Results 1 to 13 of 13

Thread: L65A Jubal crossover rebuild

  1. #1
    Junior Member
    Join Date
    Jan 2020
    Location
    PA
    Posts
    7

    L65A Jubal crossover rebuild

    I am looking to rebuild this crossover, figuring out the values and replacing them on the old crossover hopefully will not be much of a problem and it is well within my abilities (at least i hope so). but I have read that some do not think that the stock crossover points are ideal and they advise modifying it

    the stock cross over points are 1000hz and 6.5 khz.

    now this is beyond my knowledge of electronics. i will need schematics and list of parts and instructions. if I have schematic i can draw a pcb and and order it to be built but i will need to start with a complete ready to go schematic.

    I have looked at some other threads about this crossover and i found the orignal diagram, but i was hopiong to get some good advise on how to rebuild, what components to use? and how modifications to make.

  2. #2
    Senior Member
    Join Date
    Oct 2003
    Location
    Texas
    Posts
    1,743
    Schematic

    https://manuals.harman.com/JBL/HOM/T...Jubal%20ts.pdf

    Edit: See now that you said you found the schematic already, so you're set

  3. #3
    Junior Member
    Join Date
    Jan 2020
    Location
    PA
    Posts
    7
    Quote Originally Posted by JeffW View Post
    Schematic

    https://manuals.harman.com/JBL/HOM/T...Jubal%20ts.pdf

    Edit: See now that you said you found the schematic already, so you're set
    Thanks man. I guess I will start by rebuilding the stock as it is. I think some like to push the tweeter higher maybe 8k to 10khz by modifying the crossover a bit.

    I was also hoping that people could give m he some advice on what components to use i.e. Brand and model. I have never built a crossover before and I could use some ideas on what is tried and true by jbl experts. When I was browsing thought other threads I saw solen capacitors mentioned. What about for the coils? I would like to use air core but I don't know what to use. I have never bought a solenoid before.

  4. #4
    Member
    Join Date
    Sep 2018
    Location
    U.S.
    Posts
    63
    Quote Originally Posted by DaaDaa View Post
    Thanks man. I guess I will start by rebuilding the stock as it is. I think some like to push the tweeter higher maybe 8k to 10khz by modifying the crossover a bit.

    I was also hoping that people could give m he some advice on what components to use i.e. Brand and model. I have never built a cover before and I could use some ideas on what is tried and true jbl experts. When I was browsing thought other threads I saw stolen capacitors mentioned. What about for the coils. I would like to use air core but I don't know what to use. I have never bought a solenoid before.
    use the in house search feature
    you will get back thousands of posts on the subject and I am certain quite a bit on your specific model
    the question what BRAND of parts to use is a losing game - you're just asking for trouble with that one just like at all audio forums on earth except maybe England
    execution however is another story for advanced rebuilds like charged networks
    pretty low count for caps
    I'd use Daytons with a .01uF film and foil by pass on each main value (you install those in series with the main value)
    have fun!
    Michael

  5. #5
    Junior Member
    Join Date
    Jan 2020
    Location
    PA
    Posts
    7
    Quote Originally Posted by Michael Chavez View Post
    use the in house search feature
    you will get back thousands of posts on the subject and I am certain quite a bit on your specific model
    the question what BRAND of parts to use is a losing game - you're just asking for trouble with that one just like at all audio forums on earth except maybe England
    execution however is another story for advanced rebuilds like charged networks
    pretty low count for caps
    I'd use Daytons with a .01uF film and foil by pass on each main value (you install those in series with the main value)
    have fun!
    Michael
    i think you are exaggerating a little whjen u say a thousand. i think you mean one: http://www.audioheritage.org/vbullet...p-Needed/page2

    whats so special about England that people agree on audiophile capacitors there? lol

    I am looking to use good quality caps that are not ridiculously expensive so Dayton will probably be what i will go with actually.

  6. #6
    Junior Member
    Join Date
    Jan 2020
    Location
    PA
    Posts
    7
    I'll be starting off with this i guess, from the late great Zilch:

    Quote Originally Posted by Zilch View Post
    Well, you lucked out on the 077 not being damaged. Yes, check the R1 resistance, and physically, for any damage. That one looks hardly smoked, but I don't have it in hand to tell for sure.

    As I see it, you have four options on recapping the crossover:

    1) Solen capacitors, no bypasses. A bright, crisp sound, perhaps overly so with 077.

    2) Dayton capacitors with AudioCap Theta bypassers. Stock sound, but cleaner.

    3) ClarityCap capacitors, no bypass. Reputedly smooth and mellow, I've not tried them myself.

    4) Biased, using Solens. The best, but a major deal, from scratch, very likely.

    I'd start by getting the existing crossover running. Just stick a Dayton in it.
    i dont understand option #4. i mean i dont understand what that sentence means so option #3 seems to be the way to go

  7. #7
    Senior Member
    Join Date
    Oct 2003
    Location
    Texas
    Posts
    1,743
    Biased is charge coupling, a small DC voltage is applied to the junction of a pair of series capacitors. The size and number of capacitors in a given crossover is doubled so expensive caps are rarely used there, and there's plenty of threads discussing the implementation.

