Class D is just Dandy!

@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.

Do you know if there is a difference between the 543NC and the 523NC?  I know there is more wattage, but does that equate to better sound for difficult speakers?

@jrunr

No, not necessarily. :)

Usually you can tell by how low a speaker impedance it is rated for (8 --> 4 --> 2 --> 1 Ohm) and how well the power doubles each step down in impedance. So for a 50 watt amp the best should put out 400 Watts at 1 Ohm. :) :

50--> 100 --> 200 --> 400

This is how Krell go their fame, with a 50 Watt class A amplifier that output 400 Watts into 1 Ohm.

Of course, these amps are beefy, but also usually ridiculous. :)

It's also important to understand exactly where your speaker is hard to drive. Digital amps tend to do better in the bass than the treble, which is good because most conventional speakers are hard to drive in the bass. nCore modules are famous for being less sensitive to where your speaker is hard to drive.

Best,

E

So I just checked out ATI's multi-channel nCore amplifier. It looks really interesting, except packing that many channels (8) into a single chassis limits the total simultaneous output.

If you only have a pair of hard to drive speakers, this should not be a problem. Also depends on what you mean by "hard to drive". This is a big range.

Still, 8 x 200 watts = 1,600 watts total. That is a lot of output!!

Best,

E

Here is the relevant part:

The AT52XNC amps are rated at 200W RMS per channel at 8 ohms
with300W RMS at 4 ohms and are available with 2 to 8 channels.

The AT54XNC amplifiers use two N-Core modules per channel in a differential bridged output configuration delivering 500W RMS per channel at 8 ohms and 900W RMS at 4 ohms. The AT54XNC amplifiers are available with 2, 3 or 4 channels.

It seems the 54xNC series are bridged, and therefore have half the channels of the 52xNC models.

Since the power supply is linear, ATI is limited in what they can put in a single chassis. A 1,600 watt linear supply is BIG and HEAVY and EXPENSIVE.  This wattage / size limit is driving everything else.

If you limit the channels to half, you can double the per channel output (more or less).

Personally, I'd rather go with a pair of unbridged 52xNC models, but limit the channels. 3 or 4 channels in each would give you a lot of power supply capacity/channel and ensure you had the best low-impedance drive possible.

Best,

E