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In Reply to: Re: Zu Druid - myths and experiences (long) posted by Tom Brennan on February 4, 2007 at 13:50:40:
"The Zu speakers need to be burned in properly to sound the
best and at full potential. Yeah, one hears that line with bad speakers all the time. I never heard a bad speaker get good."Agreed. Driver break in is fully accomplished in 100 hours tops. Beyond that all that changes is that you get so used to how they sound that you don't notice their faults any more.
Follow Ups:
Hi BillA 10 ring I suspect RE: your comment
Here is the after 100hr part, things you need to get used to eh?http://www.soundstagemagazine.com/measurements/zucable_druid/
No wonder Bose can sell so many speakers. Obviously a great many don't listen to graphs.cheers,
AJ
The threshold for disproving something is higher than the threshold for saying it, which is a recipe for the accumulation of bullshit - Softky
... if you look up the review from which those measurements are taken, and look at the pictures, you can see that those were the earlier version. I believe both drivers have been changed significantly.If as suggested elsewhere the enclosure is a mass-loaded transmission line, the notch at 160Hz seems most likely to be an underdamped column resonance, which they may well have modified - I know I would, after the publication of measurements like that! :^)
A final note - someone said that 100 hours is plenty of breakin for anything. I would think that the time required to loosen an initially stiff suspension would be related to the displacement and frequency - it is basically a mechanical fatique process, after all. Running a speaker rated for 300 watts with a 4-watt SET amp would logically require many times as many hours to obtain the effect - certainly 1000 hours would not be unreasonable. Feeding 100+ watts to a speaker of 99dB or 101dB or whatever sensitivity in the midrange for 100 hours seems painfully impractical unless you really need to break your lease. If as someone else has suggested the driver is based on a 10-inch Eminence design, their typically rugged suspension could easily require a lot of mechanical displacement to settle in.
"the notch at 160Hz seems most likely to be an underdamped column resonance"About the only way you can get a notch like that is via an out of phase reflection. I've seen it claimed that the problem was caused by a ground reflection to the mic, but that doesn't wash if the measurement was done in an anechoic chamber. The impedance chart is classic bass reflex with a 50Hz fb, it doesn't even resemble an underdamped TL, let alone a stuffed TL, which has a single peak at fp. A quarter-wavelength driver to internal boundary reflection is most likely, being a tower I guess there could be a 1.7 foot internal path that wasn't rendered non-reflective. If they did fix it I've never seen a new measurement.
Bill, that notch looks to me like a cancellation notch, probably centered on the frequency where the internal path length is 1 wavelength long such that the backwave emerges from the line terminus 180 degrees out of phase with the frontwave. I would guess the Druids have an underdamped line roughly 85-90 inches long.This guess based on my own experiments back in the 80's.
It's a cancellation notch for sure, without seeing a cutaway of the box difficult to say the cause, though a TL so poorly underdamped to give that result should have more rippling in both the response and the impedance. I just checked the Zu site again, no chart is posted, and they still claim 101dB sensitivity to 35 Hz. They should have entered it at the NYC subwoofer shootout last week, eh?
interesting any links?
It's on PSW, reviews section.
hello Bill...PSW is pro sound web.. I got that... but where are the reviews? sorry... a site search of "review" brought up 50 pages of links...
thanks...
http://srforums.prosoundweb.com/index.php/f/7/0/
nt... duh!
The impedance curve doesn't back up my theory, though I did get similar frequency response curves from underdamped (though not totally undamped) TL's back in the day.With a mere 20 dB of boundary reinforcement, the Druids obviously go down to 35 Hz. So what's your problem, Bill? You're not still in the dark ages, following those outmoded so-called "laws of physics", are you??
Duke
Anechoic chambers aren't reflection free at low frequency. They don't usually have thick enough absorption wedges for that. One would want to measure on a ground plane, even in an otherwise reflection free environment to avoid the notch from floor bounce.
I've seen that before, guess that one must have had only 500 hours on it. Surely another 500 hours will fill in that dip at 150.
Yeah, cancellation is like that, it will go away someday.
Best,
that this "chart" is dated 2002. It doesn't sound like my speakers do for some reason. Couldn't get it to play at all ;-) Maybe the enjoyment factor file is not attached.
