Onken box for Fe206 ...

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#6
Ehehehe...

Let me try to explain: I'm not precisely interested with that cabinet, what I’d like to discuss is if an onken box can be a good solution for fostex Fe series. The reason is quite simple: I want to try one of that speakers (probably the fe167) in a bookshelf enclosure and I’m trying to investigate, due to the fact that I’m not so skilled both in speakers design and fullranges, if there is any reason to use an onken load instead the standard fostex vented boxes.

Now, put the cubic box aside for a minute… which are the pros and cons of onken's enclosures? There is, out of all the FE series, a speaker that should be able to work in that box better than in its vented one? And maybe, better than all the other in their own vented box?

Mhmm I hope that what I’ve wrote result understandable 😕 …English is not my strong point :smash:

Mark
 
#8
An Onken is simply a different way of venting an enclosure.

FE206E would require at least 4 ohms series resistance to make it suitable for a vented enclosure.

I have a FE207E in a 45L vented cab tuned to about 40Hz, it needs 2 (or 3?) ohms series resistance to align correctly. It still has some of that bass reflex "boom", but not obnoxiously so.
 
#10
zobsky said:
an "onken" bass reflex has a larger port cross sectional area than a normal circular reflex port, resulting in lower vent speeds and hence less vent noise
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I was expecting this.

1) You can make the normal vents as big you want. For a sub even 0.5*driver diameter is not exagerrated.

2) With a fullrange driver it's very hard to reach the nominal limit of 17m/s air velocity even with normal sized ports.
 
#11
mark_titano said:
Yes, cubic shape is not exactly the best solution for stationary waves.
I’m not skilled with onken boxes, have someone used them with fostex fullrange?

Landroval, onken is not more than a Jensen Ultraflex, look here:

http://www.studiomaudio.com/onken.html

Mark
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Greets!

Which are just a layout variation of Thuras's 1932 BR patent #1,869,178, fig. 1 design, so 'what was once old, is yet new again', and again........ Plagiarism IS the sincerest form of flattery, at least after the patent expires. 😉

Anyway, if they designed it properly, the internal dims won't be anywhere near cubic since the vents go almost to the backwall.

No experience with Fostex, but a number of other FR drivers, and while they have certain desirable performance attributes, I prefer using an MLTL to achieve ~the same performance in a much simpler to design, build cab.

GM
 
#12
Landroval said:
I dont see any difference between onken and normal vented box. Maybe the box is a little stiffer because of the 'double' walls, but that's it.
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Greets!

Using multiple vents adds a resistive component, making for a much better damped alignment than a BR with a single large vent.

GM
 
#13
GM said:

Anyway, if they designed it properly, the internal dims won't be anywhere near cubic since the vents go almost to the backwall.
Click to expand...

Ehmmm...you're right...external dimension/shape is not necessary equal to the internal one. Particularly in that kind of box. :Popworm:

GM said:

No experience with Fostex, but a number of other FR drivers, and while they have certain desirable performance attributes, I prefer using an MLTL to achieve ~the same performance in a much simpler to design, build cab.

GM
Click to expand...

I've got some "dimensional" problems. I need a bookshelf cabinet with max dimensions like 300*300*500 [mm].
I've thought to use an Fe167 in its standard fostex vented box but maybe an onken one could be even better. I don’t know, I’m not skilled in speakers design, at all.

Sure, TL is a good solution but I think that, with that kind of load, a bookshelf box is not the right size for better performance. I’m wrong?

Mark
 
#15
GM said:
Greets!

Using multiple vents adds a resistive component, making for a much better damped alignment than a BR with a single large vent.

GM
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What do you mean by 'damped alignment'?

Also of course the airflow will have less turbulence in multiple small vents than in one big. This can also be achieved with thin walls splitting the internal space of the big vent (like fill the vent with McDo straws...)
 
#16
mark_titano said:


Sure, TL is a good solution but I think that, with that kind of load, a bookshelf box is not the right size for better performance. I’m wrong?

Mark
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Not necessarily. The PMC DB1+ monitor uses a 5' TL folded into a near mini-monitor-sized cabinet. OK, so that's a 2 way design, but I can't think of any reasons why it shouldn't be possible to do something similar with a good single driver. Just a thought.
Cheers
Scott
 
#18
mark_titano said:

I've got some "dimensional" problems. I need a bookshelf cabinet with max dimensions like 300*300*500 [mm].
I've thought to use an Fe167 in its standard fostex vented box but maybe an onken one could be even better. I don’t know, I’m not skilled in speakers design, at all.

Sure, TL is a good solution but I think that, with that kind of load, a bookshelf box is not the right size for better performance. I’m wrong?
Click to expand...

Greets!

I believe so, there's just enough height/Vb to fold a tapered MLTL for the FE167E tuned as low as ~35 Hz, assuming the efficiency loss due to using series resistance to flatten out the FR in-room is acceptable. If a high output impedance amp is used, then that's probably all you'll need.

GM
 
#19
Landroval said:

What do you mean by 'damped alignment'?

Also of course the airflow will have less turbulence in multiple small vents than in one big. This can also be achieved with thin walls splitting the internal space of the big vent (like fill the vent with McDo straws...)
Click to expand...

Greets!

'Alignment' is just a general box design reference that you can further define as 'max flat'/whatever. 'Damped alignment' just means the vent is overdamped to some degree (port output has a wider effective BW).

Hmm, it's my understanding that the smaller the pipe, the greater the turbulence due to friction/head losses and why filling the vent with small straws turns it ~aperiodic. Anyway, yes, the Onken's vent system is based on this principle, just not as well damped unless you use more smaller, longer vents.

GM
 
#20
Re: Onken's open sounding

salas said:
Onken sounds more open in the bass in my experience, though it sacrifices some considerable extention.
Click to expand...

Greets!

This is true only if you choose to use the Onken alignment of n = 6.34. Increasing it to 10.00 makes for a nice EBS alignment.

GM
 
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