Want more bass? Seal your speakers

[michaeljhsda2]

This was another area where air was leaking out of the cabinet. The cardboard tube is hollow and extends to the back of the speaker and exits to the outside. What is the purpose of this long hollow tube I wonder?

[michaeljhsda2]

I love hot glue :D

[michaeljhsda2]

Just finished hot glueing, Dynamat and Mortite of the left channel cabinet and it only took 5 hours with the help of my friend Jerry aka thejermon!!! To say these speakers sound better is an understatement. My listening room is in a finished basement with carpeted concrete floors and the bass is response is a million times better now. The sound is very full and rich. Now the speakers sound like they should sound IMHO.

[F1nut]

You know, there is such a thing as over damping. Those drivers need to move and if you make it harder for them to do so, well that's called over damping.

No Mortite, silicone, fancy screws, etc. and I've got bass....in spades.

[michaeljhsda2]

You know, there is such a thing as over damping. Those drivers need to move and if you make it harder for them to do so, well that's called over damping.

No Mortite, silicone, fancy screws, etc. and I've got bass....in spades.

Well good for you .

1. You didn't criticize Darqueknight and everyone else who has used mortite so why are you giving me grief when I use it?
2. The inside cabinet is supposed to be sealed.
3. Fancy screws? They're the same ones Polk uses.
4. The speakers sound better to me.

I'm sick of you and your negativity.
You've been added to my ignore list.

[F1nut]

Well good for you .

1. You didn't criticize Darqueknight and everyone else who has used mortite so why are you giving me grief when I use it?
2. The inside cabinet is supposed to be sealed.
3. Fancy screws? They're the same ones Polk uses.
4. The speakers sound better to me.

I'm sick of you and your negativity.
You've been added to my ignore list.

1. I have stated previously that I will not use Mortite on my speakers, so keep up.
2. Obviously, you don't understand the concept of over damping.
3. Why do you think everything I said was directed AT you? Others have mentioned using "fancy" screws, so keep up.
4. Bully for you.

I'm sorry that your false pride/ignorance prevents you from recognizing help when it's offered.

I've got a Franklin that says you read this post.

[heiney9]

No Mortite, silicone, fancy screws, etc. and I've got bass....in spades.

My 1C's too! I have more bass than I know what to do with. I will do Mortite and dynamat with the 5B's and may just leave the 1C's alone.

[F1nut]

My 1C's too! I have more bass than I know what to do with. I will do Mortite and dynamat with the 5B's and may just leave the 1C's alone.

I'm sick of you and your negativity, H9.
You've been added to my ignore list. ;)

[dbnh]

Disconnected crimp connectors from every MW and tweeter, applied Deoxit Gold, and then reattached. Disconnected the wire harnesses, applied Deoxit Gold and then reattached.

Now there’s bass!!!

Some time ago, on my 1Cs I cleaned the above mentioned items with Deoxit (red), then applied Walker SST. Made some instantly noticeable positive difference, including with bass reproduction.

[NJPOLKER]

Well good for you .

1. You didn't criticize Darqueknight and everyone else who has used mortite so why are you giving me grief when I use it?
2. The inside cabinet is supposed to be sealed.
3. Fancy screws? They're the same ones Polk uses.
4. The speakers sound better to me.

I'm sick of you and your negativity.
You've been added to my ignore list.

Now now Mike, you have to understand this is all over the computer and you have no way of knowing if F1 has being critical just from what he wrote. I know you are real proud of your new work and should be but don't be soooo defensive. Constructive criticism is great because it generally accurate info. and everyone learns a lot. And it was not all directed at YOU but for everyone to learn from. Just my opinion.

[DarqueKnight]

As I stated in a different thread, the inside cabinets of my 1.2 TL’s were not completing hot glued in all of the inside corners and they were leaking air like a sieve from various other locations as well. However, after sealing them up with hot glue and applying Mortite there’s been a dramatic improvement in bass response.

You know, there is such a thing as over damping. Those drivers need to move and if you make it harder for them to do so, well that's called over damping.

