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toddrr
04-11-2006, 05:52 PM
Ok, I figured out that i have a jbl L 65 (A) model Jubal (see attachment)

I have researched this site and found out lots of information
before i started another thread. Here is what i know.

Three models of Jubals.
Jubals (126a woofer),
L65a (122a woofer),
L65b (128h woofer)

Question A: Can i use a different woofer than the 122a?
Question B: Is one of the 3 woofers above considered the better woofer?
Question C: If i use a 126a woofer, does it have a diff. polarity or
anything else i should know?

other photo's of my speakers...
http://www.audioheritage.org/vbulletin/showthread.php?t=10150

Thanks guys I am learning so much from all of you!:D

Zilch
04-11-2006, 06:09 PM
128H(-1)'s not in any of them, but it's the recommended replacement woofer.

The networks are each different:

http://manuals.harman.com/JBL/HOM/Technical%20Sheet/L65%20Jubal%20ts.pdf

http://manuals.harman.com/JBL/HOM/Technical%20Sheet/L65A%20Jubal%20ts.pdf

http://manuals.harman.com/JBL/HOM/Technical%20Sheet/L65B%20ts.pdf

edgewound
04-11-2006, 06:18 PM
The woofer in the L65B is a 129H. The 122A gets reconed with C8R129H which is a current product. Recone price is $172.00 ea. That would be the thing to do.

126A has a small spider and lacks the bass extension of the other drivers.

Robh3606
04-11-2006, 07:45 PM
"Can i use a different woofer than the 122a?"


The 122A and 129H are the same woofer with the exception of Alnico vs. Ferrite. The 129H's are few and far between, 122's are on Ebay all the time. You may want to keep an eye open for a pair they are your best bet.

Rob:)

markd51
04-12-2006, 05:53 AM
Howdy Edgewound/All, Just joined the forum.

I am not quite sure about the fact that the 126A driver used a smaller spider, nor had a poorer bass extension?

Not that I'm saying you are incorrect, but my standard L-65 doesn't seem to lack any bass extension at all.

No doubt there are differences in the Driver, and X-Over Specs between the three models, the L-65 L-65A, L-65B, otherwise JBL would've never changed the model.

One should no doubt believe, and correctly assume that JBL back then wouldn't certainly go backwards in technology, later resorting to poorer performance within this speaker model, or any other of the speaker models of the day, and that the A, and B versions should indeed be an improvement versus the standard, first L-65 Version, correct?

I wonder exactly how much difference in frequency specifications there was between these models, and if the X-Overs made up for any lack in the original 126A Bass Driver? I gather there were some similarities between the three drivers, such as magnet size, basket size, and shape, voice coil diameter, but as you say, the spider may have been different, materials slightly different, etc.

No doubt the very reason why the recone kits are not interchangeable between the 126A, and 122A. Mark

Robh3606
04-12-2006, 07:15 AM
The 126A has a different frame than the 122A. There is also a larger magnetic pot structure on the 122A. Different frame different spider diameters

Here is a 126A, 122A and a 129H cone

Rob:)

edgewound
04-12-2006, 08:10 AM
Howdy Edgewound/All, Just joined the forum.

I am not quite sure about the fact that the 126A driver used a smaller spider, nor had a poorer bass extension?

Not that I'm saying you are incorrect, but my standard L-65 doesn't seem to lack any bass extension at all.

No doubt there are differences in the Driver, and X-Over Specs between the three models, the L-65 L-65A, L-65B, otherwise JBL would've never changed the model.

One should no doubt believe, and correctly assume that JBL back then wouldn't certainly go backwards in technology, later resorting to poorer performance within this speaker model, or any other of the speaker models of the day, and that the A, and B versions should indeed be an improvement versus the standard, first L-65 Version, correct?

I wonder exactly how much difference in frequency specifications there was between these models, and if the X-Overs made up for any lack in the original 126A Bass Driver? I gather there were some similarities between the three drivers, such as magnet size, basket size, and shape, voice coil diameter, but as you say, the spider may have been different, materials slightly different, etc.

No doubt the very reason why the recone kits are not interchangeable between the 126A, and 122A. Mark

Howdy Mark...

As Rob so kindly pointed out, there are clearly differences in the 126A driver as compared to the 122A/129H. The frame/magnet is more like a D123.

