Dust Cap Glue Line

[1audiohack]

I wonder just how thin one can make the dust cap glue line and have it endure. I am thinking I am going to find out!:) As you can tell I like them thin!

These are done with Moyen.

[cooky1257]

Good question, the dustcaps have a chamfer on the underside to lay flush with the cone-I applied the moyen black stuff to that being generous on the inner edge so from the front they look very tidy indeed.

[grumpy]

I'd expect that unless you really hammered them, that would be fine.
I actually find comfort in, and like the look of the thicker/stock line :).
Maybe Edgewound, GordonW, 4313B... (someone with significant experience
and training) can give a better answer if they have the time and interest.

I've only done this once, on an Altec driver, and it was a real goober job,
not having the right glue -or- the experience. AHack or Cooky, how do you center
the cap with the glue on it without making a mess (dryfit and mark first?)

-grumpy

[1audiohack]

AHack or Cooky, how do you center
the cap with the glue on it without making a mess (dryfit and mark first?)



Good question. There is no glue under mine besides what soaks in/under from the top.

[herki the cat]

Good question. There is no glue under mine besides what soaks in

YES, Mr. 1audio hack, "dryfit and mark first," then apply the cement recommended in the following topic bellow with an appropriate hypodermic needle & syringe to both cone and underside of the cap edge; make shure the cement solvent wets the cone & cap paper surface. Rehearse the application mechanics with out cement first.

This next topic commands a "Heads Up" to prevent a disaster.



You must choose a cement that is not !" Based on "Acetone or MEK Solvents whose violent vapors trapped under the dust cap will melt the polyurethane foam plug located in the vent hole of the speaker-motor center pole-piece inside the voice coil. This melted polyurethane goop will run into the voice coil gap and gum up the the voice coil gap.... Note, Most JBL speakers have this foam plug.


C. P. Moyen has "Toluene-Solvent Based Cements that are totally compatible with cone paper and cone edge foam

C.P. Moyen Co. Inc. offers a comprehensive, "Industrial Adhesives, Epoxies, and coatings, printed catalog titled: "Product Selector guide" describing specific applications on "metal, paper, foam & cloth" in loud speaker Assembly, including identification of each Moyen Adhesive Solvent System, aka: Toluene, Methy Ethyl Ketone, Toluene, or water, each solvent depends on the speaker component to be cemented.

Call C. P. Moyen Co., Customer Service at 1-847-67-6866, for the "Product Selector Guide."


Cheers, herki the cat

[cooky1257]

I've only done this once, on an Altec driver, and it was a real goober job,
not having the right glue -or- the experience. AHack or Cooky, how do you center
the cap with the glue on it without making a mess (dryfit and mark first?)

-grumpy

Hi Grumpy dry fit, line up then mask about 1" of outside area on cone with masking tape (then any goofs only get glue on masking tape) I then apply glue generously-about 2-3 mm thick line to the underside circumference and finally using blutack or masking tape to make a 'handle for the cap, place, locate then remove all tape and leave to dry-Bob's you your aunty.
Cooky

[macaroonie]

Americans don't understand the last phrase at all :blink:

[1audiohack]

Don't be too sure, I have friends from New Zealand, Austrailia and England.
I would agree that most Americans don't know those phrases.

[JeffW]

Guys, we get Top Gear, Monty Python, Gordon Ramsay, Doctor Who, Faulty Towers, David Hobbs doing the F1 commentary, etc.

Even I know Bob's nephew.

[cooky1257]

I make it a rule never to underestimate our transatlantic cousins:)
http://en.wikipedia.org/wiki/Bob's_your_uncle

[grumpy]

... came through loud & clear on this end :D

"Piece of pie, easy as cake" ;)

Disclosure: I did spend -some- time (not enough) in Oz a few years back.

[1audiohack]

Wow! I should turn on the TV once in a while.

[JeffW]

Wow! I should turn on the TV once in a while.

LOL, now I didn't say I watch all of that stuff, just that the hoi polloi might not be as ignorant as assumed. But I've seen some of it, probably all of the Monty Python episodes when I was growing up. I do watch Top Gear (semi-regularly) and F1 (regularly), and David Hobbs can't get through a race weekend without using the phrase in question.

[cooky1257]

I think is was George Bernard Shaw or Oscar Wilde who said we are "two nations separated by a common language":D

[herki the cat]

I make it a rule never to underestimate our transatlantic cousins:)
http://en.wikipedia.org/wiki/Bob's_your_uncle

'Uncle Bobs'. Generally meaning 'all will be well', and often used to indicate a successful outcome ;)

Say now! that is a very nice phrase..... Yankee cousins over here are still growing up.

Spanish culture in Spain has 22,000 idiomatic phrases or short cut expressions, for example; "A Kema Ropa" translated, literally states "to burn your clothing" & it means "point blank". Generally the Spanish language is strong, it wastes no words & immediately gets to the point. Except for the Guitar and the Bull Fight, life is just too short in Spain.:blink:

herki

[BMWCCA]

David Hobbs doing the F1 commentary...

Very funny guy. Sat with him once and watched him fall off a bar stool, pick himself back up, and continue with his story right from the spot where he'd passed out! Amazing, too, that he's usually doing the F1 commentary from a studio watching it on the "Telly".

However, I'm more familiar with the phrase as "Bob's your uncle." http://en.wikipedia.org/wiki/Bob%27s_your_uncle

[Mr. Widget]

However, I'm more familiar with the phrase as "Bob's your uncle." http://en.wikipedia.org/wiki/Bob%27s_your_uncleA nod's as good as a wink...

So how about those dust caps!


Widget

[1audiohack]

Well they have played all day. If they should come loose the solution is straight forward enough.

