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View Full Version : L65 Jubal - upgrades worth doing



chilledspode
01-23-2008, 10:45 AM
Hello

I just read a ton of L65 threads and I found the answer to my question (I think). These speakers were purchased new by my father in 1976+/- and after 30 yrs of service they are due for an overhaul. Because my Jubals have the tweeter on the left I believe they are the original L65 Jubals (vs A or B) please correct me if I have misunderstood this line of thinking.

Assuming this is correct are there minor updates/changes I should consider while I am getting these overhauled to incorporate improvements that occured enroute to the later L65B's. I gather there were some refinements to the x-overs...

I will have the L-pads replaced, the midrange reconed and the terminals upgraded - the woofers were reconed several years ago now.

Cheers

Mark

chilledspode
01-23-2008, 01:03 PM
Well, John answered my question in no uncertain terms.

He advised me to read the label - it says "Jubal" and therefore I have the first generation L65.

I would very much appreciate input as to whether or not, x-over updates from the later versions would be worth doing to these early ones.

Thank you

Mark

Robh3606
01-23-2008, 01:32 PM
Hello Mark

You need to spend some time and evaluate what the changes are doing. There were 3 woofers used and there are different inductors used for each. In the A and B there are changes to the midrange where an inductor is added to help tame the rising response of the midrange. The original Jubal does not have this.

These changes will voice the speaker a bit differently so you need to decide if you are happy with them as is or want to give them a shot. Hard to say if you think it will be worth it or not.

Rob:)

chilledspode
01-23-2008, 01:55 PM
Hi Rob,

Let me see if I can help put this into context... I am at least smart enough to know we are embarking on a " the best motor oil is..." type discussion so I guess what I was hoping to learn from people here, is were there significant shortcomings in the original design/components that if you had the chance to change you might - for the sake of improving the speaker, technically.

The whole notion of personal sound preference I was hoping to stay clear of.. :-)

Thank you for your time, Rob

Mark

Robh3606
01-23-2008, 06:02 PM
Hello Mark

The changes in the networks affect the high pass on the woofer and the bandpass and EQ for the midrange driver. If you have the original Jubals they have different woofers from the A and B. I would not just change the networks as it will effect the Frequency Response in the transition between the midrange and woofer and the midrange and tweeter

I would add .001uf bypass caps across all the Mylars or upgrade them to polpropylene. You could also Charge Couple them as well. Start with the Bypass Caps.

Rob:)

johnaec
01-23-2008, 06:19 PM
I would add .001uf bypass caps across all the Mylars or upgrade them to polpropylene. You could also Charge Couple them as well. Start with the Bypass Caps.Exactly what I was going to say! :)

John

chilledspode
01-24-2008, 07:02 PM
Thank you, Rob and John

I will convey the message to the nice chap who I have asked to rebuild them and see if he is comfortable interpreting what you have said... :-)

Electrical is simply not my forte and I am loath to learn on these wonderful old speakers. I am envious of you guys with a knack for this stuff - I call it black magic. I can barely manage basic ac/dc circuit troublshooting and some control logic programming on 4-20 devices but that is it.

I will do a search for x-over basics - I am looking forward to learning more about how much I don't know, I hope that never stops... Who know maybe I'll down load the cabinet volume software and play with it to try to understand why knowledgeable people seem to suggest the Jubal cabinet was a tad too small.

Charge coupling needs to be read up on as well...

Cheers and again, my thanks for sending me off much smarter than I was 2 days ago.

Mark

timc
01-25-2008, 02:12 AM
I have a set of Jubals that i changed the Caps in. Just swapped the original with Solen polypropylene and added bypass caps. No CC yet, but that will come later.

I felt it was a major improvement. Not necessarily because the new caps is much better, but i believe the old ones was just that; old.............


-Tim

chilledspode
01-25-2008, 06:51 AM
Hi Tim,

Can I ask you this - Rob and John seemd to suggest (if I read correctly) to replace the caps with new OR bypass them with the 0.001uf ones

From your reply, I am getting the impression you did both...

Clearly, I have a long way to go on this stuff.

Thanks

Mark

nb: I am going to print out the N65 circuit layout and see what I can glean from it...

timc
01-25-2008, 07:12 AM
Well, yes and no.

There are 3 steps to this. Bypass only, New caps only, and CC only. And you can combine them to your liking.

I have done the 2 first.


-Tim