thank you, but neither site has the exact capacitance of 3.0 and/or 4.0 uF... beware that different capacitors give different cut frequencies
JBL 4311's = system complete... for now.
- Thread starter Brainwashed
- Start date
yes, it was.
Now, given i found the dayton caps, i wanted to ask about the small bypass caps:
in the thread we're talking about 0.01 uF and 600V,
what i found are:
0,01 µF | 5% | 400 V and
0,01 µF | 5% | 650 V
given that changing the voltage will change the impedance and the load, will it be soooo dramatic ? or i can go ahed with one of these?
Thank you!
Sent you PM.
If brighter is your goal I'd consider changing the 4312s to 4312A or 4412A performance with a new crossover and 035TiA / 052 tweeter.
If brighter is your goal I'd consider changing the 4312s to 4312A or 4412A performance with a new crossover and 035TiA / 052 tweeter.
Giovanni68
Member
Giovanni, hai trovato il coraggio ?
By the way, does someone knows where to source good caps here in Europe ?
I'll let you know when I'll find time and guts
Ahah no, non ancora Michelangelo
There is the chance I might get a pair of L220 which need both foam being done on the passive woofers and a crossover to fix (one of the two speakers sounds very very low so I guess matter of crossover surgery).
I will follow this conversation since, sooner or later, I plan to make a recap of my old and beloved 4311b, they still sound very well since I bought them brand new in the early '80s with the money I saved off of my summer work in the construction business, they are not the best for some kind of music like classic and jazz but I guess the L220 would do better in this regard and, some day, some bookshelf might join the party
Keep us updated with EU sources of spares for the 4311 crossover parts and, also, if possible with pics and/or description of the removal of the front plate which is what scares me about the whole thing.
Ciao and in bocca al woofer!!!
Soldering is going on...
In the meantime some useful links for our european friends:
4x L-pads 15W 8 Ohm https://www.amazon.de/Monacor-12-0610-Lautst%C3%A4rkeregler/dp/B002HCYWKS/ref=asc_df_B002HCYWKS
2x Dayton Audio PMPC-3.0 | 3,0 µF | 1% | 250 V | Precision Audio Capacitor
https://www.soundimports.eu/de/pmpc-3-0.html
4x Dayton Audio PMPC-3.0 | 3,0 µF | 1% | 250 V | Precision Audio Capacitor
https://www.soundimports.eu/de/dffc-001.html
4x Dayton Audio PMPC-4.0 | 4,0 µF | 1% | 250 V | Precision Audio Capacitor
https://www.soundimports.eu/de/pmpc-4-0.html
these have to be connected pairwise in parallel
sonic impressions will follow
In the meantime some useful links for our european friends:
4x L-pads 15W 8 Ohm https://www.amazon.de/Monacor-12-0610-Lautst%C3%A4rkeregler/dp/B002HCYWKS/ref=asc_df_B002HCYWKS
2x Dayton Audio PMPC-3.0 | 3,0 µF | 1% | 250 V | Precision Audio Capacitor
https://www.soundimports.eu/de/pmpc-3-0.html
4x Dayton Audio PMPC-3.0 | 3,0 µF | 1% | 250 V | Precision Audio Capacitor
https://www.soundimports.eu/de/dffc-001.html
4x Dayton Audio PMPC-4.0 | 4,0 µF | 1% | 250 V | Precision Audio Capacitor
https://www.soundimports.eu/de/pmpc-4-0.html
these have to be connected pairwise in parallel
sonic impressions will follow
so, mission accomplished, i waited a week to make listening tests, and I'm happy with the recap! Now the l-pads are fully functional, one speaker was working without tweeter (still didn't understand whether it was a faulty l-pad or cap), and now I've got back the high frequencies I was missing... Still these speakers are suffering with chamber music, but for that I'll use my grundig 550b professional 2-way.
I recommend this operation to those who're skeptical or unsure about what recapping can bring.
Next, I'll consider whether to recap my marantz 2235b...
I recommend this operation to those who're skeptical or unsure about what recapping can bring.
Next, I'll consider whether to recap my marantz 2235b...
oconnorweb
Active Member
Hello JBL fans -
I picked up a pair of JBL 4312's recently and found this thread. Wow. Some great info and help.
The speakers are in fairly good physical shape. Cabinets need some work but that will be the easy part.
The sound is not so good. No separation. Muffled. Like heavy blankets are covering the speaker. Adjusting the pots do not cause any scratchiness or sound difference really. I'm hoping I can dioxit them once I get them out and they will be OK. I definitely will recap these. I have ordered the "improved original" from parts express. Holding off on the L Pads for now since they seem OK?
