To refoam or not, that is the question.

rekmeyata

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I have a pair of JBL L7s that I bought in 94, the mid-base surrounds on both speakers are starting to develop small ripples, which I know is deterioration, the rest of the speakers look fine, and the cost to refoam is around $150 each.

I had a high-end electronics store guy tell me that whenever you refoam your speakers the sound isn't as good as what they were when they were new; I contacted a speaker repair place in town, known all over the US named Speaker Workshop, and they said that was BS, that there is no discernable sound difference between factory installed original foam and refoam. The high-end guy said too that speaker motors wear out over time, and replacing the foam does nothing to address the eventuality of the motors wearing out, I didn't talk to the speaker place if that was true yet.

So, what is up with refoaming and the speaker motors wearing out?

Should I do the refoam or purchase another set of speakers?

All the high-end place carried was Klipsch, listening to Crutchfield speaker comparison with my headphones the Kef Q950 sounded the best in my opinion, and they sounded darn near as good as a $5,500 speaker, any thoughts on those Kef's?

Granted this was listening on headphones, which understandably is nowhere near what I would hear in person, but it's impossible to find places that carry any of the brands of speakers in one place.

I would rather spend $300 to refoam my L7s because I really like the sound these put out, it's why I bought them in the first place, but I don't want to spend that kind of money only later have to replace an entire speaker inside the cabinet because the motor wore out, which they don't even make those particular ones anymore so they would have to find a suitable replacement. Plus, if I spend $300 now, I might have to spend another $300 in 5 or so years for another set of speakers to be refoamed, then 5 years after that the other set needs to be refoamed, thats $900 in refoaming that could take place between now and the next 15 years; that's the cost of one Kef Q950!

There is a place in town that can refoam for a lot cheaper, around $100 for both, but I can't find out what his qualifications are or whether or not he's done good work, he said that he would refoam using a poly material which doesn't degrade, the Speaker Workshop said he would use the same material JBL put on the speaker originally, the other guy said the poly material would not affect the sound?

Thanks

Edit: some details; I listen to mostly music, from classic rock, some heavy metal nothing to raucous, smooth jazz, some classical, but very little movies. My living room is 18 x 30 feet, I run a Harmon Kardon PA 2200 which puts out 100 watts per channel, and I have a Klipsch 400 watt subwoofer. Not sure if you need that info or not but it can't hurt to know it.
 
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The magnet does get weaker over time. It is progressive and changing the foam will not massively affect the sound output, but it could affect the stiffness, and this could change the tonality of the speaker. All speakers change as they age, as yes, the motor is a mechanical component with plenty of moving parts!

TBH, the midrange driver has limited affect on the tonality of the speaker, as the LF does the majority of the heavy lifting.
 
Pardon my ignorance, but what does TBH and LF stand for?

How long will these speaker motors last? they're 30 years old now, will I get another 30 years? I've seen used speakers made in the 60's that are still original except for the foam surrounds and they still work fine, is that the kind of life I should expect out of mine?

thanks
 
Pardon my ignorance, but what does TBH and LF stand for?

How long will these speaker motors last? they're 30 years old now, will I get another 30 years? I've seen used speakers made in the 60's that are still original except for the foam surrounds and they still work fine, is that the kind of life I should expect out of mine?

thanks
Sorry, LF stands for Low Frequency - the bass driver.

The speakers will continue to work for many, many years, but will gradually deteriorate as the magnetic flux diminishes.
 
Many, many years, is what? 60 years probably? I use to own classic cars from the '50s and 60s and the original speakers still worked, and those speakers were exposed to high heat and cold, plus they were not very expensive speakers, just a cheap single speaker in the middle of the dash. Can I expect the magnets in the JBLs to last at least that long? if so, in another 30 years I'll be 95 years old, then I'll have to replace my meager 100-watt-per-channel amp with a 500-watt-per-channel amp just so I can hear the music...o_O
 
Many, many years, is what? 60 years probably? I use to own classic cars from the '50s and 60s and the original speakers still worked, and those speakers were exposed to high heat and cold, plus they were not very expensive speakers, just a cheap single speaker in the middle of the dash. Can I expect the magnets in the JBLs to last at least that long? if so, in another 30 years I'll be 95 years old, then I'll have to replace my meager 100-watt-per-channel amp with a 500-watt-per-channel amp just so I can hear the music...o_O
Perversely, cheaper lower powered speakers - particularly those designed for the rigours of operating in a car will out live a domestic loudspeaker. Put simply, they are not working anywhere near as hard and the physical movement is less.

My point is that no speaker will sound the same throughout its life, but this is not necessarily a problem. Your home speakers could continue to produce sound into the next century, but won't sound the same as they do now.