I appreciate the answers to the original question as I have only done four caps previously, with a little more glue.

I also appreciate the fun with you all!

[JeffW]

However, I'm more familiar with the phrase as "Bob's your uncle." http://en.wikipedia.org/wiki/Bob%27s_your_uncle

That's the phrase we've been alluding to, with a few auntys and nephews thrown in to keep them off our trail.

[4313B]

With dustcaps one should probably sweep from 200 to 300 Hz and listen for them to buzz. If they don't buzz then there is enough glue. The input voltage differs depending on the driver and it isn't meek.

While I like thin glue lines these examples look a wee bit too thin for my personal taste.

Also remember that the glue is part of Mms... one probably shouldn't skimp on VLF and LF transducers. Grams matter.

[BMWCCA]

That's the phrase we've been alluding to, with a few auntys and nephews thrown in to keep them off our trail.

Oh I get it—Email humor!

Always a dicey proposition deprived of the nuance of human interaction.;)


:thmbsup:

[Harvey Gerst]

For what it's worth, at JBL, we would set a speaker pole piece on top of the dome while the glue dried.

[grumpy]

Thanks Harvey, and 4313B !

[cooky1257]

Wisdom is priceless, I'll give them a fillet line of glue around the joint:)
Thank you Harvey and 4313B.

[1audiohack]

How this all got started with me is I have a pair of LE8TH's with a perfect clear glue line against the edge of the aluminum dust cap and I was always impressed by the skill of the unknown person that performed the work.

When I performed my first recone (my fabulous instructor, you know who you are) we used instant adhesive. Later I wanted to try the Moyen as it has a different look (that I like) and noticed that it soaked into the corner where the cap meets the cone a bit unevenly if you look closely. So I thought
well next time I will lay down a very thin bead, let it dry and then lay a slightly wider bead that would hopefully settle and dry very evenly. It does.

Thanks for the advise all, I left the 2123's thin, did the 2234's a little wider. I used a spray can for a dust cap weight.

Again, thanks guys.

[lgvenable]

so...I pulled out the 6 JBL2202Hs I had in storage, and somehow managed to putz up the dust cap on one. Can I carefully remove it, and then get a replacement and reglue it?
I know all too well to practice my technique more than once b4 gluing, but exactly how do I remove the old dust cap w/o messing up the cone (tearing the cone along the glue line), or damaging the vc gaps etc.
As far as an identical replacement, speakers plus or who?
I posted the pic of the one which is damaged. I cant believe it, as I was SO careful in storing these.:(

Gotta believe it was the movers when we moved here to Newburgh, as I'd never have left marks on the cone like that.

I'd also thought of getting my vacuum pump out, and then making an adapter from a lab funnel, fitting it around the cap and seeing if i could pull it out; problem is you'll see the crease lines no matter what, best approach would seem to be a new dust cap. someone who's done this particular fix help me out pls.
Larry

[1audiohack]

It appears yours are glued with instant adhesive. If it is when you scratch at it lightly with something sharp it will be very hard and impenetrable. If that's the case I cut the dust cap at the glue line with a new exacto knife. You have no choice but to leave what's left on the cone. Set the new cap in place and trim as needed at the lead bumps and glue the new one right on top of the old ring.

If it is glued with the softer Moyen you can carefully soak the cap loose, with toluene or MEK, roll the remaining glue off in little balls with your fingers and put another in it's place or just cut it as well.

Any JBL reconer can get you the correct cap.

[BMWCCA]

I've managed to repair of few with a vacuum cleaner hose. It often helps to spray a bit of water on the dome to soften it (slightly) before or if it won't come out otherwise. On the ones I've done I can't tell them from the undamaged ones now. Certainly worth a try.

[4343]

I think is was George Bernard Shaw or Oscar Wilde who said we are "two nations separated by a common language":D
Right!

"Americans think 100 years is a long time, Brits think 100 miles is a long distance..."

To quote a chap in Hants, when asked how to get to Stonehenge: "Dunno, never been there." Turned out it was about 3 hours by train (1 hour spent waiting at a station), plus 10 minutes by taxi...

[lgvenable]

I'll try the water and the vacuum, you're right, as I dont have much to lose by trying it.;)

[lgvenable]

My vacuum for the theater room has a wand with a variable valve adjustment (a smaller Dirt Devil). I wet the cone with a sponge, and then as I ramped up the vacuum level..it grabbed first one section pulling it out perfectly, I repeated this about 4 or 5 more times. You can tell it was ever pushed in. I'll post a picture after it dries, but voila it worked!
Thanks Audiohack!

I was careful to open the wand valve slowly and turned it on and off as I moved over the spot. The other places I had found about this method all concurred on one thing; dont place the hose over the cone with the vacuum on high; but try to use a proportioning valve. That said, the method works like a top.

[1audiohack]

Thanks Audiohack!



As much as I like to help it wasn't me, thanks goes to BMWCCA.

Good idea for sure.

[BMWCCA]

I was careful to open the wand valve slowly and turned it on and off as I moved over the spot. The other places I had found about this method all concurred on one thing; dont place the hose over the cone with the vacuum on high; but try to use a proportioning valve. That said, the method works like a top.

Great! I assumed anyone here would take normal care and precaution and proceed with the least invasive method first, ie. not running the vacuum full-out, but modulating the suction either with an adjustable control like yours, or by using an appropriate adapter tool on the vacuum. It goes without saying to bring the suction to the cone slowly and carefully while supporting the cone gently with your fingers. You don't want to suck the entire cone beyond its normal extension!

I used a mist-sprayer bottle instead of a sponge but its nice to know something else that worked. Once dry, there seems to be no change in the material as long as you've been moderate in how damp you made the dome. :applaud: