How do you feel about Class D amplification?

[jdandy]

There are many audio companies offering Class D amplifiers, some configured as subwoofer amplifiers, some configured as full range amplifiers, and some configured as integrated amplifiers. Class D amplification seems to be coming into its own these past couple of years. Excellent Class D offerings like the Esoteric I-03 integrated amplifier, Gato Audio DIA-250 and DIA-400 integrated amplifiers, Audio Research DSi200 integrated amplifier, NAD Masters Series M2 integrated amp/DAC, Wyred 4 Sound STI-1000 integrated amplifier, Peachtree Audio Decco65 integrated amplifier/DAC, Bel Canto, Rotel, and many other manufacturer's offerings are staking their territory in the high-end audio market.

I question whether Class D has seen a growth in popularity and whether Class D amplification is beginning to be actively embraced in the high-end audio community. Reading the reviews of Class D products presents a mixed bag of impressions, and it appears there are some reviewers who embrace the technology and others who are not yet sold on Class D truly being considered high-end gear. What do you think of Class D amplification and the possibility of a Class D amplifier or integrated amplifier becoming part of your system?

[Vintage Pete]

I don't think I would be ready to embrace Class D as a mainstay in my systems, but that doesn't necessarily mean I shouldn't be....I certainly would have no prejudice against a subwoofer that contains a class D amp.

I wonder if us "older" guys are "old fashioned" and just prefer the likes of good old fashioned power supplies in our primary amplifiers.

In any case, this is an excellent topic and will be a good thread. Kudos Dan!

Pete

[Higgens]

If I'm not mistaken, the McIntosh McAire contains a Class D amp.

[Still-One]

I tried some class D Rotel amps and they couldn't handle difficult loads. I wanted low heat generating gear so I tried Rotel. That didn't work so I ended up with a real heater in the Krell integrated

[-E-]

It all depends on who makes em.

Personally, if it sounds good, I don't care if it is Class A, AB, or D.

[Johnbr]

I think give them about 5 more years the look out.

[Davkj]

I think it depends a lot on the speaker being driven. In my experience they work best with easier loads, and can really sound great when properly matched.

[o0OBillO0o]

I like them, but I also like what I've got.

I would like to see a Binghamton version of a class D. 3KW!

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[jdandy]

Initially Class D amplification was all about lower weight and smaller size for professional amplifiers that were being lugged around and set up over and over by musicians and other performance artists. Big, heavy Class AB amplifiers were difficult to transport, set up, keep cool during operation, and were far less efficient. Manufactures like Crown, a professional amplifier manufacturer, began developing Class D pulse width modulation amplifier designs that ran amazingly cool, even without fans, could be stacked four and six high in professional transport racks without having to be removed to be put into service, and provided enormous output power for size and weight. Class D amplifiers have been a big hit with professional musicians and the pro-audio companies that rent pro gear for shows and concerts.

Class D amplification has been around for quite some time, but only in the past few years has it made inroads into home audio applications. I use a Crown K1 two channel Class D power amplifier in my recording studio to drive the JBL LSR6332 3-way monitors for recording playback in the studio. When I first bought the Crown K1 new in 2006 I installed it in my living room system for a couple days, comparing it to the MC300 I used in that system at the time. The Crown was impressive sounding driving Definitive Technology BP2000 speakers. In my studio control room it is installed in the bottom of one of my two engineering racks without heat issues no matter how hard I drive it. The entire case of the K1 is aluminum with no vent slots and no fan. The case is the cooling mechanism for the efficient amp. Quite impressive. I suspect that in the past seven years of Class D amplifier development since the K1 was first offered there have been substantial advances in performance, lower distortion, and better signal to noise ratios. These specifications are important to home audio enthusiasts.

[jdandy]

Originally Posted by Still-One

I tried some class D Rotel amps and they couldn't handle difficult loads. I wanted low heat generating gear, had to go to a Krell integrated.

Jim.......One of the issues presented by Class D amplification is the passive filters used in the final output stage to remove high frequencies from the pulse width modulation developed during the gain stage. Different loads react differently when connected to the filter networks of capacitors and inductors. Since we know speakers are not a fixed resistive load but are a varying resistive load, as well as a varying capacitive and inductive load, getting a Class D amplifier properly matched to its connected speaker load is critical to the amplifier's performance. This may be one of the most critical aspects of getting the best performance from a Class D amp.