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Pete B

Filled Fillet Foam on AR-9 8" LMW

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Has anyone refoamed the AR-9 8" with filled fillet foam?

And how did it turn out/sound if so?

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Pete, I've done a few AR4x's with filleted foams. But no 9's that I can remember. Did the AR9 8 inch OEM woofer have the bead of polymer around the inner side of the roll?

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I'm not following the question Carl, is this a coating on the foam or on the cone itself?  

Front or back if so?

I'll take a look at the woofer later today.

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I 'believe' this is what Carl is describing.  The circle of polymer around the inside edge of the surround.

As to the polymer being a stock feature, on the LMR, my AR90's didn't have it.  The AR9 may vary.  But, they're supposed to be the same LMR.

 

s-l1600.jpg

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Ah, got it.  That was probably done to reduce breakup modes in a similar way that filled fillet does.

I think I'll use FF type.

Thanks!

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Yup, that's it Stimpy. IIRC, that was AR's initial attempt at addressing cone edge breakup - long before the creation of the filleted foam. 

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A look thru the AR drawing files for the AR9 8 inch would answer the question regarding the application of that bead of polymer. 

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Thanks, very interesting.

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47 minutes ago, DavidR said:

Detail 'A' on the attached drawing shows a 'Treatment' in that area but does not specify what the treatment is (unless I missed it somewhere else on the drawing)

AR-LMR drwng.TIF

Detail A refers to "Process Spec # 104011".  But, Process Spec # 104011 is also referenced in Note 11.  Then, Note 11 refers to the inner dust cap.  So, I'm not sure if Process Spec # 104011 points to an additional step for the surround, the dust cap, or both?  I guess I need to check to see if Process Spec # 104011 is listed and explained in Ken's documents?

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Thanks, David, for digging up the correct part drawing - - interesting to note that this is one of those double dust cap woofers. I recall that we discussed this issue not too long ago - - I've been curious about this, too - - and there are several 6" and 8" woofers that include this "treatment". Attached pic shows this bead of goo on an 8" Tonegen replacement woofer from an AR-7. In the previous thread, I initially described this substance as feeling like silicone, but David more correctly likened it to rubber cement, and it does feel very much like that. And, only on the driver parts drawings that include this treatment can the note be found which requires minimum 16 hours cure time prior to testing, so I suppose this does specifically refer to this rubberized treatment.  

However, as soon as you begin to assume that this substance was applied at the interface between the cone and the foam roll to create similar effects that the filled fillet achieves, just then a very different application appears. The 8" woofer part no. 200037, found in the AR-18s and 28s and 18B models (see detail attached), shows this substance (process spec. #104010) applied to the underside of this same cone-surround interface. :blink: Now its purpose becomes something of a mystery - - to me, at least. 

Stimpy, in the drawing you commented on for the 027 woofer, note 11 does refer to this treatment, but in the section drawing, item 11 simply refers to the inner dust cap mentioned in the parts list. The nomenclature may be a bit confusing, but these items are not related.

 

woofer %22treatment%22.jpg

037 woofer detail.jpg

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It is possible that it acts as an impedance termination at the end of the cone

and it doesn't matter if it is on the front or the back.

Might it be latex, anyway to find out from some of the people who were there at AR?

What are the experts doing with these AR woofers when they refoam them, does

anyone do the bead there when a non-filled fillet foam is used?

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I believe it's rubber cement. There was a company called Carter Ink that manufactured rubber cement and they were located down the street from AR. Possibly a supplier.

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Hi David.

first off, congrads on your AR9 snatch.   Its truly an Impressive speaker.  I have them as well.

 

 

That could be rubber cement....interesting.   

I am in the process of investigating -asking questions of glue used.  I have found over the couple of years in refoaming, certain woofers sealing better than others.   In particular, the poly ar woofers I have refoamed are far more tight in seal than the paper cones.   Going further on that, The poly woofers got a black glue that may have been solvent based.   The white glue went on paper cones.      Also, my first surround job was with simply speakers and they use some type of solvent based glue-seems like rubber cement.    This may seem like a minor detail, but im wondering about the glue.

 

Also, in the picture above, that does have a nice wide roll on the surround.   That brings it to WHO is supplying the wide rolls surrounds today.   I know there were some suppliers in the past...but in 2018 the surround material looks different than in the past and some also have better sealing than others.

 

 

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Vintage_AR and Looneytune2001 on eBay. Make sure you tell them you want the wide roll, dark grey/black compliant surrounds.

There may be other vendors that other members here are aware of.

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2-10-18

O.K., hold it rite there!
Back in late 1989 when I reactivated my LSTs and there was seemingly not a soul who made foam surrounds, I was stuck and had no options.

I resorted to using rubber-cement on my falling apart surrounds in combination to dryer-sheets as a solution. I have to say, it took about a year for the rubber-cement to sort of dry out and disappear or soak into the remaining foam. I continually added more cement whenever necessary. A chore and not fail proof.

