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Thread: 4301B Crossover Rebuild

  1. #1
    RIP 2011 Zilch's Avatar
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    4301B Crossover Rebuild

    Schematic here:

    http://www.jblproservice.com/pdf/Net...%20Network.pdf

    Original L-Pads were fine, but the capacitors measured 10% high.

    Heat gun melts the globbed-on components loose and allows scraping off the old glue.

    Four solder terminals are mounted with countersunk flat-head screws from the underside. Nylon-insert locknuts make them secure.

    4.3 uF + 2.7 uF = 7 uF

    15 uF + 1.5 uF = 16.5 uF

    AudioCap Theta 0.01 uF bypass caps are nestled between them.

    Inductors relocated and secured with hotmelt adhesive.

    Component leadwires redressed, cut to appropriate lengths and resoldered.

    Cable ties organize the input and speaker leads, and provide a measure of strain relief.

    Before and after:
    Attached Images Attached Images  

  2. #2
    Senior Member ratitifb's Avatar
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    Nice job

    Hi could you post schematic with part list. Is 4301 sounding affected ?

  3. #3
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by ratitifb View Post
    Hi could you post schematic with part list?
    I edited to provide a link to the schematic, above. I have reused the original inductors. The capacitors are Dayton metallized polypropylene and AudioCap film and foil from Parts Express.

    The parts are not expensive, but it takes several hours to do each one.

    Quote Originally Posted by ratitifb View Post
    Is 4301 sounding affected?
    These are not mine; I am rebuildiing them for a forum friend. He will likely be reporting on the performance here once they are reinstalled.

  4. #4
    Senior Member oznob's Avatar
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    SIMPLY AMAZING!!!

    I got the re-built crossovers from Zilch yesterday but didn't get a chance to install them until late this afternoon. I have been listening to them for about four hours now and the sound is simply amazing! I always felt the tweeter was a bit harsh with the stock crossovers. Harsh no more with extention cleanly into the higher registers, again, amazing! I have always been a metal tweeter guy but I may re-think that opinion? One of my all time favorite recordings is from an old Blue Horizon album of the original Fleetwood Mac with the great Otis Spann. It's disc two of the "Blues Jam in Chicago." The track is a loose studio recording of "Someday Soon Baby" without effects, one track, with Spann on piano and vocals, Peter Green on lead guitar, John McVie on bass and Mick Fleetewood on drums. To me it's one of those magical moments of music that not many have ever heard. I have listened to that track more times than I can count but NEVER better than through the "Zilchified" 4301B's! I could go on but I think I made my point. I am one happy guy! Now if I could just get the S3100's to sound this good!

    Thanks Zilch, you're the best!!!

    I would be remiss if I didn't send a special thanks to Edgewound who did a great job re-foaming the 116H's. Top notch job Edge, thanks!

  5. #5
    Senior Member ratitifb's Avatar
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    Lucky man who is so close to such reliable JBL people

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    Senior Member tweeter's Avatar
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    4301B = Simpliest is the Best

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    4301B Crossover Rebuild

    I'm still useing a pair of 4301B in my second system and still think they are terrific. I was wondering if the crossover rebuild would be a project an "amature" could do with a RS soldering iron and no background working on electronics. If it's beyond my limited skills I could purchase the parts and ask my local JBL pro shop to build the crossovers.

  8. #8
    Senior Member oznob's Avatar
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    Quote Originally Posted by majick47 View Post
    I'm still useing a pair of 4301B in my second system and still think they are terrific. I was wondering if the crossover rebuild would be a project an "amature" could do with a RS soldering iron and no background working on electronics. If it's beyond my limited skills I could purchase the parts and ask my local JBL pro shop to build the crossovers.
    Why not send them to Zilch and let him work his magic on them! I am thoroughly enjoying mine more and more each day!

  9. #9
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    4301b Crossovers

    OZNOB I'm sure Zilch did a fantastic job rebuilding your 4301B crossovers. Also I'm sure he is very busy and I wouldn't want to impose on him. In the past I'v acted in haste, sometimes for better and sometimes for worse. If anything Zilch has given us it's a lot of information to think about when it comes to makeing choices re JBL speakers. I want to explore all my options before I consider the 4301b crossover upgrade which I'm sure would be a marked improvement. What I'm considering is a pair of L46 that I already have to replace the 4301B in my second system. Another option is a JBL three way speaker, something like a 4412 I believe Zilch has mentioned in the past as having a lot of merit. I really don't want to make a quick decision on this one till the jury is in on what direction to go and I'd really listen to any advice offered. As of now the 4301b are bolted to heavy duty JBL pro wall/ceiling mounts about a foot or so from the ceiling angled down to my listening position in a 10x12 foot room with 7+ foot ceiling. If the 4301b stay or are replaced with another JBL speaker they will also be on the wall mounts.

