Mortite Speaker Seals For SDA's

[DarqueKnight]

Would you like to read something audio related for a change? Are there any other forum members who have SDA's? If so, do you like tweaks?

One good thing leads to another with SDA's. MSP's recommendation for replacing the stock foam speaker seals with Mortite caulking cord is given in the first post in this thread.

Ok, since the Mortite recommendation came from a credible source, I got some. I also got some speaker seal tape sold by Parts Express and some vinyl foam weather strip tape from Home Depot to do a mini shootout.


Left to right: Parts Express speaker gasketing tape, Mortite caulking cord, Frost King
3/8" wide x 3/16" thick vinyl foam weather strip.

The stock seals were replaced by Mortite on the right speaker and compared to the left. My preamp was switched to mono operation and the balance control was shifted left and right.

Mortite

A 90 foot roll cost $4.98, inclusive of tax. The roll was 11.25 feet long and came preformed into eight 1/8 "cords" that were stuck together side by side. The cords are a little more than 1/8th inch in diameter. Most of the time, the individual cords were easy to peel apart. In cases where the separation didn't come easy, the putty was easily cut with scissors. Due to the elastic nature of the putty, cutting with a knife is not as efficient.

If you are of the "a little is good, but more is better" mindset, don't use more than one cord of caulk around a driver, tweeter or passive radiator perimeter. For the RD0198 tweeters, I placed the caulking cord just inside of the plastic rim around the underside. Using more than a single cord will make it difficult to screw down the driver and the added thickness will decouple the driver from the baffle.

I thought Mortite would be stiff and it would make it difficult to screw the divers back flush with the baffle, but it was very soft and flexible. It's consistency was similar to soft modeling clay and it was very easy to work with. It has moderate adhesion to wood, metal, plastic, and masonry, but does not stick to fingers. It is very easy to peel off of surfaces it is adhered to.

Mortite made a better air seal than the stock foam seals. The drivers took almost 3 seconds to float back down after the passive radiator was pushed in. It takes 2 seconds with the stock seals.

After application, the mids and highs were clearer. 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. Growling sounds made by bass instruments were a bit lower pitched and more well defined. I was hearing cleaner, more articulate bass (less resonance) due to the Mortite having a firmer grip on the driver rim. This, coupled with the previous foam tape application to the baskets, drastically reduced the vibrational energy that was coloring the vibrations of the driver cones, tweeters, and passive radiator.

The bass instruments were apparently much faster. On songs where the activity of the drummer was previously blended into the background, the drum kit now called attention to itself because of the increased speed and clarity. It was somewhat annoying at first because there now seemed to be a spotlight on the drum kit. This spotlighting faded away as my ears got more accustomed to the more accurate tonal balance. The next day, the bass spotlighting effect was gone and everything was tonally cohesive.

Another thing I noticed was that is was much easier to follow the drummer's hands as he was playing various parts of the drum kit. The drum kit and other heavy electronic percussion sounds were also pushed further back in the sound stage on some recordings.

Parts Express Speaker Gasketing Tape

Mortite was clearly superior to the stock seals, so it was left in place on the right speaker and the left speaker's stock seals were replaced with the Parts Express gasketing tape.

A 50 foot roll of this tape cost $14.45 ($5.49 for the tape and $8.97 for shipping). This stuff was bad...awful...horrible. It has the consistency of cork and it acoustically decoupled the drivers from the cabinet. It would only compress a little, therefore the drivers would not screw down flush with the baffle. It sounded like I had inserted an equalizer and filtered out the bass. The highs took on an edgy, "electronic" sound. The monoliths hated it...but your speakers..and ears...might like it. Different strokes and all that.;)

This tape made a slightly better air seal than the stock seals. The drivers took a little over 2 seconds to float back down after the passive radiator was pushed in.

Frost King Vinyl Foam Weatherseal

The Parts Express tape was hastily removed from the left speaker and replaced with Frost King vinyl foam weather strip tape. The cost, inclusive of tax, was $1.95 for a 17 foot roll.

This foam was 3/16" thick and was very soft and would compress down to paper thinness. It was a softer foam than the stock seals. It sounded like the stock seals from the midrange and up, but it didn't couple the drivers to the baffle as well as the stock seals, therefore the bass sounded a little slower, less defined and had less tactile impact than the stock seals. Its bass performance was far, far below that of the Mortite.

