Foam surrounds suck

[DizRotus]

We should grab pitch forks and torches to descend upon Klipsch/Audiovox to demand the banishment of foam surrounds.  Talk about planned obsolescence?  Foam surrounds don't last.  The treated paper surrounds in Klipsch Heritage drivers last indefinitely.

 

I enjoy the sound of my Klipsch ProMedia 2.1 while toiling at my computer, but I know the foam surrounds will fail eventually.  Show me an old speaker with foam surrounds and I'll show you a re-cone waiting to happen.

[CECAA850]

We should grab pitch forks and torches to descend upon Klipsch/Audiovox to demand the banishment of foam surrounds.  Talk about planned obsolescence?  Foam surrounds don't last.  The treated paper surrounds in Klipsch Heritage drivers last indefinitely.

 

I enjoy the sound of my Klipsch ProMedia 2.1 while toiling at my computer, but I know the foam surrounds will fail eventually.  Show me an old speaker with foam surrounds and I'll show you a re-cone waiting to happen.

 

Bose business model used this very thing to get people to upgrade their 901's when the surrounds rotted out.  They got me.  I traded my 901 IV's plus $300.00 for a set of 901 VI's.

[DizRotus]

Carl-

 

I never would have pegged you for a 901 kinda' guy, but your shameless candor inspires me, so I'll out myself.  I had 901s in 1974, but I sold them before the surrounds had a chance to fail.

 

There is no honorable excuse for using foam surrounds.  They're part of the "throw away" economy and culture.

Edited March 4, 2015 by DizRotus

[Fjd]

I realize you are talking about a speaker system targeted to a certain market (computer speakers) and I still find it interesting that I see scores of the 4029 model of the Realistic Mach One for sale where the surrounds just vanished after a few years. 

 

However, I believe that JBL Tech Note 1-3A has a wealth of technical information regarding the engineering decisions that go into designing transducers for certain applications and explains the various characteristics of surround material to consider for evaluating trade-offs when designing a driver and choosing different types of surrounds such as; half-roll of polyurethane foam, double half-roll cloth, triple-roll treated cloth, multiple-roll accordion pleat, and one piece cone/compliance with treated edge.

 

http://www.lansingheritage.org/html/jbl/reference/notes/tech1-3a.htm

 

One thing to note is that, in general, the various types of surround material available these days is much better than most anything before the 1990s technology (especially any surrounds from the 1970s such as the 901s employed) and it should be fairly easy to get close to 20 years from foam. 

 

I’m sure there are the engineers more familiar with design and others here with much deeper insight and may be able to clarify or correct any poorly written assumptions I will make below. 

 

Often times, the purpose of the driver will dictate the type of surround.  I’ve known a few guys over the years that rebuild and restore old speakers for companies such as JBL and did it after for a living and from what they tell me, the most significant differences found between foam surrounds and fabric surrounds are the acoustic differences that are caused by different shape and different damping properties of the selected material.

 

From my understanding, the selection of a material for certain characteristics in a design will have an audible impact as the response of a driver will be changed. For example, in general, a foam surround will have lower distortion at high excursion and the roll “shape” of the foam helps dictate the level of “noise” reduction vs. a fabric surround as the vibration motion of the surround counter to the cone movement is less.

 

I believe that a few of these relationships are why many monitoring applications will use half roll foam or rubber surrounds as these materials tend to give the most linear response and most desirable damping characteristics in a specific design that are needed in that specific application setting.  Essentially, the way it was explained to me is that the cloth surrounds have been considered a “compromise” where a certain level of linearity and distortion is sacrificed for increased power handling in situations where a more rugged driver is needed.

Edited March 4, 2015 by Fjd

[jason str]

I have owned many speakers where the foam has deteriorated.

 

Advent

Pioneer

Infinity

Jensen

Cerwin vega

Klipsch

And probably some i forgot about....

 

Not to mention subwoofer drivers and car speakers.

 

The foam that has lasted the test of time was used in my (white van) American acoustic 4 ways from the 1980's and a good friend has a pair of MTX 3 ways that probably date from around the same time.

 

Why spend the extra buck or two ( if that) on a treated foam product that will last, obviously the way to make foam surrounds last has been around for decades but nearly all choose profit margin over everything else.

 

I would be happy to pay a little more for a better, longer lasting product but admit most consumers only care about savings over all else.

 

I highly doubt much has changed over the years, i still see rotten surrounds on products that are not that old.

 

Sure they can be replaced but why should we have to in the first place.

