Jump to content

Sealing your speaker enclosures better


dynaco_dan

Recommended Posts

Posted

Hi there

When I worked at the AR local warantee depot in the late '60's they supplied a sealant strip that was used to seal their drivers into the enclosures.

I don't remember any brand name or other identifiable information but I did buy some for myself.

I bought a box of 3M black strip-calk part no. 8578 from an auto body material supplier back then.

I wouldn't have bought just anything, so I must have had some information that this was the equivalent to AR's sealant strips.

Anyhow, 3M has a web site which you can check out new part number 08578 for their data sheet and hazardous material sheet.

You may find a friendly local body shop that may let you have a few strips for the asking.

It comes in 60 - 1 foot strips about the size of a pencil.

You pick up a strip and it lays in the grooves just like putty.

My box has been open and unsealed for about 35 years and some of the strips are just as pliable as when I bought it.

It is black and you peel it off the carrier and place it around the speaker recess.

AR probably bought this stuff in bulk strips in the beginning.

It obviously was faster and cheaper to insert the white stamped out foam gaskets during production on the assembly line later on.

Off the box I have data;

Ideal for auto body sealing, fills body seams, bridge wide gaps or openings, seal fittings housings joints, seal retaining clip holes for interior or exterior trim.

They must have forgotten to include speaker enclosure sealer. lol

Directions for use:

Remove all dirt, grease and foreign material

Press bead of 3M brand Strip-Calk into area to be sealed

Smooth out with fingers or putty knife as desired

For large openings press several beads of 3M Brand Strip-Calk together

May be painted immediately after application or later

3m Adhesives, Coatings and Sealers Division

I've worn many hats in my life and among my many wonderings I came across an alterative for a sealant.

This compound is grey in colour and is basicly putty.

Home Depot and probably any electrical type hardware department store will have it.

Being grey, this would not be my first choice with the 3M putty being readily available.

Model #DS-130 1 pound brick

Pug Duct Seal

GB Electrical

Milwaukee Wi.

UPC 032076899172

$2.50/1lb here in Vancouver.

The only reason I would even bring up this topic is because we all want to seal the speaker cabinets as best we can, but still be able to remove the drivers without difficulties later as well.

I hope this is of interest to some of you.

Enjoy

Posted

I'm Back Again

I did a little more research and found a term you should be very cautious using.

If you go to a autobody supplier be sure the person, who may be bigger than you, is across a large counter, first.

I just heard the term yesterday for the first time in decades.

You can ask for "Dum-Dum" and hope the other person doesn't swing at you in case they haven't heard that term before. lol

They might take offense if their english is not too good.

Anyhow, Dum-Dum is a term used in autobody putty which in this case is manufactured by:

Pro Form Products Ltd

430 Harrop Drive

Milton Ontario

Canada L9T 3H2

905.878.4990 1.800.387.7981

www.proformproducts.com

UPC 624214500530

Model PF 300 Black

4.7mm 3/16" dia. x 12" long strips

908 gm 2 lbs box

available in white or black

Check out their website for specs. and safety issues.

A box is approx. $14.00 cdn

They're in rows of 14 and 7 layers.

About 94 feet of putty or enough to supply most of this web site.

Say's it won't harden and feels real soft and pliable.

Say's not to eat it, duh.

You will undoubtably have an equivalent made in the US I'm sure.

The 3M 08578 is still, for my money, the exact replacement sealer.

We now have several choices that are readily available, for the proper sealing and future removeal of our drivers.

Enjoy.

>Hi there

>

>When I worked at the AR local warantee depot in the late '60's

>they supplied a sealant strip that was used to seal their

>drivers into the enclosures.

>

>I don't remember any brand name or other identifiable

>information but I did buy some for myself.

>

>I bought a box of 3M black strip-calk part no. 8578 from an

>auto body material supplier back then.

>

>I wouldn't have bought just anything, so I must have had some

>information that this was the equivalent to AR's sealant

>strips.

>

>Anyhow, 3M has a web site which you can check out new part

>number 08578 for their data sheet and hazardous material

>sheet.

>

>You may find a friendly local body shop that may let you have

>a few strips for the asking.

>

>It comes in 60 - 1 foot strips about the size of a pencil.

>

>You pick up a strip and it lays in the grooves just like

>putty.

>

>My box has been open and unsealed for about 35 years and some

>of the strips are just as pliable as when I bought it.

