Looking for recommendations: 12" woofer for L65

[4313B]

No, that's just a conjugate designed to flatten the impedance curve. It counters the impedance rise of the LF voice coil. I've posted those types of curves before on the forum but where they would be I haven't a clue.

Sometimes JBL would use a single parallel resistor and sometimes they'd use a full conjugate (zobel). Sometimes they'd use nothing. The LX30 was a wee bit more expensive than the N65 so the conjugate got "paid for".

A good example would be the 3113B versus the N96/N112/N150A. The conjugate was left out of the low pass of the N96/N112/N150A and the capacitor on the LE5 was changed accordingly. It's no small wonder why we tended to use the "more expensive" 3113B network in our personal L96's, L112's, and L150A's.

[porschedpm]

Thank you for all the suggestions. It would appear that I first need to make an initial decision as to whether I want to keep my Jubals as original as possible, or do I want to try to change out the the LF and MF drivers and the crossover network to try to achieve a better overall sounding speaker. Just thinking out loud, if I'm going for originality, I should get a pair of 126A's to replace the 2213H's in there now and call it good. This would provide a balanced, complete system as designed and engineered by JBL. However, it seems from reading the myriad of posts on this site that the sound from a stock pair of Jubals is not as optimal as other 12" 3 way JBL speakers, ranking somewhere below the 43xx monitors but above the L100's. Therefore, if I take a matched component approach, and switch out the LF and MF drivers and the crossover networks, basically building a system around the 077's, theoretically I might end up with a much better sounding speaker. The risk though is that I may end up with a system that sounds worse than the stock Jubals. Giskard hinted at using a 124/2203 or LE14 as the LF driver. Giskard also suggestion:

"I would probably go for a 2202 or 2204. I'd be inclined to see if the 376/2441 diameter would fit in the enclosure and if so then I'd bolt an HL93/2311 in the LE5 hole. Use a 4355 filter. "

I'm leaning towards upgrading my Jubals to try and achieve a better sounding speaker. It sounds like there are several DIYers out there. Is my goal achievable or am I trying to exceed what's possible by mating a 12" driver to the 077 in a Jubal cabinet?

[porschedpm]

Hi, boputnam wrote:

"First, the 126A is a positive polarity transducer - you swapped-in the 2213H, which is a negative transducer. Unless you cross-wired it (i.e., BLK to Red LF post) you've encountered some quite unintended consequences, I'd think. "

I thought I had the polarity figured out on this but the more I look at it the more I get confused. When I hook up a small battery to the input leads on the back of the Jubal cabinet ( battery + to red input, battery - to black) the cone on the 2213H moves outward. Is this correct in relation to what the MF and HF drivers are doing? If the original 126A's were installed and I performed this same test, would their cones move inward. I appreciate your help.

Ed S.

[4313B]

"I want to try to change out the the LF and MF drivers and the crossover network to try to achieve a better overall sounding speaker."

It is fun to try out all kinds of combinations.

"Just thinking out loud, if I'm going for originality, I should get a pair of 126A's to replace the 2213H's in there now and call it good. This would provide a balanced, complete system as designed and engineered by JBL."

Well, JBL did a total of five versions of this system that I know of, L65, L65A, L65B, S21, S21-1. When the Jubal first came out we though it was the best thing since sliced bread. Fortunately we got over it. It is still considered a viable system by many and if they're happy that's all that counts.

"However, it seems from reading the myriad of posts on this site that the sound from a stock pair of Jubals is not as optimal as other 12" 3 way JBL speakers, ranking somewhere below the 43xx monitors but above the L100's."

Fortunately JBL didn't consider the L65 the ultimate 12-inch 3-way. They didn't bag all future 12-inch 3-way system development and we ended up with fun little bookshelf systems like the L112, 4411, 120Ti, and 4412 along with fun little floor standing systems like the L100t and L100t3.

"Therefore, if I take a matched component approach, and switch out the LF and MF drivers and the crossover networks, basically building a system around the 077's, theoretically I might end up with a much better sounding speaker."

It is possible with persistence and perseverance.

"The risk though is that I may end up with a system that sounds worse than the stock Jubals."

