The story I heard directly from Randy Patton of JBL was that on lunch break one day he had been thinking that the tweeter on a consumer speaker would look better silver. So on the way back to JBL he stopped at a store and bought a can of silver gray spray paint. Went back to the shop and hit a pair of plastic domes with the paint and put them back into the speakers. Being well pleased with the resilts he was looking at the paint can lable and read that it contained Titanium oxide as part of the color. That was his tale. I have no reason not to believe Randy. This had nothing to do with the pro drivers. Best regards Moray James.
That sounds like Randy and I think I remember that story too ("if it ain't true it outta be!"). Remember that JBL was silver painting phenolic domes well before the whole Titanium fad started.
I'm not saying that JBL doesn't use Titanium, just that there were some "transitional" units that were aluminum alloy with a little bit of Titanium, that the marketing department latched on to.
The real improvements to the drivers came from Fancher Murray's good efforts (the diamond surround) and were achieved with alluminum. Titanium was more in a marketing answer to Japanese developments, rather than an engineering requirement.
I was there too.
David S.
I'm not saying that JBL doesn't use Titanium, just that there were some "transitional" units that were aluminum alloy with a little bit of Titanium, that the marketing department latched on to.
The real improvements to the drivers came from Fancher Murray's good efforts (the diamond surround) and were achieved with alluminum. Titanium was more in a marketing answer to Japanese developments, rather than an engineering requirement.
I was there too.
David S.
Hello David
Yes they did the original Diamond surrounds in aluminim. The story I heard was they were having issues with metal fatigue in conjunction with the new surrounds and they started looking for a more tolerant material which ended up being Titanium. From what I heard they had a couple of embarissing compression driver failures with the new diaphrams ie 2441's in new theater installations and that's what started the ball rolling.
The phenolic 066 tweeters used in the L166 Horizons, L212's, 4313's were originally vapor deposited Aluminum. When the machine broke they changed over too silver spray paint.
I have no idea if this is truely correct but it's funny how things morph. We are all playing telephone with this lore. Except for you of course, you were there.
Rob
The aluminum diamond surrounds frequently failed.
Whether the transition from titanium to aluminum was marketing or market driven, the longevity factor increase using titanium was incredible for those of us who had to continually replace fatigued aluminum diaphragms.
In my early days in the pro PA business (1975-81) we replaced many dozens of 2440/2441 and 2420/2421 diaphragms due to the stress cracks in the aluminum diaphragms. Our shop and homes had $100 diaphragm ashtrays on every bench and table.
After switching to titanium diaphragms, in the period from 1981 to 1992 not a single diaphragm was lost to metal fracture, and I owned four times the amount of HF drivers in 1992 (around 148) as in 1981.
Art Welter
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Hello David
The phenolic 066 tweeters used in the L166 Horizons, L212's, 4313's were originally vapor deposited Aluminum. When the machine broke they changed over too silver spray paint.
I have no idea if this is truely correct but it's funny how things morph. We are all playing telephone with this lore. Except for you of course, you were there.
Rob
Yes, but it sounds like you guys are remembering a few more details than I am, so I'll bow to your superior knowledge.
Thats true about vacuum deposition on the earlier units. I believe that was also a relatively expensive process.
Art, good to hear from the perspective of the user in the field. I wasn't aware of the high number of field failures.
David S.
David,
For low volume home use, aluminum can hold up well, but when pushed to concert levels, they were like racing tires, you only got a certain amount of trips around the course before they were shot.
When I departed from Eclipse Concert Systems, I took all the 2482 (phenolic) drivers, as not a single one had failed in the years I was there.
I had in that time became quite adept at changing the 2440s out, they just could not sustain the excursion demanded by the 500/800 Hz 12/18 dB crossovers common at the time.
My partners continued with the 2440 pots, with 2441 diaphragms they could get by (sort of) without the 2420 and 2410 "tweeters" which I also departed with. Later, most everyone in the sound business replaced aluminum with titanium, as the 2445/2446 fit the 2440/2441, though the 2482 was a different size and could not be retrofitted.
The 2420 aluminum would last quite a long time when crossed at 5K, but in monitor use down in the 1200 Hz range would crack.
I had eleven 2420s used in monitors, probably replaced each diaphragm at least once in the course of two years. They then went in to a house sound installation in a punk club environment, by that time the titanium 2425 were available as replacements, and I don't recall any going out in that abusive environment again for almost 10 years.
I recall it being fairly easy to stick my thumb through an aluminum 2440 diaphragm, but I could not break through a titanium 2445 diaphragm.
As an aside, I experimented with some of Aljes Renkus (I have probably butchered the spelling of his name) aluminum polyamid surround drivers, they were much smoother than the 2425, but the aluminum to metal glue joint proved to be more failure prone than the 2420's aluminum surround.
