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Positive Feedback ISSUE 38
july/august 2008


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Thank you, Dr. Sardonicus for previewing the PXK Direct Coupling System.

Direct coupling is material science. The materials of the rack and the filter regulate the mechanical interaction between the component and the energy in the listening room.

Loudspeakers are machines; drivers are pistons. The pistons pump energy into the air. Air has mass and the air transfers energy to everything in the listening room. Direct coupling taps into this abundant source of energy which loudspeakers are preordained to supply every time music is played.

In the direct coupling paradigm, loudspeakers are transmission towers and the PXK rack is an antenna. Energy is propagated through the antenna in every direction. The filter is coupled to the rack using tungsten carbide balls fixed in place by CNC'd sockets machined into the trapezoidal corner brackets. There is no movement, no decoupling, no damping and no isolation; the ball is a high energy transfer conduit. Energy plows into the filter from the rack. The component couples to the filter through the pulling action of the resting area surface. The filter reprocesses the velocity of the waveforms in both directions without storing energy and ultimately completes a 2-way circuit between the component and the floor.

We would like to point out that the Marantz amps were seated on Grand Masters during the preview listening period and say without equivocation that the Black Label Series of isolation products will remain the cornerstone of our product line up. We think audiophiles now have more choices with Critical Mass Systems ranging from great to "Extraordinary".

One final word on the subject of price: We continually strive to keep our prices down but there is a cost for excellence including parts, materials and manufacturing that is unavoidable.

Once again, we thank Dr. Sardonicus for giving the new PXK Direct Coupling System an audition. There's a lot of noise in audio and he has a way of cutting through it.

All the Best,

Joe Lavrencik

Critical Mass Systems

Please allow me to express a deep and heartfelt thank you to John Zurek and the rest of the staff at Positive Feedback Online for the opportunity of having our Consonance Cyber 845 tube monoblock amplifiers reviewed. As an obvious reflection of the staff there, PFO has come to represent the gold standard in online high-end audio reviewing websites.

John's physical description of the amps should serve as a road map for how it's done. But, after all, this is the high-end audio hobby, and what matters most is what's inside, the heart and soul of the component. I greatly appreciate the work John put into this end of the review. To say he captured the true sonic essence of our product would be how I put it. With 28-wpc, this is not the typical SET amplifier strictly limited to the highest in high efficiency loudspeakers. Rather, most reasonable speakers can be accommodated quite well indeed, as witness the synergy achieved with the traditional Daedalus Ulysses, a product which I personally spent a good amount of time with at THE Show 2008.

Tube amplification is the core competency of Consonance, and the Cyber Series tube monoblock amplifier line represents our flagship. We invite you to give this truly reference line of products a listen, as we have an exceedingly well fleshed out line of amplifiers that should fit most any
audiophile's need.

Once again, my sincere thanks to John Zurek for an outstanding job in reviewing our amplifiers. Well done!

Joe Trelli
UltraViolet Audio

I enjoyed your DV-60 reviews, but I have an issue near the end of the recent Part 2. You mention that the DV-60 may someday get an HDMI 1.3 connection so it can play, among other things, lossless TrueHD. I'm sorry to say that TrueHD is a Blu-Ray (and now defunct HD-DVD) audio codec, not a DVD one. The DV-60 will never be a Blu-Ray player, firmware or otherwise. The real advantage of HDMi 1.3 is simply carrying DSD encoded material for DSD decoding at the processor end, as opposed to converting it to PCM before sending.

Ted Brady

Hello Ted...

Thanks for the correction. You are correct, of course, that TrueHD is a Blu-Ray codec and not one for DVD video. My thoughts were already moving ahead to future iterations of the DV-60 (or some future equivalent Esoteric universal player) that would be able to play Blu-Ray and handle SACD's DSD surround via HDMI 1.3 (or a later specification) ...but I should have kept present reality and speculations about the future more clearly divided in my comments.

Blu-Ray audio specifications and SACD surround via HDMI are putting a strain on older processors and I/O specs, and the proliferation of cabling and HDMI devices will mean that fine audio and video firms will have to get with it pretty quickly. I love the new lossless surround soundtrack specifications (much better than heavily compressed Dolby Digital) ...though I wish that DSD surround had been adopted on Blu-Ray ...but finding surround processors that do a good job with these new standards via HDMI is an exercise in slim pickin's.

The folks at Teac Esoteric are well aware of Blu-Ray, of course. In my recent correspondence with them, they stated that they are watching the development of the new standard carefully, but are waiting for the quality of the implementations to improve before making a commitment to Blu-Ray. We'll see ...but based on my superb experience with the DV-60, I certainly hope that they do.

And yes, I've told them so on more than one occasion....


All the best,


Just want to say, I agree with Teresa's high estimation of the HDTT discs—and I've not even heard the high-rez items!

Clark Johnsen

Great article, Dave... glad I didn't go through all that. At least you're showing people that properly done computer playback requires time and diligence. And, of course, there's more to do beyond what you've done already.

