Foam Woofer Surrounds

[der]

There's an ongoing thread on another forum discussing woofer surrounds. Someone stated that AR considered foam surrounds to be superior to cloth surrounds. I don't recall that statement being made anywhere by anyone from AR. But, there are certainly more knowledgeable folks here than I. I have personally always preferred the sound of cloth surround AR woofers over foam.

der

[owlsplace]

There's an ongoing thread on another forum discussing woofer surrounds. Someone stated that AR considered foam surrounds to be superior to cloth surrounds. I don't recall that statement being made anywhere by anyone from AR. But, there are certainly more knowledgeable folks here than I. I have personally always preferred the sound of cloth surround AR woofers over foam.

der

In some respects I think foam is superior to cloth but you can't get the original AR foam surrounds these days and cloth done correctly lasts and lasts and lasts ...

Roger

[Steve F]

Der,

Go back to the 1969 full-line brochure or the 1971 full-line brochure and read the AR-5 description. The AR-5 was the first AR speaker to use a foam surround. In their description of the new surround, they use words like "advanced" to describe it, but they never ascribe any specific, quantifiable, measurable or audible improvement to the new foam surround. They just say it was "advanced."

My feeling and that of other designers is that foam might be slightly more linear in its back-and-forth movement, so perhaps a very slightly lower THD. Cloth can have a tendency to "pucker" a little and not always in the exact same way going forward as going back. Audible at normal SPLs while masked with full mids and highs over it? I'll give you five bucks if you can reliably beat the statistically-random odds.

Likewise, many people say, "I've always preferred the cloth surround woofers over the foam ones." Again, if they could reliably and repeatedly identify one over the other in a blind A-B (which I doubt), my gut feeling is that people are reacting to audible traits other than just the surrounds per se. Perhaps the older ones had a lower Fs or perhaps some of the old Alnicos were .5dB more efficient or perhaps the older cast-basket frames suppressed extraneous clarity-diminishing resonances just a little better than the later stamped steel frames. Perhaps it was a combination of these kinds of things. The fact that these woofers had cloth surrounds was coincidental, not causal.

My two cents. I've been wrong before. But I've been right before, too.

Steve F.

[der]

Steve - There is, of course, another factor in my stated preference. I heard and listened to foam surround AR3a woofers in another environment - not in my home. I've never claimed to have golden ears and you're likely correct, I couldn't tell the difference in a blind listening test.

My question was, of course, did AR claim that foam was superior to cloth? You've answered that - thanks. I should have left my unscientific personal observation out of the post.

der

[Carlspeak]

I also think AR was accellerating their production of speakers in response to the brands popularity and needed to find ways to make good, reliable products at lower cost quicker to improve margins; thus the transition to stamped steel frames, foam surrounds and ceramic magnets.

[ar_pro]

Page 5 of the 1969 catalog references these attributes of the new AR-5 woofer:

"The cone of the woofer, for example, is molded by a new low-vacuum process developed for AR, which greatly reduces the tendency to coloration heard in conventional cones of paper or polysterene.

At the cone's outer edge is a new suspension of urethane polymer, which helps to achieve very low distortion at low frequencies."

Full agreement with Steve regarding the perceived sonic differences between woofers, especially the 12" AR-3/3a types.

I doubt that the surrounds accounted for this sort of thing; my guess is that the cast frame made more of a difference.

Carl's deduction is probably right on the money, too.

[ra.ra]

Re: foam surrounds. Being a new type of product with no time-tested track record, I'd be curious to know what AR engineers/developers expected from this new urethane polymer material with regards to product longevity. With the oldest AR speakers being only about 15 years old in 1969, there was possibly not much thought at all, and probably no accurate projections available, to be used in predicting the useful life span of these early speaker products, be it cloth or foam surrounds.

Just wondering if anyone ever consciously expressed a thought such as .... "These surrounds should be good for maybe twenty years, if properly cared for, before they crack, crumble, and turn to dust."

[Steve F]

I should have left my unscientific personal observation out of the post.

