View Full Version : 4315 Refoam ???
05-27-2003, 08:32 PM
My uncle recently gave(!) me a pair of JBL 4315 studio monitors, and the 12" woofer (model 2203) and 8" midrange (model 2108) need new surrounds. Will standard aftermarket foam surrounds work, or do I need a JBL-specific kit?
Some places list JBL-specific re-foam kits, but I can only find other models (LE8, 122A, 2214...) - will one of these work (i.e. Did the LE8 replace the 2108)? Is this something I should attempt myself? If not, what should this job run? Are these even worth the trouble?
I hooked them up to an older integrated receiver, and all the speakers played (I kept the volume VERY low), the pots on the level adjustments were a little scratchy, but that cleaned up as I worked them back and forth several times.
At first I thought one of the 2105's was actually blown, but I hooked it up by itself, and it plays fine - probably just a loose connection between the x-over and the driver, or maybe a bad component on the x-over, but that should be an easy fix...so, what's the verdict? Apologies for the length, and thanks in advance!
05-27-2003, 08:59 PM
No they are junk please let me know where you live I will be right over!~
You lucky dog!!! Yes they are worth the trouble!
If you are not sure about the foam kits and have never done one you may not want to start with these. The are not difficult to do but it depends on how "hands On" you are. There are several places that can do the re-edge/ refoam. JBL does not sanction refoams just recones but there are JBL reconers that will re-foam them. Orange County comes to mind but there are several more depending on where you live.
Put some time into them and clean them up. If you don't like them you can sell them easy enough. I have never heard a pair but there will be guys after me who have.
05-27-2003, 09:13 PM
I kinda thought they'd be worth it, that's why I asked! I don't think he knew what he had - he just saw that they were in bad shape, and knew that I was into all things stereo, so he called me. I live in MD - know anyone reasonable on the East Coast?
[QUOTE]Originally posted by Robh3606
[B]No they are junk please let me know where you live I will be right over!~
You lucky dog!!! Yes they are worth the trouble!
05-27-2003, 09:24 PM
I am in New York so I will be right down! I have heard of a good shop in Pensylvania that was recommended by the JBL Pro parts guy. Can't remember the name. You could always give JBL Pro parts a call and ask for Dave. He was very helpful. I don't know if they re-edge but it's worth a try. I am sure there are other too let's see what the rest of the guys have to say.
05-28-2003, 04:58 AM
The 12" foam surrounds become extraordinarily fragile and brittle after 10 years. Once you get a crack, it seems to travel. It doesn't affect the sound quality as much as you would think. I found the frames get 'stuck' to the blue panel and need to lever the drivers off with a screwdriver. You will astounded by the ordinary hookup wire that JBL use inside cabinets.
The 4315 are excellent in adsorbent rooms and deserve (require ?) a good tube amplifier.
The trim pots are always scratchy and almost useless. The 9 o'clock position is the only tolerable one. See the earlier posts on this x-over subject and general 4315 sound quality.
05-28-2003, 09:08 AM
You can get great resurround kits and complete instructions from Rick Cobb at firstname.lastname@example.org - he frequently posts them on eBay, but will also quickly reply to emails. The work is not difficult, only real tedious. And, depending upon the composition (and condition) of the original surrounds, the clean-off can be a real gummy, tar-like experience. Final alignment is crucial, but Rick can sort you out on that, too.
Just email him you need kits for the 2203 and 2108 and he'll fix you up. Cobb's surrounds are to JBL specs, and fit excellent.
As well, I think Rick will do this outsource for you - ask him. I'd do them too, for a case of Heineken (or one bottle of old vines Zin...) per pair. Let me know...
05-28-2003, 02:43 PM
I will second that on Rick foam kits. I have used several of them now and all were right on the money.
05-29-2003, 07:29 PM
"Once you get a crack, it seems to travel. It doesn't affect the sound quality as much as you would think."
Perhaps you might not hear anything amiss (which seems highly improbable considering how important enclosure tuning is) but the transducer itself can be subjected to undue stress due to system losses introduced by holes in foam surrounds. A hole or crack in a surround is similar to having an incorrect value capacitor, resistor, or inductor, or a combination of such, in a filter.
"The 4315 are excellent in adsorbent rooms and deserve (require ?) a good tube amplifier."
I know of no tube amplifier that has low enough output impedance and can dump sufficient current to properly drive a 124/2203 LF transducer. That doesn't mean they don't exist, it just means I haven't heard of any.
I can definitely see putting a tube amp on the 8-inch 3-way portion of a 4315 but not on the 124/2203.
"The trim pots are always scratchy and almost useless. The 9 o'clock position is the only tolerable one."
Replace the minimal 10285 L-Pads with the 58450 L-Pads and put the "standard" 3 dB attenuator on the LE5/2105 and 077/2405. (2.4 ohm resistor in series and 20 ohm in parallel with the L-Pad). You want the L-Pads to be as full on as possible.
"You will astounded by the ordinary hookup wire that JBL use inside cabinets."
Replace with Monster Cable or your favorite heavier gauge wire.
Also install the usual poly bypass caps :)
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