The mouse opening is about 100 cm^2, throat is maybe 20 cm^2.
Impedance is for FE108EZ.
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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.
dave
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.
Totally agree 🙂
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
The best enclosure we have tried for FE108eS is Aiko, which still takes some liberties in terms of size.
dave
Dave, just wondering, 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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The spec sheet says that the 8ohm version is for bass-reflex or a back loaded horn while the 16ohm version is only for bass-reflex. Any particular reason why I shouldn't use the 16ohm driver in a BLH?
Both are a fudge (although I can see what they're driving at), but you should be able to use the 16ohm version in a back horn if you wish.
I really should update Aiko at some point... that was quite a nice little box.
I really should update Aiko at some point... that was quite a nice little box.
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
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
just thinkin' - well, if such electrical activity qualifies as such - is Fostex aware of what the abbreviation "SOL" is colloquial for amongst certain subcultures? 😀
Is Radio Shack 40-1197 (FE103), sold in the 1960's, an early Fostex? The pair that I have were made in S. Korea. It's amazing that I have these in my possession still, I don't know how that happened.
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