Masonite Ring

[cARver]

I have a pair of 12" woofers ready to refoam however one has the masonite ring and the other does not. Researching this it seems best to add the ring back to the woofer. Any recommendations? Is there anyone making them for sale?

thanks for your feedback

[KlausDK]

The masonite ring needs to be in place for correct operation of the woofer, I have seen several woofers, where it was removed, probably in relation to a refoam by a person with less than adequate knowledge of AR-woofers. I make the ring myself from a piece of masonite, you can get the dimensions for the intact one. As far as I remember, the thickness is 3.4 mm, here in DK we only have 3.2 mm, which is what I use. On the picture the ring is fixed for gluing, this is the early type woofer with the broader ring.

BRgds Klaus

[cARver]

 Thanks, I did see this post earlier. Your ring looks wider than the original.  How long did it take you to make those? Was the material available at Lowe's Home Depot? Will the wider ring cause any interference with the 91 plastic type face cover? 

Thanks again!

[DavidR]

The ring was made narrower on later model woofers than the one Klaus has shown.

Lowes and HD should have masonite. Just measure the thickness and width you have on yours that is still intact on the woofer. The time required to make one depends on your skills and what you have for tools.

The AR91 plastic face cover will not interfere with the ring. The masonite ring on my 91s are approx 1/4" wide IIRC.

[michiganpat]

1/8" masonite (3.25mm thick) will work....the easiest way is with a stationary scroll saw, and make a fixture to clamp to the table of it, that has a dowel or pin for a pivot point. clamp so the pivot point is the OD radius from the   take a square of masonite ~12" square, drill a hole in the center for the pivot, and a hole at the OD and ID radius so you can feed the blade through.  cut the OD, shift the fixture to the ID radius, repeat.  I did the same thing, but on a band saw, which required me to cut a slice in the ring to get the ID cut, then super glue the cut back together....

[lARrybody]

I have one of these gizmos and it seems to very easy to use.

http://www.homedepot.com/p/Dremel-Circle-Cutter-Attachment-3-4-in-to-12-in-Diameter-678-01/202713389?cm_mmc=Shopping|THD|google|&mid=sfHqDAqWe|dc_mtid_8903tb925190_pcri 

[cARver]

4 hours ago, larrybody said:

I have one of these gizmos and it seems to very easy to use.

http://www.homedepot.com/p/Dremel-Circle-Cutter-Attachment-3-4-in-to-12-in-Diameter-678-01/202713389?cm_mmc=Shopping|THD|google|&mid=sfHqDAqWe|dc_mtid_8903tb925190_pcri 

I guess I would cut the outside diameter first then the inside diameter?

[DavidR]

I would cut the inside then the outside. Gives you something to hold/clamp on to while cutting

[lARrybody]

I used my Dremel to cut a spacer ring to use a smaller basket AR2ax woofer in a larger opening. Used 3M double sided tape to hold the 1/8 in. hardboard in place on a scrap piece of plywood while cutting. The secret is not to let your material move around while cutting. I have also cut woofer openings in new speaker grills. 

[KlausDK]

On 05/13/2017 at 7:48 PM, cARver said:

 Thanks, I did see this post earlier. Your ring looks wider than the original.  How long did it take you to make those? Was the material available at Lowe's Home Depot? Will the wider ring cause any interference with the 91 plastic type face cover? 

Thanks again!

I find the early type wider ring much more comfortable for gluing the sorrounds on to.  I ordered a buch of masonite square large enough to cut the rings from. Cut inner before outer ring, I agree. What is available at Lowe's Home Depot is hard for me to tell, since  we don't have them here in Denmark.

BRgds Klaus

[michiganpat]

well, if you're using a jig or circle cutter, cut the OUTER before the INNER, otherwise you won't have a center hole to rotate about.

[cARver]

19 minutes ago, michiganpat said:

well, if you're using a jig or circle cutter, cut the OUTER before the INNER, otherwise you won't have a center hole to rotate about.

Thanks everyone, that's what I thought outer first.

[Stimpy]

 

I need to bring this thread back to the top.  "DavidR", "AR surround", and I have been discussing the Masonite rings.  So, that got me to wondering about their history.  As such, a few questions.  First, when did AR start using them?  From the beginning, with the AR-1?  Only on the 12" woofers?  All 12" woofers; paper and poly?  And finally, for how long?  Just curious, as I sometimes see 12" based speakers without them.  I guess the rings were incorrectly removed, during a refoam?

Thanks for any info that can be provided!

[RoyC]

23 hours ago, Stimpy said:

 

I need to bring this thread back to the top.  "DavidR", "AR surround", and I have been discussing the Masonite rings.  So, that got me to wondering about their history.  As such, a few questions.  First, when did AR start using them?  From the beginning, with the AR-1?  Only on the 12" woofers?  All 12" woofers; paper and poly?  And finally, for how long?  Just curious, as I sometimes see 12" based speakers without them.  I guess the rings were incorrectly removed, during a refoam?

Thanks for any info that can be provided!