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    4301B Crossover Rebuild

    I want to update that Zilch rebuilt my 4301B crossovers. On first listen the difference was not noticable but after about two weeks the new components had time to burn in and the sound is now much smoother, detailed with extended bass/high end compared to the old/original/stock crossovers. The 4301B easly compete if not better a pair of 4406 I recently purchased. THe 4301b are very good to start with and now the performance has been taken up to a much higher level. If you have a pair of 4301B it would be well worth your while to have the crossovers upgraded. As to be expected Zilch did a beautiful job and the sound is terrific.

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    Hey. Very nice rebuild ! Do you think this crossover network would be a worthy upgrade to my Decade L16 (with 116h woofers) ? If so, is there a way to find the adequate inductances ?

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    how to build these myself or have someone else do it

    I own a pair of the 4301b's and am interested in doing a crossover recap. The pictures Zilch left us are a huge help and I think I could take this project on if only a few more pics were provided, and the associated parts list was a little more clear to my VERY inexperienced eyes.

    That, or is there someone on these boards who would build these for me for a reasonable fee?

    It goes without saying that without Zilch, I never would have owned these speakers to begin with. When I bought them, it was with a lot of insight from him both here and over at Audiokarma. His loss is felt by many including myself who barely ever exchanged a PM with the guy. RIP Zilch.

    thanks for any help in advance,
    peter

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    All he did, aside from tidying up the board, was to replace the two capacitors (round objects in the lower left corner) with new equivalents.

    Evidently, the original caps were 16.5uf and 7uf. He simply placed a 15uf and a 1.5uf in parallel to make the 16.5uf, and a 4.3uf and 2.7uf in parallel to make a 7uf. Then put an AudioCap Theta 0.01 uF in parallel with each new "bundle". That's just a bypass capacitor to help the sonic qualities, it doesn't change the value of the bundle enough to matter.

    You could just make up these two bundles of caps, clip the leads going to the two existing capacitors, and insert the bundles into the clipped leads. Zilch just went the extra mile to clean things up, and reducing all that extra wire can't hurt the circuit.

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    JeffW
    Thanks! A couple follow up questions.... and it appears I may have to do some wikipedia reading!

    1. "In parallel" would mean that one lead from the original cap would be soldered to BOTH the 15 AND 1.5uf caps. And then the other lead from the old cap would again be soldered to BOTH the 15 and 1.5. Similarly with 4.3 and 2.7?

    2. Does signal direction matter with those Dayton capacitors? Meaning does it matter which way the signal goes through those caps?

    3. What would those extra bypass capacitors be doing? Cleaning up the signal 'noise' or something?

    4. I'm assuming partsexpress will handle these four caps no problem correct?

    Thanks for your help, sorry if I'm asking obvious questions, I'm just very new to all of this.
    take care
    peter

    Quote Originally Posted by JeffW View Post
    All he did, aside from tidying up the board, was to replace the two capacitors (round objects in the lower left corner) with new equivalents.

    Evidently, the original caps were 16.5uf and 7uf. He simply placed a 15uf and a 1.5uf in parallel to make the 16.5uf, and a 4.3uf and 2.7uf in parallel to make a 7uf. Then put an AudioCap Theta 0.01 uF in parallel with each new "bundle". That's just a bypass capacitor to help the sonic qualities, it doesn't change the value of the bundle enough to matter.

    You could just make up these two bundles of caps, clip the leads going to the two existing capacitors, and insert the bundles into the clipped leads. Zilch just went the extra mile to clean things up, and reducing all that extra wire can't hurt the circuit.

  15. #15
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    Quote Originally Posted by peterz View Post
    JeffW
    Thanks! A couple follow up questions.... and it appears I may have to do some wikipedia reading!

    1. "In parallel" would mean that one lead from the original cap would be soldered to BOTH the 15 AND 1.5uf caps. And then the other lead from the old cap would again be soldered to BOTH the 15 and 1.5. Similarly with 4.3 and 2.7?
    Right. Just lay the caps along side each other, parallel as it were, and gather all the leads coming out each end together. You can see it in the pic Zilch provided.

    2. Does signal direction matter with those Dayton capacitors? Meaning does it matter which way the signal goes through those caps?
    Nope, they are the same in either direction.

    3. What would those extra bypass capacitors be doing? Cleaning up the signal 'noise' or something?
    Something along those lines, yes. There's more to it, of course, but adding them adds little cost or complexity.

    4. I'm assuming partsexpress will handle these four caps no problem correct?
    Looks like.

    http://www.parts-express.com/dayton-...capacitors.cfm

    http://www.parts-express.com/audiocap-capacitors.cfm

    Thanks for your help, sorry if I'm asking obvious questions, I'm just very new to all of this.
    take care
    peter
    No problem. Good luck on your project!

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