Javs' Modular Tower WMTW - 15FH520 / Beyma 12P80ND-V2 / TPL-150H - Page 2 - AVS Forum | Home Theater Discussions And Reviews
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post #31 of 68 Old 06-06-2017, 02:05 AM
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Javs your un unbelievable!

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post #32 of 68 Old 06-07-2017, 04:18 PM - Thread Starter
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Quote:
Originally Posted by chrapladm View Post
Javs do you know which 15's work in small enclosures for a 40hz tune? Or 30hz tune?

Didnt know if you knew this off hand is all. Also always been curious about trying some FP drivers in a design. Didnt like how my last purchase went so I have stuck with BC/Beyma. BUT I am still very curious to compare.

PLUS I am hoping to see if I can make some large towers and somehow squeeze some 18's in the sides.
Not too sure sorry dude...

What was the bad FP experience you had? Buying from where?

Man, you always have build ideas you are working on, make sawdust!

What are you using right now?

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post #33 of 68 Old 06-07-2017, 04:55 PM - Thread Starter
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Ugh, man I just typed a twice as long version of this post and accidentally hit back, and lost the whole thing! Happened more than once to me, and I just fixed the issue from ever happening again by installed a Firefox extension called CACHE VIEWER. I set it to keep any text field entries as I type them for up to 6 hours... And it seems to work, phew, because that is incredibly frustrating when it happens. I recommend it...

Anyway, here is the gist of the post again:

MODULE CONSTRUCTION:

Boxes are coming together nicely, I have all the MDF cut out for both towers now, I am just finalising the bracing in the LF box, which is almost done, then I can glue the rest of those up, I have all modules for both towers in various states of gluing, to the point I now need to add the internal bracing before I can close up the boxes...

I will add some more bracing to the rear walls in the Mid and AMT modules today, I just want to join that rear wall to the side walls to make the boxes a little more inert back there, and then I think it will be perfect.


FINISH:

I have been playing around with wood finishes on various pieces of veneer glued to little square MDF panels in the past week. I think I have decided on Boiled Linseed oil coat to really deepen and enhance the grain, and then use a wipe on gloss poly finish applied 4 or 5 thin coats... The last towers I did ended up with a satin finish, but I would like just a tiny bit more of a deep wet-look to these, but not a mirror shine, I don't want it to look like glass, I still want these to kind of look and feel like wood, so I guess almost approaching semi-gloss would be nice.


BAFFLES:

Has anybody got a link to, or experience with mating a baffle to a totally finished box?

I kind of want a small 2-3mm shadow line right at the area the baffle mates to the box. Last build I did for my towers, I had the baffle glued to the box after the veneer was done, and then I finished both the baffle and box together, I painted the baffle and oiled and coated the box with the baffle attached, while I did protect each respective piece when I did it, though, I was never totally happy with the intersecting line where the two pieces mated, it wasn't perfect up close, and kind of had a little bit of a raised build up of finish/paint there where it built up on the edge of the tape etc.

So, I want to be able to completely finish the box with poly etc, and paint the baffle, and then mate the two without any worry of glue leaking through the seams, which is one reason I think a very small shadow line would be great, not to mention visually cool.

I also don't want to use screws or bolts to attach the baffle as I have seen in some other builds such as the linkwitz ones.


GRILLS?:

Toying with the idea of inserting neo magnets under the surface of the front baffle and making grills, never done that before, but it might be nice to have, I am getting a little sick of looking at dusty cones, they are a real bastard to clean the tacky paper cones!! Plus my little 13 month old troublemaker sees paper cones and wants to scratch them for some reason, yet walks right on by any speaker with a grill.

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post #34 of 68 Old 06-07-2017, 05:45 PM
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My 7 little ones will scratch right through the paper cone and surround of any uncovered speaker. (cats, fur-babies)

Are you going to employ any CLD techniques on your baffles?
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post #35 of 68 Old 06-07-2017, 06:14 PM - Thread Starter
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Originally Posted by Steve Hanna View Post
My 7 little ones will scratch right through the paper cone and surround of any uncovered speaker. (cats, fur-babies)

Are you going to employ any CLD techniques on your baffles?
What does this mean?