Der,

Never, ever stop giving us your personal observations! That's what this Forum is all about. Everyone's input is equally valuable and interesting.

The subsequent posts are all on the money as well.

One other thing that foam does, as well, and AR could very well have had an eye to this: They're probably more uniform from unit-to-unit than cloth, so there may have been fewer QC rejects and consequently greater production output, with reduced cost. I wouldn't be surprised if foam surrounds lowered the cost of the woofer, too.

I would be shocked--shocked!--if AR or anyone else at the time had any inkling as to the limited lifespan of foam surrounds.

Steve F.

[owlsplace]

Steve - There is, of course, another factor in my stated preference. I heard and listened to foam surround AR3a woofers in another environment - not in my home. I've never claimed to have golden ears and you're likely correct, I couldn't tell the difference in a blind listening test.

My question was, of course, did AR claim that foam was superior to cloth? You've answered that - thanks. I should have left my unscientific personal observation out of the post.

der

der,

Your personal perspective is valid and I appreciate hearing it.

I didn't have any exposure to the original cloth surrounds back in the day so I am lacking memory input. Some of the surrounds from the "4" series have degraded to the point of affecting audio output. Hey, the warranty period was five years ... we are at ten times that now

Roger

[der]

Oh, I have no issue sharing my opinions - none at all. I've been listening to AR products the better part of 45 years now. My point about my listening comparison was that was basically invalid because of environmental issues. And, that is and was not a scientifically controlled listening experience. The foam woofers 3a's were located in another room, in another house. The left speaker was always too close to a corner as I recall. The bass from this set was too heavy and didn't have the type of realism that I have always loved from AR loudspeakers. I'm not really interested is listening to "speakers", I want to listen to music. I prefer jazz and have heard quite a bit of live jazz over the years. I want to experience as close to that live experience as I can in my home.

der

[DavidDru]

i thought it a curious question as well. Always just considered it as Carls says just the results of time passing, much like how cabinets got simplified in construction yet still equally functional.

Also liked the posts about weather or not the staples in the grilles were original and the unfinished pine cabs with the contact paper covering. My guess on the staples is that they are original.

[owlsplace]

There's an ongoing thread on another forum discussing woofer surrounds. Someone stated that AR considered foam surrounds to be superior to cloth surrounds. I don't recall that statement being made anywhere by anyone from AR. But, there are certainly more knowledgeable folks here than I. I have personally always preferred the sound of cloth surround AR woofers over foam.

der

Here is an AR-4x cloth surround failure probably caused by over-driving. Cloth has a grain to it and it is stronger in one direction than the other. If the stress had been equal on this cone the fracture would have been concentric.

Foam surrounds will stretch under stress -- cloth, not so much and unequally. So my guess is foam surrounds are more forgiving of mistreatment, especially in the long run as cloth surrounds are prone to harden with age and put more stress on the cone.

This driver is currently being offered on the auction site along with the rest of the drivers from the speaker pair which were apparently replaced with substitutes.

Roger

[der]

i thought it a curious question as well. Always just considered it as Carls says just the results of time passing, much like how cabinets got simplified in construction yet still equally functional.

Also liked the posts about weather or not the staples in the grilles were original and the unfinished pine cabs with the contact paper covering. My guess on the staples is that they are original.

I saw a picture of a white staple that looked like it was near the center of the grill. I wondered if that was original.

der

[ra.ra]

Re: anticipated foam longevity, I totally agree with SteveF and this was exactly my point - - I suspect that AR designers felt that the new foam technology was more-than-good-enough to go forward with for the debut of the AR-5 and virtually all subsequent speaker models. Whether there was an audio performance-based 'need' to replace the reliable cloth surrounds with a different material is another matter altogether, and this is where the discussion enters the realms of product marketing, cost control, materials procurement, and assembly processes at a time when the loudspeaker industry competition was really beginning to heat up.

(note to David and der: re:staples and contact paper, you may be confusing this discussion with a thread from another audio forum where these issues were discussed regarding an older pair of AR-2ax.)

