[UpperCut]

Would like to hear your thought on this!

I.S.C.T. stands for an advanced building type method called ‘Innovative Slice Construction Technique’ or also better known from way back as a Sandwich building method. In any case in the late 90th – early 2000 years there were a couple of DIY projects around yet in relevance to the so beloved rectangular enclosures quiet minimal as building with this type enclosures was not the norm as it is quiet labour & time intensive say the least!

Now as everybody has there own preferences I assume not many of you reading this are to familiar with Slice construction, and the at times excruciating & tedious and so repetitive work which is associated with it? Anyway, I personally have worked with this technique since the mid 90th ongoing, and so I find it quiet rewarding because of its 'Creative Perspective' which is very important in the ‘Pursuit of Perfect Sounds’ - Reproduction, but also the options in how I.S.C.T. can be used is simple refreshing, like Vertically or Horizontal, variable volume size to adapt more precisely to chassis specifications, shape design & of course the way of approaching the reduction of resonance through (not using flat panels as such) and with it using ways of newer and more advanced Energy Absorption & Wave Dampening like the following for example.

Over time I have used very successfully single, double or triple resonance dispersion panels in my build ups which were not only very effective but also did look the part! Then on the other hand I also like options and so I developed only quiet reasoned a type of ‘Air Cushioning – Area Trapped Air Arresting Motion Suspension’ which is quiet what the doctor ordered and predominantly fitted in the inside of an enclosure, but if you are as myself very particular when it comes especially to Quality, Clarity and Mid-Range Purity then using it on the outside as well - Believe Me - is getting a project to quiet another level, and the most astonishing fact of this all is that when an enclosure is covered on the outside say with some GB, IT or NZ leather the enclosure has a warm quiet pleasant feel to it which is very hard to explain and truly is only possible when you touch it!

I’m a great believer in exotic shapes (I mean anything different then only the ever so very boring rectangular type) and with it of course angles which are as very important in audio & enclosures design and development, and as mentioned before I.S.C.T. becomes a choice of ‘Infinite Possibilities’.

Years ago somebody wrote some very fitting words about it all which I like to share with you as it portraits what I.S.C.T. stand for:

DRAMATICALLY CONTROLLING, REDUCING OR EVEN ELIMINATING THE SO VERY MUCH UNWANTED RESONANCE / VIBRATIONS IN LOUDSPEAKER ENCLOSURES THROUGH MOSTLY UNCOMMON ENCLOSURE SHAPES, AND THEREFOR MINIMIZING THE EFFECT'S THAT GENERALLY FLAT ENCLOSURE WALLS HAVE BY ACTING JUST LIKE UNCONTROLLED SOUND TRANSDUCERS . . .

Regards UpperCut

[JLM]

I've been around construction and audio for 40 years (interested particularly in speakers) and have almost no idea what you saying.  Part of our house was built 10 years ago using Structural Insulated Panels (SIP) that are basically sheets of chip board glued to either side of a slab of styrofoam (insulates very well and are very strong).  Am I close?  Please give links and images of I.S.C.T. as Google is coming up empty.

What are build-ups?  What are double/triple dispersion panels?  What is 'Air Cushioning - Area Trapped Air Arresting Motion Suspension"?

And by the way, are you really from the 90th century?  Do they routinely say "quiet" when they apparently mean "quite"?  Or is your computer giving you as many fits as mine?   

[UpperCut]

Rough cut side test panel with New Zealand Maori Ornamental Carving:


Sandwich method for a body housing a 350 RMS Super Bullet Tweeter (these are so precise made that they are only need to be press-fitted.


This Image shows a automotive Sub with dual floating Dispersion Panels each side, and the smaller white one in the background is a single panel arrangement



Well, there is a saying in the German language, and I’m not sure if I can translate it but I will try anyway as I do not mind to do that for such a young person as yourself!
‘Alter schuetzt for Dummheit nicht’ OK let’s try this ‘Age does not save you for been Un-Knowledgeable’ I think or just on these lines!

My advice would be if I may: Only because it could not be found on the Big-G does not mean it is not existing!!! And as I was talking about Design & Development so noting would be set in stone. Sandwich construction is quiet simple in a vertical or horizontal way I mean if it is possible to grasp - 1 Layer say MDF 18 mm - Sealant & another Layer MDF, Sealant & another Layer MDF and so on.
In one of my projects presently that would come up with 18 Layers to create the basic form (the body volume) further more two (2) outer panels each side would complete the enclosure which would be in total 22 slices of MDF. The outer panels are one the side carrier, and the second can be used as an Ornamental carrier for example incorporating as I do Leather, Wood Carving or other Art …..
The MDF has in this project 5 sides with alternating thickness and each slice would have as body the appropriated design incorporated to make up all cavities needed etc.
Build –Ups are for me a type of test enclosure which I use to exactly develop my design into minute detail before hand-crafting the set!

I apologize for me not been quiet so perfect in my English, but I never actually learned English in school as a second language as that was not the way they did it then long – long time ago!