This tape provided an air seal comparable to the stock seals. The drivers took 2 seconds to float back down after the passive radiator was pushed in.

Mortite Wins

I replaced the left speaker's stock seals with Mortite and proceeded to get acquainted with my 1.2TL's "new sound". I had to get used to the "new sound" the same way I had to get used to subwoofers that produced clean, ultra low distortion, minimum resonance bass. It took me about 45 minutes to get re-acclimated.:)

Now, don't get alarmed when it seems like some of your bass has gone away. Give it some time. Close your eyes and concentrate on the bass vibes flowing through the room...and through you...go back and forth between the Mortite treated speaker and the stock seals speaker. If you still prefer the sound of the stock seals by the next day, then by all means reinstall them. It's your world.:)

For those who find new, more thunderous bass and enhanced detail from top to bottom, who would have thought that window caulk would contribute to Such Good Sound?


Enjoy your retirement...you old bass stealing thieves!


The monoliths are glad to finally be rid of those parasitic seals.:)

[Face]

Another heads up on the PE speaker seal. Eventually the adhesive comes through the front of the gasket and attaches itself to the drivers, making it very difficult to remove the drivers if you can't apply pressure from behind.

[thsmith]

DarqueKnight , excellent post and test. I am picking up my new to me SDA 1Cs this weekend. As I update the tweeters after getting them home and want to remove the MW drivers to verify correct model and placement I will be adding Mortite.

THANK YOU !

[MillerLiteScott]

Raife,

Where did you buy the Mortite?

Scott

[DarqueKnight]

Home Depot. In the same area as the weather stripping tapes.

I'm doing the SRS's in my HT this evening.:)

[thsmith]

DarqueKnight, did you happen to snap some pics of the drivers after Mortite was applied ?

[DarqueKnight]

No, but I can tell you what the application looked like. A continuous cord of caulk was placed midway between the outer and inner edges of the driver and passive radiator rims. At the bolt holes on the drivers and passive radiator, the caulk cord was run between the space between the hole and the inner rim edge. For the tweeters, a continuous cord of caulk was placed just inside the plastic ridge on the back.

[thsmith]

No, but I can tell you what the application looked like. A continuous cord of caulk was placed midway between the outer and inner edges of the driver and passive radiator rims. At the bolt holes on the drivers and passive radiator, the caulk cord was run between the space between the hole and the inner rim edge. For the tweeters, a continuous cord of caulk was placed just inside the plastic ridge on the back.

Great, Thanks !

Will pick up sum. 2 days before I leave for a 1000 mile trip to pick up my first SDAs.

[hearingimpared]

Boy oh boy more work to do.:D

[DarqueKnight]

I neglected to mention that my tweeters are the silk dome RD0 models on my SRS's and my 1.2TL's. The rear of the SL2000 is similar to the RD0 tweeters, so a single cord of Mortite should suffice. After looking at the SL3000 tweeters that I took out of my 1.2TL's, I see that the rear surface is deeper inside of the perimeter ridge than that of the SL2000 and RD0's. For the SL3000, I would apply a cord of Motite, press the tweeter into its baffle slot to level the caulk, then remove and apply another cord of Mortite on top of the first leveled cord.

[dbnh]

Thanks for this low cost tip, I look forward to implementing it in the near future. Just another reason why I often enjoy this forum and the informative input of a number of its members. :D

[billbillw]

This is no surprise. I used to use Mortite back in the 80's to seal my car subwoofer boxes. I used it around the drivers, in all the seams, around the ports, around the terminals, you name it.

One word of caution. After a couple years in my car sub boxes, I noticed this stuff hardens up pretty good and it proves difficult to remove the drivers. I remember it actually pulled away some of the MDF when I removed a set after 5+ years of car use. Of course, car use is a bit different than home use. Severe temperature extremes, humidity, etc. Perhaps the product has improved over the years as well. I notice that the box say non-hardening, easily removed.

[BrettT1]

Thanks for some more great information!!

[mhardy6647]

I think Moretite is just a great name for a product, don't you?
I was thinking about having a cheap knock-off product formulated and selling it as Lessloose.

[MillerLiteScott]

Picked up some Moretite today. I got a project for the weekend.

DK did you moretitelize (new terminology) your terminal cup?

Scott

[heiney9]

Picked up some Moretite today. I got a project for the weekend.

DK did you moretitelize (new terminology) your terminal cup?

