Hello all. My first driver for the Tiny40s project has arrived, and she looks like a lil monster. The most relevant test box is 4L internal, 2x passive radiator in fibre reinforced plastic sandwich and it's worthy of a project of its own. I'll take this opportunity to add something missing in my rig. A mini porch type PA/DJ/Karaoke system
Since such events tend to start with some energetic wine downs and end with a drunken coolie uncle dance or two, she will have to be heavy duty and survive potential knock overs and things
Having learnt a lot from this forum, maybe I can present something in return that could potentially add to the many ways of making cabs
I am inclined to use foam as the core but will consider ply instead if there is enough interest in that. So guys, let me know what's more interesting, ply or foam?
Thanks and regards
Randy
Since such events tend to start with some energetic wine downs and end with a drunken coolie uncle dance or two, she will have to be heavy duty and survive potential knock overs and things
Having learnt a lot from this forum, maybe I can present something in return that could potentially add to the many ways of making cabs
I am inclined to use foam as the core but will consider ply instead if there is enough interest in that. So guys, let me know what's more interesting, ply or foam?
Thanks and regards
Randy
If ply is chosen, it will also be used as a core material rather than as a panel in its own rightI would say foam as we might learn something new.
Ply is good but conventional.
Hey man, very possible. If you’re serious about that then throw up some basic general arrangements drawings and I’ll take you through how to quickly and painlessly loft it as a hull with all the frames and stringers as on the inside of a foil
You will be surprised as to how little there is to do to get to cutting stage
As I mentioned earlier, this needs to be a heavy-duty build. For the load lines in a 4L cab, 4mm hardwood ply core would be heavy duty but in foam, lots more thickness is needed and unfortunately a very thick 9mm PVC foam must be used here as a minimum according to how I like to set up the scantlings for a project like this. Being a PA type system, XPS foam is not suitable. The screenshot is of just one of many places that sell this. In the drop-down menus, I have preselected the size of board needed. Qty needed will be 3 pieces
People on this board are pretty tech-savvy so no boring design details. Just 4 odd litres of chamber, give it any shape you want and can model, and we'll arrange the bulkheads and stringers to suit your shape (bracing that is part of the body). The shape that I am making for the ZR6 does not require anything on those stations
Pardon the jargon, but we will use terms found in the Gougeon Bros handbook. Just post up any queries regarding the terms. Also, I should mention that there is a very easy way of modelling any cab like this, and I am more than happy to take folks through it. A very awesome individual from the high-end side of automation had freely made resources available just so that like-minded sailors can have massive amounts of fun. I think he even accommodated speaker makers, as there are some boxes in the templates
Now to address some positives for those who would prefer foam. This build can be done on a table covered with a sheet. No power tools are needed, but would make the job easier if available. A CNC is not required, but can be used by Virgos. Additional materials would be some manufactured bamboo plank or balsa for the baffles, as foam and ply are not suitable for mechanical fasteners with the exception that ply is suitable for nailing to batons with panel pins
Apart from the glass cloth, BOM will include epoxy, isopropyl, white vinegar, fumed silica, chopped cotton, silicon carbide type papers, art brushes, drum shell wrap, electronics and optional 3D printed TPU
There isn't any dry dust made in the entire process apart from the baffles and that is very lil mess with a coping saw and sand papers. If one happens to live in a small apartment, just clamp the plank to a table and cut it with a coping saw, then head down to the beach with some papers and sand away
Protective wear is a must with fibre glass, and wood dust is not good for those like me with acute rhinitis. A mask, long sleeves and gloves are what I use for only the raw glass work and that's just a one stage thing in this process. The rest of the process is wet and mostly water based, and the whole thing is washable while working on it. A lot can be done in the running shower too at the fairing stage. There won't be any fibreglass ground after that first stage, so all these other process is as mild as washing talcum from skin
Ply has its own advantages in cab of such small sizes too
My PVC foam boards are on its way. This one is a good deal for AU tinkerers as when I added 3 units to the cart, it applied a discount of one unit
People on this board are pretty tech-savvy so no boring design details. Just 4 odd litres of chamber, give it any shape you want and can model, and we'll arrange the bulkheads and stringers to suit your shape (bracing that is part of the body). The shape that I am making for the ZR6 does not require anything on those stations
