Zu Druid MK IVs vs. Essences

I respect your opinion, but really that`s all it is

Agreed. Same goes for me and Dock's comments about the measured response. Just think of it as a service to prospective buyers and the OP - to be aware of some of the limitations of the products under discussion. Perhaps Bjesein might not have lost $600 if he had been forewarned here on Audiogon and been able to make a more considered or informed decision.

FWIW - these speakers do wonderfully well with a flea powered amplifier. They definitely have some major advantages for some.

>>shows that the Zu Druid is a Paul Voight type design<<

It isn't. In Druid there is no interior taper and no progressivity in managing the rear wave. Also, the driver is placed at the top of the tube, which is not the usual Voight approach. It's also not a transmission line, though the speaker might externally resemble that. Druid was the first instance of Zu's proprietary acoustic impedance matching model, and it is only a partial implementation, relying on both a specific cabinent interior volume as well as precise distance from driver to the floor via the floor-facing vent and the user-adjustable plinth-to-floor gap. The result is that the floor gap has much more than 3db effect on the free-space frequency anomalies. The speaker does not sound like the free-space test curve. If it did, no one would have bought it.

In later Zu models that are not sealed, the Griewe acoustic impedance model is complete, though slightly differently implemented in the straight cabinet and tapered cabinet speakers. In those cases the free-space (off-floor) performance is far closer to the on-floor performance, because the Griewe model is enforced within the cabinet rather than nakedly dependent on a user-adjusted gap between cabinet and floor. However, in Druid, the user adjustable floor gap does give the listener a valuable tuning device for managing the always problemmatic speaker/room interactions in the bass frequencies, in normal domestic construction.

Phil

Disclaimer: I am the present owner of the Zu Soul Superfly, and I have previously owned the Druid Mk4, and the Essence.

The summary so far is:

1. Some people who have heard Zu speakers like them.
2. Other people who have heard Zu speakers do not like them.
3. There exists a set of measurements conducted by Stereophile in 2002 of an older version of the Zu Druid and these measurements are unflattering to Zu.
4. People who like Zu speakers consider the 2002 Stereophile measurements as not being an accurate representation of the capabilities of the 2002 Druid owing to a somewhat unique design.

What is interesting too is a recent Stereophile review of the Zu Essence. In it, John Atkinson measures the Zu Essence and has this to say about it:

"In many ways, the Zu Essence is an underachiever, measurement-wise. But the surprise for me, when I auditioned it in AD's room, was how much of its measured misbehavior was not too audible, other than the rolled-off highs and the lack of impact in the lower midrange. I suspect that Zu's designer has carefully balanced the individual aspects of the Essence's design so that the musical result is greater than the sum of its often disappointingly-measuring parts."

Also, Art Dudley in the same review of the Essence says this:

"With its very good bass extension, superb musicality, lack of egregious timbral colorations, and impressive spatial performance, the Zu Essence qualifies as the first loudspeaker I've heard that combines genuinely high efficiency with a level of audiophile performance for which no excuse needs to be made, all while being priced within the reach of the serious-but-not-crazy hobbyist. I'm really impressed with the Essence—and, yes, I could happily live with it myself: It's that good."

So I think even Stereophile says it sounds better than it measures.

In Druid there is no interior taper and no progressivity in managing the rear wave.

What you are suggesting is that it is even simpler - a quarter wave pipe.