[owlsplace]

I also think AR was accellerating their production of speakers in response to the brands popularity and needed to find ways to make good, reliable products at lower cost quicker to improve margins; thus the transition to stamped steel frames, foam surrounds and ceramic magnets.

The use of foam surrounds would have eliminated this step in the production line. Archive photo #61

And I believe at one point there was a cobalt shortage due to a trade embargo against Zaire which would have affected alnico magnet production. Any design dependent on a limited resource would be doomed to failure.

And then there was the corporate takeover in 1968 with their natural focus on bottom line.

Roger

[der]

Which woofer looks and feels more robust? The cast frame one with an alnico magnet and cloth surround or the stamped metal one with a ceramic magnet and a foam surround? What AR engineers felt at the time of the transition is nothing more than speculation and I must agree with Roger that like most things in manufacturing (a sector that I spent my working life involved with) the bean counters won the day and production changes proceeded from there.

EDIT: Lest anyone get the wrong idea I'll say that engineering changes to take cost out of a product don't necessarily mean you end up with an inferior product. I wasn't there but I strongly suspect the move from cast frames and cloth surrounds was driven by cost savings. AR also went from solid wood to veneer finishes on their turntables and it didn't affect their performance.

der

[owlsplace]

Re: anticipated foam longevity, I totally agree with SteveF and this was exactly my point - - I suspect that AR designers felt that the new foam technology was more-than-good-enough to go forward with for the debut of the AR-5 and virtually all subsequent speaker models. Whether there was an audio performance-based 'need' to replace the reliable cloth surrounds with a different material is another matter altogether, and this is where the discussion enters the realms of product marketing, cost control, materials procurement, and assembly processes at a time when the loudspeaker industry competition was really beginning to heat up.

(note to David and der: re:staples and contact paper, you may be confusing this discussion with a thread from another audio forum where these issues were discussed regarding an older pair of AR-2ax.)

Even though one reviewer stated that AR finally got it right with the AR-5, sales were flat and AR continued to produce cloth surround woofers for several models into the mid-70s.

Meanwhile JBL was producing cast baskets and cloth surrounds for the famously popular L100. I think AR tried to slip underneath them price-wise to acquire a greater marketshare. They may have succeeded if popular music spl's didn't keep climbing higher making fried drivers more of an issue.

I dropped out of the scene around this time before ferrofluid cooled drivers came on the scene. The charming days of one of New England's cottage industries was coming to an end.

Life goes on -- if it was static we wouldn't want to listen to music

Roger

[stupidhead]

my $.02. I have three sets of 2ax, one with cloth and orange tweet, two with foam and black tweets (two different styles!). I definitely prefer the sound of the cloth over the foam in this instance. This is hardly a study and even doing a blind test (wife at the controls) it is a valid observation. What is curious however is that after a short break in period I experienced a distinct snap from the woofers. It has been said that some of the glue joints from basket to spider have failed and might be the problem. I have inspected as best I can, (magnified) and can find no breeches in these joints. The problem seems to happen with both the cloth and foam version, and my take away is that it is likely distortion, not a speaker issue. I am using a refurbished Marantz 2325 to drive, and the snap occurs if I bump volume over 12 o'clock. For what it is worth, the actual sound seems to be sort of electronic sounding as opposed to mechanical if that makes sense. Amp issue? Cap issue in the speakers (Solens)? I even considered the possibility of the snap on the cloth ones to be like snapping a towel, but that seems like folly now that I have the same condition from the foam set?

[Jeff_C]

The common denominator is the Marantz amp. I would look to that for the "snap" problem. It seems too unlikely to me that 3 sets of speakers would exhibit identical issues like that.

[owlsplace]

Here is the latest version of an AR cloth woofer I have seen using a ceramic magnet dated mid-1977. It is also on the auction site currently. Best guess from the seller's remarks is that it came out of an AR-8 or perhaps an AR-2x and could possibly have been a replacement at some point.

The screens were removed from the basket.

Or, was AR putting cloth woofers into the AR-14 which was in production in 1977? Seriously doubt that but ...

Geoff: Failing semiconductor in your Marantz...

Roger