>

>It is black and you peel it off the carrier and place it

>around the speaker recess.

>

>AR probably bought this stuff in bulk strips in the

>beginning.

>

>It obviously was faster and cheaper to insert the white

>stamped out foam gaskets during production on the assembly

>line later on.

>

>Off the box I have data;

>

>Ideal for auto body sealing, fills body seams, bridge wide

>gaps or openings, seal fittings housings joints, seal

>retaining clip holes for interior or exterior trim.

>

>They must have forgotten to include speaker enclosure sealer.

>lol

>

>

>Directions for use:

>

>Remove all dirt, grease and foreign material

>

>Press bead of 3M brand Strip-Calk into area to be sealed

>

>Smooth out with fingers or putty knife as desired

>

>For large openings press several beads of 3M Brand Strip-Calk

>together

>

>May be painted immediately after application or later

>

>3m Adhesives, Coatings and Sealers Division

>

>I've worn many hats in my life and among my many wonderings I

>came across an alterative for a sealant.

>

>This compound is grey in colour and is basicly putty.

>

>Home Depot and probably any electrical type hardware

>department store will have it.

>

>Being grey, this would not be my first choice with the 3M

>putty being readily available.

>

>Model #DS-130 1 pound brick

>

>Pug Duct Seal

>

>GB Electrical

>

>Milwaukee Wi.

>

>UPC 032076899172

>

>$2.50/1lb here in Vancouver.

>

>The only reason I would even bring up this topic is because we

>all want to seal the speaker cabinets as best we can, but

>still be able to remove the drivers without difficulties later

>as well.

>

>I hope this is of interest to some of you.

>

>Enjoy

>

>

  • 2 weeks later...
Posted

Back once more with some more information.

3M Strip-Calk part no. 051135 - 08578

UPC 051135085783 Black

20 yards (60 feet) 1 foot lengths

Approximately the size of a drinking straw.

Read Material Safety Data Sheet at the 3M web site for safety and alergy concerns.

With taxes included and bought at retail $30.00 cdn.

This has the appearance of the original AR speaker sealer putty and as close as darn to the original package I bought back in 1970.

Only a little research with the 3M Corporation would reveal the different formulas.

The original formula may have contained asbestos or other fibres that are not in use today.

Well we now have at least 2 black putty choices and one grey but there is other colours as well.

I hope this data helps you make an informed decision on re-sealing your AR or other brand speakers.

Enjoy

>I'm Back Again

>

>I did a little more research and found a term you should be

>very cautious using.

>

>If you go to a autobody supplier be sure the person, who may

>be bigger than you, is across a large counter, first.

>

>I just heard the term yesterday for the first time in

>decades.

>

>You can ask for "Dum-Dum" and hope the other person doesn't

>swing at you in case they haven't heard that term before. lol

>

>They might take offense if their english is not too good.

>

>Anyhow, Dum-Dum is a term used in autobody putty which in this

>case is manufactured by:

>

>

>Pro Form Products Ltd

>

>430 Harrop Drive

>

>Milton Ontario

>

>Canada L9T 3H2

>

>905.878.4990 1.800.387.7981

>

>www.proformproducts.com

>

>UPC 624214500530

>

>Model PF 300 Black

>

>4.7mm 3/16" dia. x 12" long strips

>

>908 gm 2 lbs box

>

>available in white or black

>

>Check out their website for specs. and safety issues.

>

>A box is approx. $14.00 cdn

>

>They're in rows of 14 and 7 layers.

>

>About 94 feet of putty or enough to supply most of this web

>site.

>

>Say's it won't harden and feels real soft and pliable.

>

>Say's not to eat it, duh.

>

>You will undoubtably have an equivalent made in the US I'm

>sure.

>

>The 3M 08578 is still, for my money, the exact replacement

>sealer.

>

>We now have several choices that are readily available, for

>the proper sealing and future removeal of our drivers.

>

>Enjoy.

>

>

>

>>Hi there

>>

>>When I worked at the AR local warantee depot in the late

>'60's

>>they supplied a sealant strip that was used to seal their

>>drivers into the enclosures.

>>

>>I don't remember any brand name or other identifiable

>>information but I did buy some for myself.

>>

>>I bought a box of 3M black strip-calk part no. 8578 from an

>>auto body material supplier back then.

>>

>>I wouldn't have bought just anything, so I must have had

>some

>>information that this was the equivalent to AR's sealant

>>strips.