    I wouldn't replace the inductors. Aside from the inductance, the DC resistance has to be accounted for. Slap a big ol' air core inductor in place of where an iron core once resided and the DC resistance is going to be quite a bit different. Plus inductors are pretty robust, if they aren't melted, they should be fine.

    Resistors, capacitors, terminals and L-pads are where most of the issues seem to spring from. L-pads especially. JBL never used uber exotic capacitors in the L65A days, just get a good brand and have fun.

  8. #8
    Member
    Join Date
    Sep 2018
    Location
    U.S.
    Posts
    63
    Quote Originally Posted by DaaDaa View Post
    i think you are exaggerating a little whjen u say a thousand. i think you mean one
    I meant what I wrote guarantee it
    refine your search
    what's special about English audio forums, MOST of the time, is they don't have wanker flame arguments over wire and cap brands, although no nationality is immune I'm sure
    that's what I meant by that
    or tubes versus transistors or records versus cds
    that sort of crap
    the L65A came with film types to begin with and are decent quality types but if you want to change for whatever use Daytons
    Michael

  9. #9
    Junior Member
    Join Date
    Jan 2020
    Location
    PA
    Posts
    7
    Thanks to you both. Exactly the information that I needed. I was about to make a relatively costly mistake with those inductors. I will only do the caps and the l pads.

  10. #10
    Member
    Join Date
    Sep 2018
    Location
    U.S.
    Posts
    63
    Quote Originally Posted by DaaDaa View Post
    Thanks to you both. Exactly the information that I needed. I was about to make a relatively costly mistake with those inductors. I will only do the caps and the l pads.
    the JBL pot is a wirewound variable resistor
    don't know if you want to fool with it or not but a good and careful immersion cleaning of the pots that came in your speakers, anti corrosion treatment and bushing lubrication will make them good as new as long as they haven't suffered mechanical damage
    the originals are from Japan and finding ones of comparable quality and specs today can be very expensive

    you can find plenty that look basically like what's in there but the only way to get the OES quality is to buy either used or get lucky and find a seller with some new old stock
    that's why you see all those scavenged from cannibalized L100 networks selling for seemingly stupid money
    people in the know are harvesting and refurbishing the pots
    same with the original Acoustic Research wire wound pots
    lot of regret now for tossing the Atena-Pollaks

  11. #11
    Junior Member
    Join Date
    Jan 2020
    Location
    PA
    Posts
    7
    it is here and it sounds glorious. its a keeper. i prefer to dial down the brilliance to two. one of the pots is a little scratchy. so i will do the cleaning and deox as suggested. will do the caps but nothing else. love the sound. love the midrange even better than the bass and the size is so manageable. my wife would have hated every second of the 4430 in our living room but she likes this as furniture. she doesnt like it as much as that mahogany ribbon veneer omega that i sold last week but she thinks its fine with grill on. so im glad i went this direction. driven by a pair of liberty audio B2B-100 in mono configuration and from my own DIY soekris R2R DAC. at first the system was all balanced but i strongly preferred the VTA SP-14 before the amps so now its single ended. i think i will stick with this.

  12. #12
    Member
    Join Date
    Sep 2018
    Location
    U.S.
    Posts
    63
    Quote Originally Posted by DaaDaa View Post
    it is here and it sounds glorious. its a keeper. i prefer to dial down the brilliance to two. one of the pots is a little scratchy. so i will do the cleaning and deox as suggested. will do the caps but nothing else. love the sound. love the midrange even better than the bass and the size is so manageable. my wife would have hated every second of the 4430 in our living room but she likes this as furniture. she doesnt like it as much as that mahogany ribbon veneer omega that i sold last week but she thinks its fine with grill on. so im glad i went this direction. driven by a pair of liberty audio B2B-100 in mono configuration and from my own DIY soekris R2R DAC. at first the system was all balanced but i strongly preferred the VTA SP-14 before the amps so now its single ended. i think i will stick with this.
    glorious, keeper, love the sound, love the midrange

    so why f$#k with the caps?

    clean the pots thoroughly and carefully and leave a happy thing a happy thing

  13. #13
    Junior Member
    Join Date
    Jan 2020
    Location
    PA
    Posts
    7
    no ill change them

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Urei 809 crossover rebuild
    By Urei809 in forum Lansing Product DIY Forum
    Replies: 8
    Last Post: 07-26-2016, 05:17 PM
  2. Model 19 crossover rebuild
    By Altec-Lansing in forum Lansing Product DIY Forum
    Replies: 0
    Last Post: 04-02-2016, 09:55 PM
  3. L65A Jubal grill construction
    By _Frank_ in forum Lansing Product DIY Forum
    Replies: 2
    Last Post: 07-28-2013, 03:48 AM
  4. L65A crossover Help Needed.
    By fotodan in forum Lansing Product Technical Help
    Replies: 23
    Last Post: 04-16-2007, 01:10 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •