Ar 3a woofer

[ironlake]

Have two refurbished ar3as and when I pushed in the woofer cones I did not get a very slow back movement. Checked with vintage ar who suppllied me with one rebuilt woofer and he told me to seal the dust cap on both as they are the 1st generation woofers. I used simply speakers foam fixer for the caps and wow, now the cones come back nice and slow like about 1 second. Deep bass is really powerfull now. The 30 hz cd from one of the foam dealers now shakes the photos on the wall if I turn it up to about 10 oclock.

[bhamham]

I just refoamed my AR-3a woofers and after pushing the cone in they come back fast too. They have the foam gasket and was thinking the leak may be there and was going to refit using plumbers putty.

I may try to seal the dust caps first as I got my refoaming kit from Vintage AR. I have the Permatex High Tack Gasket Sealer - wonder if I should use full strength or dilute?

[RoyC]

Have two refurbished ar3as and when I pushed in the woofer cones I did not get a very slow back movement. Checked with vintage ar who suppllied me with one rebuilt woofer and he told me to seal the dust cap on both as they are the 1st generation woofers. I used simply speakers foam fixer for the caps and wow, now the cones come back nice and slow like about 1 second. Deep bass is really powerfull now. The 30 hz cd from one of the foam dealers now shakes the photos on the wall if I turn it up to about 10 oclock.

ironlake,

The voice coil of the AR-3a woofer is not open to the interior of the cabinet. Re-sealing the dust cap is usually not necessary, nor should it make any difference in terms of sealing the cabinet.

There are other areas where the cabinet could be leaking (ie other drivers, level controls, and the front terminal board). In any case, I'm sure nothing was hurt by the light application of sealant.

bhamham,

Plumbers putty is too thin to use as a driver-to-cabinet gasket. Electrical putty ("duct seal") is much better, as is clay-like Mortite type weather stripping. Parts Express has a very good black putty (PE calls it "caulking"). If there is any benefit to sealing the older alnico woofer dustcap (I personally doubt it), it certainly does not apply to the foam surround/ceramic magnet woofer.

Roy

[dynaco_dan]

Hi there

As Roy wrote, do not use plumbers putty.

I have seen enough in usuage to know that the cream coloured plumbers putty cracks and crumbles after a period of time, as well.

The electrical putty has the right characteristics, low price and availablity to track down.

[bhamham]

Many thanks Roy & Dynaco Dan.

Parts Express shipping to the UK is a bit dear. Do you think this 3M electrical putty will work?

http://www.3mselect.co.uk/p-1553-electrical-putty-scotchfil-insulation-putty-38mm-x-15m-1-roll.aspx?gclid=CKyZo_ac9LECFQ0htAodj3IAJQ

[RoyC]

Many thanks Roy & Dynaco Dan.

Parts Express shipping to the UK is a bit dear. Do you think this 3M electrical putty will work?

http://www.3mselect....CFQ0htAodj3IAJQ

Looks good...should work well.

Roy

[dynaco_dan]

Hi there

Sorry, but I do not agree with Roy on the acceptibility of this particular rubberized tape.

It reminds me of Pico-flex tape, a rubberized filler tape we used to fill in large gaps on underground gas pipe fittings prior to wrapping with Polyken tape.

It also likely could be used for wrapping the connection end of motor starting capacitors.

The electrical putty is certainly an option that has proven to work without a problem.

It is available likely at smaller electrical stores, and definitely electrical wholesalers.

It comes in a butter sized brick and weighs about 1/2 pound and costs about $3.00.

[RoyC]

Hi there

Sorry, but I do not agree with Roy on the acceptibility of this particular rubberized tape.

It reminds me of Pico-flex tape, a rubberized filler tape we used to fill in large gaps on underground gas pipe fittings prior to wrapping with Polyken tape.

Hi Vern,

I believe I know the stuff you are referring to. The 3M material in bhamham's link is actual black putty, not rubberized tape.

<<"Electrical Putty - Scotchfil™ Insulation Putty, 38mm x 1.5m, 1 Roll">>

It appears to be similar to the Parts Express putty (see attached photo), which is excellent!