Regards UpperCut

[GentleBender]

So like what Vapor uses in many of their speaker designs? I'm not saying they were the first, but they do make great stuff. Very heavy speakers for sure!  http://www.audiocircle.com/index.php?topic=135834.0

[BobRex]

Take a look at Vapor Audio.  They use "sandwich" construction almost exclusively to great success.  They are one of the major proponents of this.  Some of your other terms are foreign to me too.  Is a "dispersion panel" mass added to panels to lower the frequency and change the distribution of resonant panel modes? 

[UpperCut]

Hi there and thank you for your constructive input!
YES you are right to the T! And from your Link mentioned this was the best Image which is explaining it perfectly! http://www.audiocircle.com/index.php?action=gallery;area=browse;image=15199

I seen many different ways people (If They Do It) approach this type of building and you are so right in saying that these for that matter are heavy, very heavy, but that is one of the good reason to work with this type to gaining mass.

Now about the dispersion panels: YES again even so they do not have the big stamp of approval from a big company yet that would not make them demisable as this works all with the physic laws of ‘Density’ simple in a way to start of with MDF which is Medium Density Fibreboard which takes the brunt of everything if used in an enclosure.

I find over the years that if new items emerge anywhere in electronics, mobile etc. name it then it is always the best since sliced bread yet if it comes to audio reproduction & enclosure issues then OH NO advancement here is always that most people writing replies do know or better I say do not want to know as it seems that they still live in the middle ages and most of all they pull out the age card in showing I’m of an age I can’t learn a thing or two! Or mention the Big-G …..

Anyway, through trials and a few enclosures I can say with certainty that the difference is astonishing especially when it comes to Bass!!! And if anybody ever looked for a real Resonance Buster to get a (well personal opinion – perfect deep-deep CLEAN / CLEAR bass) so just imaging this on a smaller scale as a single action set up to a mid-range set. I can truly say that with such improvements I could hear such minute details from the program details on CD’s which I had listened too for many times before, and I had never heard for all these years.

It was a very simple idea as to the use of it says for example dual action: Free floating is imperative (and the layer in between the panels it is important to use the right bonding material), and then it is only medium to soft, to extremely hard, to soft, to extremely hard – not even mentioning the surface treatment of the panels.
 
There is so very much out there to go on with if people would only take out time to think about some items the world of Loudspeaker design & development could be much more Interesting – because it is!!!

Regards UpperCut

[JLM]

My enclosure priorities:

- High mass (to reduce overall vibrations and the frequency(s) that they vibrate at)

- High stiffness (to reduce vibrations of individual enclosure panels/pieces)

- Shape that directs back-waves away from drivers (to reduce smearing of frontal wave with reflected back-wave that "leaks" through cone/dome material)

- Point source, keep mid/treble drivers close together, voice coils vertically aligned (to improve coherence/imaging)

The "perfect" B&W Nautilus would be a good expression of those goals.  Shape provides stiffness, point source, and directs back-waves away from the drivers.  Weight = 190 pounds with plinth. 

[UpperCut]

Hi again,

What you are mentioning are all fair & logical points to L/S enclosure design & development as they have been there for many-many years now, and I agree with most of them yet I also like to state that many are missing or greatly outdated. Anyway, as I believe there will always be some missing as it can be a lot to think of, and it is always how to prioritise as in the type of enclosure you are building at that time etc.

High mass …. OK
High stiffness ….
Well, I assume you referring to the ordinary rectangular enclosure shapes, flat panels heavily braced and so on? Well, this can be mostly already avoided by disregarding such ways of building & through using angles in deigns, and making bracing a part of the enclosure.

Shape that ….
Well, this can be mostly already avoided by disregarding such ways of building & through using angles in deigns etc.

Point source ….
Same as the last two as that is only relevant to the or better I say mostly ordinary rectangular enclosure shapes. The Link and associated Images above which were kindly given can show that very well! And as I myself work with Hi-Fi & Automotive (I like to discard cars, but refer to Vans as in people mover 7 / 8 seated like my most favourite one Nissan Elgrand for example) enclosures which can be very similar in both fields.
So my interests are to go for the highest quality of reproduction of sounds for both and in cars well 96% impossible, but in Vans because of the air displacement volume 80 cubic feet +, we are talking progress.

Imaging / Staging in automotive is not even remotely possible with enclosures which are offered anywhere worldwide these days for sale!!! I mean anywhere. Yet to have your Van set up sounding as you were sitting in a concert hall just as you do with your home Hi-Fi does not require much at all, and that for little money as well.  But for now it would be too much to go into.

What I was implying to is actually the Hi-Fi arrangement and the mostly missing angles (referring to rectangular enclosure shapes) so with a different building technique like I.S.C.T that would be of no consequence any longer! And once again most of all the difference can be like day & night!!! Sorry, IS LIKE DAY & NIGHT.

rgs UpperCut

[JLM]

Trying hard to understand what you are saying.  (Your English is 1,000,000,000 times better than my German.)

What are single, double or triple resonance dispersion panels?  Is that anything like diffusion (scattering of sound via different sizes/depths of bumps/depressions)?

