hi all
a while ago i had a brainfart i posted in justins flat to 30 topic.
then martin came up with a variation on it here.
then another variation here.
olsound(stanley) requisted to work the last variation out so i gave it a try.
i put it in akabak with my limited akabak knowledge.
i just put all tubes in series,front to back so all volume is counted for.
maybe someone could check it
here is the script.
pros and con's as far as i can see(please add if i missed some)
pro's : even distributed load on the cone
symetric fold so u could use them for endfire/cardroid config easyer.
strong cab,no bracing needed.
con's : complicated to bild
more wood/heavier then a standart config.
here is a 2d sketsh,red the wave is moving away blue the wave is moving towards the viewer.
i'd like to here some toughts on it .
regards erik
edit/
a while ago i had a brainfart i posted in justins flat to 30 topic.
then martin came up with a variation on it here.
then another variation here.
olsound(stanley) requisted to work the last variation out so i gave it a try.
i put it in akabak with my limited akabak knowledge.
i just put all tubes in series,front to back so all volume is counted for.
maybe someone could check it
here is the script.
pros and con's as far as i can see(please add if i missed some)
pro's : even distributed load on the cone
symetric fold so u could use them for endfire/cardroid config easyer.
strong cab,no bracing needed.
con's : complicated to bild
more wood/heavier then a standart config.
here is a 2d sketsh,red the wave is moving away blue the wave is moving towards the viewer.
i'd like to here some toughts on it .
regards erik
edit/
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Modeled response looks NICE. Great job guys. Does look a bit time consuming. But, you only have to build it once - enjoy forever 😉
tnx justin.
here is another option.
it uses a bit less wood and is a little easyer to bild.
the oval mouth is just feature,it could be square or hexaconal or whatever.
i put a top view pic in to show how the wave travels.
btw the woofer needs a spacer to allow for x-limmit.
here is another option.
it uses a bit less wood and is a little easyer to bild.
the oval mouth is just feature,it could be square or hexaconal or whatever.
i put a top view pic in to show how the wave travels.
btw the woofer needs a spacer to allow for x-limmit.
What do they say about the gift horse? OOPS too late. LOOK at the mouth on this thing! So Stanley how are your miter joinery and or wood bending skills?
Countryman skank?
Countryman skank?
Neo Dan
My carpenter skill is at beginners level.
A skill carpenter will be building it.
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hi dan
the oval mouth was just a feature,it could be square or hexaconal or watever,as long as the s vallue is the same.
the oval mouth was just a feature,it could be square or hexaconal or watever,as long as the s vallue is the same.
Eric,
Although the cone loading appears to be evenly distributed, that may not have any particular benefit.
High frequency drivers use a symmetrical phase plug (and often symmetrical horns) yet the diaphragm still exhibits rocking motions.
So far, I have seen no distortion or power compression figures attributable to symmetrical designs that show any benefit that would not be achieved by the good bracing they provide.
A long path length is required for a TH to play low, a symmetrical design has only half the path length per volume and wood used.
At the LF frequencies of concern, a symmetrical fold and any other fold pattern would make little or no difference in an endfire or cardioid array, other than the heavier symmetrical cabinets will "walk" less.
Art
tnx 4 your reply art
the only way to find out is to try it.
the asymetric designs wil be a bit more unpredictable,but then again cardroid usualy is anyway.
the only way to find out is to try it.
well the last one(post 4) is 525 ltr and can be done with 2 sheets 4'x8' with left over,but in general it uses more wood yes
after rereading my post again the next day ,i came to the same conclusion,but it was to late to edit.
the asymetric designs wil be a bit more unpredictable,but then again cardroid usualy is anyway.
I've been playing with this concentric square concept some too...I'm making sawdust tonight & tomorrow & will toss some info out hopefully later this week. One thing I've been trying to decide is, would there be any benefit to an alternate geometry to the ends of the turns....since they are essentially triangular segments it seems likely that some keystoning of the openings between them would reduce turbulence or improve pressure flow.
