Hello
I would like to read an english version of this article
La Mini-Onken
I am considering to make a mini onken with supravox 215 GMF
or if there is a better choice for driver .on top iwata 300 with a decent cd
Best regards Vegard
I would like to read an english version of this article
La Mini-Onken
I am considering to make a mini onken with supravox 215 GMF
or if there is a better choice for driver .on top iwata 300 with a decent cd
Best regards Vegard
The mini-onken was used with a fullrange driver on top. I heard the pair that were built in that article and they used a Lowther on top. A 300Hz Iwata horn seems a bit overkill. Better suited to the petit onken or the bigger one.
If I get the time, I'll translate the article. It has some rather good info on the Onken tuning.
A section of the article asks: "Is the Onken a classic, well tuned bass-reflex box?"
After doing the math the answer was: "In conclusion we can confirm that the Onken box (derived from the Jensen baffle) is a perfectly tuned bass reflex that rigorously follows a 4th order law."
There you have it. The hard part is figuring out the tuning of the slot ports.
If I get the time, I'll translate the article. It has some rather good info on the Onken tuning.
A section of the article asks: "Is the Onken a classic, well tuned bass-reflex box?"
After doing the math the answer was: "In conclusion we can confirm that the Onken box (derived from the Jensen baffle) is a perfectly tuned bass reflex that rigorously follows a 4th order law."
There you have it. The hard part is figuring out the tuning of the slot ports.
Thanks
as you can see the proposed volume for 215 gmf is almost twice the cabinets for focal 10c01.I stumbled across the supravox driver as one of few ? suited for a smaller onken cab.Any proposals for another driver resulting in a smaller cabinet ?
Links to information on the ports dimensions and how to settle them ?
best regards Vegard
as you can see the proposed volume for 215 gmf is almost twice the cabinets for focal 10c01.I stumbled across the supravox driver as one of few ? suited for a smaller onken cab.Any proposals for another driver resulting in a smaller cabinet ?
Links to information on the ports dimensions and how to settle them ?
best regards Vegard
IIRC, the Onken box likes a driver with high Vas and low Qt. Many modern drivers are not like that.
Basically you're building a bass reflex box with a port area about 75% of the cone surface area. There are many ways to do that, of course, but with the Onken you'll have slot ports along the sides. Figuring out the port correction for those slots is not something I've been able to do, but the spreadsheet helps. You may also notice that the 3 boxes designed in Paris have a port length right at the long edge of "acceptable."
Basically you're building a bass reflex box with a port area about 75% of the cone surface area. There are many ways to do that, of course, but with the Onken you'll have slot ports along the sides. Figuring out the port correction for those slots is not something I've been able to do, but the spreadsheet helps. You may also notice that the 3 boxes designed in Paris have a port length right at the long edge of "acceptable."
I can definitely confirm the first and last sentences, (and >80% of sd on port area IIRC) the ports on my Onkens are just a small number of cm shorter than the maximum allowed. I'm still as thrilled with them as the day I built them.. (About 5yrs ago now!) Pano incidentally provided a lot of encouragement.
Hmm, if I did the math right, a mini-Onken would be ~ 57.69 L net, so tuned to Fs, its vents would be quite long, though tuned up around its ~60 Hz 4th order roll-off, they should just barely meet the max recommend length for minimum vent area.
GM
It's interesting because the Onken Calc wants it in a 133L box, I see it as going in about 1/2 that, or 72L net for bass reflex. Greg sees it in an even smaller box, of about 58L.
The 133L tuned to 43Hz looks like an Extended Bass Shelf with a little peak at the bottom. Might play down into the upper 30s.
The 133L tuned to 43Hz looks like an Extended Bass Shelf with a little peak at the bottom. Might play down into the upper 30s.
You apparently didn't take the 2 ohms series resistance [Rg] into account [Qes = 0.438] that will increase the net Vb to a bit > the Onken's. After a quick scanning of the mini-onken article, it turns out I was using Jean Hiraga's 'ultra-bass' [actually mid-bass] alignment which doesn't consider effective motor strength, only Fs, Mms, effective piston radius. That would be dealt with in choosing a tuning point. The mini-onken appears to be only 'mini' referenced to the original Altec due to its smaller driver, differing specs.
Personally, if the specs being simmed are reasonably accurate, I'd follow the well proven design criteria used by WE, Altec and their 'clones', i.e. find the net Vb where Fs is raised 1.56x in a sealed cab, then vent it to Fs or ~99.2 L. No clue why the 'K' factor is 1.57 as I've read nothing to justify it being different, not that it will make an audible difference AFAIK.
GM
Personally, if the specs being simmed are reasonably accurate, I'd follow the well proven design criteria used by WE, Altec and their 'clones', i.e. find the net Vb where Fs is raised 1.56x in a sealed cab, then vent it to Fs or ~99.2 L. No clue why the 'K' factor is 1.57 as I've read nothing to justify it being different, not that it will make an audible difference AFAIK.
GM
sorry
The server dropped out during posting.
It was mentioned that the three Onkens made in Paris have vent lenghts just shorter than the allowed maximum.
I tried to achieve the same with supravox 215GMF but it is not possible without redusing the n factor well below 5.
as is wentlenght effective between 20/24 cm.To short ?
Gm I will look into your suggestion later.
As for the specs accuracy ,I do not know maybe an email to supravox will do.
Best regards Vegard
ps Supravox suggested this:
http://www.supravox.fr/kits/jensen215.pdf
The server dropped out during posting.
It was mentioned that the three Onkens made in Paris have vent lenghts just shorter than the allowed maximum.
I tried to achieve the same with supravox 215GMF but it is not possible without redusing the n factor well below 5.
as is wentlenght effective between 20/24 cm.To short ?
Gm I will look into your suggestion later.
As for the specs accuracy ,I do not know maybe an email to supravox will do.
Best regards Vegard
ps Supravox suggested this:
http://www.supravox.fr/kits/jensen215.pdf
according to
Supravox 215GMFHow to tweak this driver to better performance
year 2006, the volume of the Jensen box is 102l , 312 cm^2 port areal (300mm lenght)
And fs was apparently 65 hz. specs of today says 45 hz
Even though the driver has different specs they still recommend the same enclosure ??
What are the consequences of letting vent areal become larger than drivers SD ?
Supravox 215GMFHow to tweak this driver to better performance
year 2006, the volume of the Jensen box is 102l , 312 cm^2 port areal (300mm lenght)
And fs was apparently 65 hz. specs of today says 45 hz
Even though the driver has different specs they still recommend the same enclosure ??
What are the consequences of letting vent areal become larger than drivers SD ?
Last edited:
No
(strange maybe )
Guess if I regret choosing german as my second foreign language 30 years ago.
I have done some attempts to convert the picture of the article, and run it through google translate.The result is mediocre.
(at least when translating to norwegian)
So I am typing the french words in a new document, it seems to yield something understandable when running translation to english.It will take a few weeks due to lack of sparetime.
I will post it here when ready.
(strange maybe )
Guess if I regret choosing german as my second foreign language 30 years ago.
I have done some attempts to convert the picture of the article, and run it through google translate.The result is mediocre.
(at least when translating to norwegian)
So I am typing the french words in a new document, it seems to yield something understandable when running translation to english.It will take a few weeks due to lack of sparetime.
I will post it here when ready.
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