As Diapraghms Age Do They Degrade Sonically ?

[ka7niq]

or are they like a transistor, in that they work perfectly, or not at all. If you have compression driver speakers that are 35 years old, but still working, are there any benefits to be had by replacing working diapraghms >

[Groomlakearea51]

Arguably....yes they do.... It's the biggest issue with old K-77's and K-55's. they are made from phenolic resin and they simply dry out and become brittle. Eventually they can fail.

[ZAKO]

Yes they do... Both phenalic and metal phrams,,, in home use they will last along time mine are 40 yrs old,,,But in concert about a week or two.

[garyrc]

Yes they do... Both phenalic and metal phrams,,, in home use they will last along time mine are 40 yrs old,,,But in concert about a week or two.

In the concert example, wouldn't that be degradation due to heavy use, rather than age?

The compression drivers in my Khorns lasted 24 years, and were still O.K. when I replaced them with the AK-4 upgrade.

I believe -- but can't confirm -- that the JBL speaker systems installed in 70 mm Todd-AO theaters under the auspices of Ampex (contracting with Todd-AO) in 1955 and 1958* lasted until they were setting up for Star Wars (changing over to Dolby's 70mm configuration) in 1977, or 19 - 22 years of daily use at very high SPL, and they sounded great up until the change, better, IMO, than the 1977 replacement system, at least in San Francisco. I assume that they used metal diaphrams, and I think the compression drivers were pro versions commisioned by Ampex that were highly similar to the home 375 midrange driver used in the JBL Hartsfield, the Paragon (for a while), and many of their pro systems combined with bass horns of the "scoop" variety such as the C55.**

* The 1955 installations were for Oklahoma! When Around the World in 80 Days (1956) occupied those same theaters well into its second
year (late 1956 through early 1958) a second set of theaters were equippped to accomodate South Pacific. Virtually all of the 70 mm films of those days placed great dynamic demands on speakers, Ben-Hur most of all.

** JBL reinforced this belief by advertizing the 375 as a theater driver
that could handle "... steep wavefronts of explosive intensity." The
mid/high horn-lens attached to these drivers in the Todd-AO systems was
different from the home version and looked a little like the DLH used in
the lesser home 175 DLH. There is some info about this on the Lansing
site, but there is also some garble -- they reversed the Alexandira and
the Coronet theaters, etc., so I can neither vouch for the info posted
there, nor in my own post here.

[ka7niq]

My EV Sentry III's were made back in like 1976. They use the EV 1823M midrange driver, and the EV ST 350A Horn Tweeters. I wonder if it is time to slap some new diapraghms in them, since they are 34 years old ? They work flawless, but I just wonder if i am missing out on the way these drivers really sound ?

Any way to tell, for sure ?

[ZAKO]

It depends how much you use them,,,and at what level,,,I replaced some old JBL 375 phrams that were pretty old,,and WOW !! what a improvement in clarity,,,So its possible yours could use some fresh ones,,,,the constant flexing takes its toll on the outer surround, causing fatigue,,just like bending a piece of metal back and forth will weakin its strength,, A friend of mine travled with a well known rock group,,phrams didnt last that long,,But it depends how you treat your home system,,35yrs is along time,,its your call.

[ZAKO]

Gary,,,,most good theaters carried spare diaphrams and spare amps,,,The pro version of the JBL 375 is the 2440,,really the same unit,,,AMPEX was also licensed to manufacture JBL drivers and woofers,,,I dont know if JBL supplied the phrams,,I believe they did. I,ll have to check my files.

[ka7niq]

I can get them for about 30 each for the mids, haven't checked on the ST 350A diapraghms, I am sure having fun with the EVSentry 3's Maron, but I miss my Tannoys too Maron, if that makes sense ? Fortunately, I still have the Tannoys, I like them both.

[ZAKO]

Some interesting findings,,Ampex made some rare JBL woofers,,useing the JBL 150-4 fifteen inch woofers with special heavy paper cones,, but used the 375 magnet pot on the back, they were huge,,They made 30 of these for TOD-A-O...very rare,,,Ampex set up a special factory to make JBL speakers,,,for Cinema at that time..

