Fostex FE EN series Factory B.R designs. - diyAudio
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Old 5th November 2013, 07:58 AM   #1
gsd is offline gsd  United Kingdom
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Default Fostex FE EN series Factory B.R designs.

I seem to have a problem when trying these BR designs with WINISD.
If I input the data for FE 126, 166 or 206 EN in the spec sheet recommended
alignments ( or any other BR alignment) WINISD shows cone excess excursion, making the designs unusable above a watt or so of power.
Is this an WINISD 0.7.0.900 anomaly, poor manafactures design or a misunderstanding of the sesults on my part?
Any help with this would save me more hours of head scratching!

Regards,

gsd.
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Old 5th November 2013, 08:58 AM   #2
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A bit of all.

-The Fostex factory BR designs for the En series drivers are IMO mediocre at best. Actually, they weren't even designed for the En series units, they were designed for the previous E series drivers which, at least according to the published data sheets, in most cases had rather different specs. They have simply carried those, and the back-horns for that matter, over to the En series.

-Most of the En series units are not all that well suited to BRs as-is, without some help from Eq, or a high output impedance amplifier (which the previous E series units were intended to be used with & presumably also applies to the current En models).

-Xmax is not the point at which the driver flies to pieces. Fostex drivers have a very short VC & VC gap, so they nominally have only a small amount of linear travel. However, they overload relatively benignly (relatively), and Xmax itself is a nebulous concept: there are multiple definitions, all of which give different results if applied to the same driver, & manufacturers rarely state the method they used to give a figure for it. It's a useful rough guide, but that is the best way of viewing it. All of the En units you mention are regularly pushed way past the nominal figure by the majority of their users.

-If any of the above bothers you, you might want to look at alternatives; Fostex's own FFxxwk units, which are better natural matches to BR boxes, the Mark Audio and Tang Band drivers etc.
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Old 5th November 2013, 10:52 AM   #3
gsd is offline gsd  United Kingdom
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Thanks for the detailed reply regards real life use of the fostex units.
I am looking to construct some new speakers to replace my JX92's to match a newly built 10w triode connected kt120 amp and so require max efficiency from small boxes.
I have an existing in wall 75ltr block built sub with 500w amp giving a theoretical
25hz response which I usually cross over at 80hz.
I really need to build small satellites with a min 93db (I think!)
Unfortunately even the ffwk series don't look good on excursion when a 10w signal
is applied. The main concern is not so much the L.F. excursion as the amp could be rolled off to suit but peaks seen to appear over the 100hz mark which I find worrying.
there doesn't seem much point in having high efficiency if you are unable to use it.
If I simulate the alpair 10p for example then although it has less efficiency, you do seem to be able to use it all!
I want to build these speakers to a high cabinet spec and so only want to do it once. Any other suggestions would be appreciated. Your comments on real life use of the Fostex drivers has been duly noted but I am a little cautious


Thanks again for the help so far.

gsd.
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