I got the drivers out with some patience. Next is removing the foilcals. I got to say I'm nervous. One of them is already pulled up a bit at a corner which I take as good news. Slow and steady. Blow dryer and thin putty knife. I've read most of the threads on these speakers (and similar) and videos. A lot of posts. Thanks to all who took the time to help. BTW, I do not see why JBL put a thin piece of metal over the access screws for the cross over....? What gives? Guess they never expected anyone would want to replace the crossover components...?
Well here I go.
I picked up a pair of JBL 4312's recently and found this thread. Wow. Some great info and help.
The speakers are in fairly good physical shape. Cabinets need some work but that will be the easy part.
The sound is not so good. No separation. Muffled. Like heavy blankets are covering the speaker. Adjusting the pots do not cause any scratchiness or sound difference really. I'm hoping I can dioxit them once I get them out and they will be OK. I definitely will recap these. I have ordered the "improved original" from parts express. Holding off on the L Pads for now since they seem OK?
I got the drivers out with some patience. Next is removing the foilcals. I got to say I'm nervous. One of them is already pulled up a bit at a corner which I take as good news. Slow and steady. Blow dryer and thin putty knife. I've read most of the threads on these speakers (and similar) and videos. A lot of posts. Thanks to all who took the time to help. BTW, I do not see why JBL put a thin piece of metal over the access screws for the cross over....? What gives? Guess they never expected anyone would want to replace the crossover components...?
Well here I go.
Last edited:
oconnorweb
Active Member
I see that I have a small tear in the one woofer. Has anyone had luck with the coffee filter and glue on the inside?
Any other recommendations?
Thanks for any help -
Any other recommendations?
Thanks for any help -
change them. They look cosmetic good, just as did mine... You can't see that, if the resistance is gone. Since you're doing the job, do also this.
Did you check each driver for output before disassembling? Be sure that they all work first, any repair starts with a proper diagnosis.
Also, the lack of separation sounds like they might have been out of phase (if all drivers were working properly). If you had them wired properly externally, it is possible that someone has been inside and hooked up one or more drivers incorrectly.
Best of luck.
Also, the lack of separation sounds like they might have been out of phase (if all drivers were working properly). If you had them wired properly externally, it is possible that someone has been inside and hooked up one or more drivers incorrectly.
Best of luck.
JBL would make a new set of foilcals with your S/N as a replacement part at the time.
oconnorweb
Active Member
Michelag -
When you say the resistance is gone, do you mean physical resistance?
The L Pads take some effort to turn so there is "resistance" if that's what you mean.
I thought I'd recap, reinstall the crossover, dioxit the L Pads but hold off on reapplying the foilcals until I give it a long listen.
I can get the new L Pads if needed. Thoughts?
oconnorweb
Active Member
Jeff thanks for the response -
I am sure they were wired correctly externally as I hooked them up a couple of times. It does not seem they were ever opened before so I don't think someone messed up the drivers. I also took some pics as I removed the drivers. Each driver has a solid colored wire and also another wire with the same color with black running through it.
The solid color wire went to the positive terminal with the bi-colored wire to the negative. That's what the technical manual for the 4312's show. Do I have that right?
If it matches the technical paper, it should be correct.
oconnorweb
Active Member
Oh and Jeff I did test the drivers. I used a 9 volt battery which caused the drivers to pop and move. Then I used a multi-meter and measured the resistance. They mostly came back between 4 and 5. These are all 8 ohm drivers I believe but I thought I read somewhere its normal for the readings to come back at 4 to 5. Is that right?
With the meter you are reading DC Resistance, the drivers are measured in total (resistance plus inductance) reactance, so yes, resistance will be significantly lower.
Yes
I meant electric resistance, l pads are variable resistors.
Yes, replace the l pads.
I meant electric resistance, l pads are variable resistors.
oconnorweb
Active Member
Well I started to remove one foilcal from my 4312. It was slightly raised at one corner so the blow dryer flexible putty knife worked fine. I did warm up the entire cabinet with a space heater from a few feet away for an hour or so (this also helped me to drop out the drivers early on). I realized after I had the foilcal 1/2 up that I could access the 2 screws for the crossover. I went ahead and loosened them and dropped the crossover down and out the woofer hole. I some lost one of the dang screws in the speaker. I have no idea where it went. I'm aggravated now so I will look later.
The white wires for the mid range are glued in so I have to decide where I will cut them to remove the crossover to work on it.
Anyway, anyone else just partially remove the foilcal? Seems to be a good idea so long as I can eventually re glue it down when I am finished. Here are some pics.
The white wires for the mid range are glued in so I have to decide where I will cut them to remove the crossover to work on it.
Anyway, anyone else just partially remove the foilcal? Seems to be a good idea so long as I can eventually re glue it down when I am finished. Here are some pics.