Pardon the jargon, but we will use terms found in the Gougeon Bros handbook. Just post up any queries regarding the terms. Also, I should mention that there is a very easy way of modelling any cab like this, and I am more than happy to take folks through it. A very awesome individual from the high-end side of automation had freely made resources available just so that like-minded sailors can have massive amounts of fun. I think he even accommodated speaker makers, as there are some boxes in the templates
Now to address some positives for those who would prefer foam. This build can be done on a table covered with a sheet. No power tools are needed, but would make the job easier if available. A CNC is not required, but can be used by Virgos. Additional materials would be some manufactured bamboo plank or balsa for the baffles, as foam and ply are not suitable for mechanical fasteners with the exception that ply is suitable for nailing to batons with panel pins
Apart from the glass cloth, BOM will include epoxy, isopropyl, white vinegar, fumed silica, chopped cotton, silicon carbide type papers, art brushes, drum shell wrap, electronics and optional 3D printed TPU
There isn't any dry dust made in the entire process apart from the baffles and that is very lil mess with a coping saw and sand papers. If one happens to live in a small apartment, just clamp the plank to a table and cut it with a coping saw, then head down to the beach with some papers and sand away
Protective wear is a must with fibre glass, and wood dust is not good for those like me with acute rhinitis. A mask, long sleeves and gloves are what I use for only the raw glass work and that's just a one stage thing in this process. The rest of the process is wet and mostly water based, and the whole thing is washable while working on it. A lot can be done in the running shower too at the fairing stage. There won't be any fibreglass ground after that first stage, so all these other process is as mild as washing talcum from skin
Ply has its own advantages in cab of such small sizes too
My PVC foam boards are on its way. This one is a good deal for AU tinkerers as when I added 3 units to the cart, it applied a discount of one unit
Ok, the window for ply vs foam is now closed, Only one forum member interested in foam and none for ply. Due to this construction tech not being of interest to aspiring speaker builders, I'll log the build of this particular cab and leave any elaboration as a call and response thing
An update, my ePR is looking promising with the mechanics working as expected. I'll use this cab to test the proof of concept and plenty of black encapsulation learnt from a lifetime of working resin
So with that all that being said and earlier presentation on benefits of working with foam, please allow me to properly introduce the Cub Sandwich. 4L cab volume passive radiator test box for the Tiny40s sub challenge. If the PR system delivers, then this cab will be used in the porch party DJ rig
To the best of my knowledge, this is also the first public presentation for making a speaker box as a powered vessel that works to deliver a tuned acoustic output rather than an acoustically tuned cabinet built with common furniture construction methods. Please note that any model colours are just my settings to see better while modelling and not a two pack bright auto paint. At this stage I intend to finish it in drum wrap as this should not be yet another boring black PA box but an instrument for music
I will make the assumption that anyone following already knows how to model and cut out sheet material to make a cab and would be comfortable cutting with a blade for a change rather than table saws, routers and other power tools
Cool, so next up will be the SOR (statement of requirements) and GA (general arrangement)
SOR
Be tiny
Be powerful
Be very robust
All are welcome to prepare an SOR for any personal builds that can use a similar volume and welcome here for discussion
GA
Usually a drawing, either 2D or 3D showing the layout from which a working model is derived. Acoustic sims should be done first to predict performance for target volumes first. A GA is recommended as it greatly helps keep things in track and in check. I'll come back later with the GA for the test box and then loft it to a 3D working model. Acoustic sims were already done in the Tiny40s thread
An update, my ePR is looking promising with the mechanics working as expected. I'll use this cab to test the proof of concept and plenty of black encapsulation learnt from a lifetime of working resin
So with that all that being said and earlier presentation on benefits of working with foam, please allow me to properly introduce the Cub Sandwich. 4L cab volume passive radiator test box for the Tiny40s sub challenge. If the PR system delivers, then this cab will be used in the porch party DJ rig
