Easiest cabinet for Fostex FE206en

12345chris

Member
2010-01-14 9:55 pm
Hello All, I have the oppertunity to get a used pair of Fostex FE206en drivers.

I used to have these drivers in some very elaborate cabinets & the fostex back loaded horn and absolutley loved them.

I am not in a position to have big speakers any more ( wife!) and I cant build anything complex.

Can any one recomend a very simple cabinet for a fostex fe206 please?

I`m not looking for the ultimate & bass extention isnt important - I just need something slim and easy to build that the wife wont hate.

Currently using frugal horn mk3 with 4inch drivers.


Thanks
 
I had the same question a year or two ago from a friend and tested a lot of possiblities in simulation and some in real life in mdf (for testing) At the end the only real solution is use them as midtop in a small reflex and use a sub below. It's almost impossible to get below 100Hz on reasonable volume without a backloaded horn with this driver, above a lot is possible.

The cabinet we build was a 12l reflex with a 7cm diameter tube of 6,8cm long as port on the back and an active crossover at 90Hz to a 8" scansepaek subwoofer. The owner uses them as deskspeakers. with the sub at his feet. Amps are a diy 300B set amp and a hypex 400 kit for the subwoofer, crossover is also custom (the owner is an electronic engineer, he build those himself)
 
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OK, I'll bite as I've a spare minute. Assuming you're running a voltage-source amplifier, you can force it to work; with about 6.8ohm series resistance, max-flat is about 45 litres, Fb of 50Hz, assuming . With a 50mm diameter vent, that's an Lv of about 25mm assuming a cylindrical duct and the box lagged on opposing faces (top, back, one sidewall), 25mm bonded acoustic fibreglass board or a near equivalent (not acoustic foam). You can drop Fb to about 46Hz for a slightly better damped alignment by increasing duct length to 34mm.

For the sake of convenience, you can use the vented box Fostex show on their FE206En (and FE206E) data-sheet; just adjust the vent dimensions and add the damping & series R. Make sure it's a decent power-resistor rated to 50w or parallel, say, 4x 27ohm 10w rated resistors and place in series with the driver, in either the + or - lead; this is AC so it makes no difference. Job-jibbed.

If you want something a bit taller (and appreciating you can't accommodate very large speakers), then a relatively compact semi-MLTL (in Imperial), assuming the same ~6.8ohm series R is applied:
L = 40in
CSA = 99in^2
Zd = 13 31/32in
Zv = 33 15/16in
Dv = 3in
Lv = 2in
Lag opposing faces 1in bonded acoustic fibreglass board or equivalent (again, not acoustic foam)
Fb = 40Hz
F6 = 34Hz [nominal anechoic]

Both the above are assuming the published spec., with a small adjustment to Vas, which doesn't line up if the others are correct. A few words on series R. Yes, it / they will get hot hence it / they needs to be either a dedicated high wattage power resistor, or multiples to get the power handling up & improve heat dissipation. Don't place them in close proximity with either the damping, or the driver for obvious reasons. The 206En was nominally rated at 96dB 1m/2, or just over 97dB 1m/2.83v. The resistance will drop that to around 93dB 1m/2.83v. Note that power-handling on paper is limited as it's a short coil gap & coil, nominal Xmax is 0.8mm. Xmech is much longer though, and Xmax is just a rough & (to put it mildly) rather limited guide to distortion.
 
….the only real solution is use them as midtop in a small reflex ...
Such a small reflex exists. It does not go low. To do that well you really need a horn.

https://frugal-horn.com/downloads/centre/dFonken206-centre-190118.pdf (now free for personal use)

But sealed to a woofr probably makes more sense.

https://frugal-horn.com/downloads/centre/FE206En-sealed.pdf
FE206En-sealed2.gif


The vented box does not go much lower ultimately but will have more kick in the upper bass.

Both would XO to the woofers at 110-130 Hz.

dave