Zu Druid questions

Ha! A question on how the measurements are flawed turns into a discussion of them. I'm not sufficiently adept technically to answer these questions completely, but I'll speculate wildly (something I'm good at too).

Shardone - Some of this or that might be related to rainbows and puppydogs. If the driver is breaking up anywhere in its band I can't hear it. You couldn't either. Placement of the Druids is incredibly flexible without changing the character of the sound. Hanging the Druids in free air would probably have been acceptable had they bothered to load the chamber with an attached hard plate at the base of the speaker AS IT WOULD BE IN ANY LISTENING ENVIRONMENT.

Bob - I don't know of any technical literature related to their proprietary "Griewe" loading technique. I do know it is distinct from other ventilation schemes. Where horns have wall-distances they prefer, as well as bass reflex designs, the Druids have an ideal floor distance. They don't care much how far they are from walls. Druids are extremely coherent. Blame the faulty graphs, not the speakers.

Bear in mind also, these measurements were made on a two-generations-old model.

I don't pretend Druids are perfect for everyone, but misinformation and derivative speculation should stop.

In the real world of sound, the druids sound like a superior speaker to many regardless if people are stuck on some crazy thoughts that a guitar will sound like a violin thru or something crazy... They easily exceed real world listening conditions in the application, even over some of the best Altec lansing Computer speakers :) (last part was a sarcastic joke) Try them to learn the truth for yourself..

These are an extremly sucessful speaker so don't get caught up listening to all the static noise coming from behind your computer screen and pool of internet speculation, most companies would be out of business if most of the stuff shown was true or truley effecting performance... Take K-horns till this day people don't believe the design is really any good, and the are still one of the better most popular classics, it was seen as nutty at the time too from reading the history on it. Yep you need Corners to make them work or they are pretty much crap.. same issue applies here, but nowhere near the Requirement to put you speaker on a floor vs. having open corners!!

I have built underdamped pipe speakers, and speculate that the Druid's enclosure may be a variation on an underdamped pipe.

The 150 Hz notch would indicate an internal path length of about 90 inches. When the path length is equal to one wavelength, the backwave energy emerging from the end of the pipe is 180 degrees out of phase with the front wave of the driver, so cancellation occurs. The depth of the notch makes me suspect the line is underdamped. Note that the ear is much more tolerant of frequency response dips than it is of peaks; without that SoundStage measurement, I bet very few people would know it's there.

Brave move on the part of Adam and Sean, sending their speaker to be measured when I'm sure they knew full well that its measured response would raise eyebrows.

If the 90 inches ballpark path length is correct, we'd expect to see a local response maximum at about 75 Hz, with response rolling off slowly to about 37.5 Hz and then falling off rapidly below that. This is reasonably consistent with the SoundStage measurements.

To my ears, the Druids sound like they have much more bass than the SoundStage measurements indicate is possible, even optimistically factoring in boundary reinforcement.

Normal boundary reinforcement will of course bring up the response in the lower octaves, but not all that much. I do not understand why the gap between the vent and the floor is so critical, but can accept that it is. Zu claims to use muffler technology invented by a man named Griewe, which I have been unable to find details of so presumably it's not patented. Mufflers.... hmmmm.... Jackson Browne.... hmmmm....

There are two ways to bring up the apparent loudness of a signal. The most obvious is to increase the intensity, or sound pressure level, of the signal. A less obvious way is to make the signal last longer. If presented with two brief signals of equal intensity but different duration, the ear will perceive the one lasting longer as being louder. Perhaps the muffler-like characteristics of the Griewe enclosure take advantage of this psychoacoustic phenomenon, filling in the perceived bass a bit by sustaining bass energy for just a little bit longer. "Oh won't you staaaaaay, just a little bit longer...." This is just a SWAG on my part, and I invite clarification and correction from anyone who knows better.

Duke

jack,,you still have great speakers