>>

>>Anyhow, 3M has a web site which you can check out new part

>>number 08578 for their data sheet and hazardous material

>>sheet.

>>

>>You may find a friendly local body shop that may let you

>have

>>a few strips for the asking.

>>

>>It comes in 60 - 1 foot strips about the size of a pencil.

>>

>>You pick up a strip and it lays in the grooves just like

>>putty.

>>

>>My box has been open and unsealed for about 35 years and

>some

>>of the strips are just as pliable as when I bought it.

>>

>>It is black and you peel it off the carrier and place it

>>around the speaker recess.

>>

>>AR probably bought this stuff in bulk strips in the

>>beginning.

>>

>>It obviously was faster and cheaper to insert the white

>>stamped out foam gaskets during production on the assembly

>>line later on.

>>

>>Off the box I have data;

>>

>>Ideal for auto body sealing, fills body seams, bridge wide

>>gaps or openings, seal fittings housings joints, seal

>>retaining clip holes for interior or exterior trim.

>>

>>They must have forgotten to include speaker enclosure

>sealer.

>>lol

>>

>>

>>Directions for use:

>>

>>Remove all dirt, grease and foreign material

>>

>>Press bead of 3M brand Strip-Calk into area to be sealed

>>

>>Smooth out with fingers or putty knife as desired

>>

>>For large openings press several beads of 3M Brand

>Strip-Calk

>>together

>>

>>May be painted immediately after application or later

>>

>>3m Adhesives, Coatings and Sealers Division

>>

>>I've worn many hats in my life and among my many wonderings

>I

>>came across an alterative for a sealant.

>>

>>This compound is grey in colour and is basicly putty.

>>

>>Home Depot and probably any electrical type hardware

>>department store will have it.

>>

>>Being grey, this would not be my first choice with the 3M

>>putty being readily available.

>>

>>Model #DS-130 1 pound brick

>>

>>Pug Duct Seal

>>

>>GB Electrical

>>

>>Milwaukee Wi.

>>

>>UPC 032076899172

>>

>>$2.50/1lb here in Vancouver.

>>

>>The only reason I would even bring up this topic is because

>we

>>all want to seal the speaker cabinets as best we can, but

>>still be able to remove the drivers without difficulties

>later

>>as well.

>>

>>I hope this is of interest to some of you.

>>

>>Enjoy

>>

>>

>

Posted

I've had success with the 3M caulk - it's effective, and very easy to work with.

After re-sealing a 12" woofer, I've found that it's possible to further tighten the bolts/screws on the driver after a month or so of use. In fact, I'm usually able to make this (slight) adjustment to our AR-9's on an annual basis!

  • 7 months later...
Posted

Hi there

Another rattle session.

After all this I saw where someone suggested plumbers putty as well.

There is a caution here now from me.

Plumbers putty, contains what chemicals, I don't know, should not be used with synthetic countertops.

Apparently it will stain them and I don't know if this would have adverse effect should you get any of it on the surround material or cones.

It is very popular for sealing s/s sink strainers and toilet to flange seal as a very pliable sealer/filler.

As with the change from the putty type sealant to foam gasket ring and fibreglas to foam internal insulation.

There may have been financial, health haszards or speed of assembly or all the above in these old changes.

One should not change the insulation type or density without the proper test equipment to actually monitor the differences.

Rattle, rattle, rattle.

Have a great day.

Vern

>I've had success with the 3M caulk - it's effective, and very

>easy to work with.

>After re-sealing a 12" woofer, I've found that it's possible

>to further tighten the bolts/screws on the driver after a

>month or so of use. In fact, I'm usually able to make this

>(slight) adjustment to our AR-9's on an annual basis!

Posted

Sometimes one can spend lots of energy trying to solve what appears to be a problem. The putty in an AR-1 case sealed 47 years ago was hard. An AR-3 case sealed 37 years ago with the same putty type was flexible. So, let's say the lifetime is 40 years, give or take. Long enough for me.

I can buy a roll of rope caulk in any hardware store for about three bucks. A coat of varnish on the back-bored sealing surface will prevent new putty from being forced into surface cracks simplifying removal. Works fine. If it ain't broke ...

  • 2 weeks later...
Posted

I feel you are mocking my effort.

Finding as close as possible, original components, which includes the sealant for the old drivers is something I enjoyed doing.

Your comments threw me off, because I did this on my own, at my expense and enjoyment to try to also provide other readers in other parts of the world, this elusive information.

