Best way to seal speakers while retaining ability to disassemble

Crashdot

Hi,

I was working on some of my speakers, and noticed that the sealed models (5B, 5jr+) do not have a good seal with regard to the passive radiators. When I press on the PR, the driver returns to resting position in less than a second.

What can I do to improve the seal on these while avoiding caulking or glueing everything together? It may be necessary to open these to replace a component or upgrade crossovers, so I don't want to glue it shut.

Thanks

rromeo923

See this thread

http://www.polkaudio.com/forums/showthread.php?t=74524

Crashdot

I was reading that, although it seemed to indicate that the bass would be changed, reducing audible bass but increasing tactile bass. This is not the kind of sound that I am looking for at all.

In addition, at least one thread indicated that the Mortite can harden and adhere to the driver and cabinet. Perhaps Polk still sells replacement gaskets that I can try?

I also noticed a few of the screw holes in these speakers are stripped, and cannot be tightened. I would welcome any suggestion as to how to repair these.

Thanks

TNRabbit

There are any number of places that sell round foam seal that works perfectly for this application. I bought a roll of truck bed liner at Lowe's (cut out into circles) that worked perfectly for sealing up the back panel & around the woofers on my Carver AL-IIIs.

drumminman

Crashdot wrote: »

I was reading that, although it seemed to indicate that the bass would be changed, reducing audible bass but increasing tactile bass. This is not the kind of sound that I am looking for at all.

In addition, at least one thread indicated that the Mortite can harden and adhere to the driver and cabinet. Perhaps Polk still sells replacement gaskets that I can try?

I also noticed a few of the screw holes in these speakers are stripped, and cannot be tightened. I would welcome any suggestion as to how to repair these.

Thanks

Hey Crashdot,

When I rebuilt my RTA 12C's Larry's rings were not available, so I used hurricane nuts from Parts Express:

http://www.parts-express.com/wizards/searchResults.cfm?FTR=hurricane+nuts&search_type=main&WebPage_ID=3&searchFilter=hurricane+nuts&x=32&y=11

They're like T-nuts, but with much smaller teeth. In fact, the teeth are small enough that it doesn't seem like they'll have enough bite to keep the nut from turning when you tighten the screws, but they hold like crazy!

I used the 8-32's as they're small enough not to interfere with reinstalling the drivers. I also used cap head allen screws with brass washers from Lowes/HD, and it worked great. You can really torque these to get a good seal between the drivers and the front baffle. I also used mortite as the sealant. I've never had a problem with the stuff going hard, or sticking so much that it couldn't be peeled off. :biggrin:

If you go this route you'll need to drill out the original holes. Be sure to use a drill bit that's only as wide as the body of the nut, not one that's as wide as the teeth because you want them to bite into the particle board to prevent them from turning when you tighten the screws.

The other thing I did was after drilling the holes I hand pressed the h-nut enough so it would stay, then I pressed it the rest of the way in with a C-clamp. I thought pulling it in by tightening the screws might put too much pressure on the front baffle - worked like a champ! :cool:

Good luck!

heiney9

Crashdot wrote: »

I was reading that, although it seemed to indicate that the bass would be changed, reducing audible bass but increasing tactile bass. This is not the kind of sound that I am looking for at all.

Way overstated and it doesn't reduce "audible" bass, whatever that means. Bass is a LOT better with Mortite

Crashdot wrote: »

In addition, at least one thread indicated that the Mortite can harden and adhere to the driver and cabinet. Perhaps Polk still sells replacement gaskets that I can try?

Mortite "might" harden say in 20 years, so that's not an issue to even be concerned about. No, Polk doesn't carry replacement gaskets.

Crashdot wrote: »

I also noticed a few of the screw holes in these speakers are stripped, and cannot be tightened. I would welcome any suggestion as to how to repair these.

Thanks

There are several threads about this maybe you can find them. There was a recent one as well.