To the best of my knowledge, this is also the first public presentation for making a speaker box as a powered vessel that works to deliver a tuned acoustic output rather than an acoustically tuned cabinet built with common furniture construction methods. Please note that any model colours are just my settings to see better while modelling and not a two pack bright auto paint. At this stage I intend to finish it in drum wrap as this should not be yet another boring black PA box but an instrument for music
I will make the assumption that anyone following already knows how to model and cut out sheet material to make a cab and would be comfortable cutting with a blade for a change rather than table saws, routers and other power tools
Cool, so next up will be the SOR (statement of requirements) and GA (general arrangement)
SOR
Be tiny
Be powerful
Be very robust
All are welcome to prepare an SOR for any personal builds that can use a similar volume and welcome here for discussion
GA
Usually a drawing, either 2D or 3D showing the layout from which a working model is derived. Acoustic sims should be done first to predict performance for target volumes first. A GA is recommended as it greatly helps keep things in track and in check. I'll come back later with the GA for the test box and then loft it to a 3D working model. Acoustic sims were already done in the Tiny40s thread
To prepare the GA, two things stand out in the SOR and needs to be mapped out. Tiny and powerful, the very thing that creates the problems with aspect rearing its head in the Tiny40s discussion. So the challenge for me is to fit a very 'andu' 6.5" into the target 4L net driver volume, splice on volumes required by are a pair of PR units and just over 800wrms of amplification, DSP unit and I/O and just for the fun of it, someone wanted to see propellers, so I'll fit not one but two!
Pictured is the shape that I am picking to address robust as well as panel resonance issues associated with LF speaker systems. The reasons for selecting this shape is worthy of a good chat as there are aspects that while not immediately obvious are more important than the very helpful curved panels created on two sides. I am of two minds on sharing my methods of evolving out the traditional methods as described in the handbook for powered vessels to much smaller but just as robust speaker boxes. Reason one is feeding the lurkers and reason two is stepping on the toes of vendors on this forum
The parts that apply to this cab will be in the STL and DXP files but made available without development notes. But, if vested commercial interests don't have any issues than I am sure we can comfortably discuss all that
This is the shape, and it is based on one side of an eclipse, but not a complete half. The GA will map onto this in all three dimensions, and individual cab parts will be pulled from that. This solid "blank" occupies a volume of 9L
Pictured is the shape that I am picking to address robust as well as panel resonance issues associated with LF speaker systems. The reasons for selecting this shape is worthy of a good chat as there are aspects that while not immediately obvious are more important than the very helpful curved panels created on two sides. I am of two minds on sharing my methods of evolving out the traditional methods as described in the handbook for powered vessels to much smaller but just as robust speaker boxes. Reason one is feeding the lurkers and reason two is stepping on the toes of vendors on this forum
The parts that apply to this cab will be in the STL and DXP files but made available without development notes. But, if vested commercial interests don't have any issues than I am sure we can comfortably discuss all that
This is the shape, and it is based on one side of an eclipse, but not a complete half. The GA will map onto this in all three dimensions, and individual cab parts will be pulled from that. This solid "blank" occupies a volume of 9L
So for this cab that is getting built as a powered vessel, these are the structural solids that define the cab. This is done as a hybrid of an air frame segment and a marine hydroplane. The pair of oval slots are at the baffle and what would be the transom, where the motor mounts. The middle partition is a stringer and together with the four corners form load lines that tighten up as they travel away from the motor. Instead of air frame style bulkheads, I am using a box beam running through all the verticals. There is a reason for this and it is very worthy of a chat
We come on a DIY site with intentions of tinkering with our varying levels of skills, knowledge, understanding, misconceptions and such. But the reasons are usually for making something that makes music, and this is the most innocent and fulfilling of all desires
Being cubbed in September has fixed yours truly at not being content with just a working finish. Just like I did on 360 where I am still listed as vendor in another craft, I will enjoy schooling the techniques that I'm developing here to see everyone figuring out how to out do even high-end commercial units in wrapping up the audio gear that we make as DIY'ers