I only posted the differences because, as a JBL Authorized Service Agency, I've reconed lots of these over the last 18 years...but thanks for keeping me honest.;)

toddrr
04-12-2006, 10:22 AM
Ok, this is great:D

Thanks for clarifying.
It is interesting that the replacement woofer for both the jubal, and
the L65a is the 128h according to the network information that
Robh provided. I now know the 122a and 126a woofers are bit
different in design, however its seems like they might still be
interchangeable.

thanks for your help

markd51
04-12-2006, 04:32 PM
Hi Todd, I think you mean129H, and not the 128, which others have mentioned was never in any of the L-65's.

Oh sure, the 126A would surely work, and probably blow your socks off too in the meantime!

Just like those cruddy MCS woofers worked, so would the 126A. Any 12' woofer would work provided it's an 8ohm speaker, and is a drop in replacement without having to take a tomahawk to the cabinet to get it to fit.

I've never had any need of "bass", or lack of "Bass Excursion with my stock L65's. The four of them can easily, and effortlessly shake the room, and offer plenty of clean, tight, deep bass, and I usually keep everything set flat.

I believe my standard L-65 version originally used a 1Mh Iron Core inductor for the Bass Driver, and there may be just a slight difference in value within your L-65A Unit. Maybe something like a 1.5Mh Inductor? Maybe someone else can quote the exact value.

Using the wrong driver would be akin to you owning a 55 Chevy Bel Air that calls for a 265 CI V-8, and you drop in a 283 CU V-8 instead. Very close, and it will probably work just fine, but no cigar. No doubt your best performance will be with the 122A, and your speakers will retain theri highest value will all the correct drivers inside.

I've never doubted JBL's expertise. IMO, they were some of the best speakers in the world then, and even still to this day theri vintage models can hold their own quite well in the audiophile world.
Mark

edgewound
04-12-2006, 05:13 PM
Hi Todd, I think you mean129H, and not the 128, which others have mentioned was never in any of the L-65's.


Mark

Mark,

The current replacement driver for all L65/A/B is the 128H-1...if the original is not usable. It is the only exact acoustic replacement for the 129H in the L65B.

L65 Jubal had 126A with 1mH inductor, L65A had 122A with 2mH inductor, L65B had 129H with 3.3mH inductor. I just looked at my JBL Service Manual to confirm this.

There was also a revision to the crossover networks mid band and hi pass in all three versions.

But it is nice to know that you care about the correctness, as this is the Technical Help forum and all info should be correct;)

markd51
04-12-2006, 08:14 PM
Interesting info Edgewound, and I appreciate the time you've taken to share this info (and I'm sure Todd, and others do also)

I notice that the 122A did not have a vent at the rear like the 126A, and can you elaborate some on this?
Did the 122A use a ferro-fluid or something on that order for voice coil cooling?

Although the Woofers, and X-Over changes where made with the three versions, I assume that the O77 high freq. driver was used in all. The O77 Driver in my original L-65 was 16ohm, and wonder if they were 16ohm in the A, and B versions?

And for the mid driver, on mine is the LE5-5. I assume this didn't change.

Other notables, was a change in the driver layout, and port position on the front baffles from the L-65 to L-65A. Mine (L-65) is clearly different from Todd's L-65A

About 5 years ago, I literally toasted 2 X-Overs within two of the four L-65's I own. Just like you took a propane torch to them! Ruined. I figured I had two choices, try to piece the destroyed X-Overs back together from parts from JBL (or Wherever) or, build all new.

I chose the latter option to have four very high quality
X-Overs built, and adhering to JBL L-65 Specs made by Madisound. I went from Iron Core Inductors, to I believe it was Goertz 300w (and I think the other was 100w) Air Core Inductors, and Solen Poly Caps throughout.

Madisound quickly, and beautifully (and also very reasonably) built me four "works of art" X-Overs for my L-65's! They were so pretty (And heavy), I wanted to place them on my fireplace mantle for display.
Also gone from the mix, was of those sand cast resistors from the X-Over, with more modern resistors.

As far as the sound, the custom Units didn't deviate at all from the original sound as I remembered it. I had roughly 25 years of auditioning these speakers to determine this, the mids, and highs appeared to be smoother, less grainy, better integrated, and the bass response improved, being cleaner, tighter, better defined, less flop, better control.

I should also mention all internal wiring went to the garbage, Edison Price Solid Copper 5-Way Binding Posts installed and all speakers were internally rewired with high grade copper 12ga from Binding Posts to X-Overs, from X-Overs to Woofers, and 16ga from X-Over to mid, and tweeter, 16ga also to the L-Pads. All soldered up with WBT Silver solder.

