Help with cabinet design for SB20FRPC30-8

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#122
Thanks! That is great news.
I think my biggest hurtle will be to figure out how far down I should place the driver as I’ve read even mm’s can have an effect on if some internal resonances will be cancelled.
Also I have found on my search that this SB 8” driver has quite similar (VAS,QTS,FS) efficiency and Xmax as the cube audio FC8. They have some interesting designs on their web site for DIY ers.
 
#126
Yes, I did see that other thread with the hronsrep sims for different volumes and enclosures. That’s how I decided on 66L enclosure. I did also look the the “accidental mltl thread”, which helped me immensely to clarify how a seemingly reflex design achieves quarterwave development.
I just only have Apple products IPads and such.
 
#130
Thinking about that, given that Parallels on the the new Mx processors often runs Windoz better than many Intel boxes, i wouldn’t be surprised to see a version running on Mx iPad. And also maybe WINE (& Crossover Mac) for well behaved Windoz software.

Looks a lot like this online one of the same name, https://speakerboxlite.com/

First pass thru — very cumbersome and hard to get where i wanted.

dave
 
#131
Yea I’m limited to IPads at this time for my computer power. I did use that “speaker box lite” program for a sub I put together a few years ago. You observations parallel mine with that. I did’t feel it was suitable for optimizing an MLTL design. Or at least I don’t know how to use it correctly to get what I want.
Perhaps I should just stick to a BR alignment for this and use other online calculators.
Although setting the driver at 21% line length is inline with what I have read and observed with other diy designs for a MLTL.
Another concern may be that setting the driver that low in a midsize (36”) cabinet certainly won’t be optimal for a seated listener.
Thank you all very much for your help so far!
 
#133
Bmaz said:
I have read most other threads that have mentioned this driver and many concerning MLTL design along with MJK’s site. I just don’t have access to the worksheets or Hornsrep and would rather not use “rules of thumb” to determine driver and port placement.
I’m estimating the driver being placed somewhere between 20-23% down from the top of the line and port approximately 4-5 “ up from the bottom.
Click to expand...
A belated response:

Note that driver(s), vent(s) ideally need to be at a pipe's odd harmonics, so with 'L' = internal height, 'Z' = driver and using the acoustic center of clustered drivers........

Z = (L)x ~ 0 (top), 0.217, 0.349, 0.424, 0.561

Vent offset only, depending on box HxWxD ratio: Z = (L)x ~0.651, 0.714, 0.848, 0 (bottom)
 
#135
Mosquito said:
Based on the plans for the A8, and the Altec 515 specs, I get the cabinet is around 200 dm3, with s slit 16" x 1", long 3/4 inch (cabinet walls), that tune it to something like 38/40 Hz, up to the woofer natural Fs. It's right or wrong?
Click to expand...
No clue without knowing what specs used as they changed quite a bit over the decades, nor how you're calculating a slot vent > 9:1 where it's already somewhat aperiodic. I had to experiment by 'critically' damping the vent, but in general it will be fairly large due to its high Vas and somewhat > Fs due to its powerful motor.

Dave p10's Click Test diagram.png
 
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#137
I just read that post and it seems that vertical brace is parallel to the sides. He then describes side-by-side braces going through the 'holes' in that vertical brace as well as other braces. It's not the way I'd brace it, but hey, if it worked for him.
 
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#139
Right, the pioneers found that we ideally need to tie all panels together such that it also braces/mass loads the driver to it to the point where the driver isn't coupled to the baffle other than by a sealing gasket.
 
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