Can any one out there tell me the differences between the 2440 and the 375. Is there a sound difference? Thanks for any info you can give.
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Can any one out there tell me the differences between the 2440 and the 375. Is there a sound difference? Thanks for any info you can give.
They are functionally identical. They use the exact same diaphragm, throat, phase plug, magnet and cast return pot.
The differences are color, nameplate, terminals, and depending on the vintage, possibly the back cap shape.
In the voodoo that is audio, I am sure there are those that will tell you that one sounds better than the other. The 375 and all of the consumer versions of JBLs are more collectable and therefore more expensive on the used market than their pro counterparts. If you compare a 375 and a 2440 and they do sound different, which isn't that unlikely, it is because one or both are not operating up to spec. Intact "Red Wax Seals" is certainly no guarantee of condition.
Widget
I hear ya Widget. My LE85's would cut out on certain bass notes from the LE15's. Turned out the short 3" wiring inside the driver itself was loose under the screw terminals.Quote:
Originally Posted by Mr. Widget
What can you do ? Had to pop those red cherries to fix 'em.
The chances that the used 2440's seen more rigorous service than the used 375 is probably pretty good.
You have to be careful when buying these drivers used. As Rodd pointed out, many of these drivers have been used and abused for many years in professional systems. Some have been installed in outdoor systems and suffer from rusting of the internal parts. It is a bad sign if the external paint finish is coming loose and falling off.
One fellow I know has made quite a study of 375, 2440 and 2441 drivers. He often demagnetizes and disassembles them, blasts off the old paint, removes rust, remachines the mating surfaces if necessary, repaints, reassembles and remagnetizes them. He supplies them to another friend who builds complete systems. They were noticing large variations in response curves between drivers of different vintages, and began to notice differences in construction. Ultimately they identified seven distinct versions of the drivers; changes over time in the pole pieces, phasing plug geometries, etc. They found that it is necessary to pair up drivers with similar features in order to get stable imaging from a stereo pair.
The ones to look for should have close serial numbers and a nice external appearance. Chances are they have been used in a hi fi rather than a prosound application.
Great information guys!
Thanks :)
"You have to be careful when buying these drivers used. As Rodd pointed out, many of these drivers have been used and abused for many years in professional systems. Some have been installed in outdoor systems and suffer from rusting of the internal parts. It is a bad sign if the external paint finish is coming loose and falling off.
One fellow I know has made quite a study of 375, 2440 and 2441 drivers. He often demagnetizes and disassembles them, blasts off the old paint, removes rust, remachines the mating surfaces if necessary, repaints, reassembles and remagnetizes them. He supplies them to another friend who builds complete systems. They were noticing large variations in response curves between drivers of different vintages, and began to notice differences in construction. Ultimately they identified seven distinct versions of the drivers; changes over time in the pole pieces, phasing plug geometries, etc. They found that it is necessary to pair up drivers with similar features in order to get stable imaging from a stereo pair.
The ones to look for should have close serial numbers and a nice external appearance. Chances are they have been used in a hi fi rather than a prosound application."
Yeah,That "Sam" guy knows his stuff.
Oldmics
I have six 2441 drivers purchased new in 1979-80, I have two 2440 drivers I got with a pair of lenses, dated 1972! I have always said they sound different than the 2441 from 79, even with 2441J diaphragms! Everyone said they ( the driver itself ) is the same, except for the diaphragm! The older drivers have a slightly different gap width! THEY DO SOUND DIFFERENT! I never measured the differences, but to my ears, the older drivers with 2441 phragms sound sweeter, to me anyway!Quote:
Originally Posted by Steve Schell
Thank you Steve!
At some point in the 70's (and I'm not sure what point that is) JBL started making a titanium diaphragm. To me, these diaphagms, while more tolerant of abuse did not sound as "sweet" as the earlier aluminium diaphragms. Also some prefer the "mellow" sound of the older phenolic diaphragms.
I have also run a fewsets of 2462's with Radian Audio aluminium diaphragms. I had come to like these very much (although I am running TAD's now). I'm sure the mylar surround helps the sound of the Radian diaphagms.
Rodd, the Radian design with its well behaved mylar compliance is the legacy of Jonas Renkus's work; he also designed the Symbiotik diaphragm for Altec. As I have learned from a friend who knew him well, Renkus preferred the direct reproduction of signal energy by the driver, and did not endorse complex suspensions that artificially extend response up high through breakup modes.
I also like the sound of the Radian diaphragms. Though sometimes difficult to center in the gap, these diaphragms measure well and sound very good.
So Scott, you were right all along about the differences, despite the opinions to the contrary. I have also heard for years that these drivers were identical.
Oldmics, you sure get around!
Yes, your friend's research explains a lot of the confusion that we have experienced in the past.Quote:
Originally Posted by Steve Schell
http://audioheritage.org/vbulletin/s...ead.php?t=6253
In my own tests I have noticed that different vintages from TAD vary in performance as well. I guess everyone "Reserves the right to make continual improvements":blah:
Widget
I guess I'll jump in too.
The aluminum diaphragms have better internal damping, partly because the diaphragm itself is thicker, and it's a softer metal...so it sounds "sweeter" to the ears. The titanium diaphragm is thinner and has lots of breakup from spurious resonances in the dome and diamond surround. Add that to the increasing cost of aluminum, lots of shattering diaphragms in the field, and the marketing sex appeal of titanium...lot's of manufacturers making titanium diaphragms. Here's an experiment to try, if you have the equipment...its very revealing. Take a 2445, 2446, 2447, 2450 with titanium diaphragm and apply about 3-3.5 volts signal drive and sweep it up to 18k-20khz and tell me what you hear. Do the same thing with a TAD 4001. I haven't done it with the JBL 2435...haven't had the chance to yet... Radian Drivers do sound very nice, but it took along time to straighten out the diaphragm quality issues...and they rarely did anything under warranty...even when it was obvious
Every tool that is used to make the TAD diaphragms is destroyed in the mfg process...vapor deposition process in a vacuum chamber, and the tool is acid etched away. This was explained to me by Leon Sievers, the marketing mgr at TAD a few years ago. Berrylium is the lightest of the three metals....and very toxic when in smoke or vapor form.
Edgewound
I have always used Al, still do, dont shatter them, and rarely lose a diaphragm!
And, yes, I agree, aluminum sounds sweeter!
Intersesting read guys.
A story of lessions learned.Quote:
Originally Posted by edgewound
As I was in the process of setting up my TAD 4001s I first wanted to use them without the 077's on top with direct connection to the Aleph copy on loan from a friend (with "direct" being the focus here). This proved to be a very bad move. After a couple weeks of tweaking I put a DVD in before switching the function and for brief instant heard what a video signal sounded like. It didn't take long to determine that this dumb move took out both of the TAD berylium diaphragms (at $800/ea.).
The moral of the story.
Always use a series hi-pass cap on high frequency drivers.
The up-side of the story.
I replaced the TAD diaphragms with Radian aluminium diaphragms at about $300/pair. It had a 12db peak at about 1500Hz and was only good to about 15kHz. Using a a single hi-pass cap that starts to roll off at about 3kHz gave me a (theoretically) relatively flat response from 1200Hz to 12kHz. I put the 077's in above that and it worked wonderfully. The sound is the best that ever came from my system.
berylium vs aluminium
Inconclusive. I want to say that the sound of the alumium is "softer" than the berylium but its could have been other factors like the series cap on the aluminium diaphragms. I can say that I don't miss the the original TAD diaphragms, and the $1300 I saved by buying the Radians went a long way to making me feel better.:)