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Rex Mills
07-10-2003, 12:05 PM
Anyone know the fs of the 035ti tweeter?
Thanks :)

4313B
07-10-2003, 02:13 PM
~ 18 ohms at ~ 2.2 kHz

John B
07-10-2003, 08:20 PM
Giskard

Is that for the 035ti or 035tiA. I measured some a couple years back, I can't find my notes on what they measured but I do remember that the 035tiA was several hundred hertz higher than the 035ti.

4313B
07-10-2003, 08:42 PM
Two 035Ti and two 035TiA.

2.2 kHz is roughly the Fs of the 035Ti and the 044Ti.

Perhaps my particular 035Ti's had TiA diaphragms. They all came out of 4406's.

Rex Mills
07-10-2003, 10:16 PM
2.2 kHz is roughly the Fs of the 035Ti and the 044Ti.

Giskard
That begs the question, How does JBL cross the 035ti over at 2.5 khz, 2nd order in 2 way designs and keep distortion down to listenable levels.

4313B
07-11-2003, 04:51 AM
Well, you could have read about it here

http://www.lansingheritage.org/html/jbl/specs/home-speakers/1984-ti.htm

except the pages are missing. Page 4 details the design of the Ti HF transducer and page 5 details the 18Ti. In any case the Fs is very mild. The 044Ti measures ~ 14 ohms at ~ 2.2 kHz and the Fs of the 046Ti is even milder, ~ 10 ohms at ~ 2 kHz.

Quite a difference from the days of the phenolic impregnated linen aluminum domes like the 044 which measure ~ 60 ohms at ~ 1.4 kHz.

Rex Mills
07-11-2003, 10:27 AM
Giskard

Makes sense to me. I thought 18 ohms sounded very low as most tweeters have a much higher impedance peak at resonace. I would guess that a flatter impedance would give a flatter response above and below Fs, better transients in that region, simpler crossover design and other benefits.
Not to beat this to death :) but how does a designer keep the impedance peak low at Fs, besides the obvious, ferrofluid, etc.
Thanks! :)

Don C
07-11-2003, 02:36 PM
I'm wondering about the specs of the 052ti. JBL has those priced much more reasonably,(less than half of the 035ti cost) I think that they must want us to use them. This is what was in the 4410As that I had, they look identical to the 035ti, except there are no ribs molded into the dome.

4313B
07-11-2003, 02:49 PM
Hi Don,

Have you A/B'd the 035Ti and the 052Ti? I've heard some people say they like the sound of the 035Ti better. Maybe I'll measure a pair of 052Ti's if I get a pair. The lack of ribs in the dome might be significant.

Rex,

Let's see if Don can correct the Ti series information and then you can read about it there.

Rex Mills
07-11-2003, 04:10 PM
Giskard

Thanks for the info, never too old to learn something new, as always, your answers are appreciated.:)

Don C
07-11-2003, 07:00 PM
I did not A/B the 4410s except with my 240tis. My impression at that time was that the 4410As had too much high end. I had them sitting on the floor about three feet from the wall, I suspect that they may have bee designed to go right up against the wall though. I was wishing for an L pad to turn the tweeter down about 2DB, but they are non adjustable. Other than that, they sounded great. They probably would have gotten better with some break in too.

John B
07-15-2003, 03:50 PM
Found my notes on the tweeters I tested. But in looking at them now I am more interested in what Giskard brings up about the driver Q. I had assumed some problems I heard were due to rising fs. It’s probably more due to the high Qts. The Q of the 033s varies as much as the fs does. And that in general the higher the fs, the lower the Q. Does anyone know what the factory specs are for the 033? By the resonance filter in the L110 it looks like the fs is 1200 Hz, but what is the Qts?

It’s a small sample for the 035Ti’s, but the fs varies quite a bit also, but the Qs are much closer.

I always figured the rising fs in the 033, 066 and 044 was due to surround stiffening. Much like the old Lansoly surrounds. But doesn’t the 035 use a “fold” in the titanium? Shouldn’t stiffen. What am I missing?

The first two 033s in the table are from a pair of L40s that were my bedroom speakers through the ‘80s. They became very harsh and piercing sounding. I had assumed it was due to the 1745 Hz tweeter. Although that’s not desirable with an 1800 Hz crossover, the Qts of 1.3 was probably worse.

John B
07-15-2003, 03:51 PM
Out of curiosity I plugged tweeters with a fs 1445Hz and Qts of 1.3 and one with a fs of 1600 and Qts of 0.75 into a Xover pro model of the L110s. The higher Q definitely looks worse. I modeled the same tweeters with a second order crossover as used in the L166, L112, 4313, etc. Much less affected by either fs or Q.

4313B
07-15-2003, 04:48 PM
"I always figured the rising fs in the 033, 066 and 044 was due to surround stiffening. Much like the old Lansoly surrounds. But doesn’t the 035 use a “fold” in the titanium? Shouldn’t stiffen. What am I missing?"

Well, the 033, 044, and 066 definitely wear out with use. The Ti's aren't supposed to suffer fatigue but they can suffer problems with the copper and aluminum joints. G.T. figures 20 years for any of them is a very good run for the money. The newer versions are supposed to be using CCA wire but now that I think of it, that wouldn't have started occuring until the very early 90's...

"I modeled the same tweeters with a second order crossover as used in the L166, L112, 4313, etc. Much less affected by either fs or Q."

Pretty compelling reason to go with second order filters and cut down on manufacturing costs eh?

Only the "cost no object" L250 used the first order filters during the L96/L112/L150A era.

Thanks for the graphs John! :)