AR 11" woofer driver refoam (AR9)

[donquixote99]

The stuff is fine on metal, of course.

[Carlspeak]

Sorry !

The way I used is simple but works for me.

I use some long thin wooden/plastic coffee stirrers, push them through the gaps in the basket.

Once that is done, join the stirrer ends to form a grid pattern and secure with sellotape.

Put just enough weights on the grid to weigh the cone down.

This is what I used but sure that other experts here must have better ways of doing it.

David.

Clever, and thanks! I may consider doing this for early Snell woofers that pointed up into their cabinets. Many I've refoamed have sagging spiders. The new foam helps somewhat.

[djcheung]

Hi Carl,

New foam will certainly help to pull the cone up, but it may sag again as the foam starts to soften/relaxe.

Pulling/resetting the spider height will prolong the time before they need to be reconed.

David.

[michiganpat]

Clever, and thanks! I may consider doing this for early Snell woofers that pointed up into their cabinets. Many I've refoamed have sagging spiders. The new foam helps somewhat.

I used some unsharpened pencils through the basket windows to pull the cone up on mine to hold them up enough to re-glue my rings back on after my snafu caused by sagging spider confusion in this thread: http://www.audiokarma.org/forums/index.php?threads/ar91-refoaming-question.696183/#post-9315816

it's holding the foam about 1/4-3/8" proud of the basket. I'll hit the spiders with a hair dryer before gluing on the new masonite rings I cut yesterday.....tried to make new rings on out of ABS our Makerbot here at work, but it was more hassle than it was worth--I had to break it into 6 pieces and glue together, and although I made them dimensionally correct in CAD, they first one I made ended up being between 1/16" and 1/8" undersized in OD and ID....

[DavidDru]

So I have the new foams attached to the cones. This is the first set I have done with the masonite ring on the flange and it was a little more difficult. On the first one I had to really spend a lot of time going round and round as the glue got tacky to make sure it attached evenly and at the same limit as the old foams. With the ring on the flange, the cone is lower than usual it seems. On the others I propped the cone up a bit from underneath so I didn't need to work so hard. Basically brought the cone up to meet the foam. Once dry, I let it back down of course.

This make sense?

[michiganpat]

So I have the new foams attached to the cones. This is the first set I have done with the masonite ring on the flange and it was a little more difficult. On the first one I had to really spend a lot of time going round and round as the glue got tacky to make sure it attached evenly and at the same limit as the old foams. With the ring on the flange, the cone is lower than usual it seems. On the others I propped the cone up a bit from underneath so I didn't need to work so hard. Basically brought the cone up to meet the foam. Once dry, I let it back down of course.

This make sense?

yup, this is the same issue I ran into with mine, that the weight of the cone was more than the spider could support.....like I said, 2 new unsharpened pencils would have worked good for me to bring the cone above the masonite ring to glue the surround to the cone....I glued my new masonite rings on friday night, and then glued the surrounds to them on saturday....next up is cutting the 1/8" craft foam I bought from Joann's Fabric to make the new foam that goes over the mounting screws.....

[DavidDru]

I just wedged some crumbled up paper towels between the back of the cone and each of the 4 flange supports. With the new surround resting on the masonite ring I adjusted the wadding of the paper towel to get the cone to the correct height and the surround inside edge hit the old glue mark on the cone.

Now, when I go to glue the new surround to the masonite ring, do I just attach at the point where the surround is hitting it now as it rests naturally? (centered of course)

[michiganpat]

the way I always refoam when gluing the surround to the frame is to hook the driver up to an amp (usually with insulated alligator clips on the speaker wire) and play a 30-40hz test tone while clamping the perimeter of the surround with my wife's spring loaded clothespins. that way, you can pull/center/adjust the cone/surround assembly to eliminate any potential rubbing issues without cutting off the dust cap. I downloaded audacity years ago, and that's how I generate the test tone. I've done AR2ax, realistic mach 1, 4 pair of AR 8" woofers, a pair of smaller advents, and some becker 12" woofers all this way without issue....

that's also how i did the AR58S woofs, but this time, I kept the pencils supporting the cone in, applied and spread the Aleenes Tacky Glue on the masonite ring, pulled out the pencils, then turned on the test tone and clamped the surround. I usually put the clothes pins on opposing each other, dividing the space in half (2 across from each other, then 2 more splitting each semi-circle into 90 degrees, then each 90 degree section into 2 45 degree sections, etc) until they completely go around the surround like this

[DavidDru]

Thanks Pat. Same process I've used up to this point and I have the test tone CD from Rick Cobb.