Also upgraded, were the 10w L-Pads to 100w versions, and mounted to the rear of cabinet, leaving the original 10w L-pads intact, and undisturbed.

Although I'm no longer bone stock, it was a worthy upgrade breathing new life into my now 32 year old Jubals.

If I would've had worries, or concerns about these mods ruining resale value in the future, I probably would've never done these mods, but when I leave this earth, there's going to be two coffins at my burial, one for me, and the other for my JBL's, and Mac Amps! They'll be with me till the end of time. Mark

edgewound
04-12-2006, 11:47 PM
Interesting info Edgewound, and I appreciate the time you've taken to share this info (and I'm sure Todd, and others do also)

I notice that the 122A did not have a vent at the rear like the 126A, and can you elaborate some on this?
Did the 122A use a ferro-fluid or something on that order for voice coil cooling?

Mark

Mark,
Sounds like you're very fond of your Jubals...as you should be.:)

Your mids and HF are LE5-5 and 077, respectively.

If you look more closely at the pics Rob posted you'll notice the vent hole in the 122A motor assembly. Ferrofluid wasn't invented yet when these speakers were built. I think the only low freq drivers larger than 12" from JBL without a vent hole was the LE15's and 2215/2216, 150-4 and possibly the K145(?). I'm not positive but it seems these all shared the same motor.

boputnam
04-13-2006, 09:01 AM
Seems you guys need this...

GordonW
04-13-2006, 12:28 PM
If you're reconing a 128H and want it to act more like a 129H or 122A (for which, if my info is current, no 122A/129H kits are available), you can use a 128H-1 kit, and have the reconer add 10 grams of mass (mass ring) to the assembly, before installing the dustcap. The primary difference between a 128H and 129H is cone mass (approx. 90 grams for the 128H, 100 grams for the 129H). This should put the upper-end response in check closely enough, for the factory crossover to work within spec...

I've done this before, and verified it works on LEAP/LMS... the T/S (box-tuning) parameters work, and the measured FR is proper, too.

JBL used to have 10g mass rings... but, apparently, no more. In that situation, I've made my own, using sliced-apart lead tire weights. Get a strip of tire weights, and slice it lengthwise (persistance with a very sharp utility knife will work). May take some experimentation to get the exact right thickness to get the right weight (one tip- weigh and measure the entire lead weight strip before cutting it... you can use PROPORTIONALLY smaller strip widths to get the right resultant fraction of the total strip)... but it can be done. Once the right weight is achieved, glue the resultant ring into the very top of the inside of the voice coil (as far as possible away from the pole piece down below), then install the dustcap. You should wind up with something like 1/8" thick, so it should be fine as far as cone excursion is concerned (it won't hit the polepiece)...

Regards,
Gordon.

edgewound
04-13-2006, 12:53 PM
If you're reconing a 128H and want it to act more like a 129H or 122A (for which, if my info is current, no 122A/129H kits are available), you can use a 128H-1 kit, and have the reconer add 10 grams of mass (mass ring) to the assembly, before installing the dustcap. The primary difference between a 128H and 129H is cone mass (approx. 90 grams for the 128H, 100 grams for the 129H). This should put the upper-end response in check closely enough, for the factory crossover to work within spec...

I've done this before, and verified it works on LEAP/LMS... the T/S (box-tuning) parameters work, and the measured FR is proper, too.

JBL used to have 10g mass rings... but, apparently, no more. In that situation, I've made my own, using sliced-apart lead tire weights. Get a strip of tire weights, and slice it lengthwise (persistance with a very sharp utility knife will work). May take some experimentation to get the exact right thickness to get the right weight (one tip- weigh and measure the entire lead weight strip before cutting it... you can use PROPORTIONALLY smaller strip widths to get the right resultant fraction of the total strip)... but it can be done. Once the right weight is achieved, glue the resultant ring into the very top of the inside of the voice coil (as far as possible away from the pole piece down below), then install the dustcap. You should wind up with something like 1/8" thick, so it should be fine as far as cone excursion is concerned (it won't hit the polepiece)...

Regards,
Gordon.


I will re-iterate. This the the Technical Help Forum...NOT DIY.

The C8R129H is on the latest revision of the JBL Professional Transducer Parts List:banghead:

The Tech Manual also states that the cone kit might have Aquaplas instead of mass ring.

boputnam
04-13-2006, 01:20 PM
If you're reconing a 128H and want it to act more like a 129H or 122A ... you can use a 128H-1 kit, and have the reconer add 10 grams of mass (mass ring) to the assemblyI'm not sure that concurs with what JBL is saying on their Tech Sheets (excerpted, here).

