L-150s Restore and Recap

[Jobrewer1983]

Good Morning Lansing Folks,

Hope all of you had a great Christmas/New Years. I have been in the process of acquiring a pair of the L-150s for a few weeks now. Yesterday I was able to finally get my hands on them. My friend James is a huge collector of vintage gear, he wheels and deals all over California. A few weeks back he picked up a pair of L-150s in Los Angeles at a flea market for $50.00.

We have been going back and forth on what to swap for, or a price he would let them go for. He basically did not want to sell them to me, due to us constantly bartering for gear. The past few barters he has gotten the better end of the deals, and he wanted to give them to me. He knows I enjoy restoring vintage receivers/amps and asked me if I would mind trouble shooting a few receivers for him. I gave him the $50.00 he paid for them, and I am in the process of cleaning a Pioneer SX-880, and will be working on a Sansui AU 717 for him.

On to the good stuff:

I have not had the opportunity to remove any of the drivers yet, or check the crossovers, but I am wanting to recap the crossovers. While I have replaced caps before, it’s usually a trip to FRY’s or Radio Shack for cheap caps. I am looking for some good quality replacements, any suggestions? Has anyone on the site conducted a rebuild on the X-overs for the 150s? If so, any tips would be greatly appreciated. Any upgrades that any one is willing to share?

I will be sure to take many pictures, and post them along the way. I will be doing a steel wool rub, and a Danish oil finish. The cabinets are in great shape, even the raisers are still intact. The cabinets will not require much work.

Any information would be greatly appreciated, and as always, thank you in advance.

Thanks All,
John

[grumpy]

Those appear to be in fine shape other than the obvious surround issue... easily resolved. Fun speakers

I'd check the operation of the L-pads first. Consider updating the terminals. Then perhaps a small update
to the crossover (parallel .01uF mylar or polypropylene across the larger values as JBL themselves did
with the L150A/L112/L96 line). Then see how they sound before jumping in with larger changes.

[Jobrewer1983]

Those appear to be in fine shape other than the obvious surround issue... easily resolved. Fun speakers

I'd check the operation of the L-pads first. Consider updating the terminals. Then perhaps a small update
to the crossover (parallel .01uF mylar or polypropylene across the larger values as JBL themselves did
with the L150A/L112/L96 line). Then see how they sound before jumping in with larger changes.

Good Morning Grumpy,

Thank you for the information. I figured I would spray a little Deox-it in the L-pads, is it possible that they will need to be replaced? Do they hold a value that can be lost, or would a good cleaning do the job? As for the crossovers, I'm just worried that the high end has lost its value. I'm no expert, but I have noticed that when the caps go bad, the top range seems to not be so clear/sharp.

As for the terminals, I am planning on installing some banana plugs, I just found out that my brother in-law has a box full of high end connectors and cables for me. I was talking with him over the holiday, apparently a few years back he went in on purchasing a Magnolia show room floor when they were closing out a Best Buy in the local area. I was shocked to find this out, he said he has a garage full of parts for me. I just need to make the time to go pick them up. not sure what he has exactly, but i'm sure ill find something good..

Once I finish the foam job i'll have a better understanding of where I stand. I will be running them with my L -110A's, ill take a look at the L-150A crossover schematic to see what the difference is between the L-150 and L-150A.

Thank you for the great information!! Ill be sure to outline each step along the way via the thread.

[couldbfishin]

I reinstalled the Low Frequency Driver we've been talking about. I then worked the controls for the mid and high frequency drivers. They sounded dry and a little bit scratchy at first, but loosened up some after about 5 minutes of back and forth.

Then I used some duct tape and carefully pulled out the dents in the mid and high frequency drivers. I tried a shop vac on the 033 high frequency driver, but it wasn't working. So I went back to duct tape and patiently got the dent to come out.

I then turned on the turntable and Marantz 2275 and magic, the high frequency drivers are working again, and the mid's sound much better also.

I found a guy on eBay selling some 128H-1 drivers he rebuilt. He says in the description that he refoamed them, but doesn't mention installing new cones. What was interesting is that the cones had the black coating on the backside just like mine. So, I sent an inquiry to him to see if can identify my low frequency drivers. Are there replacement cones with the coating on the backside? Maybe he can shed some more light on what has been done to these drivers.

Thanks for pointing out the difference in the cones on the passive radiators, I had noticed it. Both seem to be working, so that is the least of my concerns at the moment. I will lean more about matching them later.

I had not noticed the tear in the LE5-10 mid range driver. Someone evidently repaired it with fingernail polish or something similar. It does seem to be airtight, and working. But, as soon as I find a good one I will replace it.

I will always wonder what caused this damage to these speakers. I am assuming kids, and not cats, because of the pushed in dustcovers.

I still plan to replace the caps, so if anyone can recommend a good brand of replacements, please let me know. I will attach a photo of my crossover, as best as I could do sticking my phone up inside of the speaker cabinet.