[teaman]

I agree, the foam surrounds suck. I have SM 150 and SM 152 tower speakers by Infinity that sound amazing....but have already needed refoaming. After the second time of getting near the refoaming stage I sold the woofers and bought replacement woofers for them that sound just a nice and will never need to be refoamed.

[moray james]

foam does eat up more vibration foam will go lower as far as tuning goes but past that foam is crap. I was saddened the day JBL made the switch to foam surrounds. Foam is an excuse for a parts sale. Best regards Moray James.

[cradeldorf]

foam does eat up more vibration foam will go lower as far as tuning goes but past that foam is crap. I was saddened the day JBL made the switch to foam surrounds. Foam is an excuse for a parts sale. Best regards Moray James.

I agree with you Moray, I also have noticed that most foam surround speakers seem to have lower Fs.

[djk]

Fs is dominated by the spider, not the surround. The cloth-edged Altec 515E has an Fs=22.9hz. Eminence made some cloth-edged high x-max 15's for Baldwin with the Fs below 20hz (electronic organ use).

 

First generation of foam got hard in about 7years~10years or so.

 

Second generation foam got soft in about 10years~12 years or so.

 

Current foam lasts longer, hard to say how long it will last. Using a UV resistant sealer will extend the life (excludes molds, mildew, smoke, etc.)

 

Rubber surrounds on American speakers got hard (like the tires on your car) in about 15 years or so (German rubber lasted much longer). Current rubber surrounds are actually a polypropylene binder mixed with ground-up scrap rubber, and seem to perform better than the original rubber ones, lifespan is not known.

 

On the Madisound 6102 (a 6-1/2" driver made by Gefco), they also offered in an identical rubber surround version (identical other than the surround), the foam surround version has much, much better midrange. The current version is assembled by Misco, and they are not making the rubber version. Hal Gefvert (Gefco) died in 2009.

[DizRotus]

Of course The Klipsch Heritage surrounds are treated cloth, rather than treated paper as I referred to them in the initial post. Whatever, they last indefinitely, whereas foam definitely won't last.

[minermark]

Iv always been pretty lucky when speaker shopping, Never owned any w/foam.

Between HongKong and Yokosuka in the 70s, i got to see everything, finely honed in on some Kenwoods and shipped them home they had some interesting materials on their drivers, not rubber/foam, but soft blond looking thick/fluffy/treated paper of some sort.

Never seen it since, and never had a problem up to just last year giving them away.

[Marvel]

I refurbed woofer surrounds on a couple pairs of JBLs, I think L46s and L56s. The surrounds had little splits (no missing pieces) in them, but I patched them with cigarette paper and Weldbond (per Dennis' instructions). They are still rocking!

 

Bruce

[DizRotus]

I refurbed woofer surrounds on a couple pairs of JBLs, I think L46s and L56s. The surrounds had little splits (no missing pieces) in them, but I patched them with cigarette paper and Weldbond (per Dennis' instructions). They are still rocking!

 

Bruce

 

How did a joint like you get in a speaker like this?

[moray james]

the foam could be tuned lower because they allowed for greater excursion than did an accordian surround not that there are not some long throw accordion I take it they were either not around or just cost a lot more to make.

[moray james]

also of interest is that the jbl m2 which is their flagship loudspeaker their reference two way monitor uses the 2216 fifteen inch woofer which has an accordion suspension. http://www.jblpro.com/ProductAttachments/M2_Brochure_Jan2013.pdf

[Fjd]

also of interest is that the jbl m2 which is their flagship loudspeaker their reference two way monitor uses the 2216 fifteen inch woofer which has an accordion suspension. http://www.jblpro.com/ProductAttachments/M2_Brochure_Jan2013.pdf

 

 

Nice, it sure looks like the JBL M2 is the latest flagship for innovation and flexibility on the Pro side of JBL given that JBL has accepted DSP and equalization over all passive in applications these days.  However, the JBL pro series M2 appears very similar to the JBL Synthesis S4700 in that both actually use the 2216Nd beast of a woofer. 

 

I suspect that the most significant differences can be found in the active processing and the M2 top end, which is probably significantly more expensive than the 175Nd-3 and 138Nd used in the S4700.  I seem to remember that both may come in at about $20,000 a pair.

 

http://www.sweetwater.com/store/detail/M2System/

 

The 2216Nd may just be my second favorite current JBL production woofer and has five patents covering the design.  The first favorite on my “wish list” would be a pair of the Alnico magnet 1500AL woofers (of course, they need to come with the 476 compression drivers with Mg or Be diaphragms) that I believe were first used in the Project K2-S9800 flagship consumer speakers. I would have to check what woofer is used in the Everest series these days. 