How many readers have had actual hands on servicing experience repairing AR speakers or turntables in the late '60's or early '70's?

I have!

What I'm trying to do is, pass on what experiences and knowledge that I have while I am still able to.

The warantee depot I worked at serviced other than AR, so, I was kinda like a kid in a candy shop, for a few years.

I believe there is a lot of knowledge and experiences throughout the world which we should all try to share and enjoy as a hobby.

You may use rope caulk and varnish, I was trying for as close to the original sealant as I could possibly find.

It also requires no varnish, and is so close, in the case of the 3m product, that no black paint is needed or varnish and I defy anyone with poor eyesight to tell the difference between the original and the present sealant.

I wouldn't want the challenge of counting how many woofers were pulled to do mods or replacement drivers and they all require re-sealing, that I have read about on just the AR site alone.

Ok, granted, each box holds enough strips of sealant to seal a few dozen enclosures, but some people can share and that's a good thing. Right?

Please remember that readers are from all over the world, and access to information and materials, skills, and confidence vary.

I hope I didn't step on your toes clearing this up, John.

Vern

>Sometimes one can spend lots of energy trying to solve what

>appears to be a problem. The putty in an AR-1 case sealed 47

>years ago was hard. An AR-3 case sealed 37 years ago with the

>same putty type was flexible. So, let's say the lifetime is 40

>years, give or take. Long enough for me.

>

>I can buy a roll of rope caulk in any hardware store for about

>three bucks. A coat of varnish on the back-bored sealing

>surface will prevent new putty from being forced into surface

>cracks simplifying removal. Works fine. If it ain't broke ...

  • 1 year later...
Guest tom h
Posted

Vern,

Thx for this tip!

I just bought a box of this 3M sealant for under $15 at the local auto-body supplier.

IMO, from both its data sheet and its characteristics in my hand, the 3M caulk should be a superior alternative to the hardware store rope-caulk.

The exposed particle board under the flange of my AR9's drivers is rather rough & porous. To hopefully make the wood easier to remove old caulk in the future, I'm going to first prime those raw surfaces with Zinnser's BIN -- a shellac-based, primer-sealer.

Posted

>Vern,

>

>Thx for this tip!

>

>I just bought a box of this 3M sealant for under $15 at the

>local auto-body supplier.

>

>IMO, from both its data sheet and its characteristics in my

>hand, the 3M caulk should be a superior alternative to the

>hardware store rope-caulk.

>

>The exposed particle board under the flange of my AR9's

>drivers is rather rough & porous. To hopefully make the

>wood easier to remove old caulk in the future, I'm going to

>first prime those raw surfaces with Zinnser's BIN -- a

>shellac-based, primer-sealer.

Hi Tom;

Glad you are happy with the 3M product.

Good price too.

I am not familiar with the Zinnser's BIN, I am certain that preserving the wood surface would be a great idea to aid in future servicing.

We now have 3 or 4 or more alternatives to use for gasket sealing the drivers.

Toilet plumbing putty is so far the only putty I would definitely say, stay away from in our use.

Perhaps Mastic or window putty is another one not to use in our application either.

With the plywood cabinet fronts, I have seen some of the wood fragments come off with the old putty being removed.

When they routed out the holes, they sometimes came too close to the end of a layer of ply and splinters broke off.

This would not be so much of an issue with MDF or particle board.

Guest tom h
Posted

A mistake with I made applying the BIN primer-sealer to the wood surface under driver flange, is NOT tinting the BIN dark grey or black ahead of time.

BIN is pure white, and there was some risk of a tiny bit of white showing at perimeter of the drivers' flanges :(

So I created extra work for myself, as I opted to paint over the white BIN primer with black acrylic artist's paint.

Maybe I just should have left well enough, alone! Oh well, it's done now.

My re-foamed drivers aren't due back until next week, so in the interim I'll also re-oil the cabinets with Minwax Tung Oil :)

Posted

While i can appreciate the effort that you've put forth in researching and providing this info, i have to ask you one question. That is, regardless of how well you seal the drivers up, how well are the cabinets sealed around the various switches, pots, binding posts, etc... that protrude from them? Obviously, minimizing ANY leaks is a step forward, but it all depends on how far one is willing to go to do this.

