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Old 5th October 2007, 12:26 PM   #1
DUC985 is offline DUC985  Germany
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Default Mini Onken clone driver question

I'm looking for some driver advise to rebuild the Onken to support my Oris Horns.
It seems quite difficult to find information and background for this speaker. In all designs i find the used speakers are no longer in production and very hard to find. The only current one i found plans for are the Onkens using a Supravox 280 speaker. Which is a little bit too high priced for me. The attached Speaker used an Altec 414. I looked up the thiele & small parameters for this speaker :

RE = 6.7
VD = 11.8 cu. in. = 193.36 cm3
SD ~ 400 cm2 = 0.04 m2
FS = 30
VAS = 8.13 cu. ft. = 230 L
QTs = 0.21
Qms = 7.4
Qes = 0.21

if i use this paramaters in the Onken_Calc.XLS my results look kind of strange. The outcome is a lot smaller than the design. I have read already the two bigger Onken threads, but they did not share a lot of light to me ...

Question i have now, has somebody build this speaker already with a current production speaker that works well ?
Which kind of speakers should i look for ? QTs around 0.35 Vas, around 250L, light cone, FS around 30

thx

Mathias
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Old 5th October 2007, 12:48 PM   #2
el`Ol is offline el`Ol  Germany
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Which Supravox do you mean? The 285 GMF is not expensive compared to Oris horns.
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Old 5th October 2007, 02:25 PM   #3
GM is offline GM  United States
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Default Re: Mini Onken clone driver question

Greets!

The cab is a lot bigger due to taking into consideration the high output impedance of the amp used, inductor and wiring resistance which effectively raises the driver's Qts. I don't recall at the moment how much it increased Qts, but it was ~flat in-room down to ~35 Hz IIRC, so probably around 0.4. The cab you calc'd is correct if these aren't accounted for.

While your English is OK, I can interpret what you say more than one way. I mean I'm not sure if:

1) you already have a Petite Onken and need a driver for it.
2) want to build one with an inexpensive driver currently available.
3) want to design, build an Onken specifically for a suitable current driver.

So the first consideration is how much added series resistance will there be in the signal path? If you use a SS amp, active XO or very low DCR inductors and large enough speaker wire there won't be enough to affect the design much so you can just use the driver's T/S parameters and add ~10% to account for the driver, any bracing and a small amount of tuning flexibility.

Once we know what you want to do and what you intend to drive it with, then hopefully someone should be able to help. Note that if (1) or (2), I don't know of a simple way to find an appropriate driver other than choosing one with about the same Vas, Fs and a Qts based on the amount of any added series resistance, so AFAIK you will have to sim different drivers to find suitable ones if no one already knows of any.

GM
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Old 6th October 2007, 09:38 PM   #4
DUC985 is offline DUC985  Germany
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GM , let me try to clarify. Currently i have nothing Onken like, only the Oris supported by sealed woofers. I had the chance to listen to the same Horns supported with a Onken using Altec 414.
Since than i'm looking how to rebuild this system. At first it looked easy to find a driver close to the Altec and just rebuild the case. Aperently it is not that easy.
The only driver which seens to be close i found is a Beyma 12B100.
But using the Onken_calc i can not replicate the enclosure not with the Altec or Beyma. The issue seems to be MMs/d as soon as this parameter gets realistic to about 70 gramms L'vent is getting bigger than 100. And not <35 cm.

So basically i'm open to any design as long as it can work. I think the Beyma is a very nice driver.

The Onken will be driven through solid state, some Pass gear.

Mathias

Beyma :

FS = 29 Hz
RE = 6.6
Qms = 6.49
Qes = 0.31
QTs = 0.3
VAS = 154L
Xmax = 3mm
Moving mass = 77g
94db
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Old 9th October 2007, 06:26 AM   #5
GM is offline GM  United States
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Greets!

Again, the Petite Onken AFAIK was designed using actual driver, system measurements, so not surprising you can't reverse engineer it. I never tried, I mean it is what it is.

Since you still haven't told me anything useful about your system, about all I can say is that the Beyma's published response is nothing like the 414's, so while it sims similar to its published specs in the Petite Onken, it won't sound the same, though this isn't to imply that it won't sound good.

Anyway, here's a reasonably accurate sim of it using 414-8C published specs with no output series resistance from the amp or in-line inductors or small gage wire, so very under-damped:

GM
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Old 9th October 2007, 06:30 AM   #6
GM is offline GM  United States
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.......and loaded with the Beyma 12B100-R:
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Old 9th October 2007, 07:35 AM   #7
DUC985 is offline DUC985  Germany
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thx GM for the sims. What kind of software do you use for the sims ?

What exact kind of information do you need to know ?

Maybe i need to add that the Onken will be run with an active crossover until 250Hz.

I know that the Beyma is a totally different kind of driver and probably will sound not good. Only a try can really proof that. Another driver could be the Eminence Kappa Petit Onken with a lot of stuffing and maybe added series resistance.

It would be nice to have a recent design with theory and driver proposal, but i think there is none.

Mathias
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Old 9th October 2007, 02:29 PM   #8
Pano is offline Pano  United States
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Quote:
Originally posted by DUC985
The Onken will be driven through solid state, some Pass gear.
The Pass amp is a current source amp, right? That will make a difference.


Quote:
Originally posted by GM
...so not surprising you can't reverse engineer it. I never tried, I mean it is what it is.
I've tried, never could get the numbers to work. Maybe more series resistance or higher output impednce needs to go into the sims.

I have heard the Mini Onken. Sounds very good.
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Old 9th October 2007, 05:27 PM   #9
GM is offline GM  United States
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Greets!

You're welcome!

Those were done using MJK's MathCad worksheets and if you don't have MathCad or can justify its cost, then you can DL an old demo copy from his site, but you can't save your work other than by copy/pasting it into a WORD or similar doc: http://www.quarter-wave.com/

FWIW, the Beyma's response falls right in line with Thuras's original reflex patent alignment, which was what the Jensen/Onken alignments are based on: http://www.google.com/patents?id=MS1...PP1&dq=1869178

Anyway, I prefer to design from scratch rather than reverse engineer, so
ideally I need to know the amp's output impedance since some of Nelson's amps are current drive designs IIRC, what brands, price range of HE woofers are available to you, max speaker HxWxD dims allowed, desired LF extension, general info on room size, desired speaker locations, listening distance, etc..

Even if we can't come up with a viable Onken alignment, for sure we can come up with some form of MLTL that will perform well withing your limitations assuming they're not too restrictive.

GM
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Old 9th October 2007, 08:20 PM   #10
DUC985 is offline DUC985  Germany
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GM, very interesting i was not aware that google even offers patent research. In a couple of years Google will be the Microsoft of the Internet.

Let me try to answer your questions :

- I'm thinking of using my F1 to drive the base bins and use the J-Fet ones for the Oris Horns. The F1 has about 80 ohms.
- I'm open to all brands as long as i can get them easily. B&C,Beyma,Eminence,BMS, you name it ... all of them make a couple of good woofers. Price range would be up to 200-300 bucks per woofer max.

Important for the bass is speed and clean sound, so no long throw subwoofer crap. It does not need to go that low 40Hz is enough.

From a size perspective if it would be <150 Liters . 500x400x800cm

Current room is 3x5 Meters and speakers will be at one end around 50cm from the corners away. Not ideal, maybe improved later.
Listening distance around 3 Meters.

Mathias
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