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JBL 4401 Control Monitor Recap

C

clang444

Active Member
Has anyone here ever recapped the crossovers for JBL 4401 Control Monitors. They have parallel caps in the crossover and as per an old review by Ben Duncan: "polypropylene capacitors are wired in parallel with the reversible electrolytics to improve the top-end response, or, in JBL's parlance, "reduce the hysterisis effects... this provides improved resolution of complex transient waveforms". He also goes on to say "the polypropylene bypass, at 68 nF, is way too high to have much audible consequence, so the effect is presumably purely psychological."

Any recommendations on how to recap? Use the same parallel setup our just replace with one capacitor in each location? I believe the little yellow caps are the 68 nF (or 0.068 uF) polypropylene caps. Another basic question: Do these caps even need to be replaced?

Also - is the 14 uF cap for the L-pad? Am I correct to replace it too?

Thanks

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If you replace them all with film, you really don't need the bypasses. Or if you want them, get new ones.
Yes, of course replace the 14uF.
Also replace that 10W resistor.
 
clang444 said:
Thanks. I didn't know resisters needed replacing too.
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They can break down a bit as they age, and new ones are higher tolerance and a buck fifty so doesn't hurt.
Dayton Audio DNR-1.2 1.2 Ohm 10W Precision Audio Grade Resistor (parts-express.com)
I would only get film for the 8uF, the 12 and 32 can stay electrolytic.
Dayton Audio DMPC-8.2 8.2uF 250V Polypropylene Capacitor (parts-express.com)
15uF 100V Electrolytic Non-Polarized Crossover Capacitor (parts-express.com)
33uF 100V Electrolytic Non-Polarized Crossover Capacitor (parts-express.com)
 
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Hey - Thanks for the shopping list. The electrolytic caps are a big cost savings. I have a couple of hopefully not too dumb questions:

Why the polypropylene replacement cap for the 8 uF and not the others? Is it a cost thing or something else?

You picked a 12 uF replacement cap for the 14 uF cap in the crossover. Would a 15 uF replacement cap be a better choice or would I even hear a difference?
 
clang444 said:
Hey - Thanks for the shopping list. The electrolytic caps are a big cost savings. I have a couple of hopefully not too dumb questions:

Why the polypropylene replacement cap for the 8 uF and not the others? Is it a cost thing or something else?

You picked a 12 uF replacement cap for the 14 uF cap in the crossover. Would a 15 uF replacement cap be a better choice or would I even hear a difference?
Click to expand...
Cost and space thing, but now that I'm looking, which cap is connected to the tweeter? Make sure that's a poly.
My bad on the 14uF, use a 15uF.
 
Old thread. But how did the recap go? I have the same pair that I believe is in need of a recap.

They now both seem to have different frequency responses.

Also, how do I get to the crossover. It it connected to the tweeter pot? Or on the back of the speaker terminals?

I’ve seen other videos of JBLs where the vinyl label needs to be removed to access hidden screws.
 
Went ahead with my recap project.
If it helps a future repair for someone.

Crossover is on a board attached to the external speaker terminals.

To access it, remove the woofer speaker, remove the speaker insulation. Then the crossover will be accessible. Attached to the speaker cabinet with 4 wood screws.

In my case I replaced all caps with film caps and resistor.

Space was not an issue just hard to work around the screw holes so I could reassemble without any issues.

Fun project but more importantly, my JBLs sound better than ever. My issue was in the lower frequencies, or so I thought, but the detail in the tweeters sound more defined.
 

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I know this is an old post, taking a chance that you guys are still lurking. I’m restoring a pair of 4401 speakers. My question is non-technical, it’s about the band that goes across the grill, the one that has the model number and the high frequency level control poking through it. How does one remove that strip without destroying it? I’d like to replace the grill fabric, but to do that I need to remove that band. Thanks.IMG_0478.jpeg

IMG_0478.jpeg
 
Can the band be carefully pried from the side edges? I'd start from the JBL label side. The weak point is going to be at the HF level control hole. Be extra careful there.
 
Dave1027 said:
Can the band be carefully pried from the side edges? I'd start from the JBL label side. The weak point is going to be at the HF level control hole. Be extra careful there.
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Thanks Dave. I'm going to go at it with a semi-flexible plastic pryer and some heat from a blow dryer to see if that helps soften up the adhesive.
 
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