So the chat is about that box beam. This whole exercise is an attempt to "honey, I shrunk the kids" to a DJ subwoofer. Due to its nature as a hollow device, the use of the beam here is to optimise space consumption. This will perform double duty as a structural element as well as a dedicated compartment for the electronics that cannot be placed in the sealed passive radiator system for hard PA use. The alternative is to use bulkheads radiating away from the transom/baffle thingy
I can imagine those that encounter this would be thinking. "Hmm that all looks overly complicated and together with glass and epoxy work, the build looks all too hard"
This is just not the case and I will refer to recent threads folks have been enquiring about means of box building achievable in a city apartment and such. Another reference is the mention of how the hand plane is an item not well understood, to which my response will always be that the mouse is the hand plane not well understood! All the work here is in a virtual environment. We will make real dust just once and only where needed
Next up is design in the hard points for the active driver, dual passive radiators and dual propellers
This is GA for this cab as well as the working model that will be used to pull individual parts. Thinking about using PDF for PVC foam cutting templates as well as CNC files
The internal area for the box beam is for mounting electronics. Since that cab can be used as a sealed without passives and can be stacked without the issues of translam, It lends well to taller cabinets and arrays. A thinner stack can be done as a port. There is no orientation to the foam core material and no clamping, so no issues of translam if this is used as the technology for said taller cabs. The holes for the PR can be used for air flow to the next chamber and so on. I hope you guys can see where I am going with this and when I have completed the bridging work, you will see just how universal this can be. My TL template exploits this tech too
I mentioned in a previous failed attempt to pull a reconfigurable template from FreeCAD due to program instability, and how I managed to finally find a way of working around it. I have developed another template to continue that work for those Pioneer coax drivers, but that's another story
Next is the individual part models pulled from this GA and a tentative BOM
The internal area for the box beam is for mounting electronics. Since that cab can be used as a sealed without passives and can be stacked without the issues of translam, It lends well to taller cabinets and arrays. A thinner stack can be done as a port. There is no orientation to the foam core material and no clamping, so no issues of translam if this is used as the technology for said taller cabs. The holes for the PR can be used for air flow to the next chamber and so on. I hope you guys can see where I am going with this and when I have completed the bridging work, you will see just how universal this can be. My TL template exploits this tech too
I mentioned in a previous failed attempt to pull a reconfigurable template from FreeCAD due to program instability, and how I managed to finally find a way of working around it. I have developed another template to continue that work for those Pioneer coax drivers, but that's another story
Next is the individual part models pulled from this GA and a tentative BOM
One thing that I still don't like, this is a PA cab and will be used in the tropics. The electronics are well ventilated but splash resistant, but the sub driver has a huge motor structure and is going to see 600wrms in a tiny volume. The PR system is a sealed system with zero airflow, and I worry about this. I think this engine needs not only sports chassis but a high performance radiator
Long night on the screen and I find myself trying to rotate the pic in the above post again!! Anyways, what if I flipped the driver so that the magnet was on the outside and in that shallow tunnel in the baffle? I can make an inlay into the baffle as an engine mount to have a deeper tunnel there. This would alleviate the heat issue significantly and protect the driver cone and surrounds and capped off with a flat perforated aluminium grill that stays in contact with the back of the magnet. Does this make sense, would be nice to have some experts chime in on this in the spirit of DIY
Long night on the screen and I find myself trying to rotate the pic in the above post again!! Anyways, what if I flipped the driver so that the magnet was on the outside and in that shallow tunnel in the baffle? I can make an inlay into the baffle as an engine mount to have a deeper tunnel there. This would alleviate the heat issue significantly and protect the driver cone and surrounds and capped off with a flat perforated aluminium grill that stays in contact with the back of the magnet. Does this make sense, would be nice to have some experts chime in on this in the spirit of DIY
