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I.S.C.T – ‘12” Cylindrical Sub Enclosure’ as a (Sealed/Vented) with Dual Side Walls ….

Finally getting to work on the first (Test project D) - ‘12” Cylindrical Sub Enclosure’ in a (Sealed/Vented configuration) and for the first time in a set up with Dual Side Walls = Dual Tuned Compartment Volumes (1 Sealed & 1 Vented) which in particular makes this project so very interesting. I will use a 12” Mivoc a single voice coil chassis (German Import) which came up with the perfect specs for this project & a 10" Interactive unit. The basic build specs are presently - 18” diameter, height well - over 3 feet, with a gross volume of around 48 to 54 liter (1.7 to 1.9 cubic foot) net I want it to be close to 45 liter (1.6 cubic foot).

I have seen before a few of these cylindrical sub build ups over the years, and I liked the idea in general, but was also convinced that these had so much more to offer then just as they were presented so I saw in my case it very useful to adapt such shape to my own idea & development of a Sealed/Vented configuration (D) build up!
As this is now my fourth (4) Test enclosure in the Sealed/Vented configuration I’m able to say that it has given me great joy to develop this idea further because it has proving itself ten times over in its sound reproduction abilities as such a beautiful musical Instrument of the initial idea combining & reproducing everything of a ordinary Single Sealed & a Single Vented enclosure type into ONE unit which is truly quiet something and most of all for true musical ears.

I mentioned in one of my previous threads that this will be my last Test enclosure as planned because I want to attempted to build the big one most likely as a set combining all what I have done over the two years of researching this project type and building my four enclosures each time differently. All in all the Big one will inhered everything from these Test enclosures yet once again by itself be in shape & build quiet different from them as these were just stepping stones to prove the workings and my own idea generally.

Presently I’m waiting for a shipment with a tool I need to do this project and which has been shipped from overseas only today!

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[Nick77]

Subscribe.....

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Subscribe.....

Subscribe what  ??? please more specific as the actual workings are complex say the least!!!

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[Nick77]

Subscribe what  ??? please more specific as the actual workings are complex say the least!!!

rgs UpperCut

Subscribe to the thread to watch with interest.

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Subscribe to the thread to watch with interest.

OK, Yes now I remember - you have done this to me the second time now - we do all have our different ways! thanks rgs UpperCut

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Hi there,

This is an Image from way back when I was trying to make some templates!
The template shown is not in the right place just sitting there & the speaker chassis will be mounted from the outside & again it is just sitting there for measuring everything!

And another shaping & sizing up the bottom end.

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Hi there,

1) A Image of the nearly completed center section (just four more slices to go, and then on to the Dom section!
2) Start of the Dom section.


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Hi there again,

1) An Image of the completed center section fully glued up (before joining Dom section or Base section to it!).

2) This Image is showing a small strip of the first layer of the dampening I use (Air Cushioning - Area Trapped Air Arresting Motion Suspension) which has until now worked so perfectly without question yet I have this time a Dual side wall so this type of dampening will go into the inner side of the Sealed volume Area and on the very outside of the cylindrical body unit which is also the outer side of the Vented section (center section only!).
Please note that the small strip was only placed as it is now quiet diffucult to reach the inside area particular there Etc.

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[mresseguie]

What exactly is that dark damping strip made from?

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What exactly is that dark damping strip made from?

Sorry, I assume you are meaning the strip of damping material which is actually (silvery shiny). It’s a damping material we used in the automotive field when I was working full time as head technician Restoring European Prestige Cars & building new Jaguar E-Types throughout the whole body, floors, doors Etc. a silvery thick foil with a even thicker layer of absorbing material very sticky glue type bitumen or else. Extremely effective against Resonance, vibrations, noise Etc. but were I’m not attach it directly to the MDF wood but have several (min 3 at least) thick layer of semi elastic glue (not wood glue more a Leather / Shoe glue which is very-very tacky) on the surface of the wood before covering it with a special perforated rubber type compound and only then the actual damping material sheet and a final fiber sheet so in the end any resonance is pretty well reduced to a quiet minimal portion before even hitting the MDF wood.

That is why I called it an (Air Cushioning - Area Trapped Air Arresting Motion Suspension) as it simple works like such.

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Instead of publishing the wrong item in this thread here a latest Image of the center section finished!





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[Anonamemouse]

Wow... Lots of layers!
This is all MDF, right? I have similar constructions to this go wrong in horrible ways... I truly hope it won't for you.
I am about to start on a similar project, a tube woofer system, one woof downfiring, one upfiring, like the bossobass system. My "basetube" will be a sewage pipe of 12 inch across, with 2 layers of bendable MDF glued on.

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Wow... Lots of layers!
This is all MDF, right? I have similar constructions to this go wrong in horrible ways... I truly hope it won't for you.
.................................

Thanks for the reply!

YES, this is all MDF, but I'm not quiet sure what you are referring too in saying the above as everything has gone exactly as designed & very well throughout development as well as I can say so because I'm more or less completed the MDF routing woodwork doing now the sealed area internal dampening Etc.

You also state similar construction? did you ever attempt a dual side wall (Sealed / Vented) type sandwich layer construction?