 

According to the JBL technical notes on the 2216Nd driver, it uses a 3-roll semi cup accordion edge made of Mogami special nylon/cotton blend treated with Airflex 400 edge treatment damping.  Shoot, just from the description a person could get the feeling that the surround could cost more than the entire ProMedia system originally under discussion.   

 

Given that the M2 rating for sensitivity (1W/1m) is rated 92dB SPL and recommended amplifier power of 1,200 Watts per channel into 8 ohms, this selection of surround material still seems to me to be consistent with JBL tech notes referenced above in that JBL engineers are still considering the geometry and material properties in conjunction with the intended use of the driver.

 

Although I'm in the minority on this one for this thread as it seems all want cloth, or some type of 'indestructible' surrounds that will outlast the electronics regardless, most likely because I’m not referring to the less expensive driver category; personally, I have several pairs of various types of collectible JBL drivers that I use in various applications and I would not trade-off the sound quality inherent in these designs due to the engineering decisions to avoid a $100 repair every 15 years or so.  Of course, ymmv.

 

On a side note, from your recommendations in other threads, the opportunity recently presented itself and I picked up a pair of EV DH1506 compression drivers.  I also found a pair of tractrix midrange horns left over from the remnants of a pair of destroyed Chorus II's that had been parted-out that I snagged for a future project. 

 

With just a sampling of the sound of the EV driver alone to understand a few characteristics of the driver, I have to agree, there is a very nice sound to these drivers and from looking at the plane-wave tube published response, it seems they would not have much of a problem crossed at 400Hz in a home setting with the proper horn.  In addition, at 104 dB SPL, 1 watt at 10 ft. (not sure exactly what 1w/1m would be if converted or measured) with the HR6040 horn, it would seem that these drivers would only need similar padding to other mid compression drivers to match many of the tweeters out there if a person wanted to do a three-way system and passive crossover.

 

 

Edited March 7, 2015 by Fjd

[djk]

"(not sure exactly what 1w/1m would be if converted or measured)"

 

+9.6737004844410141027404496052491 dB

[DizRotus]

"(not sure exactly what 1w/1m would be if converted or measured)"

 

+9.6737004844410141027404496052491 dB

approximately

[hydro_pyro]

My dad has an all-original pair of JBL L15 bookshelf speakers with flawless foam surrounds. There's always a rare exception to the rule.

[TwoCables]

We should grab pitch forks and torches to descend upon Klipsch/Audiovox to demand the banishment of foam surrounds.  Talk about planned obsolescence?  Foam surrounds don't last.  The treated paper surrounds in Klipsch Heritage drivers last indefinitely.

 

I enjoy the sound of my Klipsch ProMedia 2.1 while toiling at my computer, but I know the foam surrounds will fail eventually.  Show me an old speaker with foam surrounds and I'll show you a re-cone waiting to happen.

 

It's not like the ProMedia 2.1 system is a $5,000 speaker system or something like that. Y'know? I mean, come on; it's just a $150 speaker system. $150! Besides that, look at their choice of cone material, or the choice of some rather cheap electronics and some of the cheap ways some things are designed (take a look inside the pod) and other poor choices that were made just to reduce both their costs and the consumer's (and also to maximize their profits). I'd rather complain about all that than their choice of using foam surrounds, Even so, I sincerely doubt that these foam surrounds will fail that quickly. Consider how many people still have the original ProMedia 2.1 system that they purchased in the year 2000 and the foam surrounds are still just fine. My ProMedia 2.1 system was made in March of 2003 and the foam surrounds are still perfect.

 

So, with all due respect, I say relax. There are worse (and more important) things to complain about when it comes to the ProMedia 2.1 system. Even so, like you said, they produce an enjoyable sound.

 

By the way, I have what was once a very nice Aiwa stereo system (CX-NA71) for its time that was manufactured in May 1997 that has been subjected to being in a garage with no climate control here in Minnesota 24/7 for the past ~10 years, and the foam surrounds are still just fine. The reason why it was reduced to a garage stereo system is, the CD player no longer works, and that's mostly what I used to use it for (in my room). As you know from being in Birmingham, MI, a garage that doesn't have climate control experiences extreme heat in the summer (and this garage has a black roof), and extreme cold in the winter, if the temperatures do reach extremes - and they usually do up on this latitude.

 

So yeah, I really don't think it's worth worrying about it.

Edited March 12, 2015 by TwoCables