Michael,

Jesse (F1nut) brings up a good point about over damping. SDA cabinets are passive radiator designs which are a hybrid between ported box and air-tight sealed box designs. Therefore, SDA cabinets are not supposed to be completely sealed against air leakage. Indeed, even if every possible air leakage point were sealed, air would still leak out of the fabric covering the 6-1/2" driver center caps.

Another thing to consider is that SDA passive radiators are "fluid coupled" (air coupled) to the 6-1/2" drivers by the air inside the cabinet. Some small amount of leakage, into and out of, the speaker cabinet was accounted for in the design of the speaker. If this air leakage is significantly changed, the sound of the speaker will change. This change may or may not be pleasant to the listener. However, I speculate that the change would be in the opposite direction of optimizing the design specification. You say you like what you are hearing, so that is all that really matters. My goal for modification is to realize an improvement toward greater accuracy rather than just a change. That is why I always consult with the manufacturer prior to performing any significant design modifications.

Modifications that remedy parts, design or construction compromises (such as improved, tighter tolerance crossover components) move toward optimal performance. Modifications that do not remedy parts, design or construction compromises do not move toward optimal performance, although the resulting sound might be pleasing to a listener.

The use of Mortite was specifically recommended by Matthew Polk as a higher performance alternative to foam speaker gaskets. Mortite more tightly couples the driver rim to the baffle board, thereby reducing the portion of the audio signal's energy that would be wasted transferring motion to the driver rim rather than the driver cone.

The use of foam damping material on the driver and passive radiator baskets was specifically recommended by a Polk engineer to damp basket vibration (ringing). This ringing re-radiates acoustic energy inside the cabinet that can smear details in music.

You might consider asking Polk's customer service department to pass along an inquiry to their engineering department asking if increased cabinet sealing would result in more accurate performance.

Ray

[michaeljhsda2]

Ray,
There were areas of the speakers that were never hit with the glue gun to begin with. Cracking noises were heard when lifting them. There were 3 cross braces that were just free floating in the air on one end with no glue on them whatsoever. The 2 back corners of the cabinet had minimal to no glue in them so I just added another bead of glue. A couple of the wood screws were stripped out on the PR so instead of shoving toothpicks in there or using wood putty, I decided to use a better fastening method, just like the 1.2’s have, which is threaded inserts and hex head cap/button screws. The only things I did that I don’t seem to recall others doing is that I hot glued the 8 end cap nuts and the cardboard bass brace tube, and I used mortite to backfill the holes in the MW’s (Richcando used duct tape). My friend Jerry has the 1.2’s and the bass response from his speakers were better than my 1.2 TL’s in the exact same listening position hooked up to the exact same equipment. More importantly, my speakers failed the PR pressure test before I made the above mentioned changes, so that’s when I decided to check out the integrity of the internal cabinet.
As for the Mortite and Dynamat, I simply did what Matthew Polk and his engineer suggested, and you and other CP members have done.
Best regards,
Mike

[jimbo1421]

Hello,

I have a pair of Monitor 10Bs (Peerless tweeter with bright brushed face). The bass sounds good on these M10s just as they are, but the lower midrange (lower octaves on the piano) could stand to be boosted. I am thinking opening them up and adding Dynamat to the PR and MW. What makes me hesitate is that when doing the press test the mid woofers take 15-20 seconds to return to center. This seems so good that I am reluctant to disturb them. Other Monitors that I have mortited take 3-4 seconds to return.

I have not actually used Mortite, but a similar product from MD called Replaceable Cord Weatherstrip. Is there a difference?

So what do you think. Should I do the Dynamat?

Regards,
Jim

[F1nut]

I'm going to clarify a misconception by the angry guy in this thread. I never said to you not to use Mortite. I simply stated that I'm not going to use it on mine. Big difference.



Who is this Ray guy? ;)





Jim, 15-20 seconds is a long time....seemingly too long. The tweeter with bright brushed face is not a Peerless, it's a SL1000.

