Speaker Surround Seal

[Guest Norcal]

This is a great forum! I hope you can help with a little information.

Just as a little background I have two pairs of Model 5’s in my set-up.

In reading through the forum, I see mentioned time and again about “re-sealing” the cloth speaker surrounds.

Forgive the “newbie” questions but…

1) Why is it necessary to reseal and what will I gain by doing it? And…

2) I’ve seen several different products mentioned for use in the re-sealing. Is there any opinion on what is the best product to use? I don’t want to run the risk of damaging my Model 5’s!

Thanks in advance for any input!

Gary

[joelongwood]

Hi Gary,

I have a pair of KLH Model 5s as well. As I understand it, resealing the cloth surrounds stops air leakage. Remember, these are acoustic suspension speakers and require a tightly sealed box to operate properly.

I used a thinned (with water) mixture of clear siliconized latex caulk that I purchased from Ace Hardware and brushed it on. It goes on white, but dries clear. I gave woofers and midranges a few coats. It's been a year now, and they still look and sound great.

Hope this helps.

Bob

[Guest Norcal]

Hi Bob,

Thank you very much for the information!

I'll give your suggestion a try.

Gary

[dynaco_dan]

>Hi Bob,

>

>Thank you very much for the information!

>

>I'll give your suggestion a try.

>

>Gary

Hi Gary;

You might hold off with that process.

Check out the AR forum, I believe that Armorall is used.

[tysontom]

>1) Why is it necessary to reseal and what will I gain by doing

>it? And…

>

>2) I’ve seen several different products mentioned for use in

>the re-sealing. Is there any opinion on what is the best

>product to use? I don’t want to run the risk of damaging my

>Model 5’s!

>

Gary,

There is a bit of a misunderstanding about the "seal" of acoustic-suspension speakers. Some believe (erroneously) that the "sealed" property of acoustic suspension means completely "air-tight." There is a subtle difference between an "acoustic" seal and an "air-tight" seal. In an a/s speaker, it is undesirable to have an air-tight seal -- the woofer cone would act like an aneroid barometer and move back and forth off center as barametric-pressure changes occurred in weather. The acoustic seal means that the enclosure is air-tight down to the lowest bass frequency the speaker is required to reproduce.

A slight air leak doesn't adversely affect acoustic-suspension performance anyway unless the leak is quite bad. If it is bad, such as air leaking badly around a mounting flange, the air leak will actually tend to attenuate (dampen, in this case) the speaker's low-frequency output somewhat, and cause the output to roll-off more rapidly.

I have used several things to try to seal the cloth surrounds of KLH and older AR speakers. I have had good success with Armor All Original Protectant, which is a special diluted silicone-rubber, water-based formula used to shine car tires and dashboards. I have painted it on AR speaker surrounds (usually 3 light coats with about a 30-min wait in between) and it works well in most, but not all, cases. It will eventually dry out, so it has to be done again. If the surround is badly leaking, Armor All may *not* be enough to stop or slow the air leak, and you might have to use something else such as diluted butyl-rubber compound or a water-based silicone that can be diluted to the proper consistency to seal the surround. The downside is that you have to be careful not to "stiffen" up the surround too much after applying the compound. Armor All will not affect the compliance.

--Tom Tyson

[Guest Norcal]

Thank you Tom for your very informative response!

Gary

[dynaco_dan]

Thank you very much Tom.

You are always there with the best advice.

[Guest denmarkdrivers]

if the driver stood the test of time you shouldent have to reseal it .

[soundminded]

>if the driver stood the test of time you shouldent have to

>reseal it .

If that means that after nearly fifty years in some cases, the driver should work like new, in many cases it didn't stand the test of time. Seeing the extremes many people go to in order to repair these speakers, it should be evident to those who don't own them that those who do consider their performance remarkable and worth the difficulty. Owning a pair myself I would do the same.

