JBL L300

[faber12]

I am still awake, although I have to work tomorrow. It is hard to stop listening to them. I hooked up my Kenwood KR-V8060 receiver and they sound better than on the old Sherwood which I first used because it was in the garage already. Specs on the receiver here on page 27 http://inform3.kenwoodusa.com/manuals/KRV8060.PDF

I have a few more pics, I wiped some of the dust off and pulled out the woofers. The inside looks alright, one of the woofers was wired out of phase, took care of that and then listened to some music. They are indeed bright, I think someone posted that they were, but I like them that way. It is easy to tell that they are a class above what I have listened to before.

I will try to keep you all posted on my progress on the refinish. What sheen was original to the black paint on the front/back? I will probably use satin, as it does not show imperfections like a glossier sheen, and it cleans easier and resists burnishing better than flat.

I will be picking out some new stainless steel screws for the components while I am at work tomorrow. I will paint them black if the stainless shine looks funny.

@perchdog It would be hard to beat the value for dollar here without getting them for free. I am sure that 30 watts is plenty, I barely have turned mine up for fear of angering the neighbors.

I can't seem to find any information about the rockwood subs. they are 4 ohm, but the system seems to measure about 7 ohm still. I am posting a picture of the back of the subs for curiousity's sake. With woofers installed instead of subwoofers, the midrange may come out a bit more, it seemed slightly lacking. I turned up the presence control and that seemed better.

 

[perchdog]

you may also want to throw some deoxit on those l-pads

 

[mech986]

Nice work and it is hard to stop listening, they have an effortless quality about them.

Glad you found the woofer phasing issue. Now, try reversing both woofers relative to the speaker phase - this is because the original JBL woofers were that way, positive voltage to red goes inward. Its a long story. This may give back some of the midbass or midrange as a dip or suckout can occur otherwise. Also, even though you have a 4 ohm woofer there, the crossover dominates the impedance measurements. However, the lower ohmage woofer will alter the frequency of the lower crossover as well as the bass output. The relative efficiency of the woofer vs OEM JBL will also alter the output. As a temporary driver though, it certainly gives you some idea of the system's capabilty.

When you have the woofers out again, check for any loose or missing fiberglass, and check under the bottom and side fiberglass for any objects ( dropped in from the port), foreign material, or papers. Sometime JBL cabinet docs are in there. Missing fiberglass should be replaced. Many will replace the original twist-lock connectors on the back panel for more stout gold plated 5 way type binding posts which can handle much larger wire - with a good high powered amp, plenty of current and low resistence damping factor can really take control of the woofer.

The sheen on the front baffle is indeed satin and your baffles look pretty clean. Normally there is either a cork gasket or on the JBL woofer there is a thin round cross section circular gasket to seal the woofer. Replacements can be had from ebay when you get the woofers. Always check the internal T-nuts and the surrounding wood-particle board - these can chip and flake so sometimes some reinforcement or restoration is needed.

The brightness is partly due to not having the midrange lenses, they will beam unmercifully if pointed at you. You could temporarily try using some screen mesh, fabric or metal, or some fabric over the horn mouth. Might be a good idea as it keeps dust out. Be sure to peer into the horn with a good light to be sure its clean and free or debris. Do not spray compressed air though inside to clean, the diaphragm is delicate.

The JBL woofer is probably a lot better in the midrange than the Rockwoods so you will have to make the adjustments at the electronics source or through the controls as you have done.

When you have a chance, get a couple of Milwaukee furniture dollies from Home Depot, $20 per, best money spent on getting these up a little and much easier to move around for placement and working on. Also, you can use something like a quick 6-8" tall rectangular or square base under the speaker and on top of the dolly to give you the stand height. I think you'll find some interesting changes to the sound and imaging will occur.

Good work so far. Have a good day at work. :thmbsp:

 

[faber12]

I love the way the knowledge flows from your fingertips like water from a fire hose. Thank you for all your help and encouragement so far.

We stock a wheeled base at work, kinda like this one I think.
http://www.acehardware.com/product/index.jsp?productId=2564217

I may get a lazy susan bearing for when I am working on them, I have a butcher block type kitchen table in the garage that I can use as a workbench.
I think we stock a bigger on than this, but you get the idea. would make spinning them around to work on them easy.
http://www.acehardware.com/product/index.jsp?productId=1296568

Only half the t nuts and screws are still in the woofers, they are a stock item at work, so not a problem there either. I may use allen screws for that to get the smaller head that the woofer screws originally were. I can grind them down if need be though.

I like the twist locks, they are pretty cool, and I doubt I will ever have enough wattage going to them to need heavier guage wire. They play loudly on few watts.

@perchdog, they are pretty scratchy.

 

[Jenkster]

you may also want to throw some deoxit on those l-pads

This made a world of difference on mine. I actually had to remove the back of the L-pads and used a fine wire brush with Deoxit to get the coils clean. Mine were pretty corroded. It was like taking a blanket off the front of the speakers. They are directly in the signal path and often need cleaning at this age.

Great score BTW.:thmbsp: Someone mentioned 2235H woofers as replacements. Put me in line with that recommendation. :yes: IMHO, best 15 incher JBL ever made. I have been thinking trying a pair in my S3100's but I'm sure I would need some tweaking of the crossovers.

Good luck with a great project.

 

[faber12]

I will have to do that, they may just sound better again.

I am going to start on the refinisher tonight, it says that you can start/stop anytime you need to. Wish me luck.

 

[faber12]

Got the wood cleaned on one tonight. The formbys refinisher worked really well as a cleaner, there was not enough finish there to really be removed. The random dirt/paint spots cleaned off great though. My wife commented on how much better the one looked than the other.

