would stay away from any Class D amps that uses off the shelf parts like those DIY kits (NC400) amps being sold from $500 and up. IMO, they do not represent the very best Class D has to offer. They may be the best bang for the buck but certainly not what I call tip of the iceberg. 

I know a close friend of mine recently switched from a NC400 mono amps to Mola Mola's and he swear by Kaluga's excellent sound. 

@georgehifi 

"The only current crop of D’s I’ve heard that have semi impressed, were the new Belcanto Ref 600M Monoblocks, yes they use the the newest "best" N-force NC500 modules that aren’t available to anyone but to Belcanto and other manufacturers"

You should get your facts right. It's not N-Force, it's NCore NC-500 Hypex Module. And there is no modification to NC-500 module itself. Inside REF600 there are three circuit boards: a Hypex NC500 amplifier, a Hypex SMPS1200 power supply, and Bel Canto's input conditioning board with their Impedance Optimized Input Stage, for balanced, high common-mode rejection and to provide a low output impedance to the input of the amplifier board. The active element on the board is an LME49720 Dual High-Performance Audio op-amp in what appears to be a low-pass filter configuration. 

"The only current crop of D's you heard is REF600"  -  Are you always been this short sighted that after listening to one class D amp, you see fit to under appreciate or rather condemn the recent innovations and forward progress in Class D camp. 

I wonder how many Class A/B amps you auditioned before settling with the one you currently own? And is that the 'best" Class A/B amp made in the world?

If you seek the "best" in Class D currently available, I double dare you to audition Jeff Rowland's 925/725, Mola Mola's Kaluga and Merrill Audio's Veritas before you return to another Class D thread. 

As one of the reviewer pointed out, "the REF600M didn't sound identical to some other amps was neither surprising nor a criticism of any of them. Of three recent amps of my experience, the REF600M was the warmest, the NAD Masters Series M22 the most detailed, and the Theta Dreadnaught D somewhere in between. 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"