Next order of business is pulling drivers on my L110's to see what they are, and if the cross over is original. I want to order parts for both sets of speakers at one time, and then replace them.

After reading another thread about using integrated Mac gear from the 70's with a pair of L100's and how good it sounds, I plan to hook up my recently restored Mac C20 preamp and MC-40 mono block amps to the L110s and see how they sound. The amps put out a minimum of 40 watts, but they are very clean. Hopefully the matchup will sound good.

And, I have decided to move the Marantz 2325 receiver back to the living room so I have some more wattage driving these L150s and see if that improves the sound. It is 125 wpc versus the 75 watts per channel driving them now. Marantz gear is pretty clean also and typically understated in power.

Thanks and if I learn more about the black coating on the backside of the drivers, I will keep you posted.

[grumpy]

I think what you are seeing on the cone backside is just the raw paper pulp, not a coating.

Also, in past posts I may have made statements or repeated info indicating aquaplas on the cone backside for 128H-1... given the 4412A photo I just took and others I just went back and reviewed, it appears that was incorrect and black/dark-gray aquaplas on the front was how they came from the factory.

[couldbfishin]

I removed a Low Frequency Driver from one of my L150 speakers to identify it. I have been curious as to why it doesn't have the white coating on the front of the cone like other L150s do. I was concerned that a previous owner had substituted non-JBL drivers.

What I found was that the driver is marked JBL, 128H, and has a serial number. It looks like an original JBL, not rebuilt. It looks very clean, almost new, although I have owned the speakers for 15 years or so.

I feel relieved that they are original JBL 128H drivers, or at least this one is and I am assuming the one the other speaker is like this. But, there is still a mystery about why these are installed and not the white coated 128H's.

I have read these were used in some of the studio monitors, and that they are identical in performance to the 128H's with the white coating on the front. Maybe it was a substitution at the factory, due to inventory or something, or maybe some previous owner swapped the white coated 128H's out for the black coated 128H's at some point. But, I am just glad that they are original JBL 128H drivers and they are in such good shape.

I will try to attach a short video of the back and front of this driver. I will also attach some photos in case the video does not work.

I have been looking for replacement 033 tweeters on eBay and found a couple for $60 each, that are used but look real good. If you know of other sources, at lower prices, please let me know. I don't know what a reasonable price is.

Thanks to those of you who responded.

Maybe someone else will have some of these black backed 128H drivers and this thread will help them.

[grumpy]

While indeed a 128H frame and magnet, it appears they were re-coned with aftermarket parts at some point. The black-front version is a 128H-1, the aquaplas is tinted black and applied to the front of the cone, which the provided photos don't appear to show. The large dust cap and glue-line is another indication that the recone did not use JBL parts. Doesn't mean it won't sound OK. Pic of 4412A (128H-1) woofer attached for reference. L150 is a fun speaker. I bought the -A version when it came out.

Likely the original foam surrounds needed replacement, and the owner had them "inexpensively" repaired (vs the cost of a JBL re-cone)... may not have been offered a resurround as a choice, or the coils could have been damaged. At any rate, sorry to be the bearer of unhappy news.

[Chris Brown]

Looks like you have some weird stuff going on with your passive radiators also. Neither looks like an original PR300 passive radiator. In addition, the two shown in your pictures are different. One seems to show a ribbed cone with the foam glued in back, and the other appears to show a smooth cone with the foam glued in front. The passive radiators are crucial to proper tuning of the speaker. The PR300 comes with weights on the rear that can be adjusted to tune the bass - similar to shortening or lengthening the port tube on a ported system. Using a different passive radiator with a different cone could change the sound also. Likely these passive radiators weren't installed with any consideration as to this effect, so who knows how they are changing the sound of the speaker. Mismatched passive radiators throw another element of randomness into the mix.

If you end up not being able to locate any 033 tweeters, another possible option you could look into is the 034. It fits without modification and is listed by JBL themselves as a replacement when the 033 is not available. I feel that they sound just as good as the 033. The only catch is that the 034 has a plastic front whereas the 033 has a metal front. There is no sealed tweeter chamber in the L150. That causes the whole 034 tweeter to vibrate almost like a mini passive radiator at loud volumes. If you either re-enforce the plastic frame of the 034 somehow, or improvise a sealed compartment behind the tweeter, it should be possible to eliminate any issues. I would still go with the 033 but it's nice to have a 2nd "better than nothing" option if it comes down to it.

One of those mids looks like it might have a tear in the cone. You might keep an eye out for some. Keep in mind that many of the even numbered LE5 mid-ranges are interchangeable. LE5-6, LE5-8, LE5-10, and LE5-12 are all acoustically identical, the only difference being some have a a black front, some have a silver front. You might try using a small vacuum hose to pull out the dust cap on those mids, and you could even try that to pull the dome of the 033 back out.

