My Fostex FE108E Sigma project..

There're here!!! It's like Christmas again. Sweet looking drivers. Nice and heavy.

I would like to document this project as I go to share with others and to keep as a record for myself (if that's okay with everyone?). I plan to do a lot of prototyping and testing.

First, break-in. Tonight, I will cut some baffles out of MDF and mount the drivers. I will use the 10w amp for my computer speakers to drive them. This way, I can run the drivers day and night with all kinds of voice and music.

Question: I understand volume is important to breaking in, but how loud? That's one thing I can't seem to find.

Doug
 
To run drivers in, I usually wire them out of phase, stack one on top of the other, and run 15Hz sinewave from a frequency generator at just under Xmax for 4-12 hours or so. That keeps the noise to a minimum, and seems to work well. Just keep an eye on the temperature, though in free air, and with no loading on the cones, they shouldn't dissipate too much energy.
 
I put my fe206e's into cardboard boxes with holes cut into the top and pillows in the bottom. Hooked them to my old onkyo reciever and let them play for a few weeks. I just used the volume level that wasn't disturptive to the household. It work just great.

Near as I can tell the mechanical parts of the driver just need a little exercise to loosening up. I had the drivers running for two weeks this way (about 336 hours), and I haven't detected any differance in sound quality over the next year. O' and I listen to my setup for 5 to 10 hours a day.

Anyway, I am intrested in your new project. I have my eyes on the 108 or 168 for new project. What cabinet are you looking to build?

Chris
 
Thanks everyone.

I put them in a MDF open baffle last night and will play them 24/7 for the next week or two. I have them in my basement office, where I use my Yamaha 3" speakers. The difference in sound is quite dramatic. The 108's also reveal a lot more background noise from the amp, so I am going to have to be careful what I ultimately hook them up with.

They sound really nice. A little thin, but I expected that, and, of course, no bass at all. Right now, Horowitz is playing Chopin. I do notice a dramatic improvement in the midrange and upper midrange compared to the Yamahas. Yes, vocals do sound a LOT better.

As for an enclosure, I am ultimately shooting for a Buschhorn, but I have so many ideas floating around in my head that it will be some time before I actually build something permanent. I want to experiment with the sound of open baffles, tubes, pipes, X baffles, concentric rings. The ideas just keep coming. The Replikon (sp?) looks really cool, and now I wonder what that sounds like. My wife likes Terry Cain's Abbys, so maybe I can come up with a smaller version (the "Babby").

I won't have anything specific to add to this thread for a week or two. Until then, here's a picture of the break-in baffles. The foam is to protect the finish from the screws I used. I will not use the Fostex screws until I put the drivers into their final enclosure.

Doug
 

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Taperwood said:
As for an enclosure, I am ultimately shooting for a Buschhorn, but I have so many ideas floating around in my head that it will be some time before I actually build something permanent. I want to experiment with the sound of open baffles, tubes, pipes, X baffles, concentric rings. The ideas just keep coming. The Replikon (sp?) looks really cool, and now I wonder what that sounds like. My wife likes Terry Cain's Abbys, so maybe I can come up with a smaller version (the "Babby").

Let us know how the experimentation goes. Although I will say from personal experience, that the fostex 108es is quite limited as an open baffle driver. It has such a small x-max that it's limited to either low level play back, or an extra large tweeter on an open baffle. Quite a nice driver though despite it's limitations.
Joe
 
Lovely driver! Break-in time is very very long and mine got better every passing day. I sold them to get a pair of FE168EZ. Dub reggae is the best break-in music with heavy bass beat and sizzling highs.
Back loaded horns are the best way to go if you intend to use them full-range on their own. You might find the Bushorn a bit boomy while the Fostex design seems better balanced in my opinion.
Great driver! If you plan to use it with a SS amp, try a non-inductive resistor in serie (in between 4 and 10 Ohms). Best $5 tweak for the money.
 
robertG said:
You might find the Bushorn a bit boomy while the Fostex design seems better balanced in my opinion.

If anything the B-Horn doesn't extract enuff bottom out of the 108, but what is there is very good.

The Fostex horn i'm working on still doesn't sound right (not with 108ES thou)

dave
 
planet10 said:


If anything the B-Horn doesn't extract enuff bottom out of the 108, but what is there is very good.

dave

I didn't want to turn this tread into one on theory, but I'm curious. Do you mean below the Fs of 77Hz? This is one thing I am pondering right now, and that is whether one should even try and work with the sound below the Fs point when building speakers? I have read both sides of the argument, and it seems to me that it makes more sense to just incorporate a sub into the mix rather than trying to squeeze the last drops from a single driver. Not as fun, I admit, but more practical, I think.

Since this is my first project, I will probably be quite conservative when I start building. Prototyping is another story, though :bigeyes:

Doug

Oh yeah, the speakers sound great right now. Piano sounds wonderful. After 30 hours of classical, I am now moving to acoustic.
 
Personaly I would never try to go below Fs (at least with these drivers). They have very limited excursion so they are not bass beasts. The wonderful things about FR drivers happens well above 70 Hz anyway.
Of course proper loading helps a lot in the bass/extension dept., so that's why I think a proper BLH is the best way to go (and in the Fostex iteration, does not takes a lot of real estate).
If you prefer the simplicity of the B-horn, some compression chamber tweaking is a must. But then again, the Fostex design is factory specs and from what I heard and tested (I built a couple of FE108EZ and FE168EZ BLH with different designs), they sound real good as is.
Some will argue that they are not really horns and more like a succession of expanding resonators, but if you forget about wording and listen to music, you can't go wrong.
 
Hi Doug,

Nice to hear that there are other fanatics around the world with the same passion for Fostex drivers. You won´t believe it but I finished monday my Back loaded horn with the FE108E Sigma. I used the original Fostex plans. The result is amazing!!!
It is my second project with a fostex unit. My last project was a basreflex monitor with the older FE164. It sounded good, but it needed a notch filter to smooth the midrange. Stil the mid sounded a bit to loud. Also the bass was a bit to soft. Because I realy wanted to build a horn, because of it´s bennefits, I sold my speakers and began the search for a new pair of units. Because I din´t like the high frequentie response of the bigger Fostex units, I decided to go for the FE108E Sigma. It has the smootest response, but I was conserned thet there would be enough bass. Let me tell you, there is, a lot!!!! The speakers sound better, louder, faster and deeper in bass then my last fostex speakers, with only a x-max of 0,28 mm. In your search of plans for the FE108E Sigma, you have to rememember that the excursion is very limited. In my nowledge, only a bashorn can deliver high SPL with limited excursion. Also the unit is kept under control because of the small compressionchamber ( 1.57Liter). If I hear the amound of bass produced by the horn and hear it´s added volume at the mouth of the horn, it´s amazing. And it is also a deep sound, totally without booming and because of the damping clear of amplefied midrange by standing waves inside of the horn. I really doubt that another enclosure could produce a better bass.
I have added a picture of my project, so you can see the end result. I wish you good luck with your project.

Alexander
 

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Hi,

The drivers now played for about 25 hours, just on normal music. The big differance was in the first 4-8 hours. In the geginning there wheren't much high frequenties and the sound was very flat, like there was a thick curtain in front of it. Also the music didn't came loose from the speaker. After these first hours the changes are minimal I think. But still every time Iám amazed what they can do.
I do not know how low they go, because I can not measure it. The only information I have is the frequentie response from the fostex site http://www.fostexinternational.com/docs/speaker_comp/pdf/recom_enclose/108ez_encl.pdf.
This response shows a -3 dB point around 50 HZ. I think when lisening to them, thats correct.

Alexander
 
Alexandertol said:
Hi,

The drivers now played for about 25 hours, just on normal music. The big differance was in the first 4-8 hours. In the geginning there wheren't much high frequenties and the sound was very flat, like there was a thick curtain in front of it. Also the music didn't came loose from the speaker. After these first hours the changes are minimal I think. But still every time Iám amazed what they can do.
I do not know how low they go, because I can not measure it. The only information I have is the frequentie response from the fostex site http://www.fostexinternational.com/docs/speaker_comp/pdf/recom_enclose/108ez_encl.pdf.
This response shows a -3 dB point around 50 HZ. I think when lisening to them, thats correct.

Alexander

Looks very good -the FE108Esigma horns seem to have a good reputation; it's a pity the Fostex designed horns seem to be hammered by some horn enthuiasts without good reason. Chances are if I had a pair of 108esigmas, these are what I'd build.
Cheers
Scott