I have now been using the EVDH1A which have a 3" titanium diaphragm since 1997, and have had only one surround failure out of 10 units in that time, which I think was the result of a defect in the original diaphragm stamping process, not a material failure per se.
Art
I really grew a dislike for aluminium dome tweeters some time in the past. So, when I went along with my current project with an Eminence coaxial driver, I first bought the APT50 phenolic diaphragm driver to do the highs. I never, ever got any airiness out of that. It was easy, though. But at the same time it had no real definition, it wasn't as dynamic as I expected. So I purchased a cheap ASD1001, which was a totally different animal, indeed.
It does take a little taming, to not make it sound harsh. Solid state amplification is one thing to avoid, bad crossover components is another. But when it works, it's quite clean, actually. With my tube amps, cymbals for example have a much more neutral tone, still retaining the dynamics of the driver. For just under 30 euros this is a great driver! It's got loads of more definition than the APT50, and it has more of that "whiplash"-quality the former lacks. But it only gives it when summoned upon.
So, contrary to my prior beliefs, I liked the titanium diaphragm more. I've re-evaluated them in the past few weeks against each other, so I still have an aural recollection of each ones shortcomings. I'd say, if you want "easy listening" with solid state stuff, go for the APT50. Then again, if you want to hear what is on the recording, and are running quality amplification, go for the Ti-diaphragm ASD1001.
It does take a little taming, to not make it sound harsh. Solid state amplification is one thing to avoid, bad crossover components is another. But when it works, it's quite clean, actually. With my tube amps, cymbals for example have a much more neutral tone, still retaining the dynamics of the driver. For just under 30 euros this is a great driver! It's got loads of more definition than the APT50, and it has more of that "whiplash"-quality the former lacks. But it only gives it when summoned upon.
So, contrary to my prior beliefs, I liked the titanium diaphragm more. I've re-evaluated them in the past few weeks against each other, so I still have an aural recollection of each ones shortcomings. I'd say, if you want "easy listening" with solid state stuff, go for the APT50. Then again, if you want to hear what is on the recording, and are running quality amplification, go for the Ti-diaphragm ASD1001.
Adolf,
The APT:50 has more output around 3-5K, the ASD:1001 more 5-20K, and smoother response overall, consistent with some of your observations.
The two drivers would require quite different EQ/crossover design to be made to sound similar just from a frequency response standpoint, before even thinking about what the difference in materials are doing.
That said, I have 10 APT 50 drivers, no two measure/sound the same...
Did you equalize the different drivers to the same response curve for your comparisons?
One other detail, the ASD:1001 polarity is a negative voltage at the red terminal causes a positive pressure at the output of the device, I don't recall that being the case with other Eminence drivers, it may be possible that both frequency response and polarity are different.
Art
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Regrettably, I don't have such capabilities. I lack good FR measuring equipment. But you shouldn't judge those drivers by the response they give in that particular horn. Sure, they're different, but just as different is the response given by the APT50 driver in the APT80 horn. I use them in a horn in the middle of a Beta 10CX-middriver.
That being said, I've tried both with different crossover points, different L-pads, and so on. Still, my findings stand the same. The APT50 always sounds darker and less detailed. I never managed to squeeze the same dynamism from it I got from the ASD1001, nor the same amount of "air".
Of course it still might be a flaw in the implementation, but in my experience, phenolic just sounds too polite. I'd make a scientific study if I had the resources, but sadly I don't. In my limited experience the titanium driver makes smoother, more natural music. But not without tradeoffs, since it has none of the politeness the phenolic has too much of. It needs good X/O components and good frontend to do it's best. Given that, it's sounds surprisingly natural given it's price.
The horn used of course will affect the sound as much, if not more than the driver used.
That said, the APT-50 has a pronounced mid peak, then a HF rolloff regardless of the horn. It needs quite a different EQ to sound similar in response to another driver, even if both are fitted on the same horn.
The chart below is an APT-50 compared to a PSD2002-16 on the same horn.
The titanium PSD2002 is smoother from1200 to 10K, then drops like a rock after 13K.
The APT-50 does appear to have more “fuzz” (narrow band frequency deviation) so ultimate clarity of the titanium diaphragm driver may indeed be better, though I have to admit I could hear little difference when they were equalized to a similar response.
To confound things further, the APT-50 uses ferrofluid in the gap, the PSD2002 does not, the ferrofluid might make for more “fuzz”.
Art
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Well, beryllium is certainly WAY more expensive than aluminum----- a 1/2" x 1/2" x 2 mil piece costs over $2,000 USD (Beryllium Foil BE000151 - Goodfellow Catalogue)
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