Back Loaded Horn with FOSTEX, some questions...

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This is my first post on this forum :wave2: . I'm planning on building a BLHorn to use with Fostex speakers, but i'm not shure wich driver to use. I have in mind the FE168ez Sigma, FE208E Sigma (old one) and FE208ez Sigma (the new) and I have some questions:

1) The old FE208e goes up to 20khz, the new one goes up to 14khz and needs a tweeter (Fostex recomend the U$141 each). The old one is really better than the new one, or I'll need a tweeter anyway?

2) My room have only 14m^2, would the FE168ez be a better choice over the 8'' Sigma's, giving sufficient bass? Plus it goes up 21khz!

3) Fostex recommend the T90A tweeter, wich is expensive (U$141). The Fountek NeoCD Ribbon tweeter costs U$83 could be a better choice? There is another not so expensive driver?

4) I'll make a BLHorn. The Fostex recommended plan are the better ones?

Sorry for all the questions.

I'd go with the FE168Esigma and the Fostex design. It doesn't need a tweeter, so instant saving there, and it doesn't need such a large room as the larger drivers, so will probably better match what you have than they would. I like the Fostex cabinets (I'm going to be building a doubled FE103E cabinet very soon -I've already built a pair to the original single-horn design and loved them), but there are other options available too, though they won't be as easy to build. Swan! Who said that?!

Some answers and some more questions

I had three pairs of FE168EZ (all Fostex cabs), two FE108EZ (Fostex cabs) but no FE208EZ.

If money is no object, go with the new FE208EZ. Main reason is that the FE168EZ is sometimes annoying (beaming issue). Having a seperate tweeter gives you a whole lot more control over the sound (you can use the 208 FR or roll it off a little, then add a ST to taste).

Not so with the FE168EZ, you live with what you got, unless you roll the highs and add a ST (or experiment with resistors). So it's kind of a no-brainer.

Also, both Fostex specs for FE168EZ and FE208EZ are almost the same size (BIG!).

Question, do you like bass? Do you plan to use a sub? if so, may I suggest you try a FE108EZ? This may seems like an odd proposition, but the highs in the FE108EZ are much more smooth and better dispersed than the FE168EZ, the bass extension is almost the same (but it's a non issue with a sub), except that it won't play as loud. But if you are not looking for ear splitting levels, overall, I think it's a better choice.

Ribbon ST are a real good match for the FE208EZ (none needed for FE168EZ and FE108EZ).

I hear on normal (moderate?) listening levels. I'm not going to use subwoofers, but I want acurrate bass. The FE208ez doesn't need any crossover right, just the tweeter with a 0,68-1,0uF capacitor? How low can the FE208ez go?

I like Jazz, Blues, and rock. But not opera and orchestra. I'll use a DIY Tube amplifier with 5 to 15wrms.
How Low is Low

All three Sigmas will reproduce correctly double-bass fundamental notes with lifelike quality.

I'd say the main quality of these IS the bass and mid-bass reproduction (and of course the midrange). Air is very efficiently moved by BLH, and double-bass, kick drum, grand piano and all percussive instruments sound marvelous.

BUT, some people want low bass (like 20-40Hz), and these won't provide AT ALL. The horn will unload the driver at these frequencies and since they have very little excursion capability they will bottom out if you force them to play very low.

Fortunately, there is NO bass content in acoustic music below 40Hz, so you should be happy with any of the Sigma drivers (in BLH).

By the way, they take a very long time to break-in, so you need to be very patient.
You don't need the deflectors really. The internal right angles to the Fostex horn design (for the love of heaven don't round them off!) act as deflectors, so you get plenty of that effect without any additions. No idea about the L pad, but I don't see any reason why it shouldn't be made to work. Oh, and do remember that you'll be sacrificing some bottom-end if you invert the horn and stick it on a shelf: it uses floor-coupling to boost the bass (i.e. room gain); without that, you'll loose out a bit on this front.
Yes, i'm afraid of loosing some bottom end Scott... But this is the only place that it's possible to put a loudspeaker in my room. I believe that I'll loose even more, if I put another type os speaker in the Shelf. Do you have any tip, to less this problem of loosing the bottom end in the shelf?

I'll make a drawning, and post here soon.

If you're going to use a sub, then narry a problem. The FE103E or FE108ESigma would be a terrific choice. The smaller drivers tend to have a more capable midrange and high end than the larger ones, and there's no reason why you can't still use a tweeter. You could even go for a better spec tweeter with the money you save. Or spend it on more music instead. I'm currently building a doubled factory Fostex FE103E cabinet at present, a la Terry Cain's Double BEN. Cheap does not automatically mean inferior.
Regarding the original plan with the 208s, how high off the ground will that shelf be? There are ways and means of recovering some, but it depends on the room.
Great! I like the idea of saving money, and space :D . Basicly, the shelf is 80cm (31,5 in) from the ground. Is 275cm large and 60cm deep to the wall. The listening position is almost 3 meters (9ft) away and my ears will be around 110cm from the ground. But I do not have space for a 2m tall speaker. The idea is something below 130cm. The shelf is not in corners, there is space in the sides.
You can't use the FE167E in a horn, but the 166 is a popular option. The FE103 / 108ESigma in either the Buschorn or the factory horns are also regular favourites. As your speakers are going to be off the ground though, my top choice would be to think (and fire) laterally, and go for the Fostex factory spiral horn, designed for the old 108Sigma. With a little fettling, it should work fine with the new model, and being a side-firing type, you should still get reasonable[ish] bass.

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