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post #36 of 68 Old 06-07-2017, 11:29 PM
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Constrained layer damping.
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post #37 of 68 Old 06-08-2017, 01:35 AM
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Quote:
Originally Posted by Javs View Post
Not too sure sorry dude...

What was the bad FP experience you had? Buying from where?

Man, you always have build ideas you are working on, make sawdust!

What are you using right now?
Tried ordering some 8's. Had many emails going back and forth with someone who was a dealer in Australia. Also ordered a single horn and in the end the person said they were only selling the horns in pairs. Even though I paid for the single horn already. And then when the 8's arrived to them they were the wrong Re. So in the end I got nothing from them. Nothing like waiting months for some parts and then getting nothing.

I will be building a pair of 3way towers that will fit in my living room. Just going to use the parts I have for now. That will be TPL-150's, PHL 3451 mid, Beyma SN110N pair per speaker. Building some 3ways for outdoors also.(clone JBL AM7315)

After I finally have these towers built I hope to have more disposable income. Then I will start on my TPL SH for outdoors and see how I can squeeze in some larger mains like your new dual 15 monsters.
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post #38 of 68 Old 06-08-2017, 01:56 AM - Thread Starter
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Quote:
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Constrained layer damping.
Not planning on it, no.

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post #39 of 68 Old 06-09-2017, 07:49 PM - Thread Starter
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Just a quick mock up photo of the scale these things are going to be...

Just huge! They will certainly be the biggest speakers I have ever seen in person...





1.92m high.

Have already cleared the space in my theatre so I know they are going to fit, will likely require just a touch more toe out than my current alignment is, but that's ok. These things will really shine though when I can get a room that has at least 50-100% more depth and about 50% more width...
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post #40 of 68 Old 06-09-2017, 08:00 PM
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Better get Stitch out of there or the whole project will be destroyed. lol
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post #41 of 68 Old 06-10-2017, 06:31 PM
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This picture reminds me that I need to buy a shop vac
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post #42 of 68 Old 06-17-2017, 12:05 PM
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Glad to see another build taking shape. No matter where you are in this hobby there's always someone pushing the envelope even further. Look at the size of these!! Good luck. Are you single or do you have a very understanding other half
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post #43 of 68 Old 06-17-2017, 03:55 PM - Thread Starter
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Glad to see another build taking shape. No matter where you are in this hobby there's always someone pushing the envelope even further. Look at the size of these!! Good luck. Are you single or do you have a very understanding other half
I have a happy, understanding little family

Another update to come very soon, making progress on all the boxes.

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post #44 of 68 Old 06-21-2017, 01:51 AM - Thread Starter
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Bit of progress,

Boxes are built save for the baffles, I am just in the progress of adding some additional small bracing areas to the cabinets. Just things like reinforcement triangles joining panels together and hopefully slightly reducing the resonance of some of those panels, or at least pushing it higher.

I probably should have built these with 25mm MDF, I did my towers and rears with that wood and its most definitely far more inert and rigid as a whole with that wood, bit of a bummer, so I guess just making sure I do the best bracing I can for what I have...

I have decided I am going to save the $600 cost of veneer and finish these with Duratex. I admit its the easy way out and a little bit of a shame, but the reality is, I care very deeply about BLACK theatre and maximising contrast from my projector, so, just as I have black velvet covering all the veneer and thus, reflection on my current towers, with curtains on the opposite sides completely blocking any view of the veneer, I felt it was just going to be a waste of time since the first thing I would do is cover them with velvet again, furthermore, when I finally get to be able to build a proper screen wall and stick these beasts behind an AT screen, they will completely disappear. So duratex it is. I will save the single sheet of Jarrah I have for smaller projects where the beauty can actually be on show. This does however significantly speed up the time to finish and the ease of finish, now I can just sand the boxes totally smooth baffles attached and hit them with a spray gun.





LF Boxes... still adding more bracing to these, I think I might even add some lead or bitumen to the inside, and then some foam over that. Thoughts? They will only need to play up to about 350hz crossover, and the good thing is they will be structurally disconnected from the mid and tweeter box.