In answer to your original question, yes, I would re-foam both speakers, as the surround is one of the least critical parts of the speaker. The suspension that holds the coil and cone in place, and provides the compliance of the driver is much more critical, but rarely needs replacing. The foam is simply there to provide an acoustic seal and to control the resonance of the come through damping.

If you do both, then any tonal changes will be applied equally to both speakers and the net effect less noticeable.
 
Thanks! Both mid bass speakers need to be replaced, they both are dimpling at the same time.

Now is there a difference in foam used? one shop said they would use a poly foam instead of the original style of foam, but wouldn't that change the sound dynamics? I read that different foams can alter the sound.
 
Thanks! Both mid bass speakers need to be replaced, they both are dimpling at the same time.

Now is there a difference in foam used? one shop said they would use a poly foam instead of the original style of foam, but wouldn't that change the sound dynamics? I read that different foams can alter the sound.
As above, yes it will, but not by a huge amount. You are giving the speakers another lease of life, so your ears will soon acclimatise to any small differences.
 
As above, yes it will, but not by a huge amount. You are giving the speakers another lease of life, so your ears will soon acclimatise to any small differences.
Since the other place is cheaper, and they've been redoing speakers for a long time as well, I guess I'll just take the speakers to him and have him use the poly refoam kit, I'll save about $150 to $200 from the other place.
 
I wouldn't want new foam surrounds, but would go for a rubber surround that will last much longer and, if the right type is installed, should allow more freedom of movement of the cone. Foam hasb't been used this century I don't think! I can't offer a contact for a speaker reconing specialist but a Google search should find a few.
 
I have at least 2 specialist in speaker refoaming in the city where I live, so finding one isn't the problem, just hoping the lower price one will do it correctly which I assume they will since they've been in business since 1973. That place also sells all sorts of vintage gear and some not quite vintage; they sell used home audio gear and new car audio gear, plus they do electronics and speaker repair.
 
So, what is up with refoaming and the speaker motors wearing out?

Should I do the refoam or purchase another set of speakers?

I would rather spend $300 to refoam my L7s because I really like the sound these put out,

There is a place in town that can refoam for a lot cheaper, around $100 for both, but I can't find out what his qualifications are or whether or not he's done good work,

How long will these speaker motors last?

Many, many years, is what? 60 years probably?

Now is there a difference in foam used?

You ask pertinent and reasonable questions but unfortunately there are few definitive answers.

I can't really offer much guidance, just a few thoughts and my opinion:

As I understand it, the JBL L7 were part of JBL's near top-end range - at the time. JBL's better speakers were well built and unless thrashed, I would put money (not mine, obviously!) on them seeing you out, save for the rotting foam rubber surrounds and possibly the odd capacitor in the crossover network (both of which should be relatively easy to replace/repair).

Just because you pay for a re-foaming service, doesn't mean the job will be better than if you did it yourself. There are lots of DIY drive unit re-foaming kits on the market and good YouTube videos showing how it's done. Hopefully, there's a kit out there that will fit the JBL drivers you need to repair.

Assuming you opt to re-foam, it will be virtually impossible to match some of the physical characteristics of the new foam rubber surrounds to the old (i.e. compliance) so there's a high chance they won't be identical. How much audible difference this would make is unknown to me. I would expect the greatest audible difference between old and new foam drive unit surrounds to occur with large cone excursions. You mention the mid-bass drivers - do these tend to move much when driven reasonable hard? If they don't, I'd guess the sound differences between original and replacement foam (done properly) wouldn't be huge, possible even inaudible.

I've had foam rubber surround midrange drive units that disintegrated after 15 to 20 years. Never tried repairing as I didn't much care for the sound when the units were new. There is a high likelihood that the compliance of foam rubber drive unit surrounds gradually changes over time until the degredation becomes visibly obvious. Did you notice the sound changed at all in the last few years? I didn't with mine. Bodes well for trying out a DIY refoam as perhaps any compliance difference between old and new won't make much audible difference.

Changing the type of surround from foam rubber to nitrile or butyl rubber would introduce more unknowns although rubber surrounds are likely to last much longer. Drive units with foam rubber surrounds are still sold today and it's possible that modern materials will allow a longer service life. I'm sure anyone with a vested interest in re-foaming your drive units will peddle that line! May even be true - I wouldn't know. Drive units with foam rather than rubber surrounds often have higher sensitivity (don't know why - less stiff, possibly?).

All things considered, and seeing as you really enjoy the sound of the JBL L7s, I'd be tempted to keep them and repair rather than purchasing an alternative speaker.
 