[ZAKO]

Yes Tannoys have a special place in my heart,,,too

[garyrc]

Gary,,,,most good theaters carried spare diaphrams and spare amps,,,The pro version of the JBL 375 is the 2440,,really the same unit,,,AMPEX was also licensed to manufacture JBL drivers and woofers,,,I dont know if JBL supplied the phrams,,I believe they did. I,ll have to check my files.

Thanks. I'll be interested.

[garyrc]

Maron, our posts crossed in the ether. I see you already answered. The bass always seemed tighter and more effortless in the old Todd-AO theaters --- perhaps with the Ampex made modified JBL woofers you mentioned -- than in newer the newer sub-woofer configurations, even though the latter reach much lower. The pics I've seen showed the old Todd-AO woofers as horn loaded, with big baffles between the speakers, and with a sizeable, flat, front surface in which the bass horns themselves were mounted. I imagaine all of this loads, and provides the equivalent of "room gain," lacking in some modern theaters, inc some equipped for IMAX.

[ka7niq]

Gary,,,,most good theaters carried spare diaphrams and spare amps,,,The pro version of the JBL 375 is the 2440,,really the same unit,,,AMPEX was also licensed to manufacture JBL drivers and woofers,,,I dont know if JBL supplied the phrams,,I believe they did. I,ll have to check my files.

Thanks. I'll be interested.

Gary, off topic, but I thought I would add this. The Onkyo HT RC 180 HT receiver works splendid on My EV Sentry III's and the Klipsch Conrwall 2's. It is dead quiet, and really sounds great on the EV Sentry's and my Tannoy's. For SOME reason, it is bright and spitty on my JBL S 412P's ? Go figure ? It has Onkyo's Low Feedback WRAT Amplifier, for what that is worth. It makes a pretty good one box solution, not quite as good as my Best seperates of course, but suprisingly listenable. And when all it's other features are considered, it makes a strong case for itself. 2 ch Stereo died here a long time ago, except in a small dedicated room I hardly use anymore. The Cornwall 2's live in there, they play background music for my pair of Parakeets! I did listen to the Onkyo on my Matrix 801's, before I sold them. The Onkyo drove the piss out of them, sounded pretty good too.

HDMI and age are making boat anchors out of a lot of great old stuff, it is really sad. But some of the new stuff is actually quite good, if one listens with an open mind. Why put up with that Hum from the NAD ? Heck, some of these new receovers even have 5 and 7 band equalizers, operating in the digital domain. Unfortunately, mine does not, but it's bigger brothers do! I see you have a 3 channel system, is that only for music, or for movies too ? I had a 3 ch system years ago using a belle and a pair of KHorns with an old McIntosh 3ch preamp and tube monoblocks for the 3 channels. I also had an ADS Digital Time Delay, with Heresy's on my side walls. It was a lot of fun!

[garyrc]

Maron:

Do you think that compression driver diaphrams (and, for that matter, paper woofer cones) age in an "inverted U" arc, i.e., improve with use at first, then eventually deteriorate? What do you think of the concept of "burning in" or conditioning speakers when they are new? I've heard that some people advocate a conditioning period of as long as 400 hours of use. The rub is if we listen during the conditioning, how do we know that we are not just adapting to the distinctive sound of the speakers, rather than the speakers themselves changing? I must admit that my stock AK-4 Khorn guts seem to sound a bit better now than when they were new, but I can't rule out my adaptation.

I remember that Martin Mayer said in his 1958 book (simply called High Fidelity, I think) that speakers, like fine wine, improve with age. Of course, it could be argued that in 1958, few people had compression drivers in their homes that were over 10 to 13 years old, given the post-war increase in the number audiophiles, and that the hobby didn't really get off the ground until the mid 1950's, when people were likely to be exposed to good sound (my first exposure was the Todd-AO presentation of Oklahoma! and the modestly titled "The Miracle of Todd-AO" in 1955).

ka7niq:

HDMI and age are making boat anchors out of a lot of great old stuff, it is really sad. But some of the new stuff is actually quite good, if one listens with an open mind. Why put up with that Hum from the NAD ? Heck, some of these new receovers even have 5 and 7 band equalizers, operating in the digital domain. Unfortunately, mine does not, but it's bigger brothers do! I see you have a 3 channel system, is that only for music, or for movies too ? I had a 3 ch system years ago using a belle and a pair of KHorns with an old McIntosh 3ch preamp and tube monoblocks for the 3 channels. I also had an ADS Digital Time Delay, with Heresy's on my side walls. It was a lot of fun!