Ports are rounded over on the inside of the box, so they should have good airflow, I will also round-over the exit of the port.











Mid box, will add some more bracing triangles connecting the middle window to the sides and top/bottom in that exposed front section there. I think for these I definitely will add a whole lot of bitumen or some sort, dense foam, and then even some poly fill as these are going to be sealed, I want to do my best to subdue that rear wave. 350hz - 1200hz.





Tweeter Box. Same thing with the bracing triangles here, and the bitumen, foam and polyfill. One thing I sort of discovered, I may have made that window just a little small, when I was hitting the boxes with compressed air to get some dust off, when I hit that tweeter box, it resonated, I think I have inadvertently created a sort of massive internal port. I think what I may need to do is take a drill to the front bracing window there on the sides and open it up, add some smaller 2-3inch holes on either side for eg to just break up that effect. Perhaps 4 holes on the outer corners will do.



Any thoughts on where I may need to add some more bracing ?

You think adding some strips here would do anything (See the black lines)? Or do they really need to be hitting the very opposite panel? I guess I could do that, just insert it far enough into the box that the rear of the woofer wont interfere with it.

The red lines are things I am already doing... just haven't glued them yet.

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post #45 of 68 Old 06-21-2017, 02:18 AM
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Can't wait to see how these turn out! Awesome stuff dude!
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post #46 of 68 Old 06-21-2017, 06:00 AM
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Constrained layer damping might be more effective than bitumen or lead. 3m auto glass urethane windshield adhesive 1/8" with a 1/4" plywood caps in your larger unbraced panel areas or you could use Sorbothane sheets with the constraining cap.
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post #47 of 68 Old 06-21-2017, 03:52 PM
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External damping (= unconstrained damping layer) like a putting a bitumen sheet on top of MDF is a lot less effective than constrained layer damping. And to be effective the external damping needs to be thick, roughly the same thickness as your substrate (MDF, metal sheet or whatever you wish to dampen vibrations from) This will make the cabinet extremly heavy! Constrained layer damping: MDF+a thin damping layer+MDF. An interesting thing with CLD is that going down in thickness improves damping properties a lot. Check out the diagram: http://vibratec.se/wp-content/upload...14_ver-2.1.pdf

I used some non hardening Loctite glue (an MS polymer) for my cabinets, 0,8 mm thick. There are a number of manufcturers and brands, Tec 7 etc, etc. Search for one with a rather low shore number when cured, 40-50 Shore A, should be suitable, or shear strength around 10,1 MPa / 145 lbs/in². There are other viscoelastic layers one can use also, like water based ones.
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post #48 of 68 Old 06-21-2017, 10:45 PM - Thread Starter
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I can get Green Glue here, that would do right? Same thing no?

I was planning to use something like this to actually attach the bitumen, but MDF is way cheaper, if that does the same thing or better then good.

So, INSIDE my box, cut panels of 6-9mm MDF or so, attached them to the insides with green glue between them and I should be good?

Then any foam damperning I wanted to use, I could just attach over the top of that...

So looking at my pics above, if I use this technique on sections of the walls rather than the entire walls, since I have things in the way, existing bracing etc, it will still be effective no?

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post #49 of 68 Old 06-22-2017, 12:58 AM
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GG is not an adhesive. It can work well when other fastener or fastening devices are used. I have used it on one of my cabinets to see how it would do in the past. Worked well but not sure it was mainly because the GG or overkill bracing.
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post #50 of 68 Old 06-22-2017, 02:24 PM
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Good bracing first. Then CLD.
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post #51 of 68 Old 06-22-2017, 05:24 PM
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Quote:
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I can get Green Glue here, that would do right? Same thing no?

I was planning to use something like this to actually attach the bitumen, but MDF is way cheaper, if that does the same thing or better then good.

So, INSIDE my box, cut panels of 6-9mm MDF or so, attached them to the insides with green glue between them and I should be good?

Then any foam damperning I wanted to use, I could just attach over the top of that...

