Onken bass box with 2 Eminence Deltalite ll 2510 10" bass drivers

[revintage]

It is nothing special about the Onken concept expect for the n=6,34 and the ports being equal in area to Sd. About the ports it should be mentioned that I have an article from the L´Audiophile with two 515 and very small ports and L the same as the baffle thickness!

It should also be mentioned that Onken is nothing but a 4th order Butterworth bassreflex.

This one, (but not in Excel at first) that I made years ago(when the article was published) is by the book as I used the L´Audiophile(I have very issue of it) article.


http://www.revintage.se/Onken.xls

JMMLC's corrections to mine which only uses Vas, Fs, Qts and the driver's effective radius.

That is the same as mine and also by the book. See the left version in my spreadsheet.

As you see there is no provision for Rg. So CMD´s isn´t by the book but taken a step further. As I remember it there was another article just after this where the provision was added. Will check how it was done.

The 2510´s gives us a very long port which isn´t the best but it will surely work.

[GM]

This is what JMMLC said, though WRT Sd'/Sd = 1.0, a couple of others have claimed that the Onken ideology was to use 0.9.

Yes, according to JMMLC, Onken [the company] products for the most part didn't conform to any of this, so how did this arcane design routine come about? To me, it's based primarily on Thuras's patent reflex experimental cab that Jensen resurrected as the Ultraflex.

IOW, build what you want as long as it has a multiple ducted port vent system that's large enough in total area to be around Sd and long enough to audibly 'color' [distort] the lower mids.

The caveat is that with today's [ultra] low Vas drivers, getting a large enough vent area [Av] can mean organ pipe long vents, so at this point it needs to either be somewhat aperiodic or go with a MLTL to get some 1/4 WL loading on a single large vent to further shorten it, which is what I've been doing since '68 when I got educated on the underlying theory of Olson's original [late '40s?] LC-1A high aspect ratio 'reflex' cab. He missed a good patent/marketing opportunity with that one since 'conventional wisdom' dictated that the vent be as close as practical to the driver.

BTW, how was the 'n' and 'k' number derived? Of what value is the 'k' frequency calculation? Since it doesn't use 'k', shouldn't it be a calculated value from Fs, 'n'? If JMMLC explained all this to me, it's become lost over the last ~11 years and some of the other partial explanations I've seen posted made no sense to me, so didn't save any of them.

GM

[revintage]

I have Hiragas book "Loudspeakers" somewhere. As I remember "n" was well described there.

This is a short article about Onken W. As you see, no long ports.

http://www.audioheritage.org/vbullet...t-Onken-W-quot

[revintage]

Found the article when I Googled!

La petite Onken (J.Hiraga)

[revintage]

Just for fun I added a feature to choose the number of drivers you want to run in parallell:

http://www.revintage.se/ONKENcm3414.xls

[jamikl]

I think I am with revintage on this one. The crucial part seems to be the speaker in box alignment of 6.34. It may have been accidental that the vent size is so large unless he was trying, as GM suggested, to do something like the
Thuras patent.

My feeling is that as long as the in box alignment is 6.34 then make the vents as
large as you can whilst keeping to a reasonable length and putting the vents near the speaker, maybe each side. I think the idea of stuffing the ports slightly is probably good as well. This is just intuition - no experience to back up what ideas I've come to unlike GM and revintage.
jamikl