Probably with the first few attempts.

"Giskard hinted at using a 124/2203 or LE14 as the LF driver."

I'd consider that more a fill in of history as opposed to an endorsement. I've played around with the L65 components and S21 components ad nauseum. One guy even wanted his little pancake twelves replaced with 136A's so we built five cubic foot boxes for the 136A's, the LE5-2's, and the 077's and let it rip. It sounded quite a bit better than I thought it would. Other things tried were putting 3 dB fixed pads on the LE5's and 3 dB or 6 dB fixed pads on the 077's so we could get the L-Pads opened up a bit more.

The suggestions for 128H's and 2214H's aren't bad either but I'd be more inclined to go with the 128H as opposed to the 2214H. If I remember correctly the 2214H starts it's first roll off around 600 or 700 Hz whereas I think the 128H starts it around 800 or 900 Hz. Any crossover would have to be modified accordingly.

"Is my goal achievable or am I trying to exceed what's possible by mating a 12" driver to the 077 in a Jubal cabinet?"

I think your biggest challenge is getting the 077 to balance with the LE5. The LE5 is getting a bit narrow in off-axis dispersion before it can reach the point where the 077 likes to operate. You might be able to obtain reasonable on-axis response, as was done with the 4315, but power response is going to suffer. I think poor horizontal off axis response in a home listening environment sux. The LE5 rises ~ 9 dB from 1 kHz to 6 kHz so you will have to deal with that. The L250 is a great example of using the LE5 about as high as practical. The balancing of the various twelves to the LE5 has been accomplished in many systems.

[4313B]

"The L65--the Jubal--has been looked at in some detail on this forum with the idea of what can be done to improve it. I think it is fair to say that the verdict is that the speaker is closely engineered to its design goals and trying to improve it is like attempting to improve the floor plan of a small house--it's probably already optiimum within its limitations."

Nice summary!

"The best thing is to use it the way it is and move on when you need to."

Yeah, unless one is real gung-ho and willing to go to the mat with it that's probably the best solution.

Anyone feel like getting an Ashly and tri-amping a Jubal just for kicks?

[boputnam]

Originally posted by porschedpm
...When I hook up a small battery to the input leads on the back of the Jubal cabinet ( battery + to red input, battery - to black) the cone on the 2213H moves outward.

Hey, Ed...

Sorry for the delay - I was basking in the new Ashly crossover last night...

By connecting to the cabinet binding posts for that battery test what you're seeing in cone movement is affected by the network - and, as such the 2213H should move outward if you've connected the 2213H normally, to the N65 network. Alone, the 2213H will move in on positive voltage - i.e, it is negative, as are most JBL's.

And...

If the original 126A's were installed and I performed this same test, would their cones move inward...?

, thus my point - you've inadvertantly changed the intended phasing behavior of the network. The L65 as issued, ran:

HF (077) = (-)
MF (LE5-6) = (+)
LF (126A) = (-)

You can certainly use the 2213H in that baffle, and with that network, although not optimized. But, if doing so, you need to cross-wire the 2213H at the 2213H connections.

Now, about that Ashly and tri-amping possibility...

[4313B]

Originally posted by boputnam
Now, about that Ashly and tri-amping possibility...

Yeah, it could be worth a look. One would still have the high crossover frequency necessitated by the 077 but it could be fun monkeying around with the filter Q's. If JBL hadn't been so damn stingy with the production of the 076/2403 I'd be inclined to toss that in in place of the 077/2405. We know that works a bit better although JBL still put a lens in front of the LE5 in the L220. Incidentally, we tried putting an L91/2308 in front of the LE5 in the Jubal. It looked tuff (sic) anyway...

[porschedpm]

Thank you all for all your help. I've certainly got enough to keep me busy and off the streets for a while. As a newbie to this site, I've learned more about the vintage and pro JBLs from reading the posts on this forum over the last couple of weeks than I have over the last 30 years. I thought I knew a lot about the L100, L65, L300, 4311, etc. models having grown up during their heydey, but I've discovered how little I really know. And there's so much more to learn. This site and the forum are very addictive indeed. It's like trying to put down a good book. Thanks again and keep up the good work.

Ed S.