So looking at my pics above, if I use this technique on sections of the walls rather than the entire walls, since I have things in the way, existing bracing etc, it will still be effective no?
I am speculating a bit here, but: I don't think Green Glue would be the best choice as dampening layer in a CLD for your speakers. Why? Consider its main purpose: It is used for very large surfaces, as dampening layer between gypsum sheets for stud walls in a room. Frequencies you wish to dampen then are primarily in the bass range, and a "common stud wall" with gypsum sheets and c-c 600 mm / 2 feet for the studs has a resonance around 70 Hz or so. Around 70 Hz will be amplified to the next room and lower ones passes through quite readily as well. For low frequencies a softer dampening layer with low shear strength is more effective than one with higher shear strength.

Now, consider your speaker size; you have no large unsupported surfaces compared to a stud wall and cabinet resonances should be way up higher in frequency than a stud wall. => A higher shear strength viscoelastic layer should be more suitable. The Green Glue is messy and runny and completely useless as a construction glue, never gets hard and cures. (At joints use white PVA glue or similar strength glue, over the flat surfaces use the viscoelastic layer of your choice.)

Check up the link to the patent in this post: The Science of Speaker Cabinet Design From diagrams and text in the patent it is quite obvoius the range of viscoelastic layers you can buy offers better or worse properties depending on the frequency range you wish to dampen. If the inner substrate layer and outer layer are of the same kind of material, you'll get best dampening if they are of equal thickness. If different materials, the outer could be thinner if it is stiffer than the inner one.

There are more good info in that thread which is worth reading.
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post #52 of 68 Old 09-05-2017, 11:03 PM
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@Javs

How's this project coming along? I'm quite curious how you're implementing your ideas. I've got a stack of premium drivers in their boxes driving me nuts. Still can't get started until I do some home repair projects first. I've finally returned back to work. What a trip this summer turned out to be.
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post #53 of 68 Old 09-09-2017, 05:04 PM - Thread Starter
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Quote:
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@Javs

How's this project coming along? I'm quite curious how you're implementing your ideas. I've got a stack of premium drivers in their boxes driving me nuts. Still can't get started until I do some home repair projects first. I've finally returned back to work. What a trip this summer turned out to be.
Nothing really to report at the moment, have been super busy with work, and a trip overseas etc, hope to have this done though in the next month or so.

Still debating over weather to veneer the boxes or not, this has slowed things right down since it will affect the steps I need to take to get the boxes assembled.

I did end up finding a type of glue to use for CLD construction inside the box. Its called Sika 11fc. I tested it and it dries still plyable and soft and rubbery and is able to glye two panels together strong enough there is no chance I can pull them apart again. Its used for gap sealing in bathrooms and gluing tiles etc, it also specifically mentions its a vibration absorber so it seems CLD is a use with this glue... I will use that to add a whole bunch of 9mm internal panels to my boxes and then finish with lining the walls etc. Its going to be messy but I think it will be worth it.

I tested the glue on a large panel and it definitely made the panel much more inert and dull sounding, the knock test passed as far as I am concerned.

Will report more when I start playing with it again.
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post #54 of 68 Old 09-10-2017, 03:31 AM
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Quote:
Originally Posted by Adhoc1 View Post
External damping (= unconstrained damping layer) like a putting a bitumen sheet on top of MDF is a lot less effective than constrained layer damping. And to be effective the external damping needs to be thick, roughly the same thickness as your substrate (MDF, metal sheet or whatever you wish to dampen vibrations from) This will make the cabinet extremly heavy! Constrained layer damping: MDF+a thin damping layer+MDF. An interesting thing with CLD is that going down in thickness improves damping properties a lot. Check out the diagram: http://vibratec.se/wp-content/upload...14_ver-2.1.pdf