[jimbo1421]

Jim, 15-20 seconds is a long time....seemingly too long. The tweeter with bright brushed face is not a Peerless, it's a SL1000.

Ah, so this is the SL1000. So far it is my favorite of all the vintage Monitor tweeters.

Does the overdamping you mentioned earlier specifically affect the 50-200 Hz range. That is the range that, to me, seems somewhat muted.

Regards,
Jim

[F1nut]

Yes, that is definitely the SL1000.

I couldn't say what frequency range would be affected by an over damped speaker. 3 to 5 seconds seems to be about right for the Polk's with PR's and that's why I said 15 to 20 seems a bit too long. Did the other Monitors exhibit the same muted sound as your current ones?

[comfortablycurt]

My Monitor 7A's are about the same...when I do the air tightness test, it takes about 15-20 seconds for the MW's to return all the way.

I've been planning on Mortiting them...but I can't help but wonder if it would even be worth it.

[jimbo1421]

I couldn't say what frequency range would be affected by an over damped speaker. 3 to 5 seconds seems to be about right for the Polk's with PR's and that's why I said 15 to 20 seems a bit too long. Did the other Monitors exhibit the same muted sound as your current ones?

"Muted" may not be quite the right word. Lack of presence in that low mid range might be more accurate.

I just tried a comparison with 2 other Monitor 10s using a Chopin Ballade.

Monitor 10B (1988): This one has had the Dynamat & Mortite treatment. Press test: 3 seconds. Also I replaced the SL2000 tweeters with RDO-194s. The low mid range has more presence than the M10B/SL1000.

Monitor 10A: no mods. Press test 20+ seconds. I put the low-mid range response somewhere in between the other two.

Since the SL1000 has, to my ears, the smoothest highs I would like to try the Dynamat/Mortite mod if I didn't think I would mess up something good.

Jim

[THEJERMON]

I’ve finally gotten a chance to place a post here. It was a time consuming job sealing up Mike’s 2nd speaker. Glad I wasn’t around to do the first. :D
Hanging around with Mike and listening to his stereo systems over the last 3 + years with numerous sets of Polk speakers has been a blast. I’ll be the first to say I don’t know all the ins and outs about this audio stuff but I definitely know what my ears like.
I have to say these speakers are sounding better than ever! There is a “tremendous boost ” in the bass. I can really feel the bass in my chest now. Even at low volume. There is also a “much fuller ” sound coming out of these speakers. Can’t wait to get my 1.2’s home. I’ve kept them at Mike’s place while doing some remodeling at mine. Also waiting for Ben to ship my inductor back. Expecting it later this week. Come on……. Ben!

[ANWKLO]

"Muted" may not be quite the right word. Lack of presence in that low mid range might be more accurate.

I just tried a comparison with 2 other Monitor 10s using a Chopin Ballade.

Monitor 10B (1988): This one has had the Dynamat & Mortite treatment. Press test: 3 seconds. Also I replaced the SL2000 tweeters with RDO-194s. The low mid range has more presence than the M10B/SL1000.

Monitor 10A: no mods. Press test 20+ seconds. I put the low-mid range response somewhere in between the other two.

Since the SL1000 has, to my ears, the smoothest highs I would like to try the Dynamat/Mortite mod if I didn't think I would mess up something good.

Jim

Hi Jim,

Which tweeter you like more, SL1000 or RDO-194

[jimbo1421]

Hi Jim,

Which tweeter you like more, SL1000 or RDO-194

I should say that I like the high frequencies from the Monitor 10B/SL1000 better than the Monitor 10B/RDO-194. Much smoother. The M10B/RDO-194 showed signs of abuse when I got them; I repaired open mitre joints at the bottom (maybe they gotten wet). They may have been overdriven by the young man I bought them from, which might have harmed the crossovers as well as the original SL2000 tweeters. By contrast the M10B/SL1000 were used in a bookstore their entire lives. This is the audio equivalent of the used car which was only driven on Sundays by a little old lady, i.e., they only played quiet classical music in the background.

My point is that it is the whole speaker, with its own history, that I like better, not just the tweeter. If I could punch up the lower mid range a bit I would like the M10B/SL1000 even better.

