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nesha 7th March 2010 09:07 AM

Wild Burro Onken
Hallo guys (and girls). I just received my pair of BetsyK 8" fullrangers from WildBurroAudio (at 50% discount - a bargain,he,he) and I'd like to make onken box for it. Onken calc is giving me this results :
port dimm: 4x9x32 cm, Nports=8
A big box,but I can live with that, and more important - my wife agrees .:)
I'd change dimension of the port :2x18x32cm, same volume and length ,shouldn't be a problem.
I'm just worried about those 133l, Vas is 83l, am I using calculator correctly ?

Re 5.7 ohms
Fs 49.959Hz
Sd 22.966
BL 5.471
Qms 2.798
Qes .548
Qts .458
Spl 94.6
Vas 82.914L
Mms 9.167g Thanks.

rjbond3rd 7th March 2010 05:51 PM

Hi Nesha, which Onken calculator are you using?

nesha 7th March 2010 07:13 PM

The same one Andrea was using in his Hi efficiency +Onken project
Hi-End and Hi-Eff loudspeakers system

I tried basreflex calc for ButerrworthB4 type box - result was 100 l, and Hoge type box - 130l. - Home
Thanks for reply.

kevinkr 7th March 2010 07:15 PM

I wouldn't have thought that a driver with a QTS in the >0.3 range would be a good match for an Onken box.. Maybe there is something I am missing. I haven't run the numbers in the Onken calculator yet. You are using Cyr Marc Debien's Onken Calculator (Koizumi/Mahul) aren't you? Certain parameters not being met disqualify it as a real Onken box.

Watch the port length, anything over 32cm is a concern due to serious comb filtering effects due to the excessive delay between the ports and the driver's direct radiation.

nesha 7th March 2010 07:25 PM

I just checked again : port 4x9,5 x 32,5 cm ; calculator say 35cm is critical port length.

kevinkr 7th March 2010 07:32 PM


Originally Posted by nesha (
I just checked again : port 4x9,5 x 32,5 cm ; calculator say 35cm is critical port length.

You're just inside the window.. Should be an interesting project. I quite like mine, but they're huge.. :D

nesha 7th March 2010 07:34 PM

Jes Kevin , that's the one I'm using. And I thought I can get away with 32,5cm
port length ...:(:confused:

nesha 7th March 2010 07:36 PM

So, OK?

GM 7th March 2010 08:46 PM

1 Attachment(s)
Well, when I 'run the numbers' I get a somewhat different set of values for a n = 6.34, but adding more series Rg will of course increase the cab's net Vb, but either way the effective vent length (L' vent) is less than yours, so wondering if you're quoting the acoustically uncorrected length (L vent).

Note that I adjusted Mms/d to get the desired Vas spec since it calculates a slightly larger cab.

Regardless, Qts is > ~0.403 where Vb = Vas, Fb = Fs, so cab net Vb will be >Vas and Fb will be <Fs.


Zen Mod 7th March 2010 08:51 PM

nesha - do what GM told ya - he knows these things :clown:

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