My interpretation of this is that either aqualplas or the mass ring can be added to the 126A or 122A kits - or replace with a 128H. And, the TS's say a the 128H is a direct replacement for the 129H.

:dont-know

GordonW
04-13-2006, 01:58 PM
I'm not sure that concurs with what JBL is saying on their Tech Sheets (excerpted, here).

My interpretation of this is that either aqualplas or the mass ring can be added to the 126A or 122A kits - or replace with a 128H. And, the TS's say a the 128H is a direct replacement for the 129H.

:dont-know

Ah, yes, that's right... it's the 122A that's the "odd man out" here, with the mass ring, not the 129H. And there DEFINITELY are NO 122A kits available from JBL. If you want to CORRECTLY rebuild the 122A using currently available parts (ie, C8R128H-1), it's necessary to either have or fabricate the 10g mass ring...

Regards,
Gordon.

Robh3606
04-13-2006, 02:47 PM
The mass ring!

Wait a minute the 126A and 122A can have a mass ring or aguaplas. The 129H is aguaplas only NO mass ring. The 129H is the odd man out.

Rob

edgewound
04-13-2006, 02:53 PM
Ah, yes, that's right... it's the 122A that's the "odd man out" here, with the mass ring, not the 129H. And there DEFINITELY are NO 122A kits available from JBL. If you want to CORRECTLY rebuild the 122A using currently available parts (ie, C8R128H-1), it's necessary to either have or fabricate the 10g mass ring...

Regards,
Gordon.

No...that is incorrect. A correctly reconed 122A currently specs the C8R129H recone kit, (as there is no longer C8R122A) and it is currently on the the JBL Pro price list. I've said that 3 or 4 times now....and it is listed that way in the Tech Manual also...from the factory....the JBL Factory...where JBL's are manufactured.

These recone kits use either aquaplas OR a mass ring....but not both. It says that in the Tech Manual too...posted in this thread.:yes:

Once again Rob...thanks for the pics:) .

GordonW
04-14-2006, 08:52 AM
No...that is incorrect. A correctly reconed 122A currently specs the C8R129H recone kit, (as there is no longer C8R122A) and it is currently on the the JBL Pro price list. I've said that 3 or 4 times now....and it is listed that way in the Tech Manual also...from the factory....the JBL Factory...where JBL's are manufactured.

These recone kits use either aquaplas OR a mass ring....but not both. It says that in the Tech Manual too...posted in this thread.:yes:

Once again Rob...thanks for the pics:) .

The 129H has 90 gram cone mass, the 122A has 100 grams! Using a 129H kit in a 122A will result in IMPROPER MIDBAND EFFICIENCY. With the 10g ring, it'll be correct...

Been there, DONE IT, measured it to make sure...

Regards,
Gordon.

edgewound
04-14-2006, 09:14 AM
The C8R129H has aquaplas instead of the mass ring. I think JBL is well enough qualified to spec which recone is the correct one...but you obviously don't think JBL knows what they are doing. The Tech Manual is posted right in this thread for you to read.

I've been doing it JBL's correct way since 1988.

4313B
04-14-2006, 10:05 AM
Does anybody have decent representations of these three different transducers so we can document their TS parameters? Or do we even care at this point.

If we do care it could possibly be interesting to see impedance curves and TS parameters worked up for all three.

edgewound
04-14-2006, 01:55 PM
Does anybody have decent representations of these three different transducers so we can document their TS parameters? Or do we even care at this point.

If we do care it could possibly be interesting to see impedance curves and TS parameters worked up for all three.

I'll just continue with the factory spec recone kit.;) Maybe by the time they stop making recone kits/diaphragms for all this great legacy stuff that is still better than 99% of what's on the market, it'll be time to either find a new line of work....or retire.

I have the latest TS paramenters from JBL Pro in my manual but for some reason the "snapshot" function won't let me copy and paste into this...I must be doing something wrong.

markd51
04-14-2006, 04:31 PM
Hi again all,
Just one question out of curiosity, and to gain some knowledge about these vintage JBL products.

Before I'll ask it though, I'd like to mention that the very last time I had all four of my JBL 126A reconed with the c126A Kit, the tech at the JBL Authorized repair center in Illinios did check to see if there was a cross reference to a pro kit that JBL Made, as sometimes a "pro" version was actually a bit cheaper in price, thus saving the customer a little money. he found that there wasn't.