[Doc Mark]

Good Morning, Jobrewer1983,

You got a wonderful deal on those L150's! I remember when they first came out, and I eagerly went to the local Hi-Fi stores to get some brochures on them! They looked great back then, and they still look great today! Good luck on your refurbishing job, and I'm looking forward to seeing your progress as you wend your way down that happy path. Take care, and God Bless!

Every Good Wish,
Doc

[rdgrimes]

There's a complete set of innards on eBay right now for the L150A. If I were re-doing a pair of L150, the upgrade to L150A would be high on the list of possibilities. IMHO, the 044 is a superior tweeter to the 033. You can also substitute crossovers from the L96 or L112 for the L150A.

[Jobrewer1983]

There's a complete set of innards on eBay right now for the L150A. If I were re-doing a pair of L150, the upgrade to L150A would be high on the list of possibilities. IMHO, the 044 is a superior tweeter to the 033. You can also substitute crossovers from the L96 or L112 for the L150A.

Good Morning rdgrimes,

I have not had the opportunity to test any of the 044 tweeters, this is only my 2nd pair of JBL's and my L-110A's have the 033's. Will the 044 tweeters fit the same cut out as the 033? I've read many times that the 044 is a lot better, but is it really going to make a noticeable difference to the ear?

Thank you for the information, If I go the 150A upgrade, I'm sure ill be asking many questions along the way.

[rdgrimes]

Good Morning rdgrimes,

I have not had the opportunity to test any of the 044 tweeters, this is only my 2nd pair of JBL's and my L-110A's have the 033's. Will the 044 tweeters fit the same cut out as the 033? I've read many times that the 044 is a lot better, but is it really going to make a noticeable difference to the ear?

Thank you for the information, If I go the 150A upgrade, I'm sure ill be asking many questions along the way.

I have a lot of time with the 044, and some time with the 066 which is pretty similar to the 033. The 044 is virtually indestructible, and sounds better when pushed hard. The 033/066 sound worse when pushed, at least to my ear. The 044 is pretty much the pinnacle of the development curve for soft dome tweeters, they don't get any better. Everything else is the same in those 2 models, just the tweeter and crossover need to be obtained. (unless you want the shiny frame of the LE5-12.)

[audiomagnate]

Deoxit doesn't do anything for L-Pads in my experience. If they're bad it's usually because of overheating and they need to be replaced.

[Jobrewer1983]

I have a lot of time with the 044, and some time with the 066 which is pretty similar to the 033. The 044 is virtually indestructible, and sounds better when pushed hard. The 033/066 sound worse when pushed, at least to my ear. The 044 is pretty much the pinnacle of the development curve for soft dome tweeters, they don't get any better. Everything else is the same in those 2 models, just the tweeter and crossover need to be obtained. (unless you want the shiny frame of the LE5-12.)

Thanks rdgrimes,

Ill have to track down some o44s, eBay was a bust... Just checked. There is someone on CL who has some midrange drivers, they look like the LE5-2's but they look a little newer, they are the pro series, so I'm assuming they are mid 80's-early 90's. He is asking $90 per set, and he has 2 sets, the good thing is they have the silver face. Not sure if they are the LE5-2s or not, but if so I've read that they are a little better then the LE5-12's. Any input on the differences between the 2 and 12 other than the noticeable magnet, and the inverted dome? Both seem to run near a $bill on eBay and CL, I would like to pick the better of the two if there is a difference.

Link to drivers on CL: http://sfbay.craigslist.org/sfc/msg/4825531275.html

Ill keep my eyes open for the 044's, ill check bartertown tonight as well. Thank you for the good information!

[Jobrewer1983]

Good Morning, Jobrewer1983,

You got a wonderful deal on those L150's! I remember when they first came out, and I eagerly went to the local Hi-Fi stores to get some brochures on them! They looked great back then, and they still look great today! Good luck on your refurbishing job, and I'm looking forward to seeing your progress as you wend your way down that happy path. Take care, and God Bless!

Every Good Wish,
Doc

Good Morning Doc,

Thank you for the kind words, I would love to get my hands on some original literature. I agree, the deal I got is pretty amazing. Mind you I needed to downsize a few months back due to a lack of space in my living room, so my friend James got my University's from the early 60's in new cond. I was the 2nd owner, and the original kept them in the boxes... I did not have my rack finished at the time, and needed the space. It was either store them in our parking garage, or get rid of them. I could not think of anyone who would enjoy them as I did other then my friend James. He still has them, and loves them. If you look me up on AK you can see some of the many changes my system has gone through over the past year.. Its pretty impressive for what I have paid for everything. Mind you its been years of searching and swapping... Its a hobby that I cant kick. I added a few pix of the tops to show the cond.

Again, thank you for the post.

God Bless,
John