In this particular aspect of their performance, the sealer which was applied to the cloth surround connecting the woofer cone to the frame has cured to the point where it is no longer able to maintain an effective air tight seal and therefore the speaker's bass response is no longer anything comparable to original. The difficulty of restoring it is minimal which simply consists of applying an appropriate liquid and allowing it to dry. When I am confronted with this problem, I will try to obtain one specifically intended for this purpose XL-49 from Orange County Speake Company in Garden Grove Ca. or a comparable product. The only difficulty which prevented me from doing this already besides the fact that there is no indication yet that mine need it, is that the grill cloths on my early production models are not removable without destroying them. I have not seen a comparable cloth material availabe...yet but then again I haven't hunted very hard for any.

[joelongwood]

When I received my KLH 5s awhile ago (Craigslist score), I was extremely disappointed in their bass performance. I compared them side by side with my AR3as, and while the midrange of the KLHs was much more prominent, the bass was sorely lacking. After much reading here and on other sites, I decided to seal the surrounds (both mid and woofer) as they looked rather dry and porous. I decided upon a very thin mixture of siliconized latex and water. I gently brushed it on, let it dry, and gave it another coat. The surrounds took on a shiny quality.......but how would they sound?

Well, the only test equipment I have is my ears, and my ears told me that the improvement in the lower bass was pretty dramatic. In a side by side with the AR3as, the KLHs acquitted themselves rather nicely, although the ARs still go lower....but not by as much as before the surround sealing.

I know this is a pretty unscientific test, but sealing the surrounds made a sizeable difference......at least to these old ears. ;-)

[soundminded]

The acoustic suspension principle pioneered by Edgar Villchur and his student Henry Kloss depends on the changes in air pressure inside a relatively small sealed box to restore the displaced speaker cone to its neutral position instead of the mechanical restoring force used by speakers designed around other principles. This was found to be far more linear allowing response to much lower frequencies with less distortion. By comparison, the largest horn systems are about an octave poorer than AR3a. Any deterioration which compromises this effective air spring will cause performance to be seriously degraded. As Tom pointed out, an absolutely air tight enclosure has some disadvantages because the neutral position of the cone will be determined by the difference between the exterior air pressure at any given moment and place and the pressure inside the box at the time it was sealed. Therefore a very small air leak will allow the system to work as intended while at the same time effecting an equalization of pressure when there is no electrical signal applied between the inside and outside of the box. This assures that the cone can travel through its full excursion design potential without bottoming out. Perhaps someone would like to start a thread to discuss in this basic principle of operation in detail.

[Guest denmarkdrivers]

take a look at a pair of dynaco A25 (1968-71), unless abuse took place the drivers and the surrounds on them look new every time, with no wear at all on the cone or the surround, hard to belive but its true, the pics were done with web cam but i tried to take them as clear as i could, theese are pics of dynaco drivers, not resealed or redone or reconed, orginals that did stand the test of time, even down to the rubber that attaches to papper flawlessly, made in 1968-71, I dont agree with you about the surrounds in all old speakers needing to be reconed or resealed. i've seen many pairs of dynaco A25s never once did the driver need reconing or surrounds replaced.

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[soundminded]

"I dont agree with you about the surrounds in all old speakers

needing to be reconed or resealed."

Perhaps you could point out where I said that. In fact I said exactly the opposite and I gave an example.

"The only difficulty which prevented me from doing this already besides the fact that there is no indication yet that mine need it, is that the grill cloths on my early production models are not removable without destroying them."

I bought my KLH model 6s used....in 1964. So there's one example that did pass the test of time. However, this issue is besides the point. The fact that after decades parts wore out or deteriorated in normal use gives no indication of their relative performance merits when they functioned properly. As fine a speaker and value as Dynaco A25 built with Danish SEAS drivers was, its performance was no match for AR3a. Or for a pair of restored AR3as. Sometimes producs which lack extreme longevity outperform products which don't. That only increases the challenge to those who want to restore them and keep them in the best operating condition long after manufacture has ceased and parts are hard to come by.

[Guest denmarkdrivers]

well i said, "you shouldent have to recone old speakers if they stood the test of time " maybe i dident take in all the variables, im sorry i dident mean to come off as harsh, or mistakenly misquote you, again im sorry i misquoted you, my mistake. dynaco A25s have crappy covers, fortunately they are easily removed .