I too have a bunch of clips. The ones I really like are chip clips that are about 1.5" wide which give me a little flatter pinch. I use those on the 4 main points on the 360 deg and then fill in between with other smaller clips. Some day I might cut out a ring to use to clamp down.

Now it appears that I may have to consider propping the cone up a bit while attaching the surround to the ring. The spider does sag a little and you can see in the photo how the surround sits now before being attached.

It also appears when I glue it, the edge of the surround will extend out past the edge of the ring slightly. Is this typical?

[RoyC]

surround.jpg

Thanks Pat. Same process I've used up to this point and I have the test tone CD from Rick Cobb.

I too have a bunch of clips. The ones I really like are chip clips that are about 1.5" wide which give me a little flatter pinch. I use those on the 4 main points on the 360 deg and then fill in between with other smaller clips. Some day I might cut out a ring to use to clamp down.

Now it appears that I may have to consider propping the cone up a bit while attaching the surround to the ring. The spider does sag a little and you can see in the photo how the surround sits now before being attached.

It also appears when I glue it, the edge of the surround will extend out past the edge of the ring slightly. Is this typical?

David,

The 12 inch AR replacement foam you used appears to be the less desirable version with the smaller roll and wide outer glue lip. The better version has a 5/8" roll with a smaller outer glue edge, and doesn't hang over. It is also more compliant.

Btw, one of the advantages to using shims is the ability to use friction to set the cone at various levels during the gluing process. The outer lip will lay flat much more easily without the need for clothes pins. The use of a test tone does not allow this.

Roy

[michiganpat]

surround.jpg

Thanks Pat. Same process I've used up to this point and I have the test tone CD from Rick Cobb.

I too have a bunch of clips. The ones I really like are chip clips that are about 1.5" wide which give me a little flatter pinch. I use those on the 4 main points on the 360 deg and then fill in between with other smaller clips. Some day I might cut out a ring to use to clamp down.

Now it appears that I may have to consider propping the cone up a bit while attaching the surround to the ring. The spider does sag a little and you can see in the photo how the surround sits now before being attached.

It also appears when I glue it, the edge of the surround will extend out past the edge of the ring slightly. Is this typical?

once you prop the cone up mechanically, you'll see the outer edge of the surround will fit right to the edge of the ring....

[DavidDru]

Boy, I do hope in this case Roy you are wrong buddy. I'll check what I can. I purposely tracked down what I thought was the most compliant. These were from Tom at MyAudioaddiction. Supposedly the same surrounds as what Rick has. Tom said he had the more compliant ones for the mid woofer though so I placed the order with him this time.

Pat, on brief inspection it looks like it will get lined up better as I raise the cone.

[RoyC]

Boy, I do hope in this case Roy you are wrong buddy. I'll check what I can. I purposely tracked down what I thought was the most compliant. These were from Tom at MyAudioaddiction. Supposedly the same surrounds as what Rick has. Tom said he had the more compliant ones for the mid woofer though so I placed the order with him this time.

Pat, on brief inspection it looks like it will get lined up better as I raise the cone.

David,

Check out the attached photo. The surround on the left is the better one. It isn't the end of the world if you are using the other one, but it would explain why your outer lip is hanging over the edge.

Rick Cobb, Vintage AR, and most foam retailers are acquiring virtually all of their foam from MWA in Arizona. For awhile last year MWA was shipping the cheaper AR 12 inch replacement foam. When I brought it to Larry's attention he returned his order and complained, and MWA began supplying the better foam again (at a higher cost). Many retailers are probably working through what they have on hand.

Roy

[michiganpat]

I think David's OK....judging by the color of the foam in his pic it looks like he has the larger roll.... here's a pic of what I got from springfield speaker, which they claim came from the original AR molds

http://www.audiokarma.org/forums/index.php?attachments/dsc03571-jpg.669440/

[DavidDru]

Yeah, I think it is okay. Here are some photos. The outer lip is 5/8". The inner 1/4". The roll is around 3/4", maybe just under. The photo is of the bottom side.

Also a photo of the mid woofer surrounds I got.