So, no, the rubber cement, it doesn’t work that well except for emergenciy use.
In late 1991 I found this little ad in the back of Stereofool magazine from some small operation in S.C. who offered surrounds so, I purchased four. They were the early types and were cut to fit. They lasted for a few years and by that time newer and better surrounds were on the market. 

Since that time, those foams simply decayed and I’ve replaced them a while back. I’ve read that the newer foams are better and last longer?
The foam on my speakers now have lasted since 2009 so I’m not complaining, just yet. I bought them from P.E. and I believe they're the wider ones. In the last couple of years, I found another place that was offering fabric surrounds as did someone years prior. I bet as RoyC will attest to, I'm sure, that they're not complaint enough and I'd agree unless someone with prior experience can state otherwise.
FM

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Frank, surrounds are now (in most cases) made of polyether foam and not the old polyester (?) and last MUCH longer.

I worked for an adhesives/paper and allied products company that bought Carter Ink in 1975. I still say the bead is rubber cement. It was not used as a glue down adhesive that I know of.

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45 minutes ago, DavidR said:

Frank, surrounds are now (in most cases) made of polyether foam and not the old polyester (?) and last MUCH longer.

I worked for an adhesives/paper and allied products company that bought Carter Ink in 1975. I still say the bead is rubber cement. It was not used as a glue down adhesive that I know of.

David, you may be absolutely correct. In the advertising world of yesteryear, rubber-cement was used in paste-ups and layout making.

The bead in question has always seemed like a silicone type of affair as it has some spring and bounce back to it in finger nail and pinching tests.

P.S. I guess I'm still a throw-back to the old world way of things. My vintage stereo ownership attests to that fact.

However, in early posts on this site circa 2004 or so, I went back and forth with other members and I was proven wrong when I stated it was rubber cement on the surrounds. That bead sure feels like silicone, the surrounds may have had another coating on them as my AR-3a's surround always had a shine and sticky-ness to them in 1972 and after. As my 3a's aged the shiny-ness seemed to fade much like the rubber-cement's shine did.

I'm curious what the actual substances were because I've always wondered and my thoughts about the subject have always been conjecture.

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Frank, I think I may have the msds on the product and I also have a can of it. I'll look to see if it had silicone.

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OK, the Carters Ink Rubber Cement is Latex rubber with naptha as the diluent. Elmers uses n-Heptane as the solvent.

Silicone rubber uses an acetate (probably ethyl acetate) for the diluent. Both have similar characteristics when cured. I had a can with dried rubber cement and it was just as you described.

Pick your poison: Rubber Cement or Silicone Rubber

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Boy, am I glad I 'stuck' -around for your answer, pun intended.

Well, I don't like poison, and I tried the rubber-cement almost 30 years ago so I won't use it again, except if while giving a concert I see a hole in the foam surround occurring. Wait, I don't have any and I haven't seen it in supply stores in years, though I could be incorrect.

That silicone appearing bead between the surround edge and paper cone I typically remove. As much as I'd care to leave it in place with some surrounds, it gets in the way forcing the surround to bend at that juncture so, I remove it. Though, Pete B made me wonder, maybe that bead does afford some damping?

FM

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Looneytune2001 sells a AR 8" surround.  It's recommended for the AR-18, and others.

AR-18 Foam

But, he also has Boston Acoustic 8" filleted foam, which many over at Audio Karma suggest to use.

BA Filleted Foam

It does make me wonder if there's differences between the two, and which is best?

 

 

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The inner glue down edge doesn't stick out as does the outer glue down edge on the BA foam. The inner lip is under the roll. Supposedly it helps with cone edge break up. Its more difficult (for me anyway) to get it on there neatly. I did some BA surround speakers for a friend of my brother inlaw.

130_3039.JPG

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I pulled one of the Lower MidRanges out of my 9's which need new foam. They definitely have the silicone bead treatment around the inside roll.  Also they are what I believe to be the correct drivers.

CwX0LH0h.jpg xYBjbjjh.jpg

 

Last year I refoamed some 200037 woofers with the same treatment. I tried to use rubber cement to recreate the bead, but found it to be too thin and runny. I wound up using some clear DAP silicone which turned out to be a bit challenging trying to figure out the correct method to apply the material. Later I did a set of AR 15 200001-1 woofers and used some filled fillet surrounds. I have about a dozen sets of JBL type 8 in.surrounds left, but for now I am using the filled fillet surrounds on anything I really care about.  They do fit, although they are more difficult to position correctly.

I recently re foamed a set of 200037 woofers and tried to make they look more like the 200001-1 type.

Y0KSEIYm.jpgpNCC5kml.jpg

I added a flat dust cap cut from a egg carton and a mesh dome cover over that.

7Sg1ZN3l.jpg

Here they are next to a 200001-1 with the regular surrounds. I plan on using some filled fillet surrounds on the AR9 LMR. A good Sunday projet maybe.

Om0jHfCl.jpg

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