Outside of that, there are some that feel that very small leaks in a cabinet are beneficial. That is, the leakage taking place is too small to offset any real dynamic driver excursion / damping losses, but they are great enough to help equalize the internal / external air pressure levels. If these pressures aren't equalized, the drivers can literally be displaced from their natural place of rest. Whether or not this is audible / measurable remains debatable, but once again, it all depends on how far one is willing to go in search of "perfection". Sean

>

Posted

Sean:

One must have some leakage, or as you have noted, the cone would displace from neutral when changing elevation. The small leak path that prevent this is normally around the potentiometer shafts and wiring connectors. The remaining cabinet and driver joints should be leak tight. Villchur explained to me a few years ago that his original test was to apply an 18-Hz square wave to the speaker and listen for leaks around the drivers with a stethoscope. Today, we seem satisfied with depressing the cone (carefully) and watching the time it takes to relax.

There are many ways to seal the drivers tightly. The discussion here is not about seal tighness, but long-term pliablity and ease of driver removal. The original seal used in the AR-1 era appeared to be the consistency of rope caulk, which I have used in many cabinets. Recently, Roy C told me of the electrican's putty, which is much more pliable. It is a couple of bucks in the big box stores and is easily formed into long ropes. The 3M putty described here comes in rolled form and is equally pliable. With only eight bolts on such a large bolt circle a very soft putty is desirable. As Tom noted, a seal coat on plywood baffle board is useful to prevent putty from being forced into the plywood. He has found a primer paint that works, I have always used 2 coats of varnish. Usually there is more than one way to achieve the desired result!

Posted

My AR9s were sealed using a doubled sided sticky foam tape. This seems to work very well. I've had no problems resealing it several times using the same tape. One nice thing about having more than one acoustic suspension driver in an enclosure is that you can touch one lightly and see the other one move out as the air pressure inside increases. Parts Express sells a similar tape for the same purpose and it is very cheap. When I needed to reseal my Bose 901s because the putty had cured and become hard, I didn't want to remove 18 drivers and scrape all that 35 year old gunk off. So after consulting with Bose's service department, I sealed each one carefully using GE clear silicone. It's inexpensive, you can work it with your fingers, and it sets in about 24 hours. You can remove it later if you have to without much trouble. It never cures completely by getting hard. I covered the space between the metal driver frames and the wood cabinet and I also put a dab on each of the screw heads and I think I got a perfect seal. It's just important not to get any on the cones or suspensions. I you ever use GE silicone be aware that if it is older than its use by date, it will never cure because a volatile chemical inside which is necessary for the curing reaction will have dissipated into the air (I found this out the hard way when a project I had didn't cure and I had to call them.) The putty used on AR2a that I had to remove had become like glue. It took hours to scrape out tiny amounts with a tool I fashioned to get enough out so that I could pull the woofers out. I don't think putty is the best material for this application, either of the other two are better. I'd go for the tape.

Posted

>Sean:

>

>One must have some leakage, or as you have noted, the cone

>would displace from neutral when changing elevation.

The small

>leak path that prevent this is normally around the

>potentiometer shafts and wiring connectors.

Sorry John I cannot agree with this, completely.

There will be absolutely no air leakage around the wiring connections if everything is tightened, as they usually are.

Almost negligible leakage around the pot shafts, I'm splitting hairs here, sorry, John.

The shaft defintely would not not be classified as water tight though.

AR pots used a flat rubber gasket to seal the pot body to the cabinet as well.

AR, at least for a period, added putty to the retaining body clip of the pot, to reduce the possiblity of resonances.

In the Heath/AR speaker kits they even wrapped putty around the threaded body to seal the cabinet.

In my opinion, the dust cap is the primary location for the air equalization.

This can be engineered into the woofer driver, any other leakage is by guess, by golly only.

I believe that AR would have only calculated the variables that they had consistant control of.

Many of the older dust caps were visibly porous enough that you could see the magnet pole piece top.

The remaining

>cabinet and driver joints should be leak tight.

Right off, Heathkit recommended in their speaker kits, that the kit builder glue the inside joints of their cabinets, which, by the way, were not supplied by AR or their supplier, at least not to AR's standards.

Villchur

>explained to me a few years ago that his original test was to

>apply an 18-Hz square wave to the speaker and listen for leaks

>around the drivers with a stethoscope.

Heathkit provided a piece of plastic tubing to do an air leakage test as well.

Today, we seem

>satisfied with depressing the cone (carefully) and watching

>the time it takes to relax.

>

>There are many ways to seal the drivers tightly. The

>discussion here is not about seal tighness, but long-term

>pliablity and ease of driver removal.