Took a day to ponder the heat issue and make some deductions based of regular recommendations on this forum. Most folks here appear to be very well-educated in audio and do not flinch at always pushing the sealed box over other types. Sealed and PR were the two systems very highly recommended, even for this driver. Even the Sunfire doesn't seem to worry about that much amp and sub in such tiny boxes. So this heat thing is only in my overactive imagination
Will leave the driver in its current location. A temp sensor on the mag would help monitor during testing. The aluminium cone PR units will help dissipate heat from inside the driver volume
If the temp sensor shows a need, then the driver can still be flipped without changing the baffle and a dished grill to protect just over half of the driver sticking out
This is a sub where the usual SPL enhancement methods used in PA have not been the priority. The push during the entirety of the tiny40s was a high fidelity reflex system. I suppose that defines this cab as an aspiration towards a high fidelity subwoofer system built to a heavy-duty schedule
Will leave the driver in its current location. A temp sensor on the mag would help monitor during testing. The aluminium cone PR units will help dissipate heat from inside the driver volume
If the temp sensor shows a need, then the driver can still be flipped without changing the baffle and a dished grill to protect just over half of the driver sticking out
This is a sub where the usual SPL enhancement methods used in PA have not been the priority. The push during the entirety of the tiny40s was a high fidelity reflex system. I suppose that defines this cab as an aspiration towards a high fidelity subwoofer system built to a heavy-duty schedule
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Spent a night and half a day further pondering the heat issue. See the new through slot, that is for a 10mm alloy plate to be used as a heat pickup from the back of the mag. This would be a two-piece unit, with each part entering from one side of the cab. This will clamp down on another plate on the cab surface
This caused me to recall that aluminium skins are also an acceptable sandwich material when used with PVC foam. So this design no longer requires the use of the fibre glass material on any part. Aluminium skins are also easier and safer to work with, especially in a city apartment, and the tools remain the same. Only for this subwoofer application, though, as the aluminium skins will act as the driver heat radiators. At this point, fibreglass is dropped as skin material and carbon fibre is added as an upgrade skin material from aluminium if the cab is used for a full frequency speaker
Also at this point, my development of porting the powered vessel monocoque to DIY speaker cabinets is complete. The created schedule is for a heavy-duty enclosure. The schedule for domestic duty is based on XPS and cold moulded skins using natural or synthetic materials, the choice is open and steered by desired finish. As an example, I want to do a pair of these cabs as a desktop BR for a pair of 6.5" Pioneer coaxial. The schedule that I will use for that is XPS foam and DIY cold moulded two layer real wood ply skin
Next are the appendages, there are only three items here. The heat pickup, a badge and the dual propeller mounts
Just had an idea that stays true to the whole nature of this exercise in developing and refining. See how the mouse is really a hand plane not well understood
Will change from the slot to another box beam in that location. This time in aluminium box section and fit a fan in that. Now the driver can have active cooling and another structural member. One that can sustain a huge amount of compression!
How is this for nailing the SOR and a demonstration of how little work it takes to put together a feasible plan of attack to achieve a showroom finish on the home dining table
I do hope folks can appreciate the type of thinking needed to bring such a plan together
Will change from the slot to another box beam in that location. This time in aluminium box section and fit a fan in that. Now the driver can have active cooling and another structural member. One that can sustain a huge amount of compression!
How is this for nailing the SOR and a demonstration of how little work it takes to put together a feasible plan of attack to achieve a showroom finish on the home dining table
I do hope folks can appreciate the type of thinking needed to bring such a plan together
@Erica.C
Hey Eric, this is the design where I am using my pair of FFA001 H/B boards in that 100x90mm internal box beam in the model. The boards will mount to opposing faces inside that beam and the box beam will be capped by a fan on either end
Would I be able to run one pair of fans from each board's FAN out? I need to run a total of 4 fans like the one in the pic below
Hey Eric, this is the design where I am using my pair of FFA001 H/B boards in that 100x90mm internal box beam in the model. The boards will mount to opposing faces inside that beam and the box beam will be capped by a fan on either end
Would I be able to run one pair of fans from each board's FAN out? I need to run a total of 4 fans like the one in the pic below