Scott

I will try this on my Monitor 5B's first to see how it works out and what it's like to work with before tacking my 1C's. Scott and anyone else trying this keep us posted with progress and tips you may discover along the way.

H9

[IrishNiner]

Also picked up some Moretite today. Will seal my newly moded RTA 15tl's (Big Thanks to ZINGO/Jake) :D and report back. Polk used this or something simular on my early Monitor 10's and it's still holding.

Farrell

[IrishNiner]

Thanks for this low cost tip, I look forward to implementing it in the near future. Just another reason why I often enjoy this forum and the informative input of a number of its members.

I'll second that!

Farrell

[MillerLiteScott]

Well I just mortited my 2B's and it is definitely a good cheep tweak. The word that comes to mind to describe the difference is "Tactile". The music has more weight to it, most likely from the better contact the drivers have with the cabinet thus presenting more mass.

Next time you are in HD pick up some Mortite for @ $5.00 and spend about an hour or two installing it. Clean all your contacts while you are in the cabinet. I also put a little clear silicone on the allen bolt that holds my crossover to seal that as well as possible. My speakers also have a little plastic button that goes into a hole in the back of the cabinet and I buttered that up on the inside to seal it. I used the mortite on one of my terminal cups but you have to be very careful when tightening it back up because it seemed like it would be very easy to crack the plastic cup. I may do the other one when I have my 2B's out of my system to try some other speakers because that one is not as easy to get behind to do the work.

Many thanks to Raife for 2 very cheap but very effective tweaks in one week.

Scott

[DarqueKnight]

DK did you moretitelize (new terminology) your terminal cup?

I thought about going around the terminal cup and the crossover plate but I didn't think it would make a difference because:

1. Unless there is some surface damage in those areas, any air escaping would be much less than the air escaping through the spiders and dust caps.

2. The main thing is to couple the drivers to the baffle.

In the case of the crossover plate, it might be better to use a material like neoprene rubber that would decouple the crossover board from the baffle and reduce vibrations of the components.

I'm now wondering if Dynamating the crossover components would be beneficial. Hmmmmmmm....

[DarqueKnight]

After Mortitelizing the SRS's in my home theater, the sound was so different that I thought I must have connected one or more drivers out of phase. I removed all the drivers and tweeters to check for mis-wiring and every thing was connected correctly.

I initially thought something was wrong because the sound stage seemed unnaturally wide and deep. After listening at length, I realized that the sound stage dimensions had not changed, but the weight of sounds at the sound stage perimeter (far front, far rear, far left, far right) had increased to the point where they were far more noticeable. There was also a greatly increased presentation of image layering from front to back.

[Lasareath]

Boy oh boy more work to do.:D

I need another pair just to do all of DK's mods!

[F1nut]

i'm now wondering if dynamating the crossover components would be beneficial. Hmmmmmmm....

lol....

[bsoko2]

F1nut - I finally looked at your restoration work on the SRS's and they are amazing! I WANT! One day I too will have a set of 'em.

Bill

[F1nut]

I think you mean Sal as I have not restored any SRS's.

[MillerLiteScott]

DK,

Now that you mentioned it I also noticed instruments on the outsides of the soundstage were louder or more noticeable after installing the mortite.

Scott

[thsmith]

You guys are killing me:D

Leave Dallas at 4:30AM in the morning for Phoenix to pick up my SDA 1Cs.

RD0194s will be dleivered today, need to get some Mortite and weather stripping, CAver TFM-25 arrives tomorrow, get back late Saturday night and a fun filled Sunday integrating, listening, tweeking, listening, YAHOOOO;)

Oh yea, catch heck from the Misses for spending too much time playing with Audio. :(

[Lasareath]

F1nut - I finally looked at your restoration work on the SRS's and they are amazing! I WANT! One day I too will have a set of 'em.

Bill

Thanks Bill!

[ben62670]

I'm now wondering if Dynamating the crossover components would be beneficial. Hmmmmmmm....

I know that the caps have a tuning fork effect to them when plucked. I hot glue them, and I think this will help damp them, but I have not done anything other than that.
Ben

[guptonr]

...2. The main thing is to couple the drivers to the baffle....

I'm going to reseal my 7Bs with this. Is sealing the drivers with this mainly for sealed speakers or would it benefit some ported ones I have too? I have some that could use new seals; the old ones are worn and torn.