Ken Perkin's Nebula - Box & XO Quesitons

[zenon]

Is the 0.50 cubic feet box on partsexpress the 0.55 box specified by the design?
I ask because partsexpress doesn't have a 0.55 cubic foot box but for the 0.50 cubic foot box they say the actual volume is 0.55.

I just want to clarify.


2nd, has anyone built this with the larger 0.75 cubic foot box? If so how did you modify the XO values to this?

TIA




links:
0.50 cu-ft
http://www.partsexpress.com/pe/showd...number=302-722

0.75 cu-ft
http://www.partsexpress.com/pe/showd...number=302-732

[nikonguy]

Parts Express used to offer a 0.55 cu ft enclosure, it was raw MDF. I guess they discontinued it when they came out with their line of finished cabinets.

The crossover might change slightly if the width of the baffle between the two enclosures is different, but I would think the original design would be a very good starting point. Ken P occasionally posts on the Madisound forum, you might try there.

I tried to get the dimensions of the box from www.archive.org, but it looks like they didn't completely mirror the site. The part number for the baffle for the box was 300-707, the box itself was p/n 300-708. I bet if you inquire on the Partsexpress board somebody can give you dimensions and you could build your own.

Best,

Steve

[zenon]

Thanks Steve.

one more Q,

With baffle step, doesn't box height have any effect? Since it increses baffle area you'd think it would have some impact on speaker response.
But I'm pretty sure I always hear people say width... and never height.

[JC Fardo]

zenon

There´s no baffle step affects with so small baffle dim variation from 0,55 to 0,75 cuft box. For 0,75 box you would tune the port lenght though.

You can use the 0,50 box as well since it keeps 8,00-8,50" width range.

I built my box inspired in this swedish project that uses PL18 and DX25. Por dimensions are 2"x7" and it sounds marvelous.

http://www.hififorum.nu/artiklar/hfl..._2-ritning.pdf

http://www.hififorum.nu/artiklar/hfls1/del2/part2.html

Hope this helps

JC

[nikonguy]

The height of the baffle does have some effect, but the width is more critical, it impacts the frequency where the rise in response occurs. I think if the baffle widths are within a 1/2" you're probably fine as is. I just don't know the dimensions of the old cabinet...

If you go to FRD consortium you can download BDS and play with scenarios. If you don't have Excel you can Google for a program called the Edge, it is also pretty good.