Jim

[Face]

Most others find the opposite true of SL1000's vs. RD0-194's. The SL1000's are generally on the bright side, while RD0-194's are smooth, sometimes even too smooth or mellow for some.

[heiney9]

The sl1000 and sl2000 are horrible tweeters...........especially as you move up the ladder with better and better gear. Refreshing the x-overs and then installing the RD0's is a huge improvement and both need to be done together for the best possible results.

Had the RD0 replacement not been offered I'd probably have moved on from Polk speakers. The sl2000 is unlistenable IMO and especially after spending time with the RD0's. The RD0's are smoother, more exteneded, more open and airy and delicate all at the same time and no more "shouty-ness" that was so awful on the sl2000.

H9

[F1nut]

"Muted" may not be quite the right word. Lack of presence in that low mid range might be more accurate.

I just tried a comparison with 2 other Monitor 10s using a Chopin Ballade.

Monitor 10B (1988): This one has had the Dynamat & Mortite treatment. Press test: 3 seconds. Also I replaced the SL2000 tweeters with RDO-194s. The low mid range has more presence than the M10B/SL1000.

Monitor 10A: no mods. Press test 20+ seconds. I put the low-mid range response somewhere in between the other two.

Since the SL1000 has, to my ears, the smoothest highs I would like to try the Dynamat/Mortite mod if I didn't think I would mess up something good.

Jim

Just to be sure we're on the same page.....the test should be as follows, press the PR all the way in and hold it there. The mid-drivers should push out all the way and move back slightly after 3 to 5 seconds, but not all the way back until the PR is released.

[jimbo1421]

Most others find the opposite true of SL1000's vs. RD0-194's. The SL1000's are generally on the bright side, while RD0-194's are smooth, sometimes even too smooth or mellow for some.

I know. Hence, my remarks about the history of the speakers. Rebuilding the crossovers on the M10B/RDO-194 set is on the agenda.

Jim

[jimbo1421]

Just to be sure we're on the same page.....the test should be as follows, press the PR all the way in and hold it there. The mid-drivers should push out all the way and move back slightly after 3 to 5 seconds, but not all the way back until the PR is released.

Hi F1nut,

This describes how my Monitor 10B/SL1000 behaves, slight return after 3-5 seconds, 40 seconds or more to center. My M10B/RDO-194s seem to have sprung a new leak. They used to return to center in 3-5 seconds, now it is down to 2 seconds.

Jim

[F1nut]

Yeah Jim, your M10B/RDO-194 versions definitely have an issue.

[shack]

The sl1000 and sl2000 are horrible tweeters...........

This is my impression as well. The sl2000 has a frequency spike in the top end of it's response that makes them sound really harsh to my ears. The VERY FIRST thing I would do with any SDAs with the sl2000 is to replace it with the RDOs.

[ANWKLO]

I should say that I like the high frequencies from the Monitor 10B/SL1000 better than the Monitor 10B/RDO-194. Much smoother. The M10B/RDO-194 showed signs of abuse when I got them; I repaired open mitre joints at the bottom (maybe they gotten wet). They may have been overdriven by the young man I bought them from, which might have harmed the crossovers as well as the original SL2000 tweeters. By contrast the M10B/SL1000 were used in a bookstore their entire lives. This is the audio equivalent of the used car which was only driven on Sundays by a little old lady, i.e., they only played quiet classical music in the background.

My point is that it is the whole speaker, with its own history, that I like better, not just the tweeter. If I could punch up the lower mid range a bit I would like the M10B/SL1000 even better.

Jim

I am still hesitate to replace my SL1000 by RDO-194 after my Monitor 5 x-over has upgraded. Another concern is RDO-194 not a drop-in replacement of SL1000.:(

[tonyb]

A thread with some merit for a change. I never thought of sealing up the cabinets on my old polks but it makes sense now. You move speakers around so much over the years it's only normal that seems would seperate. Thanks to the OP for the suggestions and others who contributed on the details on how to do this.