Right on, this is the main point, John.

The original seal used

>in the AR-1 era appeared to be the consistency of rope caulk,

>which I have used in many cabinets.

Recently, Roy C told me

>of the electrican's putty, which is much more pliable. It is a

>couple of bucks in the big box stores and is easily formed

>into long ropes.

I've mentioned that a few times as well, and it is readily available and affordable to everyone, at least here in North America.

Do avoid plumbers putty, window putty or mastic, for our application at least.

The 3M putty described here comes in rolled

>form and is equally pliable.

I have bought this and am certain that it is as close to the original as possible to buy today.

Packaged in strips about the diameter of a drinking straw and about 12" long, laying on a paper type carrier for easy and quick removal from the package.

Now that I have said that, it is not inexpesnive, it is black, not needing any further colouring a least, and comes with enough to do everyone's, that is a member, speakers.

With only eight bolts on such a

>large bolt circle a very soft putty is desirable. As Tom

>noted, a seal coat on plywood baffle board is useful to

>prevent putty from being forced into the plywood. He has found

>a primer paint that works, I have always used 2 coats of

>varnish. Usually there is more than one way to achieve the

>desired result!

Definitely a plus in preserving the sealing surface and allowing easy later removal.

The 3M putty is not perfect, that is for sure, as one member mentioned, he annually can tighten the screws more, with putty compression.

At least we have more options.

Posted

Hi there;

I believe you are correct at least about that ad, I also remember seeing that photo, Soundminded.

Seeing it way back then, it instilled a lot of confidence in AR and their quality control measures, back then at least.

The following is my opinion only now.

It may have been more for show, than functionality, in that photo.

I do believe that during the actual production, less quality control would be needed, as startup procedures ran smoother.

They may have actually checked only spot checks later on, once the bugs of assembly were ironed out.

I personally did not work or tour there, so I could be way off base.

I would like to see what the first few AR-1's had for, sealing drivers and fastening them to the enclosures.

The installation of, T-nuts, versus just wood screws, was an expensive but very strong method of mounting the drivers.

Edgar and Henry must have given this a lot of thought.

I believe that Edgar wanted to continue using the original woofers from another supplier and Henry wanted to make in-house woofers.

I could be wrong, it would not be the first time.

Posted

>The small

>>leak path that prevent this is normally around the

>>potentiometer shafts and wiring connectors.

>

>Sorry John I cannot agree with this, completely.

>

>There will be absolutely no air leakage around the wiring

>connections if everything is tightened, as they usually are.

>

>Almost negligible leakage around the pot shafts, I'm splitting

>hairs here, sorry, John.

Neither disagreement nor putty will stop air from permeating around any component screwed to a fiberous crossover board. It is only necessary for the cabinet to be leak tight to well below the lowest frequency of interest. A cone that takes 2-3 seconds to return to its quiescent point is considered leak tight. The cabinet only has to appear leak tight for 500 ms to fool a 1-Hz signal!

One version of the AR-4x driver uses an open mesh dust cap. I would maintain that the pot shafts represented the biggest leak in cabinets using Alnico cloth-surround drivers. After that era I would say it was the foam surrounds; some of which I could breathe through. I have never found a foam surround driver that returns to neutral as slowly as a cloth surround Alnico and both reproduce excellent bass.

Cheers,

Posted

Hi John;

We still may not agree on at least one point or two but that is ok, John.

We can agree to disagree and the world still revolves.

Like I stated, John, I was splitting hairs.

In the really big picture, we still have great speakers.

I have seen many AR-2 series woofers with a visually open weave dustcap, you can see the top of the pole piece through it.

On ebay occasionaly, I have seen and taken a photo of such an example.

On this point, I wonder what happens to those woofers, where the dustcaps are removed for shimming the voice coils and a generic dust cap is installed later.

Here we go again, dust caps with no brand name and model number, OH, OH, what have I started here, maybe?

Thank you, John.

Posted

..decided to jump in here.

Having been into a mountain of 3a's, 5's, 2ax's, 4x's, a number of 6's, a few 3's, and assorted KLH's, my 2 cents is that the primary areas of leakage are in this order:

1)Pots/L-pads...Got to go with John on this one, Vern. AR did not use a rubber gasket for the pots in any of the above models...don't know about others. The pot shaft has some play in it, and it is held in with a serrated lock washer.

