im thinking about putting together a pair of speakers using fostex FE208EZ sigma.
but i keep reading here they only work in backloaded horn configurations?
actually i prefer a "compact" version in my small room. are these drivers useless in a box bassreflex design?
also i have no experience building cases. so id like to keep it four-by-four.
i see "omage speakers" sell a standmount bassreflex with the 206 driver. is it completely different with 208?
thanks!
but i keep reading here they only work in backloaded horn configurations?
actually i prefer a "compact" version in my small room. are these drivers useless in a box bassreflex design?
also i have no experience building cases. so id like to keep it four-by-four.
i see "omage speakers" sell a standmount bassreflex with the 206 driver. is it completely different with 208?
thanks!
i cant tell you which characteristics of these drivers determine their enclosure suitability (might be qts but im not sure), but Im fairly certain you dont want to use a fostex driver that is designed for horns in a bass reflex. The fe206 and the fe207 both have bass reflex designs. If you haven't seen it yet, Madisound has a list of enclosure designs published by Fostex. Look at the bottom of the info page for fostex in the cataloq. I think the fe206 is considered to be the better of the two and I believe its more efficient.
If you want a smaller cabinet you might want to look at the fe103. It has a small bass reflex design and theres something quite appealing to the sound. Lots of designs on the web too. There are some really neat folded quarter wave pipes somewhere out there. There floor standers but very narrow and shallow. If you want the design ask and Ill try and find it again.
Yes the 206 and the 208 are different drivers.
If you want a smaller cabinet you might want to look at the fe103. It has a small bass reflex design and theres something quite appealing to the sound. Lots of designs on the web too. There are some really neat folded quarter wave pipes somewhere out there. There floor standers but very narrow and shallow. If you want the design ask and Ill try and find it again.
Yes the 206 and the 208 are different drivers.
Hi Fan... this may not be exactly what you are looking for but...
Fostex published recomended enclosures for their older Sigma line. Typically these drivers are used in back horns. I will post the graphic when i get a chance but basically the measurements for a 208 Sigma (old style with wizzer):
45 L bass reflex box
Square port 3.25" wide x 2.5" wide x 5.5" deep
Check to see how similar or different the driver you have is compared to the older style 208S.
http://www.fostexinternational.com/docs/speaker_comp/pdf/fe208sigma.pdf
Peace,
Godzilla
Fostex published recomended enclosures for their older Sigma line. Typically these drivers are used in back horns. I will post the graphic when i get a chance but basically the measurements for a 208 Sigma (old style with wizzer):
45 L bass reflex box
Square port 3.25" wide x 2.5" wide x 5.5" deep
Check to see how similar or different the driver you have is compared to the older style 208S.
http://www.fostexinternational.com/docs/speaker_comp/pdf/fe208sigma.pdf
Peace,
Godzilla
I don't think the new ESigma will work in the same enclosure unfortunately -too much changed, not least the fact that this thing really does need a tweeter as it rolls off strongly around 12KHz. Pity -I'm not quite sure why Fostex did that. The Mr Cynic in me suggests that it was so they could make more money selling tweeters and fancy caps... ahem.
However, as 'Zilla quite rightly oints out, it's a myth to think that low Q drivers won't work in anything other than a horn. you just either need to engineer the enclosure correctly, or add a bit of series resistance. Job done. The FE208ESigma will do very nicely in the Factory Horn design (I even think it looks good), but there's no reason why it shouldn't work in anything else. Give me a few minutes...
However, as 'Zilla quite rightly oints out, it's a myth to think that low Q drivers won't work in anything other than a horn. you just either need to engineer the enclosure correctly, or add a bit of series resistance. Job done. The FE208ESigma will do very nicely in the Factory Horn design (I even think it looks good), but there's no reason why it shouldn't work in anything else. Give me a few minutes...
Dead easy. Hardly had to think with this one. Here's a straight, Mass Loaded Transmission Line. If you haven't seen one of those before, they look like a nice, simple, floor-standing bass-reflex box, but they don't work in the same way. I won't go into theory here: have a look at Martin's site for more: www.quarter-wave.com Suffice to say they give you the bass of a reflex enclosure with that glorious midrange purity transmission lines are so justly renowned for.
This enclosure is 42" tall, 9.5" wide, 11" deep. The centre of the driver is 11.25" down from the internal top. The port is 4" wide, and 2" long, and is located 4" up from the internal bottom. 0.25lbs ft^3 stuffing is assumed from the top of the enclosure to 12" from the base. It might not even need this much. A 4 ohm resistor is placed in the + speaker lead to the driver. So it's not as efficient as a horn, but it's still around 91db 1w/1m, which is pretty good going: 5w will be more than ample. It'll need some baffle-step compensation too -give me a shout if you want the values.