I see mention of an Aquaplas Kit, and my remembering of the Aquaplas, was the driver the L-100 4311 used (123A?)

I gather though, that this particular kit though did not use a rubberized canvas surround like the 123A, but instead, used a foam surround like the 126A, correct?
Thanks, mark

4313B
04-14-2006, 04:38 PM
I'll just continue with the factory spec recone kit. ;) As would I.

I suspect there is more than just moving mass differences and that was the reason for suggesting someone measure good representatives of all three drivers. I fully realize that is very probably unrealistic for this particular forum.

I gather though, that this particular kit though did not use a rubberized canvas surround like the 123A, but instead, used a foam surround like the 126A, correct?Yes.

edgewound
04-14-2006, 06:41 PM
As would I.

I suspect there is more than just moving mass differences ....

Yes...there are differences in VC Le, Vas, Fs, Xmax, Eff, Pe, most notably.

4313B
04-14-2006, 07:38 PM
Yeah, it's been ages since I actually did anything with those things.
I often used the 124/2203 instead.
I can't remember any of their coil gauges, winding depths, etc.

jan_slagman
04-19-2006, 10:48 AM
Hi JBL freaks,

A friend of mine was so lucky to obtain a pair of Jubals for only € 50,00.
Unfortunately he has to refoam the JBL 126A woofers for a massive amount. But.......at this very moment someone is offering a pair of JBL 128H woofers with white aquaplas cones for only € 120,00 on Dutch Marketplace.
Note: The backside of the 128H doesn't mention 128H-1 but only 128H.
Can you guys give us a decent advise how to handle in this matter.
He was also advised to replace the 126A's foam ring by a rubber type ring. Is this an option, or will it change the sound dramatically ?
Please let us have your wisdom !!!

Thanks a lot,

Jan Slagman
The Netherlands.

edgewound
04-19-2006, 10:50 AM
Grab the 128H...then modify the network according to the schematic. Go to post #2 in this thread...the schematics are linked there.

jan_slagman
04-20-2006, 05:06 AM
Thanks Edgewound,

You have been of a great help to us. We really appreciate your input.

Jan Slagman & friend.

GordonW
04-20-2006, 08:38 AM
Hi JBL freaks,

He was also advised to replace the 126A's foam ring by a rubber type ring. Is this an option, or will it change the sound dramatically ?
Please let us have your wisdom !!!

Thanks a lot,

Jan Slagman
The Netherlands.

Never replace the foam surround ring on a JBL driver, with a rubber surround ring. It will destroy the top-end balance of the driver, by causing it to roll off too early on the high end. In other words, the woofer will no longer properly meet the midrange, and there will be a response gap between the two drivers.

Regards,
Gordon.

edgewound
04-20-2006, 12:22 PM
Thanks Edgewound,

You have been of a great help to us. We really appreciate your input.

Jan Slagman & friend.

Glad to help, Jan. I hope that works out well for you and your friend.:)

Like Gordon said, it wouldn't be a good idea to resurround with rubber...it would really change the 126A behavior and any intrinsic value.

jan_slagman
04-20-2006, 02:41 PM
Thanks guys,

That's exactly what we wanted to know. My friend thought using rubber would solve a problem on long terms because foam will only last for a limited time.
I will certainly advise him not to use rubber for his JBL 136A's !!!.

Second question: Edgewound advised me to grab the JBL 128-H's which are offered on Dutch Marketplace at this moment. He also advises to alter the crossover network, but as far as we could see the components are sealed in a kinda resinous substance.

We would be very pleased and grateful if you could help us in this matter once again.

Thanks for lending us your time.

Jan Slagman
Veenendaal
The Netherlands.

edgewound
04-20-2006, 05:13 PM
Jan...

Probably the best bet would be to use the schematic for the L65B and build new crossover networks with new, fresh, better parts.

I wouldn't mess with potted old ones.

terry37932
03-26-2010, 10:47 AM
Guys, I'm hoping you can help me out here as I'm a relative FNG here. After reading numerous posts I have finally figured out that I own a pair of L65A's that I bought through the AAFES Pacific Catalog back in 78 when I was stationed in Korea. After 2 recones and 2 additional refoams I figure it might be time to rebuild the XOvers (IMHO) anyway.

Can anyone point me in the right direction as to where I can get the parts as well as maybe upgrading the parts on the XOver boards.

Any and all reconendations would be extremely welcome.

Thanks,

T.