Not sure about the earliest AR-1 woofer, but all of the later 12 inch cloth surround woofers had masonite rings. With the exception of the rather rare first foam surround 12 inch woofer, identified by a foam damping ring on the cone (like its cloth surround predecessor), all later AR-built 12 inch woofers had the ring. Beginning in the mid 80's the Tonegen-built AR 12 inch woofer(s) had a stamped steel raised area instead of the masonite ring. These include the TSW series plastic cone woofers.

The vast majority of AR 12 inch woofers had the ring or raised area.

Roy

[lARrybody]

I recently restored some AR 2a speakers with 10 in. cloth surround woofers and they definitely had the hardboard spacer rings. I had to reglue them because the 55 year old glue gave out.

  

[Stimpy]

Good info.  But, kind'a scary too.  To me it seems many AR eBay speaker ads show 12" woofers improperly refoamed, as most are missing the masonite rings.  Just something else to look closely at, when considering a speaker buy.

[ra.ra]

Kudos for two great instructional pics in this thread from Klaus and Larry. With the 2a cloth woofers, once you've detached the ring, cleaned basket edge and are re-glueing masonite to metal, what technique is used to ensure that the voice coil remains centered as the new glue sets up?

[lARrybody]

On 7/6/2017 at 9:30 AM, ra.ra said:

Kudos for two great instructional pics in this thread from Klaus and Larry. With the 2a cloth woofers, once you've detached the ring, cleaned basket edge and are re-glueing masonite to metal, what technique is used to ensure that the voice coil remains centered as the new glue sets up?

One of the woofers was already installed back in the cabinet. Sort of a dilemma. Did I want to cut the dust cap off to shim? Did I want to redo the woofer sealing caulk? I decided to use a 30hz test tone and find some 1/2 in nuts to weigh it down. Worked out fine, but I wound up removing the woofer anyway to check the spider glue condition.

[dxho]

Good call. I blew the surround and spider off an AR-2 woofer one day during some
destructive, uh, enthusiastic testing. The system survived just fine.

[ra.ra]

1 hour ago, larrybody said:

Did I want to cut the dust cap off to shim?

Thanks for reply - - my concern was about mostly preserving the dust cap. Would this test tone method also be the least intrusive procedure for re-glueing a loose masonite ring at the spider location? 

[lARrybody]

On 7/6/2017 at 0:18 PM, ra.ra said:

Thanks for reply - - my concern was about mostly preserving the dust cap. Would this test tone method also be the least intrusive procedure for re-glueing a loose masonite ring at the spider location? 

Not sure on that one. My spider rings were still attached. I wound up taking a thin art paint brush and applying Allenes around the perimeter to reinforce them. I had a 6 hole ceramic magnet woofer on a Ar2ax give way at the spider. Terrible thump noise. Contemplated trying to reglue it, would have to remove the mesh to get access. Chickened out and wound up getting another woofer and refoaming it to match. Another future project maybe. I am thinking you probably need to shim between the former and pole piece.

 

[tysontom]

On 7/5/2017 at 2:50 PM, RoyC said:

Not sure about the earliest AR-1 woofer, but all of the later 12 inch cloth surround woofers had masonite rings. With the exception of the rather rare first foam surround 12 inch woofer, identified by a foam damping ring on the cone (like its cloth surround predecessor), all later AR-built 12 inch woofers had the ring. Beginning in the mid 80's the Tonegen-built AR 12 inch woofer(s) had a stamped steel raised area instead of the masonite ring. These include the TSW series plastic cone woofers.

The vast majority of AR 12 inch woofers had the ring or raised area.

Roy

I think all of them from the very first models had the Masonite ring.

AR-1 SN 0006:

--Tom

[cARver]

This has has got me wondering....why the ring? did the magnet have a cabinet limitation that required 1/8 less depth?

Curious 

[tysontom]

14 hours ago, cARver said:

This has has got me wondering....why the ring? did the magnet have a cabinet limitation that required 1/8 less depth?

Curious 

The reason(s) for the Masonite ring was to position the moving assembly in the correct orientation to center the voice coil in the gap.  The gap height (top-plate thickness) was 0.5-inches, and the voice-coil length was 1.125 inches in the original-style (#3700) woofer.  Without the ring, the cast-aluminum frame (and the stamped frame of later 200003-0 woofers) would need to be slightrly deeper (a taller aluminum casting) to accommodate the proper depth of the cone/voice-coil assembly.  The cone dimension/voice-coil assembly was fairly critical.  Also, gluing the spider assembly to the frame was made easier by having the spider already glued to an inner Masonite ring, and the process of gluing the fabric material directly to the aluminum material was made easier by the use of the Masonite ring on both the surround ("skiver") and the centering suspension, the "spider."

In some earlier woofers, the Masonite ring does come unglued from the frame, probably because of hardening of the glue.  It is not an uncommon problem.

--Tom Tyson   

[tysontom]

I failed to add that the inner suspension required the raised portion to prevent the spider from bottoming on the aluminum frame.  The frame has offset, and the Masonite ring gives additional offset to allow the woofer mechanism to move >1-inch before the spider hits the aluminum casting.  I was not able to upload another image for some reason, but I will try to do that in another message.

--Tom Tyson