Last time I tried to listen to a chart it didn't have much sound to it. ;0P There are several speakers on the market that don't measure very well, however, this one is particularly bad, and I do mean BAD. There are also many people that don't know what a nice clean flat and tonally balanced speaker sounds like. I tend to be very sensitive to peaky speakers. I guarantee I could pick this speaker out of any double bind test; its that bad. Don't kid yourself; don't try to justify a bad purchase; get a different speaker; chock it up to a learning experience; move on; be happy.
Hit me with some good suggestions?
Edgarhorns are a good place to look, not free (what is) but they're excellent, honest-to-goodness, high efficiency speakers. Living Voice makes some good looking designs, as does Pi speakers, or some of the larger klipsches (either vintage or current). There's also behemoths like Zingali, or Westlake, or the old standby- big Tannoys.If you're willing to build a kit, you could do a lot worse than the BK-16 from www.madisound.com, or, if you want to really get some good stuff, Dick Olsher's BassZilla is a fabulous design. I've never heard it, but I've worked with the same design principles extensively- he's not a squirrely amateur :) Hammer Dynamics, Silver Iris, Prometheus, and some others are available as pseudo kits.
My favorite reasonably priced tube-friendly speaker is the Hornshoppe Horn, excellent speaker.
No matter what your subjective experience with the Zu, they are full of it. They do NOT have 35Hz bass. Period. If they did, they'd be selling to arenas, and every pro application around: they break hoffman's iron law just for us audiophiles? I think not. They're a standard enclosure, MLTL IIRC. That driver won't even do 35Hz f6 on an infinite baffle.
If you like them, that's the important thing. But don't try to stick up for their bullshit objective claims with subjective impressions, that doesn't prove anything. I mean no personal rancor here, fwiw.
Why do they irk me so much? Because they represent what's wrong with many hifi manufacturers, and give those of us with some ethics a bad name.
Aw c'mon, Jeff! Don't be a pussy. Tell us what you REALLY think!se
I couldn't do that:I might singe some eyebrows :)
I couldn't do that:I might singe some eyebrows :)
Heheh. And nothing worse than the smell of singed hair. :)
se
Answering your question, interested in more efficient speakers
(98db+) since I prefer to drive with my tube amps. Built and
modified Bottlehead 2A3 monoblocs and tube preamp.Thanks so much for the all the info. I'm hearing deeper bass
than what I heard with my 40hz planars. Have I measured it?
No (just to get that out of the way!). For the other guys,
never claimed my experience to be a flat 35hz. But my point
was/is the Druid sounds good here, they are punchy and deeper
than what I had and I have some experimental based rationale
as to why compared to the other system I have in house.The AP Oval 9 cable is not even tolerable on the KG5.5 due
to being exceptionally bass heavy. Here they work very well.
It was a tremendous difference ditching twisted pair magnet
copper wire with vampire RCA and going to BL1 IC's.
Not subtle. So all retoric aside I'm having a good sound
experience here. It could be that there are much better
options so thanks for all of your suggestions. I'll start
checking them out and get some feedback soon! Spent a few
years getting my front end right, now looking for the right
"voice". I'm very happy with the KG5.5, but always of mind
to tinker. Have to go beyond the system that already sounds
nice, detailed, and relaxed :-) No end in sight!
The good news are there are speakers that will do low bass with a 2a3 set amp. The bad news is I doubt you can afford them. So where does the leave you? With the rest of us normal folks. The solution? Get something reasonable that you like that will go down to a 100-200 hertz or so (maybe the Zu???), add an active crossover and bass reflex speaker, and power with a solid state amp. A decent 15" eminence will be fine and any old 100 watt+ amp will do. Or you can get a plate amp like the bash.I have just started DIY speakers and the comment made above that most don't know what a flat sounding speaker is rings true. I am running a borrowed 12" in a bass reflex and have stronger bass than any commercial speaker I have ever owned. But when I measured I was only flat to around 70 hertz.
Russ
P.S. You could get something like the Pi speakers but in the end I'll bet you will end up with a 3-way. Think wide range in an open baffle with a ribbon or horn/compression driver up top and the bass bin below as a starting point.
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