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View Full Version : L150A's Back to life! Now what?



evans224
02-01-2005, 01:00 PM
I've posted here a couple of times, and I appreciate the help from the folks here. Here are a few before and after photos. I had a hell of a time with the water damage on the one speaker- it has swelled the partical board under the veneer and cracked the wood. I had to replace the veneer, and it came out great! Next is what to drive these beasts with- the instruction manual calls for around 300 watts. Any ideas would be welcome.

Regis
02-01-2005, 01:29 PM
You're not gonna need 300 wpc with these speakers. I own a modified pair and I'm driving them with a 160 wpc vintage reciever. These speakers are a sealed cabinet design and are very efficient. They don't need a whole lot of power to get them to really high volume levels. 50-80 wpc on my system thumps the hell out of the room and you have to almost shout to be heard. Nice speakers!

majick47
02-01-2005, 01:30 PM
Evans224 nice job on restoring your L150. Re power amps search Yamaha and you'll find a current thread with info re these fine amps. If your looking for plenty of clean watts the pro models will do the job for short money.

4313B
02-01-2005, 01:37 PM
These speakers are a sealed cabinet design and are very efficient.5th order "vented" ;) The black coned doohicky on the bottom is a passive radiator. If it were a "sealed" system the efficiency would be down a bit. The enclosure does have to be airtight for a port/duct or passive radiator to operate properly.

Steve Gonzales
02-01-2005, 04:27 PM
Very nice job indeed!! I love to see vintage JBL's brought back to life!! Maybe you could tell us all how you re-veneered the top piece? I for one am very interested in the how to of it all. thank you for sharing:applaud:

gassy
02-01-2005, 09:46 PM
Yes, so am I, Steve. Very nice job and a very nice pair of speakers!
:applaud:



Very nice job indeed!! I love to see vintage JBL's brought back to life!! Maybe you could tell us all how you re-veneered the top piece? I for one am very interested in the how to of it all. thank you for sharing:applaud:

grumpy
02-02-2005, 12:30 PM
My experience with trying amplifiers of different power levels is brief, but may help some...

75w/ch (high current capable amp) was OK, even in a fairly large room.
200-300w/ch (also high current capable models) was much more impressive
in both the bass region as well as "decongesting" upper ranges when playing
louder. Even non-audio-nut family members noticed the difference.

I'd recommend a quality amp (pick a definition you're happy with) that can easily
produce more than 100w as a minimum. A small room might be happier with less.
If you have access, try a few types out http://audioheritage.csdco.com/vbulletin/images/smilies/smile.gif

-grumpy

evans224
02-02-2005, 03:59 PM
I purchased the walnut veneer at a specialty hardwood store in Berkeley. There are three types

Iron on
Paper backed
Non-paper backed
I have a friend who knows a bit about cabinet making, and he suggested the non-paper backed. It comes in sheets 2ft by 8 ft and ran $45. I tried to pick out a sheet that had similar grain as my speakers. If I were to do it again, I'd make sure I had a picture. Anyway, the veneer is very thin-a little bit thicker than a piece of construction paper,maybe. I was kind of surprised at that. You don't want to sand this stuff down. It's ready to be finished. I measured and cut a tiny bit oversized using a pair of sharp scissors. I checked my fit and made sure it hung over the edges of the top of the speaker by about 1/16". I then sanded the top COMPLETELY FLAT using a a sanding block made out of a 2 by 4 cut 6" longer than the width of my speaker top. Now comes the tricky part. The veneer is glued down using contact cement. Once you stick a part down, it WILL NOT move. After coating both the veneer and the speaker top with cement, they have to dry for about 15 minutes until tacky. I put down 3 pencils on top of the speaker (they won't stick) and lay my veneer on top of them, being careful not to touch the two pieces together. I aligned two corners and a straight edge and with thumbs and forefingers stuck the veneer to the top. Once that was done, it's fairly simple to "walk" the rest of the piece on to the top, trying to press from the center out. Place a heavy object on the top, and let it sit for 24 hours. Then it's time to trim the excess. I used a razor blade and got as close as I could, then sanded off using my sanding block until the edges lined up. The veneer is so thin, you cannot tell that I put a new piece on top of the old veneer. I found that when staining, the new veneer really took the color much more than the older wood, so getting the color to match is kind of tricky. I wound up having to restain the other speaker as well to get them to match right. Thanks Steve, the Watco is a great looking stain, and the finishing wax leaves a beautiful semi-gloss finish.

