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JBL Athena 99

pmsummer

pmsummer

simul justus et peccator
Picked up a pair of JBL Athena S99 speakers a couple of months ago, cheap (ish). I refinished (sorta) the beat-up cabs and limbered the woofer surrounds. But I was very unimpressed with their sound.

Finally got around to replacing the 35+ year old Chicago caps today. Not a great improvment, but better. Seemed to smooth 'em out and make the tweets less brittle. But still...

Then I unhooked them from my Tandberg reciever, and mated them to my newly acquired HH Scott 299-D tube int/amp.

MUCH better! The mids now stand nicely as a support for the highs (previously, the mids were almost absent). Even though this speaker was designed for solid state (the Lancer version of the S99 was SS self-powered), the tube amp seems to have civilized the speakers... but then again, almost EVERY speaker I've tried with the little Scott sounds better than before.

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Funny that you bring this up today, as I was at work daydreaming about tweaking a set of these. You are more than correct, on SS they are almost unbearable but with tubes it is a whole new beast, controled and ever so smooth. My little EL84 amp ran out of steam at almost where I wanted them to be, even so it is a superb combo.


PS PM I will get to looking for a grill for you
 
Hi:

You say you "limbered" the woofer surrounds. I assume that in their found state they were quite stiff. Curious what you did to limber them up.

My expereince with the LE14A with the "inverted" (concave) Lansalloy surround is that movement of any sort will cause them to crack. The only means I've found to soften them up is the application of brake fluid...yeah I know what the purist think but it's the only effective solution I know of...unless you've come a cross a better one. No one makes a functionally correct replacement surround AFIK.
 
Steve O said:
Hi:

You say you "limbered" the woofer surrounds. I assume that in their found state they were quite stiff. Curious what you did to limber them up.
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Nothing but the finest Castrol DOT 4/5 brake fluid. Zilch keeps reminding me to take them to my local JBL repair center for new surrounds. Now that these things sound good enough to keep, I'll seriously consider doing that.

I was on the verge of just parting them out and throwing their entrails to the ebay vultures, but now I'm considering a longer relationship after hearing how well they respond to a tube amp.
 
pmsummer said:
Nothing but the finest Castrol DOT 4/5 brake fluid. Zilch keeps reminding me to take them to my local JBL repair center for new surrounds. Now that these things sound good enough to keep, I'll seriously consider doing that. snip...
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Brake fluid...not surprising. My experience so far with the "early" LE14As is that brake fluid is the only readily avail fix for stiff surrounds.

I queried Zilch on this issue about a month ago and it appears that the official JBL fix is total recone. The recone kits are sporadically avail apparently at the whim of JBL and based on perceived demand. I hear the recone kits are very expensive too (>$200). I've not found any aftermarket foam that properly replaces the original Lansalloy; I've got two LE14As and four refoam kits to prove it.

Since Harmon Intl is about to be purchased by "private equity" organizations, I expect that it will be parted out to highest bidders. According to article in WSJ, the OEM automotive divisions are what the buyout artists are really after so I have no great hopes for continued support for JBL "legacy" products like the LE14A. Conclusion: If you're going to get your LE14s reconed, find someone who can do it and do it now. Otherwise accept the brake fluid fix. For my situation, $400 is way too much for my lancer 55s so I'm going for brake fluid unless someone comes up with a proper foam kit. I'm not holding my breath.
 
There was one guy selling surround kits on epay who SWORE they were right size and design, but I passed. When folks "swear" some part will fit, I usually end up "swearing" a lot while trying to install it!

The brake fluid seemed to do a good job, and there's no way I'm gonna put $400+ into a re-cone on these. Wouldn't be prudent. :no:
 
A partial answer (still investigating):

1) For a while, only LE14H-1 recone kits were available. They have a narrow-roll convex surround mounted to the rear of the cone.

2) Original LE14A is narrow-roll concave surround mounted to the front.

3) My preferred method to resurround LE14A is narrow-roll convex mounted to the front. Residual from removal of the front-mounted original necessitates front mounting, typically.