[Guest denmarkdrivers]

I wasent comparing the AR line to the dynaco A25s sonically, i was comparing the A25's drivers themselfs to other drivers of that era. If you want me too compare them i can , i dident like the AR speakers ive heard, im not positive it was a AR3a but almost positive, maybe it was his room , maybe it was his amp, but i wasent impressed at all. I highly doubt a pair of AR3a rehabbed would beat a pair of A25s rehabbed, im not a fan of older speakers other then the A25 so maybe im bias, all my speakers are newer models other then the A25's, The A25s only drawback was the effciantcy factor and the worn down caps. i think your claim that the AR3a are better sonically then the A25's is a blind claim due to peoples preferences. have you heard a rehabbed pair of A25s in a good room ? You claimed dynaco A25's are no match for the AR3a but i couldent disagree more, maybe my ears are messed up though

[Guest denmarkdrivers]

both the AR3a and dynaco A 25s were nice, I just think the dynacos have an articulate bass without overdoing it. The AR3's need a big room to open up with and dont deul together in a large room as well, I know the AR3a's are worth more but if you google dynaco A25 vs AR3a's you will find plenty of comparisons, I think the A25s have a better midrange, good bass without overdoing it, I thought the AR3as are power hungry speakers more bass, not as sweet in the mids, overall i like the dynaco a25s more in the rooms i heard them in, But i know most people would favor the AR3as, The AR3a use a foam surround dont they ? and the A25s obviously use rubber surrounds. I was intitially comparing the driver itself to the AR3a's and nothing more then that, i think its obvious the driver was made better all the foam ones are wearing out even if they havent already they will wear out before the A25's do thats the bottom line as far as the drivers go

[Guest palomar]

I never heard a pair of A25's and AR3a's side by side, but my recollections of listening to both at different times is that while I like both speakers, I personally prefer the AR3as. But the fact that a speaker that was so much less expensive (I believe the Dynas listed for about 90 each vs 250 for the ARs) could aquit itself so well was indeed remarkable.

FYI, Stereophile magazine, when reviewing the Dynaco A25s, actually said they preferred them to the ARs, so you're not alone in your assessment. Since I am both a big AR and Dynaco fan, I have no bias one way or the other. But I've just always loved that AR sound... Ok, maybe a slight bias!

Gary

[dynaco_dan]

>I never heard a pair of A25's and AR3a's side by side, but my

>recollections of listening to both at different times is that

>while I like both speakers, I personally prefer the AR3as. But

>the fact that a speaker that was so much less expensive (I

>believe the Dynas listed for about 90 each vs 250 for the ARs)

>could aquit itself so well was indeed remarkable.

>

>FYI, Stereophile magazine, when reviewing the Dynaco A25s,

>actually said they preferred them to the ARs, so you're not

>alone in your assessment. Since I am both a big AR and Dynaco

>fan, I have no bias one way or the other. But I've just always

>loved that AR sound... Ok, maybe a slight bias!

>

>Gary

Hi Gary;

Comparing the Dynaco A-25's to AR-3A's, when both were actively being sold here, you could buy AR-3A's for about $350.00 - $450.00 each, versus the A-25's at $54.00 each, rock bottom discounted.

One would have a difficult time saying that they even came close in sound quality for that price difference, at that time.

Trouble was back then, we all couldn't afford the AR-3A's, so the Dynaco A-25's were a very affordable option, for the masses.

I will stick my neck out again and say that the Dynaco A-25 and the AR-3a sounded more closely related, than a pair of AR-5's and AR-3A's.

The Larger Advent speaker, was also an AR-3A wannabee, at $185.00 vinyl finish each here (fixed price), versus the AR-3A's lowest $350.00 discounted price, meant a lot of Larger Advents were sold as well.

[Guest denmarkdrivers]

>>I have never heard them side by side either, I have heard the AR3's in another room with someonelses amp, that doesnt really count as an official comparison.