I used some non hardening Loctite glue (an MS polymer) for my cabinets, 0,8 mm thick. There are a number of manufcturers and brands, Tec 7 etc, etc. Search for one with a rather low shore number when cured, 40-50 Shore A, should be suitable, or shear strength around 10,1 MPa / 145 lbs/in². There are other viscoelastic layers one can use also, like water based ones.
So what material would you recommend for optimal CLD in a typical 3 way tower speaker? Also what would you recommend as the adhesive? Assuming the enclosure would be built out of 3/4" plywood or 3/4" MDF. I have read through most of the thread on this subject, but to be honest, most of it was over my head.
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post #55 of 68 Old 09-11-2017, 04:25 PM
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Originally Posted by Tip24/96 View Post
So what material would you recommend for optimal CLD in a typical 3 way tower speaker? Also what would you recommend as the adhesive? Assuming the enclosure would be built out of 3/4" plywood or 3/4" MDF. I have read through most of the thread on this subject, but to be honest, most of it was over my head.
Like I wrote: " ... Search for one with a rather low shore number when cured, 40-50 Shore A, should be suitable, or shear strength around 10,1 MPa / 145 lbs/in². There are other viscoelastic layers one can use also, like water based ones."

The glue / constrained layer is the adhesive when applied in about 1 mm (3/64") thickness between 2 sheets of MDF or plywood. I would stay away from stuff containing silicone as it is not paintable. A glue that does not harden and stays soft over time is what you are searching for. The one I used was fom Loctite / Henkel, their "Terostat 930". It is rather costly, so you can check up other brands and glues. If it is a MS polymer, acrylic or butyl based can be of less importance. A standard cartridge contains 290-300 ml and will be sufficient for a 1 mm layer on a surface of 1x0,3 m (about 3 ft²).

For joints end-to-ed, use regular wood glue. The soft glue for the constrained layer is not suitable as a construction glue.
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post #56 of 68 Old 09-11-2017, 04:57 PM - Thread Starter
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So, since CLD was kind of a bit of an afterthought with this project and I have a lot of bracing in the boxes already, what I am doing is attaching 200x200mm panels inside my LF enclosures in a few places on the side walls, top, and bottom in between the existing bracing.

I have already attached a few of them, and it has definitely significantly changed the tone and enduring resonance of the knuckle rap test. The untreated boxes result in a much louder higher frequency, longer lasting resonance, I feel like the small amount of CLD treatments I am doing are really going to aide the bracing which is already there in mitigating some resonances in the time domain. The bracing seems to push the resonances higher in frequency, lessens the volume and they dissipate quicker, and the CLD used in the larger middle portions of the remaining panels definitely made the resonances lower in frequency but they disappear almost immediately...

I might actually set up a quick test and record the difference since I have not done all the LF boxes just yet. Will be interesting to see. None of them have baffles, but the boxes I have treated with only 4x panels per box are definitely now more inert due only to the CLD on the inside.

When we think about how CLD works, those 200mm square panels are going to be catching a lot of energy inside the box and dissipating it before its able to fully translate to the encloseres larger panel, so it seems to me, even using cut to size panels of CLD inside an already built enclosure, even a fully finished speaker you forgot to add bracing to, is going to help a ton with dissipating the internal energy in the box and not allowing the outer enclosure to resonate as much.

I will take a pic soon. Its a very messy procedure thats for sure!

This Sika 11FC glue is working really well though, and it was only about $7 USD a tube.
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post #57 of 68 Old 09-12-2017, 01:59 PM
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Congrats on your results Javs. I wouldn't be too sure the CLD actually lowers the panel resonances in frequency. More like the "duller" tone you hear now, couldn't be heard before as it was over powered by much louder and longer ringing in time of higher frequencies. A good CLD can lower amplitudes of panel resonances by roughly 8-16 dB, varies with the frequency, -quite substantial.
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post #58 of 68 Old 09-12-2017, 04:38 PM
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Javs' Modular Tower WMTW - 15FH520 / Beyma 12P80ND-V2 / TPL-150H

CLD and damping in general have no effect on the resonance frequency only the resonance Q. The reason that the frequency does shift is simply the added mass.

I had a post about this a few months back that linked a lot of articles on the topic. I really think CLD should be more widely used in DIY projects. Makes a huge difference and isn't so expensive to implement.