Remember the 208ESigma doesn't reach very high so it'll need a tweeter / super-tweeter whatever enclosure you put it in.
Best
Scott
This enclosure is 42" tall, 9.5" wide, 11" deep. The centre of the driver is 11.25" down from the internal top. The port is 4" wide, and 2" long, and is located 4" up from the internal bottom. 0.25lbs ft^3 stuffing is assumed from the top of the enclosure to 12" from the base. It might not even need this much. A 4 ohm resistor is placed in the + speaker lead to the driver. So it's not as efficient as a horn, but it's still around 91db 1w/1m, which is pretty good going: 5w will be more than ample. It'll need some baffle-step compensation too -give me a shout if you want the values.
Remember the 208ESigma doesn't reach very high so it'll need a tweeter / super-tweeter whatever enclosure you put it in.
Best
Scott
Attachments
Indeed they do: 1 reflex enclosure modelled at your request for the FE208ESigma good sir!
It's pretty good, though I cheated a bit and used a 3"x5.5" circular port as the worksheets can't yet model anything other than circular ports. Dimensions are exactly the same otherwise as those on the Fostex site for the BR box for the FE206E. There's more ripple than the MLTL, especially up in the 900Hz region -but for a reflex enclosure, this is one of the very best I've seen with a full-range unit. No kidding. Impressive. Also, it has a nicely damped roll-off below 100Hz, which should be useful when room-gain is factored in. Overall, I'd personally go with the MLTL, as it goes a touch lower, has that TL midrange I like (the stuffing I think prevents some reflections coming off the internal rearwall and through the driver cone) presents a milder impedence curve to the amp, and would also remove the necessity for a stand, but this is by no means a poor substitute. Very impressive.
BTW -are your 168Sigma enclosures built out of pine?
Cheers
Scott
It's pretty good, though I cheated a bit and used a 3"x5.5" circular port as the worksheets can't yet model anything other than circular ports. Dimensions are exactly the same otherwise as those on the Fostex site for the BR box for the FE206E. There's more ripple than the MLTL, especially up in the 900Hz region -but for a reflex enclosure, this is one of the very best I've seen with a full-range unit. No kidding. Impressive. Also, it has a nicely damped roll-off below 100Hz, which should be useful when room-gain is factored in. Overall, I'd personally go with the MLTL, as it goes a touch lower, has that TL midrange I like (the stuffing I think prevents some reflections coming off the internal rearwall and through the driver cone) presents a milder impedence curve to the amp, and would also remove the necessity for a stand, but this is by no means a poor substitute. Very impressive.
BTW -are your 168Sigma enclosures built out of pine?
Cheers
Scott
Attachments
Fan,
I defer to the above opinions. Once again conventional wizdom proves more conventional then wise ;-).
Scott,
I had been blindly subscribing to the myth of low Q drivers. Any idea why its generally believed best to avoid bass reflex on low Q drivers. Why does Fostex recommend that the driver not be used in Bass reflex designs.
Im also wondering, given that the sigma is quite expensive, if this driver would be worth the expense for what Fan is looking for. I've never heard this driver so I'm not sure whats special about it, but I do have a feeling that if Fan is looking for a small BR, that there are probably more suitable drivers to do the job. Im pretty taken with the dayton RS designs that have been popping up since the distortion measurements are so impressive and the price so low.
Id be curious to hear what admirers of the Fostex have to say regarding its virtues.
I defer to the above opinions. Once again conventional wizdom proves more conventional then wise ;-).
Scott,
I had been blindly subscribing to the myth of low Q drivers. Any idea why its generally believed best to avoid bass reflex on low Q drivers. Why does Fostex recommend that the driver not be used in Bass reflex designs.
Im also wondering, given that the sigma is quite expensive, if this driver would be worth the expense for what Fan is looking for. I've never heard this driver so I'm not sure whats special about it, but I do have a feeling that if Fan is looking for a small BR, that there are probably more suitable drivers to do the job. Im pretty taken with the dayton RS designs that have been popping up since the distortion measurements are so impressive and the price so low.
Id be curious to hear what admirers of the Fostex have to say regarding its virtues.
Thanks Scott!
Well, lookie there! Your box is bettah… see, all this modern technology can produce something good!
Thank you for modeling the ported box. Unfortunately, I will not be building it but thanks for quenching my curiosity. I really am amazed how the MathCad work sheets help maximize results… INCREDIBLE!