Since you asked[], we planned the three channel system for music only, a la Klipsch's "Wide Stage Stereo" papers of the early '60s, but soon we used it for movies as well. You know how it is. The NAD will go when our Music Room/Movie Room/Library is finally finished. At that point, to get lossless sound for movies, we will see if we can get a good Blu-ray player (or universal player), and a new control center/preamp (we want to continue to use our good sounding free-standing power amps). These two components will have whatever configuration is available at the time, with HDMI X.X DoDa whatever, and, visually, 2k x 4k resolution capability with backward compatibility (too bad they won't have 8K for the home by then, which Robert A. Harris has implied can capture the full detail of 70 mm of the 1960's, which shows us just how far home video is lagging behind the highest pq movies of more than 4 decades ago, a lag that is perhaps intentional, so they can keep selling us new equipment and software as they climb out of the quality bog and onto dry land with their new little feet). We will then shut down our electronics purchasing for a moratorium for at least 10 or 15 years, which considering our ages (63 and 68), may be the final clamp down, although I have people on both sides of the family who lived past 100. We find ourselves harboring a bit of resentment at the industry (particularly the video section) for planning to get people to re-tool so often. I wonder if they know there is a recession on? And in our large circle of friends, including many film buffs of the first water, only three have converted to any Blu-ray configuration, so I doubt if the industry's marketing is the big hit they hoped it would be. It doesn't help that so many classic "catalog" high resolution films are scrubbed of true and native detail when made available on Blu (El Cid, Patton, Spartacus), and given false edge detail instead, that looks far worse on a big home screen than does a good print in a good theater (particularly 70mm, as in the case of the three films cited). We have decided to not go to 3D for a few simple reasons: 1) We can't wait for them to perfect projection 3D for the home before getting our final projector (unless it breaks down) 2) So far, the variability between perceived depth in different shots seems to act against suspension of disbelief, rather than in favor of it IMO. Thinking "Oh, that shot has a lot of depth," tends to take us out of the story. For the record, we have seen 3D movies off and on since the 1950's, and their occasional distracting nature seems to be there in them all, even Avatar. 3) There always seems to be a subtle increase in eye-strain. One critic blamed much of the above on the fact that most 3D camera lenses (all?) are spread a little to a lot too far apart, "more like the eyes of an ape." I don't know. None of these things seem to be a problem when other, non-stereoscopic (less effective, less spectacular) cues to depth are used (wide angle photography, large format, large screens, avoidance of flat lighting, etc.), so we don't mind a little depth from those sources.

I'm printing your post and putting it in our "buying electronics" file. For the record the best sounding amplification I've heard would be our old Luxman for solid state, and for tube amps, our old McIntosh, our old Dyna, and a friend's old Marantz.

[ZAKO]

All speakers deterioate with age,,,,drivers just split or magnets lose strength,, If Thiel Small perameters change i guess break in could effect that,,,Most speakers, break in accore in just a few minutes the settle in for life with just a small loss in magnet strength one or two percent,,,400 hours???? now thats a streatch,,especially with the floppy cones of today....I have speakers here 60 yrs old,,,that sound fine,

[ka7niq]

I agree Gary. I was shown by actually hearing a full blown Western Electric Horn System that our grandfathers knew better sound then we do.

The Western Engineers did it all by ear too, and cut and try. I am a Ham Gary (Ka7niq) and computer modeling has taken over the design of directional antennas we call Yagi's, or beam antennas. One ham did some computer modeling of older Ham Radio Antennas designed on an antenna range years ago w/o any computer modeling. Suprisingly, the computer could not improve the design. I guess Grandpa knew his shit!

[ZAKO]

No grandpa new his sliderule,,,,I still use mine.

[ka7niq]

No grandpa new his sliderule,,,,I still use mine.

Well, however Grandpa did it is good by me.

[garyrc]

No grandpa knew his sliderule,,,,I still use mine.

And we have a giant one (about 6 feet wide) hanging in the garage that used to be used in teaching. No batteries to run down, and one doesn't have to have tiny fingertips.