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Well, some of the latest Images of this build up. Unfortunately I have been quiet busy with some other / new project development as well as we had a lot of rain so the job was more of protecting what was already there rather then building due to some leaks in this old workshop.
Anyway, another day or two and that one will be running. Some physical data on this project:
39.5 Kg without the base plate, 45.10 Kg with the base plate and all in all complete 52.60 Kg with a height of 42” – 107.00 cm, 1.07 meter - not quiet 18", 40.5 cm.

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Well and here we go! Completion & the first 30 minutes of running it, but still with a lot of things to finish off.

And ‘YES’ it sound like a Sealed/Vented does sound – simple ever so Sweet & very Tight, but most of all with NO Boom a enjoying mix of bass of both worls Sealed & Vented. Amazingly ‘The Blender’ piece just above the base plate does also work quiet well in directing most of the sound waves coming from the woofer towards the front (same direction as the tuned Vented section is Exhausting) as at first listening it was quiet noticeable standing in front or behind the unit.


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[Anonamemouse]

Thanks for the reply!

YES, this is all MDF, but I'm not quiet sure what you are referring too in saying the above as everything has gone exactly as designed & very well throughout development as well as I can say so because I'm more or less completed the MDF routing woodwork doing now the sealed area internal dampening Etc.

You also state similar construction? did you ever attempt a dual side wall (Sealed / Vented) type sandwich layer construction?

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MDF does not have a constant density, the outer layer is a lot denser than the center is. Because of this it splits quite easily, resulting in cabinets built like this breaking in half. I prefer birch plywood glued waterproof when building in layers.

I would love to see your drawings or plans!

The result looks great! I love it when a finished project exceeds expectations! 

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MDF does not have a constant density, the outer layer is a lot denser than the center is. Because of this it splits quite easily, resulting in cabinets built like this breaking in half. I prefer birch plywood glued waterproof when building in layers.

I would love to see your drawings or plans!

The result looks great! I love it when a finished project exceeds expectations! 

Thanks again for the reply!

I can't actually say that I ever have had it investigated in a way you describe this MDF thing, and I have to say also I never heard it in the way you mention this either. I can only say that I also never had any such problem (small or large) in all my years of building with MDF except that we here in NZ have quiet a range of graded MDF which is shown in of course the price & so in quality, and I do use different grading for different parts in my projects like this one (3 type of different graded MDF) because of the dual walls etc.

I don't believe that this one will be breaking apart because out of several / many reason.... one of these would be that the inner volume area (main area Sealed) is normally glued - plus also 7+ times glued as finish / completed unit with NOT wood glue but a special semi hardening type elastic glue which is extremely sticky & has proven itself 100%, but this was actually done for other reason then holding it together. Anyway, the next is that the whole cabinet inside-out (except the inner Sealed volume area) is heavily treated 7+ with a special high rise sealant which is extremely durable and is strengthening the MDF the whole layered cabinet construction. There are no screws used at all except a few in the bottom part were the woofer is situated.

I had only once a enclosure split on me were a screw was used way back when I used these much more, but these days no problems.

YES, I'm very happy with the overall outcome of the build up, and it seem that all came together very well as it was intended on the sound reproduction side (Sealed/Vented ever so sweet & without been bommy - I have become a great fan of this type of sound!!!) except and I'm sorry to say it is simple by far too powerful for my own liking as the punch is / was so severe actually quiet something if I may say so, and today after running it most of the day (first six hours running in period) with quiet harmless music material I had to switch it off because it simple gave me an extreme head age and that in a workshop 30 mtr by 20 mtr & about 3 mtr height.

The strange thing is it sound really-really good even with less modern material & classical music but all in all this unit - the bass it is  piercing.

Now plans etc. this is my Build Up D so the build up No.4 out off 5 projects to research / develop etc. an attempt to join a Sealed active & a tuned Interactive (not active - but tuned passive NO tubes) Vented compartment together to experience both worlds that of a Sealed & Vented together in sound reproduction. So as this is presently still an ongoing project of projects (has been for over two years now, and still missing is the No.E build up - the last one) plans and calculations, specs & measurements etc. etc. these will have to wait until a time when I can say that I have truly finished my own research & development and all the build ups with it been maybe able to prove my idea & that this is not a 4th nor strait 6th order Band pass enclosure...... nor anything else of the old school!

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[Armaegis]

"Cylindrical Sub Enclosure" is such a mouthful of a name... when "Bumblebee" works much better

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After throwing some quiet mean program materiel at this unit for the last three weeks (first 3 weeks of the three month running in period) and I’m more then happy with the reproduction of this bass unit which goes down to a nice low 26-27 Hz presently, but most of all is the Interest it has created by now many Visitors to this workshop!
Quiet funny is also the reaction by these people which firstly lay a hand on the top of the unit realizing the very low resonances & asking in general if the unit is running/playing the music which is in the workshop to hear, and further on automatically rest their elbow on the top of it just as they were in a Bar/Pub for a drink

Once they get some info they find that it would be perfectly suited for as a Pub table standing around it because it simple has the right height even with a top on and a pleasant way of experience bass pure. A finale note to this would be to mention that these low resonances you can feel in the top section are reduced about another 80% if you guide a hand down on the side walls further to virtually none in the last section!

I find it quiet amazing that with this type using a SEALED/VENTED arrangement bass can become such a pleasant part of any music type. Presently I’m as well looking for a suited covering material for the outer tube.

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