Also installed the stainless hardware and some proper terminals for the woofers.

I think I will try to make some wooden lenses, if anyone were to provide the measurements that would be great.

First picture is the clean one, the other looks worse than it is, that is just how the lighting worked in the garage.

It was fun putting them up on the table, I think I will look like I lift before this process is complete.

 

[faber12]

There is a group on facebook called "Seneca county online garage sale"
It was started by a woman in our town, which is the county seat here in the middle of seneca county. Our town has a population of about 18,000 people. The group has near 20,000 members now. Most of the stuff is junk, as you might expect. But there are a few things that pop up here and there. For instance that is how I found my L300's. If you were to start groups like that in your areas and spend a little time promoting them, you could score a few items now and then, just by searching the group every so often with the search feature built in to facebook.

If you are interested in learning more, Just shoot me a message.

 

[faber12]

Ordered the glass on my lunch hour today. About $53 at the local glass shop.

When I used the formby's it cleaned the veneer but stripped the stain from the solid wood at the top of the cabinet. I picked up some stain while at work today, along with some stainable wood filler that I can use to fill the chips and the one crack. I think I have sold my last bottle of gorilla glue. There were two trim pieces on top that were starting to pop off. I pulled them off and there is a lot of polyurethane glue left. I will have fun scraping that off.

It was too hot and humid to work in the garage tonight, so I fixed a laptop with a broken LCD for a co-worker. That took about an hour.

First 2 pics, the laptop I fixed.

Third pic is the crack near the top of the cabinet.

Fourth pic is the polyurethane glue encrusted on the wood of the cabinet. I will remove it and use a proper wood glue.

Fifth pic is the trim piece after staining held up to the veneer, may need to strip a touch of that back off to match perfectly. The cabinet I am working on first has the better wood grain designs in the veneer. I think it will turn out pretty good.

What do you think about making the lens out of walnut? My parents burn wood for heat, and I could probably find some aged black walnut in their wood pile that some lenses could be fabricated from. I actually do not like the grills, I think I prefer to see the lenses and woofers. It is more impressive that way. If I go to the work for wood lenses or the expense of the plastic ones, I want to be able to see and admire them.

@ mech986 I hope all is well with your daughter, you must be pretty stressed, I know I would be. Hopefully you are on your way home.

 

[mech986]

Faber,

Been awhile, checking in to see how your progress is. We finally got my daughter discharged from Stanford on Sept. 13, hung out a couple of days getting ready then drove home on Sept. 22-23. But wasn't home 3 hours when she spiked a fever and chills, and with a semi-central IV line, that means trouble. Went directly to local ER and was admitted and treated for 5 more days with IV antibiotics. Now been home for 8 days and doing much better.

Hope you're making progress. Let me know if you need some help sourcing the woofers.

Regards,

Bart

 

[mech986]

Making the slant lenses out of wood would be an interesting project, especially if you have really good looking figured wood to work from. Check Lansing Heritage website and forum for options on how to built them. Also search AK as I recall a couple of guys have done that, and one built a nice jig to cut out the shapes once he had sliced them out. HJames could show you the ones she has, and BMWCCA has some with variations on the size along with some beveling/chamfering of the edges.

The real key though is getting the spacing, angle and number of slats on the carrier pieces/supports, and copy the front face contours of the original L92/2308.

 

[Crestwood23]

AKer smokingjoe made some very nice black walnut lenses for mine - he said they weren't easy to make, but they sure look pretty! Maybe PM him for dimensions.

http://audiokarma.org/forums/showthread.php?t=593964

Good luck with the restore, they are well worth the effort.

 

[damacman]

IMHO you have there a pair of the finest loudspeakers from that era. They've certainly had a hard life. The woofers in them were made during the heyday of the car audio industry and the brand name "Rockwood" was an effort to establish brand recognition as being a hybrid of "Rock"ford Fosgate and Ken"wood." These products were sold at flea markets, bazaars, and liquidation events. Performance products they were not. Interestingly, Rockwood wasn't exclusive in this naming strategy - Alfine and Kenford were others.

What a buy. Once you've refurbished them you'll have a pair of speakers that are keepers for life.

 

[faber12]

Thanks guys, I will check that out. I haven't had time to do much on them for a while, but they are shaping up nicely.

Sorry to hear that your daughter is still having problems mech986, I hope she is on the mend soon.

I will post pictures again when I have painted the front of the cabinets, I have had the paint sitting there for a week or two, just no time to work on them. The glass looks great though, and I have black felt to put under them that raises it flush with the side trim.

I found a pair of L88's, that had bad caps and tweeters, I replaced the tweets and caps, and cleaned them up. I may sell them later though, the L88's were not JBL's best effort by any means. Would be great in a garage though.

 

[faber12]

Here is a picture of the glass for the tops. It fits great, I figured that the lightly smoked would look good with the black felt, and I can slide a picture under them if I want and still see it.

 

[VintagePlus]

Any updates?

 

[faber12]

Sorry, been very busy. I am hoping to get the fronts and backs painted today. I did a project for my wife that involved refinishing a hardwood floor, and it has been pretty cool here for painting.

I may have to bring them in from the garage to finish them. I am ready to start listening to them! Enough waiting already...

 

[faber12]

Spent some time with the q-tips and simple green; the tweeters are looking better

 

[VintagePlus]

Nice! Good work. Listening to them when you are finished will be amazing trust me.

 

[faber12]

They sounded great before I started, I just have them partially apart so I can paint the front and for cleaning etc, so I can't use them right now.

I carried them in the house and upstairs today, so if it gets cold I can still work on them. The stairs were killer.