Thank you for that, and that is what I've decided to do is to refoam them. Midbase speaker doesn't move a lot, and it's just those that are just starting to develop small waves in the foam, the rest of the speakers, including the big 12" woofers are fine.
 
I recently had my vintage JBL L100T speakers reconed complete with new foam.
I highly recommend:
The gentleman even had new old stock original cones in his warehouse.
 
FWIW I just re-foamed my Mission 762’s with a kit I bought on Amazon for $30. After 30 years, the original foam was crumbling. They didn’t get any strenuous use for the past 10 years, so I didn’t notice any deterioration in their sound. The original foam attached to the back of the cones, but the replace kit was sized to attach to the front of the cones. A bit of research indicated it wouldn’t make any noticeable difference, and it made the job easier since I didn’t have to clean the old foam off the cones as meticulously as I would have if the new foam was going to be glued to backs.

Job done in a few hours (second one took about 45 minutes). Let the glue cure overnight, hooked them up and cranked them with my usual audio test tracks, and they sounded great. I can’t say “like new” because that was 30 years ago, the room and receiver are different, and my ears have not aged gracefully. But even with my moderated high frequency loss, the sax solo in Linda Ronstadt and James Taylor’s “Work Out Fine” bubbled up the center, and the pedal notes in the intro to “Mr. Radio” rumbled adequately for small speakers in a small room (turning on the budget Sony sub helped considerable, but that’s outside the scope of testing the re-foam job). Doc Severinsen sounded very live and punchy. I’d forgotten how good the 762’s sound, which is probably why I bought them in the first place.

Based on my experience , I recommend the DIY method. At some point I may need to do the 4 drivers in my Mission 765’s, but they have poly cones and rubber seals that are still holding up.

Even for $300 for someone else to do them, it’s worth a shot on the JBL’s, given the cost of replacing them with something equivalent. But if you have any mechanical aptitude, you should have a very high probability of success doing it yourself. I had a moment of stress removing one of the drivers. It turned out that the foam gasket on the back of its frame wasn’t installed correctly at the factory (uncovering old sins!) and the gasket glue stuck the driver frame to the front of the enclosure hole. I had to figure out a way to pull on the frame without damaging the cone or cosmetics of the enclosure. A 2x4 across the front of the enclosure for a fulcrum, a paint can lid pulled as a hook and a small crowbar as a lever did the job.

Best of luck bringing the JBL’s back to life. I know it will be satisfying when you crank up your favorite tracks with the new foam installed.
 
At some point I may need to do the 4 drivers in my Mission 765’s, but they have poly cones and rubber seals that are still holding up.
I've never known rubber surrounds to visibly deteriorate within 40 years, based on the oldest speaker I own, although someone had an issue with their Mission 765's - maybe a different version to yours though:


Seems to be the surround rather than the cone that's breaking up though only where the surround is glued to the cone.
 
After doing a lot of research on new speakers, and reading a lot of reviews and different forums, I decided to contact a speaker repair person in town. He told me that I would be hard-pressed to find something that played as accurately as my JBL L7s did for less than $5,000 for the pair, he said that since I was used to the sound quality, I would not be happy with speakers under 5 grand. He said he could rebuild them and make them sound like new, and they would make sure the cabinets were well glued together. So, I decided to get mine repaired.

Thanks for everyone's responses.
 
I contacted a speaker repair place in town, known all over the US named Speaker Workshop, and they said that was BS
He would say that, wouldn't he (to misquote Mandy Rice-Davies) - he makes his living out of this type of work.

Another suggestion. Why not look to replace the faulty speakers, rather than spend good money on what may be a patch-up solution that may be short-term? There are lots of speaker chassis vendors and, if you can match their spec with your existing drivers, you may find this a no more costly exercise. Any mismatch in spec may require a crossover mod to resolve.

In the distant past I re-jigged my speakers with new drivers. My original large speakers had Wharfedale drivers (15", 8" and 3"), these were replaced with much newer Wharfedale units (a mostake on reflection) and then with KEF drivers (13"x9", 4" and 1"). These last drivers made a massive improvement in sound quality. Good luck anyway.
 
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The place that does the repairs where I live is known all over the US. Lots of people have had vintage speakers from the 90s on back rebuilt and never had any problems, and you will see some of those for sale on ebay advertising new surrounds. More recent speakers use different type of surround material now that are UV resistant and can last far longer than 25 to 35 years.

I thought about buying new ones, but my wife won't let me spend $5,000 to $6,000 for speakers to come close to the sound that I get from my JBLs, and if I only spend the same amount of money I spent 30 years ago I would get half the speaker I have now in sound.
 

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