2)Certain foam surrounds, if so equipped.

3)The terminal board for the front wired versions.

4)Mids and tweeters that need to be tightened or re-gasketed.

5)The crossover board where it is glued and stapled to the back of the cabinet. The glue dries out and in many cases rivets and inductor anchors have created gaps under the board. I alway run a bead of Goop glue around the edges of the board before re-assembling the innards.

For internet shoppers, Parts Express sells an excellent 36" roll of black sealant for 98 cents (US), or 75 cents for 10 or more rolls (see attached photo). It is similar in consistency to the gray electrical stuff (which, btw, is what a reputable AR parts seller re-packages for Ebay:-)).

AR began using foam gaskets in the early 70's and they actually work quite well on smooth surfaces. As mentioned above, the rather dense foam gasket tape sold by Part Express also works well in those instances.

Roy

post-101150-1185683067.jpg

Posted

>Hi John;

>

>We still may not agree on at least one point or two but that

>is ok, John.

>

>We can agree to disagree and the world still revolves.

>

>Like I stated, John, I was splitting hairs.

>

>In the really big picture, we still have great speakers.

>

>I have seen many AR-2 series woofers with a visually open

>weave dustcap, you can see the top of the pole piece through

>it.

>

>On ebay occasionaly, I have seen and taken a photo of such an

>example.

>

>On this point, I wonder what happens to those woofers, where

>the dustcaps are removed for shimming the voice coils and a

>generic dust cap is installed later.

>

>Here we go again, dust caps with no brand name and model

>number, OH, OH, what have I started here, maybe?

>

>Thank you, John.

There are 3-4 different types of dust caps available to re-foamers/re-coners. There are screen types, felt, paper and plastic. These are the most popular.The list I have is in the order of decreasing permeability. Competent speaker techs know which one to pick when installing a new DC in order to maintain the original driver's operating characteristics.

It's all about the music

Carl

Carl's Custom Loudspeakers

Posted

I'm in agreement with you on this one Roy. Especially the recommendation on the Parts Express black caulk. It's wonderful stuff. I generally include 1-2 coils of caulking when returning refoam customers woofers as a complimentary gift.

It's all about the music

Carl

Carl's Custom Loudspeakers

  • 2 weeks later...
Guest tom h
Posted

This weekend I re-installed the re-foamed drivers on my AR9s, using the 3M Strip-Caulk. While I was at it, I also replaced the squished gaskets under the upper midrange & tweeter with the 3M.

My, is the 3M stuff sticky! By comparison, the typical hardware store rope caulk is only mildly sticky.

At first I tried wearing diposable gloves while handling the 3M, but found it nearly impossible, since 3M kept sticking to the gloves.

Finally I just used bare hands, but after handling a few lengths of the 3M, my fingertips would have sticky black residues. A cloth moistened with WD40 would easily take off the 3M residue.

As the 3M caulk is intended to remain soft, pliable, and sticky for years (if not decades)in a harsh automotive environment, I have little doubt the 3M will maintain a tighter seal between drivers & cabinets, than would ordinary rope caulk.

I suppose the question is, "Is rope caulk good enough?" Difficult to answer, unless one does 2 cabinets with both caulk types and checks it years later.

I am hoping I don't have too much difficulty removing drivers and re-cleaning surfaces 15 years from now, when drivers need re-foaming again!

Posted

The rope caulk looks like what AR used in its AR-1 and early AR-3 units. Mine stayed flexible more than thirty but less than forty years. The advantage of the two-dollar electrical putty (which appears to have much the same consistency as the expensive 3M stuff) is that it is very soft pliable. Since there are only eight bolts on the 12-in-diam flange, a soft gasket is very desirable. That is what I switched to and found it to make a superior seal.

The issue with sealing is that a proper gasket needs to have one elastic component -- something springy -- in order to maintain a force against the sealing faces. The newer foam gasket does this admirably until such time as the foam disintegrates! Putty as you know is not an elastomer, but a plastic. Plastics continue to flow forever. So the seal seems to be made not by a restoring force but by a sticky bond between the putty and wood. I have heard that some people continually tighten putty-sealed flanges. This is a waste of time as plastic will do this forever -- eventually all the putty would be squeezed from the joint!

cheers,

Posted

>The rope caulk looks like what AR used in its AR-1 and early

>AR-3 units. Mine stayed flexible more than thirty but less

>than forty years. The advantage of the two-dollar electrical

>putty (which appears to have much the same consistency as the

>expensive 3M stuff) is that it is very soft pliable. Since

>there are only eight bolts on the 12-in-diam flange, a soft

>gasket is very desirable. That is what I switched to and

>found it to make a superior seal.