I am using Lab15 drivers, and a variation on this same concentric/symmetric concept. It isn't going to be a 'groundbreaking' sub, I could pack more raw performance into this volume with a more conventional fold. But I have a customer with two 22"x 29"x 72" spaces between booths on a patio, relatively modest spl needs, a pair of Lab15's, plenty of 3/4" birch, and I'm fascinated by the elegance and strength of this fold approach, so why not eh?
And I see the dark blue color for the innermost boards doesn't show for squat after jpeg compression....bleh
And I see the dark blue color for the innermost boards doesn't show for squat after jpeg compression....bleh
Attachments
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hi trackzilla.
if i reed your drawing correctly it is tapered ?
my bet is dont use any corner pieces or restrictions or keystone openings in the corners.
the wave wil find the way of smallest ressistance.
imo use as much volume as possible.
corner deflectors and such only use up valuable volume.
i wil follow the results with intrest.
grtz erik
if i reed your drawing correctly it is tapered ?
my bet is dont use any corner pieces or restrictions or keystone openings in the corners.
the wave wil find the way of smallest ressistance.
imo use as much volume as possible.
corner deflectors and such only use up valuable volume.
i wil follow the results with intrest.
grtz erik
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only the last two segments are tapered, the rest increases in steps as they go to the next segment...so I was guessing at splitting the difference between the volumes at each transition aperture.
the bell curve-ish drawing was a thought I'd had at reducing turbulence, it has the same area as the triangular chambers it transitions between but I have only figured out how it would work on the first turn around...half my boards are cut & I still haven't decided if it's genius or stupidity, or how to carry the concept through the other turns, so I'm putting off the decision for any end treatment for after all the tablesaw work is done hoping for an inspiration, anyone with thoughts, fire away
the bell curve-ish drawing was a thought I'd had at reducing turbulence, it has the same area as the triangular chambers it transitions between but I have only figured out how it would work on the first turn around...half my boards are cut & I still haven't decided if it's genius or stupidity, or how to carry the concept through the other turns, so I'm putting off the decision for any end treatment for after all the tablesaw work is done hoping for an inspiration, anyone with thoughts, fire away
Hi I looked at this and posted my conclusions here
http://www.diyaudio.com/forums/subw...30-ft30-pa-th-awesomeness-67.html#post2962007
and here
http://www.diyaudio.com/forums/subw...30-ft30-pa-th-awesomeness-68.html#post2962019.
In my opinion any shaping of the turns can only shorten the path length. Unless you want to use even more timber.🙄
Build is going along reasonably well. though it's far more time consuming than I'd hoped (the mrs is upset). The past several projects I've done I sent the drawings to a buddy to cut with his CNC, this time I decided to do it myself...I remember why I usually have him cut it now 😉
Tried to upload some pix, but I guess I can't do that directly? It said something about a 'security token' & failed, do I need to host them somewhere first?...meh, sleep now, post pix later...
Tried to upload some pix, but I guess I can't do that directly? It said something about a 'security token' & failed, do I need to host them somewhere first?...meh, sleep now, post pix later...
you wil need a filehost like imageshack >upload them there > then paste the url of the image in the topic.
and yes having the right tools makes life easy 🙂
and yes having the right tools makes life easy 🙂
Ok, starting my day with finding my imageshack account info & uploading the phone pix of the build so far. Included for everyone's' amusement is one showing a bit more of my 'workshop'...end of the driveway, retired box trucks as storage, 1000W Par64 hung from the back of my current truck for lighting, laptop, tablesaw, and a variety of hand power tools with dull blades 😀
http://img23.imageshack.us/slideshow/webplayer.php?id=20120524030158509.jpg
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
http://img23.imageshack.us/slideshow/webplayer.php?id=20120524030158509.jpg
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