Found this article, thought it would be appropriate here:
Speaker Design: Driver-Induced Vibrations | audioXpress
Not a lot of detail here, but some overview. Some specific products are mentioned. The references section is perhaps useful for those wanting to go into greater depth.
Speaker Design: Driver-Induced Vibrations | audioXpress
Not a lot of detail here, but some overview. Some specific products are mentioned. The references section is perhaps useful for those wanting to go into greater depth.
It would be better to use Baltic birch plywood of at least 19mm and damp the inner walls with a damping material like that used for auto sound deadening. Don't skimp on the bracing either. Trying to machine the material with goo applied sounds like a humongous mess.
Sonic Barrier 3/4" 3-Layer Acoustic Sound Damping Material with PSA 18" x 24"
Sonic Barrier 3/4" 3-Layer Acoustic Sound Damping Material with PSA 18" x 24"
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I know this is an older thread, I hope nobody minds me resurrecting it.
Has anyone seen this video? YouTube I started it at about 34 minutes because that's the part I'm interested in.
Way back in 1979 I experimented with "box in box" construction, isolating the two layers with silicone caulking material and got really good results in a 3 way system with 12" woofer, 2 x 4" mid and 2 x 1" tweeters. I used two layers of 1/2" MDF (and back then it really was 1/2") finished with oak veneer.
I'm curious to know if anyone has experimented seriously with this kind of construction on smaller stand mount or bookshelf speakers with 6 or 8 inch woofers and their impression of the technique.
Has anyone seen this video? YouTube I started it at about 34 minutes because that's the part I'm interested in.
Way back in 1979 I experimented with "box in box" construction, isolating the two layers with silicone caulking material and got really good results in a 3 way system with 12" woofer, 2 x 4" mid and 2 x 1" tweeters. I used two layers of 1/2" MDF (and back then it really was 1/2") finished with oak veneer.
I'm curious to know if anyone has experimented seriously with this kind of construction on smaller stand mount or bookshelf speakers with 6 or 8 inch woofers and their impression of the technique.
The thread has wandered around over time. It started as Constrained Layer Damping construction. This bonds the two layers firmly together with a thin visco-elastic material, such as the 1mm of Decidamp DC-30 in the video.
Alternatively one can try to isolate the two layers with a thick, soft inner layer. ex: silicone caulking. green glue (which I had no luck with in a floor-standing 3-way).
Which construction type as you interested in?
Alternatively one can try to isolate the two layers with a thick, soft inner layer. ex: silicone caulking. green glue (which I had no luck with in a floor-standing 3-way).
Which construction type as you interested in?
Thanks for the reply.
I am interested in the Decidamp. But I'm more interested in knowing how well the construction technique scales for smaller speakers.
In 1979 before materials like Decidamp came along I used a two layer construction technique that had two layers of 1/2" MDF separated by a thin layer of silicone caulking compound. This went into a rather large-ish set of speakers, IIRC 32" tall and 20" wide. I assembled it with 1x1 along the corners and way too many screws. The technique worked very well, the boxes were very inert... as shown in the video. (In fact, when I showed a friend the video he commented: "He's reinvented your speakers!".)
But that was a full on monster speaker build in an acoustic suspension cabinet, that ultimately was lost in a house fire.
So, now, some 36 years later and being an apartment dweller, I'm wondering is how well this would scale down to a larger bookshelf/standmount and possibly ported enclosure. I also find myself curious what materials advancements (eg. Decidamp) have come along in the interregnum.
Thanks for that... but not really interested in "quick and dirty"... more of an eye to "ultimately best"...
Ultimately best is to isolate the speaker ( the woofer enclosure); the only way of doing that is to make an elastic suspension where the elastic arrow falls out of working band ( below 20 Hz). Each speaker ( midrange and tweeter ) follows. Same for every component subjected to the vibrations produced by sound...or is the vibration that produces the sound ( don't answer that, it is not a question!) !?
It lead to this...
12" woofer, 2 x 4" mids, 2 x 1" tweets. All Phillips Deforest ... and one of the best sounding speakers I've ever heard. I still miss them, to this day. The picture is old, the scan isn't the best... but if you look closely at the front baffle you can see the dual layer construction.
Can we... maybe... get on to discussing my questions?
12" woofer, 2 x 4" mids, 2 x 1" tweets. All Phillips Deforest ... and one of the best sounding speakers I've ever heard. I still miss them, to this day. The picture is old, the scan isn't the best... but if you look closely at the front baffle you can see the dual layer construction.
Can we... maybe... get on to discussing my questions?
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Douglas Blake
The baffle looks like single layer to me. It's apparent at the cutout line in the shadow.
Sure this was your favorite?
Oh fer crying out loud.... Go troll someone who cares.
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Hey, douglas, calm a little bit; you recall me a fellow member...Hey, just look at the 1st page of this thread, the canadian that had his account disabled: I recall that this very topic brought him to the decision of interrupting communications
What's the story? A box into a box ? So ? Does it work?
