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jlovda
01-28-2005, 07:44 AM
I would like to upgrade a pair of L-88P speakers on the cheap but still use JBL components, probably getting them from ebay. The odds of find two new or like new M12 upgrade kits is probably one in a million. I have several questions. 1. If I can't afford LE2-2 alnico mids, what are the REAL differences among all the ferrite magnet versions; LE2-3 to LE2-12 and the model 104 used in the L100T? They all basically look the came. 2. regarding the crossover, if I removed the entire existing xover and replaced it with an L-100 xover off ebay, would the performance be acceptable? 3. The L-88P has a hidden midrange level control hole under the silver label. I assume it would almost impossible to get a new pair of L-88PM12 or L-100 adhesive backed foil nameplates. Would someone with a pair of L-100s be kind enough to measure the center to center distance between the two screwdriver adjustment knobs? If the spacing is the same as the L-100, I will just take a sharp Xacto knife and cut the circular hole in the aluminum plate for the mid control to be visible. Also, does someone know the difference between the L-88P and L-88P Version A? I know the front grille got changed along the way so the second version has basically the same cabinet and grille as the L-100. Were there any driver changes; ie, alnico to ferrite for the woofer, etc?
Thanks,
John Lovda

4313B
01-28-2005, 07:50 AM
1. The LE5-2 is the "worst" sounding of all the LE5's so any of the other LE5's will be an improvement. :p You might prefer the LE5-10 or LE5-12 with the round wire voice coil. It has a bit less bite.

2. Yes. But just build them yourself. Two capacitors and two L-Pads per enclosure. It couldn't get much easier than that.

3. Back before the WWW I tossed so many of those in the trash! :banghead: All brand spanking new with the plastic protectors still on the fronts. Oh well... :(

jlovda
01-28-2005, 08:52 AM
There is a nice looking pair of 104H-2 mids used in the L-100Ti on ebay right now. Any knowledge or opinions on these?

Thanks for your reply.

John

4313B
01-28-2005, 08:52 AM
They're fine. Pick up some 035Ti's as well and you're good to go. Here's the schematic of the network you will want to use.

http://www.jblproservice.com/pdf/Network%20Schematics/3112D%20Network.pdf

jlovda
01-28-2005, 09:29 AM
I assume the 035Ti is the tweeter from the L-100Ti? Actually the tweeters on my L-88P are visually and acoustically just fine. One thing JBL did on my L-88 cabinets was route a square depression on the front baffle the same depth at the tweeter mounting plate. The tweeter fits perfectly into this depression and makes it flush with the baffle. If this 035Ti has a round mount plate, it would be unsuable. I never bothered to remove the blank cover plate over the midrange hole. I wonder if it, too, is recessed. I'm at work now do I can't get to it until this evening.

The schmatic for the xover you referenced is hard to read. Can you confirm the values? mid cap, 10uf, tweeter cap, 3uf, tweeter inductor, 0.2 mh, two bypass caps, 0.01uf each, two 8 ohm L-pads.

Thanks,
John

4313B
01-28-2005, 09:38 AM
The schmatic for the xover you referenced is hard to read. Can you confirm the values? mid cap, 10uf, tweeter cap, 3uf, tweeter inductor, 0.2 mh, two bypass caps, 0.01uf each, two 8 ohm L-pads.Affirmative.

If you're sticking with the current HF then use this schematic:

http://www.jblproservice.com/pdf/Network%20Schematics/3112C%20Network.pdf

jlovda
01-28-2005, 07:10 PM
Well, I was outbid on the 104H mids :( but I just got a pair of LE5-8's:) . Which of the crossovers noted above would be the best for this particular midrange? Thanks again for your help!
John

4313B
01-28-2005, 07:32 PM
http://www.jblproservice.com/pdf/Network%20Schematics/3112C%20Network.pdf

jlovda
01-28-2005, 08:09 PM
Giskard:
Thanks for your help and prompt replies.

One of the two LE5-8's I will be getting has a dimple in the dustcap. I was able to remove the dimple from another LE5 with a similar dustcap by placing a small piece of very sticky packaging tape in the middle of the dimple and pulling with a sharp, rapid action. It came out very nicely. I hope the samething works with this dimple.

I did notice on another thread here that you mentioned a source; "Pro Parts" that sells the dust cap alone.

51868 D/DOME 1.31/DIA 1.16/IDW/LIP 1.75 $ USD EA

Would you please provide their web address? You mentioned replacing a concave paper cap with one of these black Al ones. Have you ever tried swaping a damaged Al cap with another identical Al cap? Is there a way to remove the whole thing including the glue flange or would I have to put the new flange on top of the existing one?

Thanks
http://i3.ebayimg.com/01/i/03/4f/0a/ab_1_b.JPG

Don C
01-28-2005, 10:13 PM
Those dustcaps appear to be aluminum. I have tried to remove dents on a few of those, with no success. If you do manage to get the dents out, tell us how you do it.

4313B
01-29-2005, 04:26 AM
Have you ever tried swaping a damaged Al cap with another identical Al cap? Is there a way to remove the whole thing including the glue flange or would I have to put the new flange on top of the existing one?Plenty of times. Use an x-acto knife and cut out the dome leaving the flange, then very carefully and patiently remove the flange without tearing the cone. In other words, work from the center of the dome out. Be aware that there is a magnet right under the dome. :p

http://www.jblproservice.com/parts.html

jlovda
01-31-2005, 08:21 AM
Don C asked a question:

I have had no luck popping out paper dustcaps but I did have an LE5-8 that I fixed quite nicely. I did not realize the cap was aluminum, I thought it was plastic. I used Scotch packaging tape. This is the clear 2" wide tape that sells for about $2 a roll at Wal-Mart and is very sticky. Cut the tape to fit inside the dimple, maybe 2/3rds of the diameter. Take a round, smooth object and rub the tape so it is making good, strong contact on the entire area inside the dimple. Take two fingers of one hand and hold down the cone on either side of the dustcap. You don't want to yank the whole cone assembly and damage it. Take the loose end of the tape (enough extra to make a handle) and yank sharply upward, perpendicular to the concave surface of the dimple. It took me two tries to pull the dimple out. Be aware that just like a car fender dent, if the aluminum is creased around the periphery of the dimple, the dimple will disappear but remnants of the edge crease will probably still be present.

As soon as I get the two LE5's I won on ebay (and shown above), I'll let you know How successful I am at removing the dimple.

John Lovda

jlovda
02-10-2005, 06:21 AM
Giskard:
I would appreciate your expert advice again. Last night I bid on and won a pair of LE5-5 mids off ebay.:) These appear to be cosmetically perfect and have the same front visual appearance as the LE5-2 (inverted paper dustcap and brushed silver basket) that was originally intended to be used in L-88P's as part of the M-12 upgrade.

Will the simple 6 db/oct 3 mfd and 8 mfd xovers still work here or do I need something more exotic?

By the way, I was able to lift the two large depressions from the LE5-8 aluminum dustcap shown in the picture above but it is by no means smooth and invisible. If I have the patience and time in the future I may try your delicate dustcap replacement technique or I might just resell them on ebay, as is.

Thanks,
John Lovda

4313B
02-10-2005, 08:15 AM
The LE5-5 will work quite well for your intended application.