Is it wrong to not use putty to seal old AR speakers?

[spark1]

I thought Mortite was a trade name for butyl rope caulk (like Kleenex for tissues). In any case the 3M rope caulk is what I've used for many years. It is still pliable after 10-12 years in a pair of AR2a speakers in my workshop.

 

[centsless]

This statement from RoyC from CSP in 2009.....hope it clarifies..
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I prefer to use "duct seal" (see pic) easily obtained from the electrical section of Home Depot. It is more pliable than the Mortite type rope caulk, and is the stuff re-packaged as "original" AR putty by Ebay's "Vintage AR". AR's putty was not Mortite (Advent's was). AR's black putty was softer and less clay-like than Mortite-

 

[Retrovert]

I find them to be different in many ways. While the butyl rope caulk is always pliable, the Mortite is stiff in comparison.

That suggests a product without filler and a different formulation.

I have only seen geriatric caulk on AR and KLH speakers which is always hard and brittle and the same color as the Mortite. Consensus on CSP was that it was Mortite.

The filler is added for bulk and stiffening, so that is intentional. Roof and window caulking is different.

Shelf live of the butyl rubber caulk is superior to that of Mortite. The 3m rope calk looks like the AR sealant, the Mortite doesn't. This is what I've observed.

Butylene caulking often has synthetic rubber elastomers added to retain the pliability. The purpose is to seal sheets of rubber together or windows to frames to prevent any ingress of water. A few years ago I had looked at some of the formulations to find a non-hardening viscoelastic adhesive for sound deadening. Some formulations also have Stoddard solvent to reduce the viscosity and make it spreadable, at least in the initial application.

What's the name of the 3M caulk you used?

 

[leftfielder]

Most people over on the Polk site say if the original gaskets are in good shape use them. Of course w/ mortite originally used this can't be done but the other alternative is Armaflex Gasket Tape on a roll @ Home Depot for about $8 and you can make gaskets for 100s of speakers air tight an ant won't survive.

 

[tubed]

What's the name of the 3M caulk you used?

 

[Retrovert]

Thanks for that photo. Made it easy to ensure I was looking at the right product. Quite a substantial price difference:

3m Strip-Caulk 08578, 60 feet, $26
Mortite, 90 feet, $6​

Not that this especially matters for speakers, of course, as one box of either will seal a number of speakers.

Just remarkable as the two materials have very little difference in materials cost, engineering costs worked out a long time ago, of course, yet such a substantial markup on the 3M product.

 

[don philipe]

I've used rope putty from Ace hardware,works great.

 

[ra.ra]

Here's the stuff mentioned in post #22. You can't beat the price or the performance. If you've ever dis-assembled a pair of Advents from the early-mid 70's, you'll know perfectly well that the light grey Mortite can never be re-used. OTOH, many AR's from ten years earlier have the darker putty which very often can still be re-used when reinstalling drivers to cabinet.

 

[reddog48]

Never seen ANY AR with oil-filled caps. Every one I have been into has used either separate electrolytic caps OR computer grade electrolytics sealed in a wax block. Most of the ones I have encountered have drifted and deteriorated over the intervening 30 or 40 years. My understanding is that the dielectric paste separating the plates of the capacitor degrades with time.

As for the seal? Oh just about sealant will do - caulk - if thick enough - foam gasket, rubber gasket. The seal doesn't have to be so tight that it will hold air for more than a few milliseconds - as the woofer is moving constantly. I have used RTV (silicon sealer) with good success. The only problem with RTV is that it tends to be too sticky - and after using it removal of the driver will cause the old OSB board that the cabinets are made to come apart. Bad.

Good luck - the AR2-ax with new L-pads and a reworked crossover is sonically a blissful speaker.

 

[centsless]

Never seen ANY AR with oil-filled caps. Every one I have been into has used either separate electrolytic caps OR computer grade electrolytics sealed in a wax block. Most of the ones I have encountered have drifted and deteriorated over the intervening 30 or 40 years. My understanding is that the dielectric paste separating the plates of the capacitor degrades with time.

As for the seal? Oh just about sealant will do - caulk - if thick enough - foam gasket, rubber gasket. The seal doesn't have to be so tight that it will hold air for more than a few milliseconds - as the woofer is moving constantly. I have used RTV (silicon sealer) with good success. The only problem with RTV is that it tends to be too sticky - and after using it removal of the driver will cause the old OSB board that the cabinets are made to come apart. Bad.

Good luck - the AR2-ax with new L-pads and a reworked crossover is sonically a blissful speaker.

If you haven't seen oil caps in any AR's, you just have seen enough... I have had several sets with oil caps. All had early serial numbers.....but they do exist.

 

[432HzBob]

I use a thin, hand-rolled bead of non-hardening model clay to seal my drivers.