I suppose it could be mounted concave like the original, as well, but I'll check on that. Probably have to try it to confirm.

LE14A recone kits are on order. I'll report on what configuration JBL is presently supplying when they come in.

Yeah, I'm cheap, too. If the voice coil is working and the cone is intact, they get new surrounds. The brake fluid fix is temporary, the compliance variable, and it risks contamination of the cone.

It may be fairly argued that the original spiders no longer provide compliance to spec, hence JBL's recommendation to recone, but it's only blown or thrashed ones that get full recones here.

New SOTA LE14H-3s are just under $300 apiece, list.... :thmbsp:
 

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Zilch said:
A partial answer (still investigating):

1) For a while, only LE14H-1 recone kits were available. They have a narrow-roll convex surround mounted to the rear of the cone.

2) Original LE14A is narrow-roll concave surround mounted to the front.
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Yes, mine are narrow/concave.

Zilch said:
3) Preferred method to resurround LE14A is narrow-roll convex mounted to the front. Residual from removal of the front-mounted original necessitates front mounting, typically.
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Yes, again. This is what I tried on one pair. Although it works after a fashion, it introduces a rearward offset of about 2-3mm effectively pushing the cone into the magnet assy by that amt. Although the speaker seems to operate OK, the offset bugs me. All four aftermarket surround kits I purchased (from different sources) look to introduce this offset. The offset issue is mostly why I'm still searching.

Zilch said:
I suppose it could be mounted concave like the original, as well, but I'll check on that. Probably have to try it to confirm.
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I tried that and it definitely didn't work for me. The roll becomes too compressed betw the edge of the cone and the edge of the frame which in turn causes the cone to pop forwards or backwards to +-Xmax plus some: A toggle effect so to speak. I suppose I could try trimming away some of the cone so that the roll ends up in a more natural state. This would require precision trimming along the perimeter of the cone and I don't have the tools to do that at the moment. A trimmed cone might also alleviate the offset issue though.

Zilch said:
LE14A recone kits are on order. I'll report on what configuration JBL is presently supplying when they come in.... :thmbsp:
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If you don't mind my asking, was my "source" anywhere near the cost of a recone kit? Does it come with the pretty white Aquaplas coating or is it generic dk grey?
 
Steve O said:
If you don't mind my asking, was my "source" anywhere near the cost of a recone kit? Does it come with the pretty white Aquaplas coating or is it generic dk grey?
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I never know the actual cost until the invoice comes, but I have no problem disclosing that once it happens.

Been a while since I ordered LE14A kits, so I don't know what'll come regarding color, etc. I'll tell all once they're here.... :yes:

Steve O said:
Although the speaker seems to operate OK, the offset bugs me.
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Well, that's kinda my bottom-line attitude about restoring these old drivers to operation. We get them cheap, we fix them cheap, they work fine, they sound fine, so I'm not agonizing about them. If the application's critical, I'm buying new and building to current specifications.

I once did comparative measurements on a full range of LE14 variants here. I'll try to dig up that thread and link it.

Edit: Well, THAT was surprisingly easy to find. Two years ago:

http://audioheritage.org/vbulletin/showthread.php?t=5777
 
The Lansalloy surrounds on mine have no cracks or tears. They were hard as rock and kinda "blistered" looking when I got them, but the careful Castrol bf application made them seem as new.

The concave design really helped the application. ;)
 
pmsummer said:
The Lansalloy surrounds on mine have no cracks or tears. They were hard as rock and kinda "blistered" looking when I got them, but the careful Castrol bf application made them seem as new.

The concave design really helped the application. ;)
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Measure Fs of both to see where you are with respect to compliance vs. the original 28 Hz spec. Just takes a signal generator, resistor, and a voltmeter to do it. If you get 40 Hz, they're not happening. More data.... :thmbsp:
 
Zilch said:
Measure Fs of both to see where you are with respect to compliance vs. the original 28 Hz spec. Just takes a signal generator, resistor, and a voltmeter to do it. More data.... :thmbsp:
Click to expand...