Aside from Larry's rings, Mortite does a fantastic job in my experience, it's cost effective, easy to use and available locally. If you don't like that, there have been numerous threads on other alternatives from places like Parts Express, etc.

Search Darqueknights threads for his very detailed Mortite analysis. You are way over analyzing this. Mortite works very well.

H9

geoff727

Crashdot wrote: »

Hi,

I was working on some of my speakers, and noticed that the sealed models (5B, 5jr+) do not have a good seal with regard to the passive radiators. When I press on the PR, the driver returns to resting position in less than a second.

You can try a brand new foam seal from Parts Express or something like that. But, keep in mind that the "return time" of the drivers on both sets of Monitor 5's will be faster than on your RTA12's. The dust caps on those 6.5" drivers are a non-air-tight screen mesh. So, the air pressure inside the cabinet works its way throught the spider and then out the dust cap, quickening the "return time". The drivers on your 12, by contrast, probably have a doped felt dust cap that doesn't pass air too well.

Also, over time, and this happens with most speakers, all the screws work their way loose, maybe even on the crossover cup. Tightening them up might help. To fix any holes that have stripped, cut a toothpick short and glue it into the hole. It will be as good as new.

G~

geoff727

http://www.parts-express.com/wizards/searchResults.cfm?srchExt=CAT&srchCat=818&CFID=26350844&CFTOKEN=96965570

There's lot of this stuff out there from various companies. You just have to start searching for a size taht you think is appropriate. Or, alternatively, try the weather stripping section at Lowe's/Home Depot/etc. and think creatively. Just remember, this seal will really be MUCH more air tight than the non-doped dust caps on the mid-bass drivers.

G~

jim 249

I agree that mortite makes a mess. Spend a bit more time and make new foam gaskets. Check this link out where I made my own new gaskets.:biggrin:


http://www.polkaudio.com/forums/showthread.php?p=1592479#post1592479

heiney9

I have no idea what kind or conditions you guys are woking in, but Mortite has never made a mess for me, nor has it been difficult to work with, not even close. It's not even sticky. It's sooooo simple and effective to use.

To the OP, choose whatever, I'm just pointing out some of the over the top statements people seem to be making. There are lots of alternatives, feel free to explore them on your own and report back.

Mortite is one alternative that has been used by a lot of members and it's a no fuss way to effectively do what you are trying to do with no downside.

H9

F1nut

When I press on the PR, the driver returns to resting position in less than a second.

Did you press and hold or press and release?

I have no idea what kind or conditions you guys are woking in, but Mortite has never made a mess for me, nor has it been difficult to work with, not even close. It's not even sticky.

I had to scrape the Mortite off the driver rims and use a solvent to remove the residue after I decided I didn't like the results, so yeah, it's very sticky.

heiney9

F1nut wrote: »

I had to scrape the Mortite off the driver rims and use a solvent to remove the residue after I decided I didn't like the results, so yeah, it's very sticky.

I haven't had that issue and neither did Raife, so that's what I was basing my response on.

Again, the OP has a plethora of options some tried, some not. Once I put in the rings I obviously won't need the Mortite anymore.

Good luck to the OP, whatever method he decides on.

H9

Crashdot

drumminman wrote: »

Hey Crashdot,

When I rebuilt my RTA 12C's Larry's rings were not available, so I used hurricane nuts from Parts Express:

I think that the stripped screws are on the tweeters, but I will have to evaluate all of them once I make a decision about the gaskets. Thanks for the information on the nuts, and I'll also try to find out more about Larry's Rings.

Cheers

Crashdot

heiney9 wrote: »

Way overstated and it doesn't reduce "audible" bass, whatever that means. Bass is a LOT better with Mortite

Search Darqueknights threads for his very detailed Mortite analysis. You are way over analyzing this. Mortite works very well.

Hi, this is not my analysis, since I have never heard mortited speakers, but what DarkqueKnight described:

DarqueKnight wrote: »

The bass seemed to be lower in sound level, but had increased in clarity and weight. In other words, my ears heard "less" bass, but the tactile sensations, vibrations and rumbles coming through the floor, furniture, and air were heavier.