...and I would not be surprised if it isn't much the same as this 3M product sold by MCM...

http://www.mcmelectr...08578-/108-3190

Roy

[ironlake]

Have two refurbished ar3as and when I pushed in the woofer cones I did not get a very slow back movement. Checked with vintage ar who suppllied me with one rebuilt woofer and he told me to seal the dust cap on both as they are the 1st generation woofers. I used simply speakers foam fixer for the caps and wow, now the cones come back nice and slow like about 1 second. Deep bass is really powerfull now. The 30 hz cd from one of the foam dealers now shakes the photos on the wall if I turn it up to about 10 oclock.

All I know is the rebuilt alnico magnet I got from vintage ar had the dust cap sealed and after putting the speaker in using dennis window caulking ,( white cord like soft putty) runing around the edge of the wood of the cabnet as a sealer for the speaker to the cabnet and torquing the screws in two different times across the speaker movements using setting #1 on my portable drill( the least tight setting) and then going aound one hole at a time on torque setting # 2 I had nice slow backward movement when pushing in the cone. So I tried the simply speakers stuff as it would not screw up a dust cap and stay flexible to coat it I got nice slow rebound from my other alinico speaker. Awsome bass from these. The telarc 1812 cannon shots a awsome with the 3as. No distorition like I had on my large advents, but nice loud clean sound that seemed to be reproduced with ease.

This also told me I did not need to reseal my one 3a woofer with the cloth surround as it is the one I did the dust cap sealing on. The rebuilt alnico speaker received a new spyder and foam surround and I can not tell the difference in sound. Both woofers put out the exact volume of bass on the radio shack level meter.

I know on a web site for jensen speakers (pa) they have sound diminstration for their alnico speakers vs ceramic speakers which sound the same to me on my laptop but most likely they will sound different on a good system

[dynaco_dan]

Hi there

As Roy has posted a photo of some fibre strips that may be 3M black strip-caulk.

This has the appearance and packaging method of what AR provided to warantee depots at least.

The colour and texture is slightly different than the original package I bought in the mid '70's when I wanted to buy some locally.

I bought mine at an autobody supplier shop.

Same model number on package.

Another trade name is or at least was dum-dum, used to wedge into car body nooks and crannies to deaden rattles and buzzes.

Of course the package that was supplied by AR was a white box, no I.D.

I have that original package I bought still almost full and bought the current version about 10 or so years ago.

They are slightly different in colour and texture.

They are laying in strips almost touching each other and have a sheet of carrier to aid in their removal from the package.

There may have been fiberglas, asbestos, or other compound in the original formula which was dropped.

Following through on that link to 3M I found 3M Black Strip-Caulk box of 60 x 12" long.

This may also be sold on a similar shape strip with a paper like backing carrier, such as that used for window sealing.

[genek]

Modern caulking putties are all made from vinyl or neoprene mixed with kaolinite or titanium dioxide based clays. The natural color of this combination is an off-white. Various brands of the stuff are colored grey or black, but the color is just that, color.

Black caulking putty from the 50's and 60's was an asphalt-based compound. Asphalt was phased out as weatherproofing caulk because it had a tendency to dry out, which caused it to crumble and become leaky when exposed to weather, and because the "crumbs" are highly toxic if consumed by children or pets.

[dynaco_dan]

Modern caulking putties are all made from vinyl or neoprene mixed with kaolinite or titanium dioxide based clays. The natural color of this combination is an off-white. Various brands of the stuff are colored grey or black, but the color is just that, color.

Black caulking putty from the 50's and 60's was an asphalt-based compound. Asphalt was phased out as weatherproofing caulk because it had a tendency to dry out, which caused it to crumble and become leaky when exposed to weather, and because the "crumbs" are highly toxic if consumed by children or pets.

Hi Gene

Thank you for this wealth of information.

[tysontom]

I just refoamed my AR-3a woofers and after pushing the cone in they come back fast too. They have the foam gasket and was thinking the leak may be there and was going to refit using plumbers putty.

I may try to seal the dust caps first as I got my refoaming kit from Vintage AR. I have the Permatex High Tack Gasket Sealer - wonder if I should use full strength or dilute?