>>I'm just bias when it comes down too it, The dynaco A25s are probally the only vintage speakers i've really enjoyed.

>>I dident know sterophile reviewed them against the AR3a but i never take someonelses opionion as fact, I've been told by the people at my audio shop that the genesis are a better speaker then the A 25 and i couldent disagree more, they have also suggested some newer expensive amps that the let me loan to test out and i wasent impressed at all, anyway its all subjective. ( vern i would still love to see that article. )

My orginal bickering was more about the driver on the A25 and how it has really endured the test of time, both the cone and the surround have no wear in every pair ive seen, unless they were abused of course.

>> I must apologize to the AR fans for not thinking before i posted earlier, i was just being bias to what i love and not taking in all the variables, like the room or what amp they are using and so on. I'm sure the AR3a are a better choice under some circumstances and tastes. .....craig

[dynaco_dan]

>>>I have never heard them side by side either, I have

>heard the AR3's in another room with someonelses amp, that

>doesnt really count as an official comparison.

>>>I'm just bias when it comes down too it, The dynaco

>A25s are probally the only vintage speakers i've really

>enjoyed.

>>>I dident know sterophile reviewed them against the

>AR3a but i never take someonelses opionion as fact, I've been

>told by the people at my audio shop that the genesis are a

>better speaker then the A 25 and i couldent disagree more,

>they have also suggested some newer expensive amps that the

>let me loan to test out and i wasent impressed at all, anyway

>its all subjective. ( vern i would still love to see that

>article. )

>My orginal bickering was more about the driver on the A25 and

>how it has really endured the test of time, both the cone and

>the surround have no wear in every pair ive seen, unless they

>were abused of course.

>>> I must apologize to the AR fans for not thinking

>before i posted earlier, i was just being bias to what i love

>and not taking in all the variables, like the room or what amp

>they are using and so on. I'm sure the AR3a are a better

>choice under some circumstances and tastes. .....craig

>

Hi there;

Sorry, what I should have said was, it would seem illogical that a $50.00 speaker could be compared to a $400.00 speaker.

I never had a fair comparison with both set up behind a screen, so that one could not see which speaker was in operation, to give a fair test.

This would have also required a large solid state amplifier for that blind test.

Size and price would have then been out of the picture.

Size and price cannot be considered for best sound quality, we sometimes assume the more we pay, the more we get.

I have both speakers systems and I enjoy each for it's enjoyment factor.

I hope I didn't make any Dynaco A-25 speaker owner feel, that the speaker is not a capable performer, it really is.

I have been using a Seas pair only, and until I run my Scan version I don't blanket my comments.

I will test my Scan version in a month or two, and I will report back any and all differences.

There were a number of woofers that used and do use neoprene surrounds.

Neoprene or rubber surrounds, does not guarantee quality drivers either.

It appears that they run on almost forever.

I still remember when AR started using the new and improved, "FOAM", surrounds.

There was no audible difference reported to me, from the earlier cloth surrounds, in a letter from AR.

I do believe I kept that letter.

Unfortunately, I had AR-3A's at the time and the woofer cone and magnet was different as well.

I was only concerned with the surrounds back then, little did I know.

It is obvious to me though, that only time and the environment would have showed up the rot.

It is now a cash cow, as replacement of surrounds, replace the drivers or buy new speaker system is the only options.

The only thing that could have been worse, was for the mids and tweeters to be made of the same foam.

They only rot out, after their warantee expires, built in obsolescence.

[Guest denmarkdrivers]

I didnet know A 25s were 50 bucks new.

Intresting because they consistantly sell for 200 bucks on ebay today, and almost double that if they are A 35s.

I knew the AR's were more expensive new and used but i dont place much value in price.

I think the port system and drivers on the A 25s are outstanding, and the sound is bliss to me.

The AR3a's i heard were not side by side so its hard to judge, on different systems and different rooms i thought the dynaco sounded more realistic and sweeter.

I may not think that if i had a pair of AR3a's here to test on my syetem.

i like really natural mids and bass the A25s are good at that and resolute enough in trebble for the range they cover.