What's the purpose of a box? Is it soundproof ? Why does it have to be made of BB or MDF ? What's the collapsing point of a layer of silicone?
Maybe all this things together bring to madness
So don't care!
And read my "ultimately best"...that does work
for every component in the system, from pick-up to transducer
What's the story? A box into a box ? So ? Does it work?
What's the purpose of a box? Is it soundproof ? Why does it have to be made of BB or MDF ? What's the collapsing point of a layer of silicone?
Maybe all this things together bring to madness
So don't care!
And read my "ultimately best"...that does work
for every component in the system, from pick-up to transducerI gotta tell you guys, this is bizarre in the extreme. Both of your reactions border on the irrational. Neither of you is making the first bit of sense... NONE.
YES that is a dual walled cabinet I'm standing next to in the picture. Click on the thumbnail to get the full sized image... look around the woofer and midrange cutouts, you can see the two layers.
YES it works and it worked well enough that I ended up building several pairs for other people.
There is no madness at the end... and where did you get that from anyway?
I was doing this 40 years ago... this thread originated over a decade ago... the video is from last year. I'm just trying to catch up.
I simply do not understand your objection to this conversation.
Seriously ... WTF???
YES that is a dual walled cabinet I'm standing next to in the picture. Click on the thumbnail to get the full sized image... look around the woofer and midrange cutouts, you can see the two layers.
YES it works and it worked well enough that I ended up building several pairs for other people.
There is no madness at the end... and where did you get that from anyway?
I was doing this 40 years ago... this thread originated over a decade ago... the video is from last year. I'm just trying to catch up.
I simply do not understand your objection to this conversation.
Seriously ... WTF???
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The principle behind constrained layer damping for a speaker would lead to a strongly bonded stiff damping material in order to maximise the dissipation of energy in the cabinet. Given a desire to minimise wall thickness the structural layer would tend to be thicker than the constraining layer.
The principle behind a box in a box is perhaps more along the lines of isolation (the objective is for the designer to state) where the material between the load carrying and outer layer would be a soft spring without any need for damping. Again a desire to minimise wall thickness would likely lead the inner structural layer to be thicker than the outer layer. The inner layer may still need some damping but possibly not as much as a single layer cabinet.
Constrained layer damping has been used commercially by speaker companies for both small and large speakers (e.g. Acoustic Energy). It is also widely used in engineering to achieve fairly high stiffness with significant levels of damping. It is possibly the most effective, reasonably DIY friendly approach to cabinet construction but seems to be rarely used possibly due to a lack of DIY guidance on what is required to be effective.
I have seen DIY folk refer to a box in a box with a soft material between but this has tended to be by more hands on types. The bottom panel carrying the weight may need to be different to the other panels. Care would be needed in order to avoid introducing something stiff that bridges the two boxes. Driver mounting will need consideration.
Are you looking at isolating two boxes, constrained layer damping or unsure? Smaller cabinets tend to be stiffer than larger ones but still need effective damping (or isolation) if they are to remain quiet.
@Allen and @Andy ... thanks for your replies.
Going back to my 1979 adventures in cabinetry. What I called "box in box" isn't what people think of now when I say that. It was constrained layer, but I didn't have a name for it at the time. (I wonder if anyone did, actually)
The idea in my noggin was very much the principle demonstrated in the video at about 40 minutes ( YouTube ). Playing with scrap materials gave me about the same result as his three square panels did near the end.
So to clarify, as my picture (rather poorly) shows it was a dual layer cabinet made of 2 layers of 1/2 inch MDF with about 1/16" of silicone between them. I applied the silicone from a calking gun and evened it out with the notched tool they use for the glue on a tile floor then positioned and clamped the panels for a few days to let it cure before final assembly.
I did wonder, when looking for more on this whether it was a case that some unknown reason existed to not use it or if people simply didn't know about it or know how to use it. From back then it struck me as a pretty easy technique that only required careful measurements when bonding boards together. (One has to account for the thickness of the overlaps between layers when mounting the inner one)
It is encouraging to hear that some speaker companies are using the technique with good success and even more so to hear that it does scale down to smaller cabinets. My current minds eye is on an 8 inch three way system using it.
The suggestion for polyurethane foam brings up the question of which products I should look at. If as Scott says it is more like marshmellow there might be a question of it being too soft. As the video points out a fair bit of resilience is required to make this work.
I've used Sorbothane for speaker "feet" for quite some time. I can certainly attest to it's ability to damp vibration from speakers. I ran into a problem with my current speakers coupling bass energy into the structure of the building. The poor guy downstairs was being pounded pretty badly. Standing the speakers on four disks of sorbothane totally eliminated the problem with no measurable effect inside my own apartment. But as the video points out it ain't cheap... a pack of 8 2" x 1/4" disks cost me $30.00
The Decidamp material appeared to give very good results in the video but then I'm left to ask what I would ever do with the rest of the bucket? So it might not be quite the bargain he indicates. But there's no denying the result of his hammer test.