What is ‘Air Cushioning – Area Trapped Air Arresting Motion Suspension’?  Is that anything like passive radiators or 2 chamber ported designs?

What is a "Resonance Buster"?  Again when I try to look it up I get large bubble sculptures and knives??

You mention "free floating" but don't explain how it's applied.  Please explain.

You also mention alternating materials in sandwich construction.  Several manufacturers make panels out of alternating materials, is that what you're referring to?

What is "L/S enclosure design & development"?


Stiffness can come from thickness, reducing the effective span, increasing Young's modulus of the material, or taking advantage of shape (curves being inherently stiffer than straight).

I was not thinking of just rectangular boxes, in fact they can be some of the worst acoustic shapes possible but are more easily understood and built.

Here's a link to the B&W Nautilus (nearly 100 kg each so massive, no flat panels so inherently stiff, no reflections of back-waves that return to the drivers):  https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwiRlZijtO_JAhUBOSYKHQUUCx8QFggdMAA&url=http%3A%2F%2Fwww.bowers-wilkins.com%2FSpeakers%2FHome_Audio%2FNautilus&usg=AFQjCNGUYJJsddZQJRSURh4I2_K9mZxKFg&sig2=_JEr3vTsvu18QVdzioTy5w

Point source is relevant to mid-bass - treble frequencies in enclosure types of speakers, not bipoles, dipoles, or vertical arrays.  Naturally various designs that use single drivers that cover these frequencies are considered point sources.

Of course there is more to enclosure design than what you've discussed so far, but certainly worthy of discussion.

[UpperCut]

Well, I like to start with answering your very last sentence first: Sorry to say that rectangular type of enclosures are not any longer part of any discussion I would want to be part of as that definitely is a subject of midlevel times, and simple should not count any longer .

Now, as a foreigner which never had the proper schooling in the English language it is not of any surprise that you do even so unintentional, but still think deep down in the way you learned your language adapting it to the English you speak & write!

OK, now to stay on subject and as you are definitely which likes B&W (anybody which does not like the ultimate?) I like to mention something on that B&W web site which J.Bowers was saying – ‘The best loudspeaker isn’t the one that gives the most, it’s the one that loses the least‘and that I fully endorse!!!
So asking for the two resonance reduction methods again which I’m using is simple a little understandable for me as the description itself should spark your own imagination and vision of understanding this as ‘Resonance Dispersion Panels’ are exactly what it is they saying there are ‘Panels which are dispersing resonance – diminishing greatly unwanted resonances which do a lot of harm to your sounds’ As I send an old Image of a sub box previously with a dual set up shows these panels which must be at a different size of course, and ‘Free Floating’ means that both panels must be free floating not physically touching the enclosure wooden side panels nor any sides of it or each other. Of course there is a special compound separating them and needed which is suited as it is not just any compound, and I get mine send from Germany. The other items which keep these correctly apart from each other are ‘Dowdies’ which you find in the automotive field (simple is a Alu ring which incorporate a rubber insert sticking out each side as a soft lip type arrangement normally for sealing, but in my case for floating / decoupling the panels against each other!). Absolutely brilliant on any sub, and if used on midrange the clarity with them is out of this world, and the resonance reduction measured was around 80%+.

The of course there is ‘Air Cushioning – Area Trapped Air Arresting Motion Suspension’ this is even simpler.
As the description does say: Air Cushioning!, Area Trapped!, Air Arresting!, Motion Suspension and that is as basic explained as like this.
Instead of bounding any type of damping material to a Wood panel I use a special material which is perforated underneath the damping material which is creating Area Trapped, Air Arresting type Air Cushioning - Motion Suspension and I assume we all know what an Air Cushion & Motion Suspension is??? So instead the pressure wave created by the speaker hitting the enclosure walls in full force (just dampened by some damping material) it now hits the material in the same way yet the material is not directly connected to the panels it now has bounce through the Air Cushioning then reaching the enclosure walls. Here as well the measured reduction was 80%+.
As much it is of help on the inside of my enclosures in the reproduction of detail, and truly pure sounds in general you would be blown away by its performance when using it also on the outside!!! Yet here with the covering as in my instant I use genuine / artificial leathers, vinyl etc. So another Air Cushioning ….. but this time it gives a real feel a warmth to a otherwise dead item!!!

I refer to ‘L/S Enclosure Design & Development’ as a DIY subject when somebody is designing & developing something which is away from the sheer boring norm, have vision and a feel not only in the electronics like amps, wires, chassis etc but also see beyond all this, and make changes be adventures, open minded and most of all have ideas which compliment.
As with rectangular you build an enclosure roughly suited, braces etc. yet with I.S.C.T you create a modular item which in the end is one item throughout – a piece of Ingenuity & Art. As for alternating materials with I.S.C.T you can use glues or special sealants to bound the slices which already will give you diminishing resonance, and instead of butt joints you use it horizontally or vertically with alternating thicknesses, materials, shapes & sizes ………

Unfortunately I’m not able to show any Images as yet of my latest projects as I’m waiting to get my damping material which unfortunately I and the suppliers have run out of.

rgs UpperCut