Mortite is a type of plumber's putty, and it works superbly well for sealing the drivers to the cabinet. It is available in "rope" form, and two ⅛" or two ¼" diameter strands around the circumference are usually perfect to seal any driver, using the alternate-screw tightening technique (such as tightening a wheel to a car) by tightening one screw slightly, going across 180-degrees and tightening the one across, etc., until the frame is pulled down evenly and sufficiently. Mortite is very inexpensive, below is a link to Amazon to purchase it; the 3M electrical putty is typically "3M expensive" and over-kill when used for a gasket material, as it has a high petroleum tar content built in to serve as a dielectric material—not necessary for caulking purposes.

Link to Mortite:

http://www.amazon.co...ulk%2Caps%2C179

Leave the dust cap alone. There was a small amount of butyl-latex compound painted on the dust cap from the factory, but a certain amount of air is allow to move through it, as air pressure builds up below the cap and around the voice coil, expelled through the holes in the bobbin. Usually the dust cap will not affect the performance of the driver adversely.

The best way to determine an air leak is to use a stethoscope and a sine-wave generator. Using the generator (or a test-tone CD) to produce 30 Hz tones, listen with the stethoscope for the "hissing" sounds where there are leaks. Tiny air leaks are okay—usually air leaking through the level-control shafts—to assure pressure equalization within the sealed cabinet with outside air. You do not want your woofer cones to move in and out with changes in atmospheric barometric pressure, acting like an aneroid barometer. On the other hand, when you press in the woofer cone, it should not bounce back, but it should return slowly.

--Tom Tyson

[RoyC]

Mortite is a type of plumber's putty,

--Tom Tyson

Tom,

It may be related to plumbers putty, but the stuff called "plumbers putty" usually comes in a container, and is much too thin. Rolls of Mortite are usually found in the weather stripping department of hardware stores. It is more clay-like than the electrical putty or duct seal materials.

The softer Parts Express black caulk looks similar to the 3M stuff, and is preferable to Mortite, imo. Mortite is too stiff to use under tweeters, and will distort the flange even more than the original cailk did. The PE material works well for all drivers. It is $10 for 72 12 inch strips. This is my personal favorite.

Duct seal is probably the best "deal" of all at $2/lb. It is the stuff that Larry/Vintage AR repackages for sale on Ebay. It is also soft enough for thin flanges.

Roy

[tysontom]

Tom,

It may be related to plumbers putty, but the stuff called "plumbers putty" usually comes in a container, and is much too thin. Rolls of Mortite are usually found in the weather stripping department of hardware stores. It is more clay-like than the electrical putty or duct seal materials.

The softer Parts Express black caulk looks similar to the 3M stuff, and is preferable to Mortite, imo. Mortite is too stiff to use under tweeters, and will distort the flange even more than the original cailk did. The PE material works well for all drivers. It is $10 for 72 12 inch strips. This is my personal favorite.

Duct seal is probably the best "deal" of all at $2/lb. It is the stuff that Larry/Vintage AR repackages for sale on Ebay. It is also soft enough for thin flanges.

Roy

Roy,

You are right that Mortite is a lilttle tough to deal with when you are mounting thin sheet-metal-flange tweeters, such as the AR-4x or AR-6 tweeters with their thin flanges; however, it was used originally, and if a limited amount of the soft Mortite is used, and the cross-screwing is used to gradually draw the driver down on the T-Nuts, Mortite usually will work okay -- at least in my experience. In the final analysis, it probably doesn't matter too much what material is used so long as the driver is sealed to the cabinet, and the flange isn't badly distorted. The 3M stuff is specifically not as well-suited as a gasket, since it has so much asphalt or tar content. it will certainly do the job, but it is messy and probably difficult to remove later if a change is made.

One mistake that some people make is to try to make the cabinet nearly air-tight, and this just isn't necessary. If you wanted to reproduce 0 Hz (dc), then a completely sealed enclosure might be desirable. Since nothing much below 20 Hz (and very limited at that) will ever be reproduced by the standard woofer, a slight leak will not have any effect. In effect, the speaker should be "acoustically" sealed, not "hermetically" sealed.

--Tom Tyson

[genek]

The Mortite that Tom linked to is a titanium dioxide based weatherproofing caulk. A plumbers putty would be a similar material, but would have oil added to further retard any tendency to dry as well as to make it more resistant to moisture. This additional oil is what tends to make plumbers putties "wetter" than caulks. You probably wouldn't want that oil leaching out and getting absorbed by the cabinetry or the driver cones, either.