One point though. Damping isn't needed, wanted, or of any value in LF enclosures like subs. It matter only for full range speakers operating in the midrange. With LF cabinets the only thing that matters is rigidity as they functionally act as a pressure vessel below resonance and you want to operate them below resonance. The best way to think of it is that full range speakers should seek to push the panel resonance as low as possible and operate only above that resonance. You want lots of mass and high damping. LF cabinets should push the resonance as high as possible and operate below the resonant frequency. Mass and damping don't matter, only stiffness matters. Of course really stiff often means really massive too.


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post #59 of 68 Old 09-12-2017, 07:41 PM - Thread Starter
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Originally Posted by Mpoes12 View Post
CLD and damping in general have no effect on the resonance frequency only the resonance Q. The reason that the frequency does shift is simply the added mass.

I had a post about this a few months back that linked a lot of articles on the topic. I really think CLD should be more widely used in DIY projects. Makes a huge difference and isn't so expensive to implement.

One point though. Damping isn't needed, wanted, or of any value in LF enclosures like subs. It matter only for full range speakers operating in the midrange. With LF cabinets the only thing that matters is rigidity as they functionally act as a pressure vessel below resonance and you want to operate them below resonance. The best way to think of it is that full range speakers should seek to push the panel resonance as low as possible and operate only above that resonance. You want lots of mass and high damping. LF cabinets should push the resonance as high as possible and operate below the resonant frequency. Mass and damping don't matter, only stiffness matters. Of course really stiff often means really massive too.
So CLD should be more beneficial in full range boxes rather than LF?

My LF boxes are likely to be crossing over decently high 250/300hz... so Its starting to really be midrange.

My project is literally split into enclosures for each speaker which is already good in terms of pollution from one driver affecting the enclosure from another driver, I was not really planning on adding any CLD to the mid range and tweeter boxes, do you think I should? those boxes are quite a bit smaller and there is less room to add in the CLD panels after the fact. I was just going to put a whole heap of damping inside the box.

They are fairly rigid, but the sections in which I have added the CLD are problem areas which had quite large untreated areas due to the size that the drivers will take up, preventing window bracing the way I had done it. those few problem areas are not definitely better with the CLD treatments.

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post #60 of 68 Old 09-12-2017, 08:03 PM
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Rigid isn't necessarily good in a midrange box. The midrange boxes should be fairly lossy in the sense that they should absorb and dissipate a good amount of the energy. Rigid is good for low frequencies where the boxes operate largely as pressure vessels.

Small doesn't mean that it doesn't need damping. Those sections will still resonate and still allow a bit of sound to leak through. CLD is most beneficial in the mid and high frequency section. It actually serves no benefit for low frequencies at all. At low frequencies (those below the resonant frequency of the enclosure walls) the dictating factor is the rigidity of the walls. Even mass doesn't matter, if you can believe it. Mass can even make matters worse. Raising the mass lowers the resonant frequency. Since it's so difficult to dissipate large low frequency energy through a lossy box it makes more sense to raise the resonant frequency and raise rigidity. It's more effective and keeping the negative effect of the resonance out of the operating range and this out of the area that matters.

I can't remember the resonances I was picking up in my large sub boxes with the accelerometer. I want to say they were centered pretty high, in the 100's of hz.

Because your boxes are operating up pretty high I guess I might still try to push up the rigidity/stiffness as much as possible to get those resonances as high as possible. Bracing helps too. While at very low frequencies the braces don't have the ability to fully subdivide the panels, that is true at higher frequencies.

If the resonances are sufficiently high the CLD will damp the resonances and be of benefit. I don't think you wasted effort necessarily. It's just in sub boxes where it's a counterproductive waste. It may not provide as much benefit as it would in the midrange boxes.

There is a lot of misinformation with regard to acoustic transmission loss. My own understanding originally came from the diyaudio forum and this one. I misunderstood, misinterpreted, and largely was misinformed and thus built a lot of silly boxes. It was only recently when I began studying the phenomena for soundproofing that I had the full understanding I have today. I read a lot of scientific journal arrivals and engineering texts specifically on transmission loss rather than sound proofing to better understand the physics. I stumbled on a number of papers focused on TL in speaker boxes and saw the parallel with that and soundproofing.


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