4301B Crossover Rebuild

[Zilch]

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:

[ratitifb]

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

[Zilch]

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.

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.

[oznob]

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!

[ratitifb]

Lucky man who is so close to such reliable JBL people

[tweeter]

4301B = Simpliest is the Best

[peterz]

thanks to the fast responses and my general intrigue into 'how I did', I was able to void the PE shipment and create a fresh new order with 12(!) caps, 6 for each speaker!

anyone need to find me, I'll be putting the dunce hat away ...
peter

[80n]

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 ?

[peterz]

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

[JeffW]

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.

[peterz]

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

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.

[JeffW]

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!

[peterz]

JeffW,
All 6 caps have been ordered. Thanks for the clarification and help. More on this after the work gets done.

what a simply amazing site this is!

thank you
peter

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.



Nope, they are the same in either direction.



Something along those lines, yes. There's more to it, of course, but adding them adds little cost or complexity.



Looks like.

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

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



No problem. Good luck on your project!

[peterz]

well I should probably look for some threads on good clean soldering stations and techniques, because my 'new' crossovers aren't exactly as pretty as the ones Zilch did in this thread.

All the same, the upgrades went MUCh easier than I expected and would easily suggest the information in this thread is enough for just about anyone to take on.

And I'm probably going to be splitting hairs and certainly don't want to step into the morass of 'upgraded crossovers vs originals' debate, but I am really liking the immediate 'improvements' I'm hearing. Immediacy. Pace. The veil that felt like an extra grill cloth or something, are all improved immediately upon completing. They are now 'burning in' (again, please let's not go there on burn in or not) or at least getting put through their paces all afternoon.

Thanks again for everyone here. Looks like the bug has hit, I'll probably be looking for a thread on upgrading L Pads next! ha.

take care and thanks again everyone, a VERY happy 4301b upgraded crossover user.
peter

[mech986]

Now that you've lived with it for a few weeks, how's the 4301B sounding now?

Anyone ever decided to go with a charge coupled crossover? That might be interesting too!