I'm currently in the conceptualizing stage of this build, so any and all real information is appreciated.
Going back to my 1979 adventures in cabinetry. What I called "box in box" isn't what people think of now when I say that. It was constrained layer, but I didn't have a name for it at the time. (I wonder if anyone did, actually)
The idea in my noggin was very much the principle demonstrated in the video at about 40 minutes ( YouTube ). Playing with scrap materials gave me about the same result as his three square panels did near the end.
So to clarify, as my picture (rather poorly) shows it was a dual layer cabinet made of 2 layers of 1/2 inch MDF with about 1/16" of silicone between them. I applied the silicone from a calking gun and evened it out with the notched tool they use for the glue on a tile floor then positioned and clamped the panels for a few days to let it cure before final assembly.
I did wonder, when looking for more on this whether it was a case that some unknown reason existed to not use it or if people simply didn't know about it or know how to use it. From back then it struck me as a pretty easy technique that only required careful measurements when bonding boards together. (One has to account for the thickness of the overlaps between layers when mounting the inner one)
It is encouraging to hear that some speaker companies are using the technique with good success and even more so to hear that it does scale down to smaller cabinets. My current minds eye is on an 8 inch three way system using it.
The suggestion for polyurethane foam brings up the question of which products I should look at. If as Scott says it is more like marshmellow there might be a question of it being too soft. As the video points out a fair bit of resilience is required to make this work.
I've used Sorbothane for speaker "feet" for quite some time. I can certainly attest to it's ability to damp vibration from speakers. I ran into a problem with my current speakers coupling bass energy into the structure of the building. The poor guy downstairs was being pounded pretty badly. Standing the speakers on four disks of sorbothane totally eliminated the problem with no measurable effect inside my own apartment. But as the video points out it ain't cheap... a pack of 8 2" x 1/4" disks cost me $30.00
The Decidamp material appeared to give very good results in the video but then I'm left to ask what I would ever do with the rest of the bucket? So it might not be quite the bargain he indicates. But there's no denying the result of his hammer test.
I'm currently in the conceptualizing stage of this build, so any and all real information is appreciated.
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The vibration absorbing sheets used in car doors are tuned to higher frequencies than we have in cabinet walls, in my experience. I had to use a much stiffer inner layer than MDF/plywood with them to get substantial reduction in vibration.
Looking at Decidamp on its website, it sounds the same - aimed at damping thin sections of metal.
Whatever material you use for the absorbing layer, try a test panel with a much stiffer inner material. Say 1/4" aluminum or bathroom tile. I used tile and loaded vinyl automotive damping sheets - my test panels were dead, no ring. but my finished cabinet was good but not fully dead. not sure why.
The stiffer layer might make a big improvement over his Decidamp results. They are good but not as good as I would like.
There is a Sikaflex polyurethane caulk material (291 ??) mentioned in several threads as visco-elastic. No one had tried it in the threads I read several years ago. You would need to spread it using the toothed trowel method. It cures using moisture from the air - this would take a VERY long time in a thick sandwich.
Looking at Decidamp on its website, it sounds the same - aimed at damping thin sections of metal.
Whatever material you use for the absorbing layer, try a test panel with a much stiffer inner material. Say 1/4" aluminum or bathroom tile. I used tile and loaded vinyl automotive damping sheets - my test panels were dead, no ring. but my finished cabinet was good but not fully dead. not sure why.
The stiffer layer might make a big improvement over his Decidamp results. They are good but not as good as I would like.
There is a Sikaflex polyurethane caulk material (291 ??) mentioned in several threads as visco-elastic. No one had tried it in the threads I read several years ago. You would need to spread it using the toothed trowel method. It cures using moisture from the air - this would take a VERY long time in a thick sandwich.
@xandreson
Thank you for the reply.
I've seen the automotive damping sheets and I doubt they would be very useful as box dampers in audio.
There is a product called "NoRes" which I suspect would be equally disappointing.
The idea of aluminium or bathroom tiles is intriguing but I suspect prohibitively expensive. I will look into it.
To be clear, I'm not talking about building a box then adding something inside. I'm on about the actual construction of the box itself... The whole thing would be made from 2 layers of MDF with the goo in between them. At least that's what worked the first time around. The actual constraining layer was something like 1/16" thick.
A visual might help here...
The thumbnail shows how I was thinking of building and corner joining the box...
Thank you for the reply.
I've seen the automotive damping sheets and I doubt they would be very useful as box dampers in audio.
There is a product called "NoRes" which I suspect would be equally disappointing.
The idea of aluminium or bathroom tiles is intriguing but I suspect prohibitively expensive. I will look into it.
To be clear, I'm not talking about building a box then adding something inside. I'm on about the actual construction of the box itself... The whole thing would be made from 2 layers of MDF with the goo in between them. At least that's what worked the first time around. The actual constraining layer was something like 1/16" thick.
A visual might help here...
The thumbnail shows how I was thinking of building and corner joining the box...
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