I don't want the kind of bass that seems to be described here, as I am more interested in tight midbass, and do not care for low bass that causes vibration. I can take everyone's word that bass is improved, but if I were to go on the above description alone I would not have considered mortite based on my personal sound preference.

I am not looking to reinvent these speakers, but just to restore them to proper working condition.

Thanks

Crashdot

geoff727 wrote: »

You can try a brand new foam seal from Parts Express or something like that. But, keep in mind that the "return time" of the drivers on both sets of Monitor 5's will be faster than on your RTA12's. The dust caps on those 6.5" drivers are a non-air-tight screen mesh. So, the air pressure inside the cabinet works its way throught the spider and then out the dust cap, quickening the "return time". The drivers on your 12, by contrast, probably have a doped felt dust cap that doesn't pass air too well.

Hmmm... I hadn't considered that at all. These 12Cs do not have the original drivers as far as I know, but I can't recall of they are the same MW6052's that are in the leaky speakers I am working on. I guess I could try swapping a driver to see if that is the cause of the perceived problem.

Thanks

Joe08867

I am not a fan of mortite either. I have tried it and removed it.

I suggest you use jim 249's idea and make your own gaskets. You can find the foam at AC Moore, Michael's, or any fabric store. I have used this method forever and it works. The bass extension didn't drop off, the rumble didn't increase. It just tightened everything back up the way it should be.

Crashdot

F1nut wrote: »

Did you press and hold or press and release?

Press and hold - the same test with the 12Cs allows the drivers to stay out almost indefinitely, but on these 5s, the return almost immediately.

I had to scrape the Mortite off the driver rims and use a solvent to remove the residue after I decided I didn't like the results, so yeah, it's very sticky.

It seems that some users here have bad both good and bad experiences with Mortite, so at least that is something to consider. I could test some elsewhere to see how it behaves before committing to a full installation.

Cheers

Joe08867

Crashdot wrote: »

Hmmm... I hadn't considered that at all. These 12Cs do not have the original drivers as far as I know, but I can't recall of they are the same MW6052's that are in the leaky speakers I am working on. I guess I could try swapping a driver to see if that is the cause of the perceived problem.

Thanks

Don't start swapping drivers from the RTA's to the 5jr's. Each speaker has a specific model driver that works with it. The SDA2 had 6501 the SDA1 had 6511. There is a reason for the differences. And the crossovers are setup to the specifications of that driver. If you switch them you will throw the frequency curve way off. Let alone the differences in Ohm's ratings which could fry your receiver.

Crashdot

Joe08867 wrote: »

Don't start swapping drivers from the RTA's to the 5jr's. Each speaker has a specific model driver that works with it. The SDA2 had 6501 the SDA1 had 6511. There is a reason for the differences. And the crossovers are setup to the specifications of that driver. If you switch them you will throw the frequency curve way off. Let alone the differences in Ohm's ratings which could fry your receiver.

No, I meant swap drivers for the purpose of testing to see if the source of the leak was the type of driver dust cap. I wouldn't actually connect the driver. Obviously there is no point in spending 20 hours obsessively trying to seal these speakers if they are still going to leak out of the drivers that go with them. I just can't think of any other way to test the other seals than to use a driver that I know does not leak.

FYI, the vast majority of vintage Polk Audio speakers that I have here are 4 ohm models, so there is little more I can do to risk my receiver than I am already doing. I'm not even powering the Monitor 5B or 5jr+ at this point, just doing the push test.

Thanks

Joe08867

Are any of these speakers ported? If so the push test won't work on them.

I am guessing/hoping you are working on the other speakers but one never knows around here.

Crashdot

He-heh... No ports on these, although it would be pretty funny for all of you if there were! Both of these models have passive radiators. I push on the radiator and watch for the drivers to push out. On the 12Cs, the drivers stay out until I release the radiator. On the 5B and 5jr+ the drivers return to resting position quickly.

Thanks!