Jeff Rowland

Chad, I am a tube fan, just don't want the longer term maintenance issues. You can read threads and reviews and time after time the highs are always mentioned as not being quite right on Class D. Maybe it doesn't bother a lot of people. I've certainly heard my share of A and A/B amps that I didn't like the highs on too.

I'm an electrical engineer and know a little about amplifiers and after doing a little studying on how Class D works, I could see why it would sound not quite right. It works in a quite different manner from standard amplifiers. Class D is often referred to in terms of digital amplifiers and that's more or less how it works, doing very fast pulses almost like a bitstream but more like a discrete Fourier transform IMO. I think it probably suffers the same problems as digital recordings do. I think they could improve it if they increase the switching speed to a much higher rate. I'm sure technically the engineers decided to make it fast enough that it meets predetermined specifications but I think there's still a difference. An analogous situation exists for CDs. That's a 44.1 kHz sampling rate is supposed to be able to reproduce all the freqencies that the human ear can hear. I bought an album off of HD tracks and downloaded free samples recorded at the 96 kHz rate. I hear a big difference. Not in the audible frequencies but in the warmth I used to hear with albums and analog. I know I'm not supposed to be able to but I do. It's very clear and I had a friend over recently and he said the same thing.

I think Class D will clearly improve but like CDs it'll take some time. It clearly has some benefits such as power consumption, efficiency, and easy power. I think it's probably great for the consumer electronics, the HT crowd and others.

OTOH, according to Dan D'agonstino the output waveform is not clean. That's something fairly easily objectively verified. Lastly when someone says, this or that item is great but you have to be concerned with cables or upstream components, that's a red flag for me. I went through a lot of expensive equipment and I definitely know what you mean. A lot of the good stuff requires a lot more of the good (expensive) stuff to make it sound good. I don't like that. I finally settled on McIntosh for my main system and it makes 90% of what I listen to - which is pretty much everything - sound very good. Yeah, I don't get the amazing jaw-dropping sound I used to get on 10% of my recordings with some of the high-end stuff I've owned but I can listen to current system for hours. I have good cables, speakers, interconnects but I don't sit there and think about how I need to improve it all the time like I used to. Anyway kind of a long rant but why not? It makes for interesting discussion. And who knows - one listen to a JRDG Class D piece might and I might find it's what I've been looking for all this time.

Wireless, I fear Mr. marks may be a little behind the times. While it is true that some early and basic ICEpower implementations may have yield foreshortened or glassy treble, switching amp technology has made incredible strides in the last few years and is now delivering world-class musical reproduction, a least comparable in quality to that of any other technology. You are correct that all JRDG amplifier are now based on class D ICEpower modules. . . yet, it is worth pointing out that these switching amps range in price from under $2K to approximately $30K. With the price tag goes design sophistication, and with that sonic/musical performance. Even the relative entry level 102, 201, 501, and Continuum 250 devices, which may occasionally seem on the slightly lean side of neutral for some audiophiles, can be significantly enhanced with external power factor correction (PFC) based power rectifier units called PC-1, which will bring their performance much closer to that of the higher end JRDG devices, like Continuum 500, 312, and 301, which are already equipped with internal PFC. I personally have a JRDG 312 and could not be happier. I discovered it 3 years ago at RMAF in Denver. . . I was in general disheartened about the sound of the majority of amps at the show, and the 312 was one of only a handful that delivered to me what I call music.

Please note that JRDG is by no means now the only manufacturer of class D amps that is delivering truly high end musical reproduction. I invite you to audition with an open mind also Spectron and the Bel Canto Ref 1000 Mk2 and 500 Mk2 monos, just to mention the ones I am most familiar with. I am sure that other readers of this thread will be delighted to add their own treasured discoveries in class D amplification.

The aledged inherent inferiority of class D amplification is a trite urban legend, propagated by the ever shrinking crowd of the hyper-nostalgic. You owe it to yourself to make your own informed opinions based on what your own ears tell you, rather than on anyone's aprioristic writings: Go listen for yourself to class D amps. . . like with any technology out there, you will find fabulous amplifiers, as well as products for which you will have serious reservations. . . isn't it the same thing with tubes and classic solid state?

By the way, class D amplifiers using ICEpower modules are not digital, they are analog devices.

Feel free to PM me if you want to chat. Guido

Guido, when you say the modules are analog devices, I think that paints with too broad a brush. The actual switching controller and output stage still put out a series of variable width pulses or rectangle waves that are subsequently fed into a filter that converts or "filters" them back into analog looking sine waves. The *input* to the switching controllor can be analog (or digital). Still, ultimately the signal is formed by rapidly switching or pulsing a circuit on and off. This technique is how the effeciencies are gained and basically what a Class D amp is. This is different IMO than simply amplifing an analog signal. Maybe they've got it worked out. I think I noticed a Bel Canto device in the Class A components of Stereophile. I don't think it could be that bad since that's the case. The idea and benefits are appealing but the implementation and sound of Class D I'm not so sure about. I bet you find 10 to 1 posts saying it doesn't sound right. Kind of like what you read about McIntosh or Krell. :)

". . . the implementation and sound of Class D I'm not so sure about."

You are absolutely correct Wireless, you can't be sure about something that you have not experienced personally in depth, regardless of what reviewers say, including yours truly. May I recommend that you give your ears greater credence than you credit the anachronistic pronounciations of the 'ancient regime' of audiophilia, or by sophistic arguments? Whether or not there is an ounce of truth in there existing a 'digital' core lurking inside an ASP1000, it does not change the fact that so many of us have found that ICEpower amplifiers, very much like tube and classic SS amplifiers, range in sound from the horrendous to the magnificent.

It is interesting that you mention McIntosh and Krell, as negative examples. . . would you consider condemning all tube amps and all class A solid state amps because the house sound of these 2 manufacturers may not be particularly liked by some?

Get out of the house and audition with an open mind to a Bel Canto Ref 1000 Mk.2, JRDG 312 and 301 monos, latest Spectron monos, and a smattering of other switching amps ranging in price from $500 to $50,000. . . I have no idea if you are going to like any of them, but at least you will be able to form an educated opinion based on your very own experience.

The article in Stereophile is being misunderstood here. I see it as him pointing out what are current classics and can be purchased at good prices and still yeild excellent results. The ommission of newer designs is obvious, they are new, not (yet) classics.