Steve Gonzales
02-02-2005, 06:18 PM
Super results, especially having never done the veneer deal beforehttp://www.audioheritage.org/vbulletin/images/icons/icon14.gif !. I'm pleased that you liked the WATCO/finishing wax combo. The wax will preserve the wood too because it is a very good conditioner. Would you be willing to get some of the veneer for me and others? I've tried to find it in lil' ol' Bakersfield and they act like it doesn't existhttp://www.audioheritage.org/vbulletin/images/icons/icon6.gifhttp://www.audioheritage.org/vbulletin/images/icons/icon5.gif . I don't want to cause you to be overwhelmed with orders but, "I sure could use some,uh huh!" (Slingblade). Thank you again for sharing, that is a GOOD detailed how-to.

Earl K
02-02-2005, 07:17 PM
Lovely Stuff evans224 ! :yes:

Now what were those 3 pencils actually for ( spacers/rollers ) ? :blink:

( I'm a bit slow - so please bear with me ) :crying:

:cheers:

PS : one day I'll actually know this stuff and feel confident enough to renovate my S99 cabinets . :p

Zilch
02-02-2005, 07:32 PM
http://www.macbeath.com/

Look out for the ELEPHANT!

evans224
02-03-2005, 07:17 AM
The pencils were used as spacers so the veneer wouldn't touch the top of the speaker while aligning the pieces. And yes, MacBeath's is the place to get the material. They open the drawer and you pick out the one that matches best for your project. I didn't realize they had online stores, but if you need me to pick up some, let me know!

tmckien
02-03-2005, 01:08 PM
I have the original L150 (not "A") driven by a vintage Yamaha M60 (160 watts/channel @ 8 ohms). It does a very nice job, but I think 300 would be better if you want to play some cds... like the organ passages in Phantom of the Opera... at room shaking volumes. In new amps, I was looking at QSC (Bo's favorite?) and Adcom 5802. I made some mods to my speakers... added bypass caps to the crossover (dramatic improvement), replaced the mid with a 104H-2, and the HF with an 035ti. I am still trying to find replacement crossovers (N4412 was suggested in this forum), to provide the proper crossover point and levels for those drivers. I think that the result will be similar to a 4412 with deeper, tighter bass... In any event, they sound terrific to me, even without the proper crossover!

Zilch
02-03-2005, 01:22 PM
I am still trying to find replacement crossovers (N4412 was suggested in this forum), to provide the proper crossover point and levels for those drivers. I think that the result will be similar to a 4412 with deeper, tighter bass... Did you check with JBL Pro parts? That's an item they may just have on the shelf there, if you want the originals. Get the ones with level controls, of course, not the newer "A" version. :p

tmckien
02-03-2005, 01:41 PM
Thanks Zilch. JBL Pro does have them - $114 each ... under misc parts... #66953-0062-B I'm trying to find them used... or I may build them from scratch if I can't find used ones. Terry M

Regis
02-03-2005, 01:58 PM
Regarding the crossover,
You might want to consider the 3113b variant. For my L-150's I modified an L-112 Crossover to the 3113b as well as replacing the L#5-10 with a more efficient LE5-9 (big difference!) and the 2214H woofer from the L100T. The result is very nice depth, detail and powerful crisp bass. The L-150A is a direct bolt-in from the L-112 (unlike my L-150's, which aren't "A"'s) and the low frequency crossover coil on the L-112 is a much beefier unit than the lightweight little L-150 coil. Plus, they aren't going to run you $228 a pair, just wait for a pair of L-112 Crossovers to come up on Ebay.

One of our senior members (who I'll not name) was extremely helpful and offered this from his extensive knowledge


"Yeah, the L150 used a network similar to the L110, L110A and L212. I couldn't remember off the top of my head what the capacitor value on the LE5 was in the original L150. The L150A used the same network as the L96 and L112.

If I were you I'd use the 3113B network in your L150's. Download the 3113B schematic from JBL Pro and build it. Don't worry about the 033 being there instead of the 044 or 066. Compare the 3113B schematic to the L96, L112, or L150A schematic. You can also use any of them and just add the 3.0 uF capacitor to the 13.5 uF capacitor (The 3113B already has the 16.5 uF capacitor). You might need to put a different conjugate on the 2214H and that's pretty easy. If you use the LE5H, LE5-9, LE5-11, or 2105H (3113B, N96, N112, N150A) instead of the LE5-10, or LE5-12 you should notice an improved midrange. The LE5-10 and LE5-11 both have the black face in case that matters.

I've actually replaced the N212 networks in my L212's and the N96 networks in my L96's with the 3113B's and definitely like the greater presence, especially on DVD playback. "

Here's a link or two
http://audioheritage.org/vbulletin/showthread.php?t=2832&highlight=L-150

http://audioheritage.org/vbulletin/showthread.php?t=1961&highlight=L-150

Many months later, I am still very happy with these and have modified my little brother's L-150A's as well. I did do an A-B comparison before modding his pair of L-150A's and my speakers clearly sounded much better.

Just a thought.