T/S Parameters for Onken What should I be looking at?

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perkri

Member
Joined 2017
#1
Hi,

Trying to figure out what are the relevant parameters for an Onken enclosure?

EBP is helpful when working through Horn/ported/sealed types of enclosures.

Any thoughts on what the pertinent parameters are when designing an Onken?

Thanks!

Per
 
#2
I only have a moment, but an Onken is ultimately just a vented box with a large distributed vent CSA. So assuming you don't want some colouration from vent harmonics (some do, and the combing is likely responsible for the characteristic presentation of some Onken designs), then ideally, you want a unit that requires a reasonably large Vb for a given tuning in order to keep the duct length down.
 
#4
Thanks (as always) Scott!

I’m thinking of using some kind of large coax speaker for this experiment.

More research 🙂

Scottmoose said:
I only have a moment, but an Onken is ultimately just a vented box with a large distributed vent CSA. So assuming you don't want some colouration from vent harmonics (some do, and the combing is likely responsible for the characteristic presentation of some Onken designs), then ideally, you want a unit that requires a reasonably large Vb for a given tuning in order to keep the duct length down.
Click to expand...
 
#6
Do a search for the older Onken threads here, there is a lot of information in those threads. There are several experts on Onken here on the forum - hopefully they will find this thread soon.

I built 11 cu ft Onken cabs back in 2006 which are still in use today.

The Onken Mini is considered to be an Onken as far as I am aware - a number of my friends have them and they're just smaller (12 inch drivers) but otherwise very similar.

The Onken is based on the older Jensen Ultraflex design.
 
#7
Scottmoose said:
I only have a moment, but an Onken is ultimately just a vented box with a large distributed vent CSA. So assuming you don't want some colouration from vent harmonics (some do, and the combing is likely responsible for the characteristic presentation of some Onken designs), then ideally, you want a unit that requires a reasonably large Vb for a given tuning in order to keep the duct length down.
Click to expand...
Translated into Thiele Small parameters, that roughly means Qts = 0.4 - 0.6 .
Slightly higher is acceptable if the frequency response does not have to be perfectly flat.
 
#8
Onken cabs around here were built with drivers like the 515, 416 and 412 which are all low qts drivers. I believe TBTL's recommendation would result in somewhat flatter overall response than designs traditionally based on lower qts drivers.

Mine are built around Iconic 165-8G which are essentially a 515-8G.
 

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#10
A driver that sounds good.
And works in a vented box.

Its basically a reflex box.
With a unique dual slot ports.

Keeping in mind if you want a 12" coaxial speaker that has a woofer that can crossover high enough to work
its usually gonna be a pro sound type driver. And most but not all live sound coaxial drivers are designed for stage monitors.
Which are typically small boxes.
 
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#11
perkri said:
Trying to figure out what are the relevant parameters for an Onken enclosure?
Click to expand...

Greets!

N = 5.7 performance wise is near enough identical to this T/S max flat design routine:

Vb = 20*Vas*Qts'^3.3

Fb = 0.42*Fs*Qts'^-0.96

N = 6.34 is more like an EBS, i.e. bigger cab with a higher F3 'shelf' for apps with high[er] room/boundary gain.

In short, a large Vas or high Qts' or a balance between the two is required for a typical LF driver's Fs.

[Qts']: [Qts] + any added series resistance [Rs]: Calculate new Qts with Series Resistor
 
#13
TBTL said:
Translated into Thiele Small parameters, that roughly means Qts = 0.4 - 0.6 .
Click to expand...
I misread Scottmoose's post, I missed the 'for a given tuning' bit. A highish Qts > 0.4 results in a large vented enclosure (therefore short ports), but also results in a low tuning frequency, for a given fs. A low tuning frequency increases port length again.

A highish Qts driver (> 0.4) in a vented enclosure, needs a highish fs to keep the tuning frequency moderate in the absolute sense.
 
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#17
Hi

I also want to build (mini) Onkens. I have two Wharfedale super 12 drivers, the t/s parameters differ unfortunately:

Driver 1 Driver 2

R(e) 11.28 12.39

F(s) 34.99 29.61

Q(ts) 0.3863 0.2816

Q(es) 0.4415 0.326

Q(ms) 3.095 2.07

L(e) mH(10k) 0.4835 0.5162

M(ms) 34 34

V(as) 336 liters 240 liters

Any idea whether these would work in Onkens?
 
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