Anyone listen to Zu Audio's Definition Mk3?

Good discussion folks,
Most often when a cable manufactuer has both silver and copper offerings the silver is considered the higher end and better/further up the line choice(with rare exceptions). Silver is believed to be the more neutural,transparent,resolved and open etc. Tubes and in particular SET amps historically mate well with silver as they don`t usally require added warmth,fullness or body to enhance their natural tone and harmonics.

The ASR is class AB and uses OP amps in the input stage(thus introducing negative feedback in the circuit). This will certainly lower the low order harmonic distortion(2nd and 3rd) but unfortunately produces the higher odd order(5th,7th and 9th) that are really nonexistent with the SET amps(which do have higher amounts of 2nd distortion(this of course varies quite much depending on the particular SET amp used).

If would seem logical that the Kubala Sosna which is 'generally' considered a 'warm' and 'rich' cable will complement the ASR lean/thinner presentation(compared to tubes). A good silver cable won`t add this full body(nor subtract)thus there`s no masking or embellishment for the ASR.

Marshall Nack`s findings do make sense to explain this synergy. His discovery just makes the point clearly with regards to proper matching to get a desired result.

>>Friederich Schafer has worked on that design for over 30 years. Maybe he should hire you as a consultant?<<

I commend his persistence. I heard the early amps. I had hopes for more progress by now.

>>Silver is only nominally better as a conductor compared to copper (6% better). Translates into "louder" and not an increased bandwidth. Why is it that SET owners gravitate to silver? Hmmm.<<

You are correct that the percentage improvement of silver's conductivity over copper is small, numerically. In coils or in wire weaves however, the bandwidth and revelatory differences between metals can be real in addition. Having worked on silver vs. copper based audio product development efforts, I am speaking of both measured and audible differences, first-hand. Regardless, compensating for any loudness difference is easy. More to the point, I get equally good sound out of SET amps with copper, copper + silver content and silver cabling. But the middle option does it at moderate cost. I don't have a bias for silver cabling for silver itself. I don't really care what's in a cable as long as it is sonically neutral or close to it.

Put another way, if an amp is musically convincing, it ought to be also credible on Paul Speltz' inexpensive Anti-Cables, and then the owner can decide how far to take cabling. I know I could do that with any SET amp I consider exceptional on its merits.

>>Why not minimize second harmonic distortion?<<

The best SET amp designs do minimize 2nd order harmonic distortion. They just don't go so far as to incur the downsides of negative feedback to push that one performance attribute to vanishing levels. There's more to perception of fidelity than vacant harmonic distortion.

>>I have talked at length with a manufacturer who makes what many consider the best tube amplification in the world, and he felt that SETs present so many disadvantages from a design standpoint that they were not worth pursuing despite the plump and pleasing midrange.<<

He's entitled to that view. Obviously SET amp designers disagree. Great SET amps don't have a "plump and pleasing" midrange. There's nothing "plump" about the midrange of the most convincing modern SET amps. It's the midrange qualities that you describe that kept me from embracing early examples of the SET amp revival. You just have to hear more credible examples, properly tubed. What they do have is a tonally complete, realistic midrange. What the design primarily gives up aside from high power is some ultimate bass control. It's a small price for the gains in real music fidelity in 90% of the aural range.

>>No need to sweat the details regarding wire, conditioning, and even your room.<<

If you choose the right gear to start with, the details are far easier to sort out. Music is the intent, not fetishism. I think it's great ASR amplification works for you. I'd rather see people happy in this pursuit than frustrated and chasing their tails.

Phil

I'm really not sure why this amp-Zu Def 4s synergy argument is generating quite so much heat. It's great to see such heartfelt opinions, but there must be a fair amount of latitude in choosing the amp that works best with the Def 4s in any given room.
I have to say that moving away from belt drive tt/pivoted arm, to direct rim drive/linear tracking means I'll never go back, but I'd never say my way would suit everyone. Similarly, those who've progressed from SS to tubes, or vice versa surely wouldn't claim their way was the only way?
Surely a spkr with as much flexibility in being driven (100dB+ eff) is really going to allow a whole extra range of tube amps esp. SETs to work with it, and similarly it's lack of crossover surely will get the best out of a range of SS choices.
It so happens in my case I stumbled across a really holistic tube pre/SS pow combination in the Hovland HP200/Radia, and I can't wait to hear how it struts it's stuff with the Def 4s. It would seriously have to be found wanting for me to consider another round of costly upgrading.
Really happy with new tt/arm, have got ideas for upgrading current carts/phono, cd great, amps fine, new speakers...looking fwd!

Overall, Zu makes a line of speakers that is amp-friendly to a wider range of electronics than any speaker brand I can think of. 101db/w/m efficiency that can also handle high power tube or solid state amps without distress. Relatively flat impedance curves, controlled floor & ceiling effects in Omen Def and Definition, check. Omen, the older Druid and Presence are/were ambidextrous about solid state or tube suitability. Superfly, the upcoming Coax and Definition "work" with anything but are considerably more exclusive about amplifier compatibility to sound musically outstanding (though this isn't strictly a cost issue, as the synergy between Quad II & II-Forty and Zu demonstrates). They are less forgiving of compromises in solid state designs than same in tube amplifiers, but overall there is a much narrower range of optimum amps for Superfly, Definition and the upcoming Coax. Still, people who don't like or don't want a tube amp have a half dozen compatible (and exceptional) solid state brands that make music with Zu. And sure, I'll put ASR among them. I think you can get much further with the right tube amplifiers but that doesn't really matter unless you're asking for direction. For whatever reason a Zu owner wants or prefers solid state amplification, they should have it. The issue here is that these forums become a permanent record of advocacy on the web.

Zu Definitions solve so many problems in music presentation that the amplifier just has to be good to put you in the realm of convincing hifi. The reason these amplifier topics become controversial is because the speaker is so good that once you hear it with even reasonable associated gear, the human brain (being a hungry beast) gets focused on extracting the nth degree of performance. And there's another thing: Zu upends the traditional weight in hifi given to the source. The amp/Zu interface becomes -- after the speaker itself -- the single most influential element in your system's sound. In a Zu system, much more rides on the amp selection than in systems built around most other speakers. Hence the heat the topic generates.

Phil

Phil,
I`m curious would a 2 watt 45 amp or say a 6EM7 tube amp drive your Def IV speakers? or perhaps a 2A3 amp? I ask because 100 db is really high sensitivity and a Xoverless design is an easy load(at least in theory).

I see posts by other gon members who use these types of amps to effectively drive Fostex single driver speakers(usally 97 db ) as well as Lowther based speakers. These listeners seem happy with the results within reasonable limits.Your 845 tube amp seems like plenty of surplus power for a true 100 db speaker.
Regards,