Jeff Rowland

I was reading in Stereophile about how the older Jeff Rowland Amps sounded great and were classics. The writer said Rowland was good up to the Concentra II but not the Concerto and anything with "rounded corners." I think the Concertos were where JR started using class D amps. Is that the case? Do all models use Class D now?

I'm sure I don't want anything with class D at this time as many reviewers have commented on the treble as being glassy or something wrong with the sound of it. The highs are what make or break a piece for me so I'm not going anywhere near Class D right now but am considering giving Rowland a try for a third system I'm building.
I recently went with the Rowland 501s (class D) and the Capri preamp. This has been a definite upgrade to the very fine Audio Research gear that I had been using. An added plus has been the great reduction of heat coming off of the componets. I believe there are really no compromises to properly designed Class D equipment.
Funny, I was just reading the article you mention but you are confusing the Plinius recommendation with the Rowland recommendation. In the article John Marks recommends early model Rowland products through the Concentra II and also recommends all Plinius pre-curved casework excluding the "baby" integrated amps, giving special praise to the 8150/8200 integrated amps.
I can't comment on the digital amps being left out. I haven't had the opportunity to listen to them.
Look for Models 2, 6, 8 or 9. The Model 6 monoblocks and Model 2 stereo amp, particularly when run from the Rowland battery power supplies, are superb amps (at used prices, they are incredible).

Yes, all Rowland amps are now based around the ICe module.
I second Raquel's comments. IMHO the 2, 6, 8 and 9 were Rowland's best work.
Hi wireless,
If the ice power versions of the JR amps were not better than the old, why would they have gone that way?

I had the JR 201 and 501 monos and years ago had time with the Model 6 and 12 monos too. All good amps. Maybe the sound of the 201 and 501 are on the lean side although with great control and definition.

I have never really understood this idea that the treble in these class d amps is off in some way. I have had quite a few ice power type amps and the gains versus very highend amps are astonishing. I could understand if you were a valve or tube fan you may find them dry and lacking rose tinted specs. I guess taste and balance plays a big part in these. Make sure you feed ice power clean power and have good cabling and source. The treble will be fine.
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.
Brian, I agree. I got my answers on the JR "classic" JR products and kind of steered the thread to a class D discussion.

Guido, I think you miss my point - meant to be mildly humorous - about Krell and McIntosh. I was simply acknowledging the fact that even good gear gets bashed regularly. I'm open minded but no local dealers here for Bel Canto and JR. I may buy a used piece to try.

One area I think Class D may work well in is for speakers that need a lot of power with low impendance drops. Those characteristics apply to a lot of high-end speakers including a pair of Aerials I own.
In that case I agree. . . it's going to be a few years before a few current switching designs become 'classic'. . . let's meet again in 10 years around drinks. . . we'll be able to share some accumulated wisdom by then. G.
Wireless, I suspect you may be correct. . . I have herd reports that the JRDG 312 for example works very well with the Ariel 20Ts as they have some of the sonic characteristics of my Vienna mahlers. Other class D amps with low damping factors like the JRDG 301 monos may not. Spectron probably will. . . Bel Canto I am not sure. G. work as well. .. but this last is just my guess.