[RoyC]

Roy,

The 3M stuff is specifically not as well-suited as a gasket, since it has so much asphalt or tar content. it will certainly do the job, but it is messy and probably difficult to remove later if a change is made.

One mistake that some people make is to try to make the cabinet nearly air-tight, and this just isn't necessary. If you wanted to reproduce 0 Hz (dc), then a completely sealed enclosure might be desirable. Since nothing much below 20 Hz (and very limited at that) will ever be reproduced by the standard woofer, a slight leak will not have any effect. In effect, the speaker should be "acoustically" sealed, not "hermetically" sealed.

--Tom Tyson

I agree, Tom...The electrical and duct seal caulks are messy when removing woofers. On later cabinets, which were equipped with foam gaskets, I've been using the Parts Express foam gasket tape. It seals better than the original gaskets, and holds up well when removing the woofer for repairs or changes.

I also strongly agree with your comments about cabinet sealing. It comes up in the endless debate about re-sealing cloth woofer surrounds. People do not realize there is a greater negative effect from applying the wrong (or too much) treatment, than to apply no additional treatment at all. In an effort to "seal" the cabinet as completely as possible, woofers have been ruined.

Roy

[ironlake]

The cloth surrounds I am familiar with tend to feel almost floppy but not quite compared to a foam surround. The cloth surrounds seem to loose flexibilty from new. How did they feel when pushed compared to the new foam surrounds when they came out.. I;ve been told that the springyness of a cone is mainly controled by the spyder and not the surrounds. The main reason is for the surround to keep the cone in the right alignment with the voice coil and the resistance to back and forth movement the spyders job? Does any of this make sense.

[bhamham]

I finally got around to resealing my AR-3a. Got what I assume is mortite from the AR guy on ebay. Well, the woofer is still leaking. I held my face really close to the cone while pushing in and could feel the slightest amount of air movement on my cheek. I think it's coming from the foam surround - got the foam from the AR guy too. I don't think it's from the dust cap. I checked the seal on both sides of the foam and it looks very tight.

I thought I'd do the permatex treatment to the foams at a really diluted rate but wanted to check with you guys first. Here's a pic of the woofer:

[RoyC]

I finally got around to resealing my AR-3a. Got what I assume is mortite from the AR guy on ebay. Well, the woofer is still leaking. I held my face really close to the cone while pushing in and could feel the slightest amount of air movement on my cheek. I think it's coming from the foam surround - got the foam from the AR guy too. I don't think it's from the dust cap. I checked the seal on both sides of the foam and it looks very tight.

I thought I'd do the permatex treatment to the foams at a really diluted rate but wanted to check with you guys first. Here's a pic of the woofer:

Applying a solvent based material like Permatex to foam will destroy the foam! The foam surround is not porous enough to require any kind of treatment.

(Actually, Permatex, which was originally suggested as a possible treatment for re-sealing cloth surrounds, is no longer recommended at all these days. Over time it has been found to harden and compromise the performance of the woofer.)

Check other areas, like the midrange and tweeter gaskets, if you believe the leakage is more than it should be. There is always some acceptable leakage through the pots. The cabinet does not need to be completely airtight.

The driver gasket material you purchased from Ebay is not Mortite. It is "duct seal" found in electrical sections of building supply stores such as Home Depot and Lowes. It costs around $2 for a one pound brick, and works well.

Roy

[DON]

I prefer Mortite in the rope form to any other sealer I've used other than an original factory made gasket. I don't have a lot of experience with AR drivers but I've never had a problem getting an acceptable seal. Tightening the bolts as others have explained here is very important in avoiding distortion of the flange which can result in a poor seal or a damaged driver.

[bassment142]

I bought 3M brand rope caulk at NAPA and do not reccomend it. The stuff is so sticky, that when you try to place it on the driver or cabinet it comes right back up with your fingers, it is infuriating!!! I love the stuff that PE sells, it is nice and soft without being sticky. I used my spare mortite around my AC unit in my window and it was perfect for keeping bugs out.

[der]

I only use duct seal. I think it's the same material that was used at the factory. If not, it's pretty close to the same thing.

der