>

>The issue with sealing is that a proper gasket needs to have

>one elastic component -- something springy -- in order to

>maintain a force against the sealing faces. The newer foam

>gasket does this admirably until such time as the foam

>disintegrates! Putty as you know is not an elastomer, but a

>plastic. Plastics continue to flow forever. So the seal

>seems to be made not by a restoring force but by a sticky bond

>between the putty and wood. I have heard that some people

>continually tighten putty-sealed flanges. This is a waste of

>time as plastic will do this forever -- eventually all the

>putty would be squeezed from the joint!

>

>cheers,

Here's an anology that may help explain John's post above.

If you've ever changed out a sink or tub drain outlet, you had to apply some plummer's putty under the flange lip of the new drain. As you tightened down the drain from below, the putty oozed out from under the flange. If you scraped the excess clean off after 5 minutes, you found a bit more oozing out after 10. The trick here is to not tighted the fitting too tight because you will indeed squeeze out all or most of the effective putty and lose the seal you were trying to attain by using the putty in the first place.

I'm not advocating use of plummer's putty for sealing your AS woofers - simply trying to illustrate a point.

My personal choice is the black speaker caulk Parts Express sells.

It's already been written about here.

It's all about the music

Carl

Carl's Custom Loudspeakers

Posted

>Here's an anology that may help explain John's post above.

>If you've ever changed out a sink or tub drain outlet, you had

>to apply some plummer's putty under the flange lip of the new

>drain. As you tightened down the drain from below, the putty

>oozed out from under the flange. If you scraped the excess

>clean off after 5 minutes, you found a bit more oozing out

>after 10. The trick here is to not tighted the fitting too

>tight because you will indeed squeeze out all or most of the

>effective putty and lose the seal you were trying to attain by

>using the putty in the first place.

>

>I'm not advocating use of plummer's putty for sealing your AS

>woofers - simply trying to illustrate a point.

For many decades now, plumbers putty has been used for the typical mating of tailpieces and other non-pressure related plumbing seals.

Putty is used with steel and brass fixtures, silicone is used for synthetic matial sinks, putty stains too badly.

I have commented many times now that this and window putty or mastic should not ever be used in our speaker driver seal applications.

Next time you have an opportunity to go to a used plumbing fixture business or a metal scrap yard you will see what becomes of plumbers putty after years of usuage.

There of course is no pressure and little vibration to cause deterioration.

It dries out, hardens and crumbles.

As a gasfitter for a few years, I was taught about 35 years ago that pipe dope is to fill in the microscopic defects of pipe threads.

This is the purpose of plumbers putty as well, to fill in a tiny void, between the tailpiece and the sink.

Yes, you can use it for a void filler under the faucet's body, to seal that major void as well, this is a standard plumbers practice.

I have even seen on TV where a, MR Fixit, in addition to the wax seal, created a ring of putty to help in a toilet seal.

Now depending on the threaded material and application there is many non-universal pipe dopes available.

For one very dangerous application, you cannot use just any pipe sealant to seal oxygen piping related fittings and connections.

In fact if you touch the inside of the pipe or fitting, with bare skin, an explosion can be produced with the high pressure oxygen coming in contact with our body oils.

The sticky putty issue mentioned here may have been used at a higher than normal room temperature.

I have not found it a sticky issue, pun intended, perhaps higher than normal room temperature and humidity is affecting it.

>

>My personal choice is the black speaker caulk Parts Express

>sells.

>It's already been written about here.

>

>

>It's all about the music

>

>Carl

>Carl's Custom Loudspeakers

I've seen a number of, not just AR, speakers with sealants being used with variable results.

Particularly with the AR routed flanges, I have seen lots of plywood slivers come out with the drivers in the putty.

It may be possible that if AR or their cabinet supplier had varnished the flanges there may not have been the sliver problem.

When the flanges were routed out, they were just at the edge of a layer of plywood allowing for breakage.

At this point in time I can see that a sealant such as varnish, for one, may be a great idea, if not another step in our re-building procedure.

I've seen many AR drivers flanges slightly warped from being over tightened at the AR factory.

They may have used pneumatic drills to drive the machine screws home, over-torqueing them at times.

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...