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miniOnken/Fonken Picture Gallery

Dave and maybe others, I was looking into this thread and other on the forum and still cant find what the difference between trapezoidal and rectangular boxes. Maybe it is not difficult for you explain on give a reference. Thanks!
Do you expect these enclosures to work with the new Alpair 10P or you will be making some modifications?


Short answer to the second question first - yes they'd "work" in the most basic sense, but to deliver full potential, revisions to enclosure designs would be required. These could vary from fairly minor adjustment to vent tuning / dimensions, to more substantial. Dave, Scott and other designers are no doubt plugging away at the math and sketchpads, and we could expect to see new designs any time soon.

Re Trapezoidal boxes - what exactly is your question? They are tapered wider in the front than at the rear, originally to accommodate for combination of the wider flanges of Alpair drivers, and the smaller required enclosure volumes than say a similar sized Fostex driver. Think of it as an attempt to make them bigger on the outside than the inside ( opposite of the Tardis ;))


From some earlier posts in this thread:

MarKenT for original Alpair12 metal, which clearly shows the taper:

bernie-marKen12-comp.jpg



The more rectalinear construction for smaller Aplair7 (note it's still tight to make the front baffle small enough to still fit the driver)

dMar-Ken7-bamboo.jpg
 
frugal-phile™
Joined 2001
Paid Member
Chris has described the difference between the Rectangular & Trapezoids, here is a top view cross-section that illustrates the difference explicitly -- dMar-Ken7.3 and dMar-Ken7.3T (note that there are 2 more trapezoids that get wider and shorter, primarily to allow greater volume for a woofT for each)

Rect-vrs-Trap-miniO.gif


A10.3 and A10p will be fitted to the A10 miniOs. Some will (likely) involve just changes in vent spacers to optimize tuning, the larger version may have an increase/decrease in volume (ie height changes) if needed to get max bass out of the driver. Once i get going on this it won't take long.

dave
 

PKI

Member
Joined 2011
Paid Member
Thanks! So it is only for playing with volume, not for inner reflections and changing geometry for air flows to the vents, right? I would like to try this type of enclosures with new A10p's, but not sure I will be able to make trap. cabs, though.
 
frugal-phile™
Joined 2001
Paid Member
Thanks! So it is only for playing with volume, not for inner reflections and changing geometry for air flows to the vents, right?

Originally the trapezoid came about as an aesthetically pleasing way of getting a wide driver into a small box. Further experimentation with drivers that would fit into either form showed that the traoezoid does have a small sonic benefit over the rectangle, particularily in its lower diffraction signature, althou the non-parallel walls also help smooth things out inside.

dave
 
Thanks! So it is only for playing with volume, not for inner reflections and changing geometry for air flows to the vents, right? I would like to try this type of enclosures with new A10p's, but not sure I will be able to make trap. cabs, though.


they are a bit more work - it certainly helps to have a 12 or 14" main blade and tall rip fence for the side panel bevels
 
Mar-Ken 12.2pTT

Here are some pictures of these speakers that I've built this sommer. I made them just for fun to put the drivers in durig the reparation of super pensils. The boxes for superpensils were made very sloppy and careless so I promised a friend to repair them. For mar-kens I used material I had around (chipboard, mainly), i didn't want to spend extra money just for experiment. Well, after some extensive listening, I'm sory I didn't use proper material, as I like them very much. I experimented with finish, just to cover the materials I used.
I'll try to attach the photos
 

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