Surprising to me that so many are unaware of the masonite ring and that it needs to stay. Did all the AR11" woofers always have it?

[DavidR]

The 8 inch surround looks to be the lighter color. That's what I got from Rick Cobb when doing a pair of AR94 speakers. They appear to be a bit thicker than the darker foam.

I've done an older pair (AR91) and newer pair (TSW610) of AR 12" woofers and they both had the masonite ring.

[RoyC]

The preferred, darker 12 inch foam is thinner and the roll is more uniform. No retailer knows who, if anyone, has the original AR molds, but the size is unique to AR. Other foam replacements, such as the 8 inch size, varies in color and is not specific to AR. The foam most often sold for 8 inch AR woofers is actually designated for Bose and JBL 8 inch woofers by the wholesaler.

Masonite rings were used for mounting the surround and spider on most AR 12 inch woofers. The exceptions are the very first version of the foam surround woofer in 1970 which had no rings at all, and the Tonegen woofer of the mid 80's onward which had raised areas stamped into the steel basket.

Roy

[DavidR]

The darker 12 inch foam is more compliant and the roll is more uniform. No retailer knows who, if anyone, has the original AR molds.

Masonite rings were used for mounting the surround and spider on most AR 12 inch woofers. The exceptions are the very first version of the foam surround woofer in 1970 which had no rings at all, and the Tonegen woofer of the mid 80's onward which had rings stamped into the steel basket.

Roy

That jogged my memory about the Tonegen woofer on the 610. It was a ring but it was not masonite.

[DavidDru]

Anybody have a photo of the surround mounted on the ring close up? Or an original before refoam? Mine was previously refoamed incorrectly so I had no reference.

[DavidR]

This is all I have:

AR91:

TSW610:

[RoyC]

Yeah, I think it is okay. Here are some photos. The outer lip is 5/8". The inner 1/4". The roll is around 3/4", maybe just under. The photo is of the bottom side.

Also a photo of the mid woofer surrounds I got.

Measurements.jpg

Both Surrounds.jpg

Surprising to me that so many are unaware of the masonite ring and that it needs to stay. Did all the AR11" woofers always have it?

David,

Your surrounds look OK. The masonite rings on the early 80's woofers are thin, and your photo made the overlap look greater than it probably is.

If you guys learn how to use shims you would find it easier to re-foam AR woofers (and others with cones below the rim of the basket) and/or narrow voice coils.gaps. You would not have to "prop up the cone mechanically" in a non-precise way to deal with the outer lip issue. Pros use shims whenever possible, and they do not use test tones or clothes pins. I have had to re-foam a number of woofers for people who have tried to use the 30hz test tone method in the last year or two. It's been good for business.

Roy

[DavidDru]

Makes sense on these being so low. Unfortunately I don't have dust caps or shims. Think I can get these originals off and back on?

And what to use for shims? The shims basically prop up the cone but from the inside center, correct?

[RoyC]

The shims are used to center the cone and also serve to adjust the height of the cone during the re-foam process. Shims and dust caps are supplied in better kits, such as those supplied by Vintage AR. I can get both for you.

Roy

[ra.ra]

Just adding my 2¢ here. While I understand the potential "convenience" of the test-tone method, I have only ever used the shim method for my re-foams. Proceeding with care, it is really not a big deal to slice out the original dust cap - - in fact, I have had great success re-using the original dust caps to retain original appearance - - - be they flat caps (see attached pic) or domed (see prior post 16). As Roy has mentioned, a nice snug set of shims allows you to move the cone up-down to any position (where it will stay put) to assist with fitting the foam, applying glue, or bringing two surfaces into contact.

The shims I have received in kits appear to be pieces of flexible clear acetate of varying mil thickness, combined together if necessary to fill the VC gap. Other semi-stiff materials can work nearly as well - - I know I have used cut strips of index card in the past. Like DavidR shows in post 45, it only takes three shims placed at 120 degree intervals to ensure centering.

[RoyC]

in fact, I have had great success re-using the original dust caps to retain original appearance

Agreed, ra.ra...

An Exacto knife, a fresh blade, and a steady hand can often cut around the original dust cap enough to flip it back. After the re-foam glue is dry remove the shims, re-glue the edge of the dust cap and "close the hatch". Thin cloth dust caps can be troublesome, but most paper and coated cloth AR 12" woofer type dust caps usually work out well.

Roy