DVM. Check.
Resistor. Can do, but what resistance and where?
Signal generator. Would a computer tone generator program do?

Now what?
 
Driver impedance rises significantly at resonance; the peak is Fs. See my first post in the testing thread I linked in #11, above. My refoamed LE14A's Fs was 26.8 Hz. You can see the resonance peak in the impedance curve there (red). For the one with hard Lansaloy surround, Fs was 98.5 Hz, i.e., not gonna get any significant bass outta that one.

*****

I'm looking at Fig. 8.3 in Dickason's "Loudspeaker Design Cookbook."

1 kOhm 5 W (min) resistor in series with the driver, AC voltmeter across the driver terminals.

"Make the measurement by varying the generator frequency between 10 Hz and 100 Hz until you locate the maximum voltage."

Hold the driver alone in free air, three feet from other objects or boundaries.

Use a volume setting such that at the higher frequencies, you are able to hear the driver, but not loud, i.e., less than 1V as measured across the driver terminals.

Note: If the driver were mounted in a closed box, that'd be the tuning frequency of the system. Ported boxes are measured a little differently, since there's TWO resonance frequencies in them, one for the driver and one for the port, but you now have the tools to determine the stock tuning of your S99s, as well as the woofers themselves.... :thmbsp:
 
The three stages of LE14A Fs...

Unmolested LE14A with really stiff surround:Fs = 150Hz!!!
Refoamed using non-optimum convex surround Fs = 24.7Hz
Molested LE14 (brake fluid) Fs = 19.0Hz

Maybe the non-optimim surrounds aren't so bad after all. The offset still bugs me however so still searching.
 
Steve O said:
Unmolested LE14A with really stiff surround:Fs = 150Hz!!!
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Yeah, they'd rather suck as woofers, no? :p:

It'll be even more interesting to see what PM Summer's Fs's are, now.

I'm told the brake fluid gradually evaporates, and the Fs rises as that occurs, 'til you're back at the "hardened" state. Getting it right would appear to be somewhat of a crap shoot, and short-lived if achieved. :dunno:

New LE14A cone kits are in stock, and should be here next week. Who's got a pair of dead LE14As to donate to science? We'll measure the factory recone Fs, too!
 
LE14A Recone Kit

Answer:

Narrow roll convex surround affixed to the rear of the cone.

That's about 1/8" of frame attachment on the outside edge.

All else is vintage LE14A, down to the Nomex coil former.

And yes, they're not cheap.... :no:

[Still waitin' for a free pair of cores to be offered up to science here.... ;) ]
 

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Steve O said:
Yes, mine are narrow/concave.


Yes, again. This is what I tried on one pair. Although it works after a fashion, it introduces a rearward offset of about 2-3mm effectively pushing the cone into the magnet assy by that amt. Although the speaker seems to operate OK, the offset bugs me. All four aftermarket surround kits I purchased (from different sources) look to introduce this offset. The offset issue is mostly why I'm still searching.


I tried that and it definitely didn't work for me. The roll becomes too compressed betw the edge of the cone and the edge of the frame which in turn causes the cone to pop forwards or backwards to +-Xmax plus some: A toggle effect so to speak. I suppose I could try trimming away some of the cone so that the roll ends up in a more natural state. This would require precision trimming along the perimeter of the cone and I don't have the tools to do that at the moment. A trimmed cone might also alleviate the offset issue though.


If you don't mind my asking, was my "source" anywhere near the cost of a recone kit? Does it come with the pretty white Aquaplas coating or is it generic dk grey?
Click to expand...
Steve O wrote: "Yes, again. This is what I tried on one pair. Although it works after a fashion, it introduces a rearward offset of about 2-3mm effectively pushing the cone into the magnet assy by that amt. Although the speaker seems to operate OK, the offset bugs me. All four aftermarket surround kits I purchased (from different sources) look to introduce this offset. The offset issue is mostly why I'm still searching."

This is a major issue IMO since the offset will take away from the Xmax and increase distortion. I wonder if there's anyway like gluing to the rear of the cone to make it right.
 
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