Btw... dbPoweramp is a wonderful ripper. Wonderful to use (Vincent recommends it) and much easier than EAC. Also sounds a hell of a lot better than iTunes. In other words, ripping engines matter.

Additionally, treating the CD prior to ripping gains mucho benefits... CD cleaning & polishing, demag'ing, Nespa'ing, and now the Xionic Gun from Brian Kyle. All these treatments are quite audible.

Alan Kafton


Max Dudious has made a dubious statement: "With about $100,000 worth of gear in operation, you'd expect the sound to be really fine." No, I wouldn't. From my experience I'd expect just the opposite! There's an investment figure ($40,000?) where philes' sound quality tends to peak, and it's well below the figure mentioned.

Clark Johnsen

Hi Clark,

To begin, there are writerly techniques that are frequently used by reviewers that you ought to have noticed by now. One is "ambiguity," where something is said that hints at an alternate meaning; as in, "Nice necktie." Another is "irony," where it is sort of clear you mean something other than what you say; as in, "Congress, in its wisdom, today replenished the war budget." Yet another is the veiled insult masquerading as humor; as in, saying to the chronic dieter, "Gee, you really look great, since you put on some weight." Then there are the other tropes: like, sarcasm ("The baritones and tenors sounded great," meaning the sopranos screeched), overstatement ("This was the best sounding speaker in the history of Western civilization."), double entendre ("Opinions are like sphincters, everybody's got one."); stressing the inflection of a pronunciation ("Well, excu-oo-o oose me!") etc. You have to learn to read between the lines. I just thought the $100,000 mark was something everyone could relate to. I'm not sure how you arrived at the $40,000 mark as the peak-performance-point vs cost, but I think I have an idea, so I won't ask. I just wanted to give everyone an approximate notion of the quality of the gear and the high performance I expected, and received. Quantifying things often gives people a "ball-park" understanding. Everyone knows you can get excellent sound for less than $100 K's. I thought that was understood. I think I've repeatedly said or implied, "The trick in putting together a first-rate system is not how one spends, but how little, without compromise."


Mr. Nack,
I know you didn't mention it, but did you have any hum or RFI problems with the unit due to the nonmetallic, unshielded, all-acrylic casework?

I have an all-acrylic Bluenote phono stage product that's giving me difficulties, but I'm tracing it to the 5,000 watt college radio transmitter three blocks from my house.

How far away would I have to move do you think to "eliminate" the interference?

Or any recommendations as to a constructed solution?

I do have alternative metallic cased phono stages, but the Bluenote is the best sounding.

Thank you.

Hi Ralph,

The Mini remained silent for the entire audition period, even with the Gain set at 65dB, and even in NYC with its notorious EMI / RFI issues. A very quiet performer.

I have in the bigger Basis Exclusive now. I set this one up like the Mini and initially it did have a ground noise. I was able to reduce this by switching to balanced cables and using a phono cable with a choice of grounding options.

But the real fix was understanding that best performance is obtained with the phono stage set to the minimum useable gain. The less this stage amplifies, the lower the noise. Set it so the volume on your line stage is the same or slightly higher for phono than it is for other sources.

There are tweaks to disperse EMI / RFI, like the ERS fabric. I have to caution you about these because I find they affect the sound in unpleasant ways.

See what you can accomplish, but don't go crazy. Phono noise is very difficult to track down. Sometimes it's best to chuck the nuisance product and move on.

Good luck,

Marshall Nack

Firstly I'd like to thank Positive Feedback for taking the time to review my modification. It is always valuable to hear the opinions of others, and while we are not always going to agree on everything, (nor is that possible or even desirable) I think certain fundamentals are true and sharing that common ground is a good thing. I am pleased to hear that what I believe and find to be true Greg also experienced and enjoyed. His many years of maggie ownership also lend much credibility to his opinions which is also important to me.

To answer a few points, first, it was unexpected but not surprising to hear him say he preferred my XO design to passive XO's. I do too, and so has every other DIY'er who has tried both passive and my XO on the 1.6 and reported back to me. There is nothing like a single, unified, full range driver and even a passive system cannot beat it.

As far as him hearing increased efficiency, his ears are not wrong. Stock, all new Magnepan models are about 86 dB efficient, however this XO design raises that to about 92 dB which is a fairly large increase, and it does this to every model so modified. This is due to the XO being used, and has nothing to do with the driver or it's size. It has also been verified by computer.

In regards to his thought about the slightly missing "warmth", I believe what he is not hearing is a by-product of the harmonic distortion created by the mdf frame as well as fuses being in the XO path. It's more of a quasi warmth (or slurring) and not a natural one and perhaps more time with them will reveal that natural warmth is still there. Also, should an owner wish for more warmth it can be made up with the use of a tube preamp that has those qualities. Another plus is the owner can then control the amount of it whereas previously it was out of his hands.

