Fostex's new Fe103 Sol 8 50th anniversary Drivers?

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How big is the mouth. Floor loaded the mouth, if untruncated, should have a perimeter of approximately 1/2 the w/l of the cutoff
A characteristic of the underdamped TL that it more closely reembles.

dave

The mouse opening is about 100 cm^2, throat is maybe 20 cm^2.
Impedance is for FE108EZ.
 

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frugal-phile™
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The mouse opening is about 100 cm^2

Making some favourble assumptions, the horn action might reach down to 300 Hz, in the region above where you would like the horn to act, so it is really a poorly designed TL. That isn't necessarily going to make it sound bad, but it does mean that more can be extracted from the driver with a better enclosure.

The best enclosure we have tried for FE108eS is Aiko, which still takes some liberties in terms of size.

Aiko-FE108eS.jpg


dave
 
Making some favourble assumptions, the horn action might reach down to 300 Hz, in the region above where you would like the horn to act, so it is really a poorly designed TL.

Hi Dave,
I'm not sure about the 300hz number, unless you are referring the -6db number un-EQed. Comparing my curve with FE108 to this
Horn Shoppe Horn loudspeaker Measurements | Stereophile.com
They share some similar characteristics, but less output at the mouth due to size. By 60hz I mean "cone-loading" frequency, not the -6db point. They're too bright in this enclosure before EQ.

That isn't necessarily going to make it sound bad, but it does mean that more can be extracted from the driver with a better enclosure.

The best enclosure we have tried for FE108eS is Aiko, which still takes some liberties in terms of size.

dave

Totally agree :)
 
frugal-phile™
Joined 2001
Paid Member
Hi Dave,
I'm not sure about the 300hz number, unless you are referring ...

I am referring to the frequency that the box is capable of acting as a horn. Since it is above what should be the acoustic cutoff of the horn, it is in effect not a horn at all. The EdHorn suffers the same to a lesser extent, being corner loaded it only needs a mouth 1/8th the size of a full-size horn.

dave
 
....that is a very big box for that small driver with minimal excursion. I expect it still to have a thin bass. Or am I wrong?

Think of the cab as an acoustic lever, so the more leverage [size, path-length] it provides, the greater the loading on the driver, ergo the more SPL/W and/or wider BW depending on the design. Properly integrated into a corner and a usable 32 Hz out of a tiny driver isn't out of the question.

Consider the early Bell Labs/WE BLH prototype with its 1" exit compression driver and special phase plug that had a usable 50 - 10 kHz BW to fill a small cinema in 4 pi [full] space on 8 W, which was a wider BW than any recorded media at the time to ensure a ~flat response. The trade-off of course was size with a ~15 ft path-length and 8 ft square mouth.

GM
 
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Indeed - as to updating Aiko - as many of the various manifolds as I've built, it's hard to remember the exact details, and I do a lousy job of archiving drawings thereof.

Would there be enough flexibility in the volume / throat aperture of the driver chamber to allow for minor fine tuning?

Personally, I quite liked the Vampyr - and rather a simpler build than the Aiko
 
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