...ever get an ice pick to the forehead?

[Titanium Dome]

The SAM1HF has an Al HF driver and a Ti UHF driver. :shock:

OMG, JBL defied the conventional wisdom of this thread!! It's totally backward.

[Mr. Widget]

The SAM1HF has an Al HF driver and a Ti UHF driver. :shock:

OMG, JBL defied the conventional wisdom of this thread!! It's totally backward.

No, they put the aquaplassed aluminum diaphragm right where it could do the most good!

As for the tweeter, they made an educated design decision and chose Ti to save money. If they had used Mg or Be, the HF would certainly be better and more costly... I won't guess why they didn't use AL for the 045, but they determined Ti was the best answer at that price point.

I have heard the Ti and Be versions of the 045. The beryllium version is without question far superior sounding... however it is also far costlier. I am not sure I would notice the difference during a musical performance presented in surround with an accompanying image up on the screen. Maybe I would, but I wouldn't bet my life on it.


Widget

[Titanium Dome]

Well, then, since we're so focused on the best possible sound, JBL should put Be drivers in all their lines and just charge the difference. Most people here would pay it, I bet.

Those of us who are complacent about it would just muddle through with our cheap Ti drivers.

[mech986]

I'm pretty sure he read it all here during one of the at least ten other rehashes of this subject.

Here's the good stuff:

http://audioheritage.org/vbulletin/s...5&postcount=46

http://audioheritage.org/vbulletin/s...9&postcount=15

http://audioheritage.org/vbulletin/s...8&postcount=31

http://audioheritage.org/vbulletin/s...&postcount=116

Hi 4313B,

True, knowledge gained and remembered, although I'm not sure I saw all the threads above. But have read them fully now

Can you also quote for us the 4th thread? I can't access that thread like you can, would love to see what was discussed there too.

Regards,

Bart

[4313B]

Can you also quote for us the 4th thread? I can't access that thread like you can, would love to see what was discussed there too.

Sure, here it is:

I am no expert, but doesn't that peak at 9KHz represent a break up mode? The 476Be has it's first break up mode beyond 20KHz... as far as I know nothing from TAD can match that, and the two TAD drivers I have tried are subjectively grainy at the top end. The 476Be would appear to be in a league of it's own. I'd stay with the 435Be/045Be until something at the level of the 476Be could be obtained.

Widget

I'm pretty sure that 9khz does actually represent the first breakup mode. I'm not sure where the assertion that the 476Be does not break up until 20khz came from. It definitely extends to 20khz, after which the limits of the phase plug geometry causes a hole in the response immediately above that frequency.

In comparison, the 435Be has its first breakup mode at 16khz. The smaller 3" diameter of the driver diaphragm is one of the main reasons for its extended pistonic response. Doug Button specifically chose the smaller diameter just to ensure that the entire design bandwidth was reproduced without breakup. For everything else being equal, a larger diaphragm is not as strong as a smaller one just due to geometry and will therefore breakup at a lower frequency. Using less stiff materials, such as aluminum and titanium, means that breakup modes occurred as low as 4khz in the 4" diaphragm 375, 2445 and 2446 etc. From what I understand, I don't think it is possible to construct a 4" diameter beryllium diaphragm that is pistonic up to 20khz without having it weigh so much that efficiency and mass rolloff issues would make it impractical.

Don

[herki the cat]

speakers Speakers

Funny, upon auditioning speakers recently my wife and I listened to Maggies and they have a definate shrill resonance in the treble, more subtle than the spikes in a Klipsch Heresy but most certainly there. After a few minutes they were setting my teeth on edge and giving my wife an earache.

Yet unlike horns Maggies are "audiophile approved" and people are free to interpret the resonance as increased detail.

There realy isn't much choice. This "tizzi, high Q Resonance is inherent in nearly all modern Electro - Static Speakers, Professional Studio Microphones, & Electro - Magnetic Panel Speakers which now use Mylar Film diaphragms exclisively .

Mylar is very durable & mechanicaly stable, but it sorely lacks the clean, lovely "Sheen" of the transducer diaphragms popular prior to the 1960's, AKA in the Quad Speakers, & other Electrostatic speakers, as well as the original classic Magna-planars.

The highly sought - after pre 1960's "Telefunken U-47 Studio Microphone" manufactured by George Neumann in Germany, used a Poly Vynal (3) micron, (1) inch diaphragm which was made by pouring the Poly Vynal in liquid state on a rotaring (1) inch dia' round optical glass disc__ spinning to flow off the excess plastic compound until the film was reduced to (3) micron thickness. A tiny short plastic cylinder was then cemented to the perifery of the diaphragm while it was still flat on the round glass disc to form a precison (can-like)assembly which could be slipped & clamped onto the mcrophone capsule body.

RCA, in the 1930's, produced dynamic microphones with diaphragms made of polystyrene as well as aluminum. there were many other benign, very good plastic films from the 1930's on.

[robertbartsch]

I have nothing against Altec and I have enjoyed a VOTT system for 30+ years. In fact, for natural reproduction the Altec aluminum framed compression driver is still my favorite.

That said, I think one short comming that helped hasten Altec's demise included drivers that did not hold up well under extreme conditions like sound reinforcement applications. Dispite their tendency to be harsh at higher frequencies, Ti frams seem to fit the bill of being very ruggid and reasonably priced.

The addition of an UHF tweeter in many cases eliminates the harsh "tsss" sound from Ti frams. I'n not sure why they eliminated the production of the 2405s and 077 slots, but they are still around in abundance.

[JBL 4645]

[quote=herki the cat;258620]THEATER SOUND

Old guy, I'm sorry to hear of your recent troubles. Are you the Old Guy of Unofficial Altec Board fame?
Bart, you got it exactly right on the titanium diaphragms. They were a solution to the problem of tearing aluminum 'phragms when things started getting loud. Folks at JBL have freely discussed their sonic shortcomings in the past.

They have a relatively poor stiffness to mass ratio, and produce a number of breakup modes in the passband, generating that constant "tsss, tsss" sound that has kept me out of movie theatres for years. Somebody please let me know when they're gone.


MY TWO CENTS
Me Too! I can not stand the poor speech intelligibilite since the gorgeous low frequency horn mid bass spectrum went bye, bye Those lovely "W" Bins, the MI-9462 Ubangis, & Altec 210's. There is nothing there for the high frequency horn to hand over in the fundamentals spectrum.

The poor damping of the high-frequency horn FS honk originaly ameliorated by the midbass quality of the low frequency horns, the poor solid state amplifier damping factor & the excessive sound SPL recomended by THX result is a disaster.

However, JBL now has a new three way theater speaker system with a new mid range horn which I am very anxious to hear.

cheers, Herki

I think there is only few in the L.A. area that have three-way JBL.
Maybe a few in New York needle in haystack.

[Ducatista47]

The addition of an UHF tweeter in many cases eliminates the harsh "tsss" sound from Ti frams. I'n not sure why they eliminated the production of the 2405s and 077 slots, but they are still around in abundance.

A reason I have heard several times was the high cost to fabricate them. When cheaper ways to satisfy the requirement are available, say bye-bye. Besides, almost fifty years is not a bad run for any transducer.

As much as I love them, it always did seem a lot of magnet for a tweeter. Old school, like me.

Clark