This modification for me was not an end, it was a journey. Along that journey I discovered that many of the hard core beliefs held about Magnepans are simply incorrect, both in what they are capable of, and what the reason they cannot attain their true potential is. My goal was only ever to make the best Maggies I could, and afterwards share that with others. For some people I make the stands, for others I give them the info freely to do it themselves. Still, and somewhat amazingly, there are those who won't even entertain that what I have done is right, good or even valid. That is why I am very glad your review was able to shed more impartial light upon the subject.

Again, thank you very much for a very well considered review, and I hope the speakers give Greg many years of pleasure.

Peter Gunn

I was quite surprised to find myself quoted twice in May Belt's latest article. [See] I offered the quoted comments in a quite different setting, and I still stand by them in the context in which they were made. I did not intend them to be interpreted as an endorsement of the RR-77 or the concept behind it, but simply as a possible part explanation of what some people were hearing, and how such a tweak could come to be. My first point about a fortuitous discovery of an unexpected benefit of something intended for different purposes was very definitely a general point. Some people think that we only develop things that work from a starting point of accurate knowledge about something. That view is most definitely mistaken, and all we have to do is to look at history to see that. We didn't have an acceptable explanation of why things fall to the earth or water flows downhill until Newton came up with his theory of gravity, but people had been devising things which worked due to gravity for several thousand years before Newton, and giving a variety of explanations we now reject for why they work. Many useful things have been discovered and developed in ignorance of how and why they worked, and that isn't going to stop.

As my second quoted statement suggests, I think that what people are perceiving is the result of a subsonic addition to the vibrations present in the room. What that statement doesn't say is that I wonder whether or not the result is desirable. It's certainly nice that it seems to add to many people's enjoyment of music, but I wonder whether or not it may not also mask some other things. I know in my system I've long strived to retrieve as much of the actual ambience of the original recording venue, and to minimize the impact of my room on the sound, thus enabling me to get as much as possible of the "you are there" feeling, rather than the "they are here in my room" feeling. 

That result is, of course, highly dependent on the recording. After reading Jeff Day's comments and my discussion at Audio Asylum with Stephaen, I came to the conclusion that what the RR-77 offers seems to be something that would not move my system in my preferred direction, as some of the comments I was reading seemed to indicate that it strengthened the listener's impression of their own room, and I have been slowly working at reducing that impression in my setup.

There is one thing I am very clear about, however, and that is that all of us who are in this hobby are here because we're interested in increasing our enjoyment of recorded music in our homes. There is a huge range of competing products and approaches available which offer to help us in achieving that goal, and I regard that as a positive rather than a negative—though it certainly can and does make for confusion, and there are certainly going to be some products/ approaches which do nothing, or even reduce our enjoyment. The only way through the confusion is the often slow learning process of discovering what it is that increases our enjoyment, what diminishes that enjoyment, and why those things have those effects. Once we have a good feeling for what it is that we want to achieve, we can move forward with quite a reasonable degree of certainty. In my experience, we make fewer mistakes as we do so, and we get more enjoyment from the music we listen to. Somewhere in that process, we also need to learn that it's more important that our systems please us than that they please others. In audio as in everything, we can't please everyone, but if we do genuinely manage to please ourselves, we often end up pleasing many more other people than we expected. There's something about a system which works together to achieve a particular personal goal that seems to result in more enjoyment for many people than a does a system in which the owner has striven to please a lot of people, since that often seems to result in a system with something to displease everyone. We need to learn to know ourselves and what pleases us before we can really start to assemble a system that not only offers us deep and long standing enjoyment, but also offers enjoyment to others. In order to do that we need to learn to listen with an open mind: not only to our systems, the components we audition, and the music that we enjoy, but also to what others say.

We don't have to agree with everyone, just as we don't have to enjoy every component or recording, but we do need to consider everything we hear on its merits and make up our own minds accordingly, while acknowledging that we will occasionally make a mistake. The only way to avoid mistakes is not to do anything at all—and paradoxically, that's the biggest mistake of all.

David Aiken

Dear David,

I am sorry if I was not perfectly clear when I referred to some of your sentences in my recent article. I am usually quite careful to make myself clear.

My intention was not to use your comment as an endorsement for the RR-77, but as exactly as you had written it—as a thoughtful suggestion as to what MIGHT be happening—i.e. that it might be the brain being tricked into believing what was being heard was far more information than was actually available from the recording—the equivalent of a sub bass!

I actually followed your comment with "This is an interesting concept which David has put forward—showing someone (David) attempting to find some rational explanation instead of the typical knee jerk reaction of 'It must be imagination'."

This really WAS intended as a compliment—it WAS evidence of a thoughtful process at work—which was to be applauded—which is what I had intended to convey and what I feel!

There ARE too many 'knee jerk' reactions and your thought process was to be applauded!

Again, my referring to your other comment—the point about a fortuitous discovery of an unexpected benefit of something intended for different purposes—was a very valid and important point which I wanted to reinforce by adding your comments. I completely agree that "Some people think that we only develop things that work from a starting point of accurate knowledge about something. That view is most definitely mistaken, and all we have to do is to look at history to see that." and I think that point should be repeated over and over again!

I agree with the other points you raise in your reply and I thank you for a very courteous response to my article.


May Belt