Stereophile magazine favored the A 25s over the AR3a's ?

I knew they reviewed the A 25s quite a while back but i dident know they compared them, do you have a copy of that article ?

They A25s give my newish pair of BW 630 i's a run for their money.

I think i have the scan version i tried to take some new pics seems my web cam is cheap and this place also resized the pics a little bit after posting them.

I think the seas version had slightly flatter surrounds and slightly thinner and flatter cones.

Not sure but i think theese are the scan version. dont think ive heard a seas version. ( i think i own one stand alone seas version, doesnt look like the same amount of care went into the seas driver as the scan driver but im not sure if the stand alone i own is a seas driver or just from a newer pair of A 25's ( its the only A25 i own that shows wear and its obvious its a later version by the makeup of the entire speaker. It looks like its a 1971 version and they cheapened up a bit on driver design placement of port ect.

weather that means its a seas or not i dont know.

one of the following pics shows a bright screw, screw isent bright just got some light refraction, cheap webcam hope the new ones look better)

speakers are usually on stands seems to help the a25s to be a little away from wall and on stands, but, ive been moving so they are not on stands in any of the pics.

Are theere the scan not seas ? i think theese are scans

( sorry about the duplicate pics/ the change the title of them when you load them up i tried )

[tysontom]

> I wasent comparing the AR line to the dynaco A25s sonically,

>i was comparing the A25's drivers themselfs to other drivers

>of that era. If you want me too compare them i can , i dident

>like the AR speakers ive heard, im not positive it was a AR3a

>but almost positive, maybe it was his room , maybe it was his

>amp, but i wasent impressed at all. I highly doubt a pair of

>AR3a rehabbed would beat a pair of A25s rehabbed, im not a fan

>of older speakers other then the A25 so maybe im bias, all my

>speakers are newer models other then the A25's, The A25s only

>drawback was the effciantcy factor and the worn down caps. i

>think your claim that the AR3a are better sonically then the

>A25's is a blind claim due to peoples preferences. have you

>heard a rehabbed pair of A25s in a good room ? You claimed

>dynaco A25's are no match for the AR3a but i couldent disagree

>more, maybe my ears are messed up though

"To each his own" when it comes to speaker "taste." But taste should *not* be part of speaker-quality evaluation. Accuracy should be the true guide to speaker quality, and in that respect the AR-3a is far superior to the Dynaco A25. This does not always mean that someone will like an AR-3a better than the A25. Incidentally, the A25 was never intended to compete with the AR-3a; it was intended to take some thunder away from the AR-4x and the AR-2ax, and it was partially successful in that respect.

Neoprene-rubber surrounds (used in the A25) have been arround for a long time, and were available when AR first developed the urethane-foam surrounds for the AR-5 in 1968. The rubber could easily have been used, but AR chose foam surrounds because they are inherently superior to rubber in their ability to damp "ringing" and resonances in the woofer cone at the high-end of their response.

--Tom Tyson

[Guest palomar]

I don't remember the Stereophile issue in which they preferred the A25 to the AR3a. They were reviewing the A25, and for some reason, they brought up the AR3a. I don't remember how the AR3a came into the review - the focus of the review was the A25's, and an AR3a vs A25 comparison. Sorry if I gave the wrong impression.

One memorable part, and probably the reason I remember it, is that they admitted that the A25's low end range was no match for the AR's, but they felt that the AR's superiority down there was somewhat academic!

Interestingly, in Dynaco's own advertisement for the A50 (their large system with a pair of 10's), they say that they have a warm sound that emulates one of the most famous speakers (or something to that effect). I don't remember the exact wording, but my impression was that they were alluding to the AR3a. Does any one know?

Gary

[dynaco_dan]

>I don't remember the Stereophile issue in which they

>preferred the A25 to the AR3a. They were reviewing the A25,

>and for some reason, they brought up the AR3a. I don't

>remember how the AR3a came into the review - the focus of the

>review was the A25's, and an AR3a vs A25 comparison. Sorry if

>I gave the wrong impression.

