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Thread: L150A's Back to life! Now what?

  1. #1
    Senior Member evans224's Avatar
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    L150A's Back to life! Now what?

    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.
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  2. #2
    Regis
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    Adequate power

    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!

  3. #3
    majick47
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    L150

    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.

  4. #4
    Obsolete
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    Quote Originally Posted by Regis
    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.

  5. #5
    Steve Gonzales
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    Good Job

    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

  6. #6
    gassy
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    Yes, so am I, Steve. Very nice job and a very nice pair of speakers!



    Quote Originally Posted by Steve Gonzales
    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

  7. #7
    Senior Member grumpy's Avatar
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    power needs for L150A's

    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

    -grumpy

  8. #8
    Senior Member evans224's Avatar
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    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.

  9. #9
    Steve Gonzales
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    Thumbs up Would you?

    Super results, especially having never done the veneer deal before !. 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 exist . 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.

  10. #10
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    Lovely Stuff evans224 !

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

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



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

  11. #11
    RIP 2011 Zilch's Avatar
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    MacBeath has 5 stores, including online:

    http://www.macbeath.com/

    Look out for the ELEPHANT!

  12. #12
    Senior Member evans224's Avatar
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    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!

  13. #13
    tmckien
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    L150A power

    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!

  14. #14
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by tmckien
    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.

  15. #15
    tmckien
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    4412 Crossover / L150 Mod

    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

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