>

>One memorable part, and probably the reason I remember it, is

>that they admitted that the A25's low end range was no match

>for the AR's, but they felt that the AR's superiority down

>there was somewhat academic!

>

>Interestingly, in Dynaco's own advertisement for the A50

>(their large system with a pair of 10's), they say that they

>have a warm sound that emulates one of the most famous

>speakers (or something to that effect). I don't remember the

>exact wording, but my impression was that they were alluding

>to the AR3a. Does any one know?

>

>

>Gary

Hi Gary;

Dynaco used to send out the review copy on request.

I only vaguely remember some of it.

We are talking about late '60's, early '70's.

J. Gordon Holt himself did the rave review.

The Dynaco A-25's ran circles around the KLH Nines, Janszen Electrostatics and numerous other speakers.

A member may have a copy of that review to download to the site.

I felt he was maybe a little overboard, but, at that time he was the, "Big Kahuna", so what did I know.

Here was, "The Man", doing what he did best.

He did sort of backstep his over zealousness, slightly, the next issue, though, if I remember correctly.

The reason the AR-3A's, etc came up was, they were the best of the best, at that time.

AR's superiority down there, is what made the AR-3A the superior speaker.

Once you feel that bass, you don't go back, unless you can't afford them.

Gut wrenching bass, beautiful.

I wrote last year about hearing or rather feeling, "Also Sprach Zarathustra's", 32 hertz bass tone, made me feel sick, loved it.

There was a comment about the best speaker available, take your choice, AR-3A's or KLH Twelves, in Consumer's Guide magazine, way back when.

I don't remember ever seeing what a KLH Twelve even looked like back then, until I lucked out a few years ago, big and heavy.

Back it those days, a $250.00 speaker system, is what most referrences were made to, rather than the AR or AR-3A's name.

[Guest denmarkdrivers]

Thats probally true to some extent, I have some very acurate expensive speakers BW 630i, they do outperform some speakers in some areas, i think speaker quality should be judged on how well the speaker is doing what its trying to do, not just range and acuracy.

It's not just that the dynaco A25s have rubber surrounds its the over all makeup of the driver cone and port system. The fact they last so long probally lends part of itself to why they drivers sound good for the price and the cone material angle ect.

The A25's dont have the impression they need more dapening, i agree they dont have a hudge range, exp in highs, they are thristy speakers much like the AR3a's.

I'm sure they are not as acurate as the AR3a's, but the A25s do perform the range they are trying to perform very well, exp in midrange.

The A25s are not good phono speakers they definately have some drawbacks, i still love them under most aplications, they seem to outperform many speakers from that era that cost more, they even seem made better then a lot of speakers from that era that cost more just not better then the AR3a's.

i've never heard a pair of AR3a at my place, not sure if the x overs were even worked on.

I can tell by the feedback on here the AR3a are much better then the A25's in range and acuracy and probally overall.

I'm just impressed how well the A25 drivers are made for a rubber surround driver. the attatchment to the cone is well done the cone is nice quality for the price of the A25's

I have heard the A25s side by side against other vintage spaekrs but not the AR3a's. They performed well against other vintage speakers, not outdoing them in every area, but impressive non the less.

Doesnt matter to me if they were made to compete with the AR3a's or not, like you said its how well you like them, maybe i just like speakers that are inferior. ( maybe my amp is not powerfull enough for AR's)( maybe it would be hard to find an orginal driver for the AR3a's)

I just read the post that they were not compared to the AR3a's, my mistake.( i was mislead my my fellow audiophiles )

I dident notice a big differnce in dampening between foam surrounds and rubber surrounds, probally because the only foam surrounds i have heard were on genesis speakers. ( kinda bright speakers) not bad for lp.

Anyone notice the surround style on the BW 220i's ( 1980's) ? they have papper cones, ( not the best cones but not bad either ) and a rubber surround, except the rubber surround is indented toward the back of the speaker instead of appearing as a bubble, was that an attempt and dampening ?