Basically, it seems even tho fostex recommends a certain box it’s not necessarily the most optimal solution. Doesn’t mean it’s a bad solution either.
As for my lovely Fostex 168S, yes, the box is 100% pine except for an inner baffle made from mdf to help the screws hold the driver in place.
http://www.zillaspeak.com/zillaspeakfostex24L168.asp
The 168S will end up in modified straight pipes. The internal volume is very close to the original ported box I built based on:
http://www2.nkansai.ne.jp/hotel/nakanou/bs-168.htm
2.5” x 8” wide at the top
8” x 8” at the bottom
60” tall
All inner dims…. Approx 1.5 cubic foot… but in the shape of a Voigt pipe. If it’s not too much trouble can a sim be done for this using the 168S? I am planning to build a powered sub to fill out the bottom… my basement is big.
I am nearly done with my Pioneer B20/Piezo redo and hope for nice sounds from it as well. The boxes are waiting for a couple coats of glossy poly. I can’t wait to hook them up and listen.
Peace,
Godzilla
Well, lookie there! Your box is bettah… see, all this modern technology can produce something good!
Thank you for modeling the ported box. Unfortunately, I will not be building it but thanks for quenching my curiosity. I really am amazed how the MathCad work sheets help maximize results… INCREDIBLE!
Basically, it seems even tho fostex recommends a certain box it’s not necessarily the most optimal solution. Doesn’t mean it’s a bad solution either.
As for my lovely Fostex 168S, yes, the box is 100% pine except for an inner baffle made from mdf to help the screws hold the driver in place.
http://www.zillaspeak.com/zillaspeakfostex24L168.asp
The 168S will end up in modified straight pipes. The internal volume is very close to the original ported box I built based on:
http://www2.nkansai.ne.jp/hotel/nakanou/bs-168.htm
2.5” x 8” wide at the top
8” x 8” at the bottom
60” tall
All inner dims…. Approx 1.5 cubic foot… but in the shape of a Voigt pipe. If it’s not too much trouble can a sim be done for this using the 168S? I am planning to build a powered sub to fill out the bottom… my basement is big.
I am nearly done with my Pioneer B20/Piezo redo and hope for nice sounds from it as well. The boxes are waiting for a couple coats of glossy poly. I can’t wait to hook them up and listen.
Peace,
Godzilla
That's based on the Straight Pipe Bob Brines built for the RS1354, right?
OK, this is the response. It assumes the dimensions you stated above, with the driver 30" down from So, and either a 3" wide, 2" long round port 2" up from the base, or the equivalent slot port in the originals. 0.25lbs ft^3 stuffing. No series resistance applied or required as you can see.
Looks like you're in business. BTW -pine. Good choice. Unjustly under-rated, at least for use with full-range drivers.
Cheers
Scott
OK, this is the response. It assumes the dimensions you stated above, with the driver 30" down from So, and either a 3" wide, 2" long round port 2" up from the base, or the equivalent slot port in the originals. 0.25lbs ft^3 stuffing. No series resistance applied or required as you can see.
Looks like you're in business. BTW -pine. Good choice. Unjustly under-rated, at least for use with full-range drivers.
Cheers
Scott
Attachments
Thanks Scott! I hope you don't mind if i use your chart in my write up on this project sometime in the future. I will credit you for providing the graph of course. I already have the wood cut ... just need to cut out the holes and attach the new baffles. Removable baffles are wonderful!
http://www.zillaspeak.com/ZillaSpeakBoxPlotFostex168-167.asp
The shape of the response you got is similar to what i get in WinISD for simple ported boxes.
The shape of the Voigt is timeless and our kids will be building similar speakers with newer full range drivers well into the future. They will probably laugh we only got down to around 50 or 60hz.
Much appreciation. You've confirmed on paper what i will build wont be a total flop... i was going to build it anyways... but you soothed my apprehension and actually got me excited about this project.
I will place these about 2 to 4" from the back wall and warm up that bass a little too. How nice it should sound!
Pine is great. My last project with the TB Bamboo's cracked front and back tho when screwing in the drivers. I did drill holes prior to screwing and it still cracked. I think it may have had something to do with the fact the wood was really not flat and forced into place with many clamps... causing stresses in the wood. In the end i filled the cracks and stained them black.
http://www.zillaspeak.com/Bamboo.asp
I still prefer pine tho and hear beneficial sonic contributions compared to similar designs i've built using mdf or particle board.
Thanks again for providing a neat chart!
Godzilla
http://www.zillaspeak.com/ZillaSpeakBoxPlotFostex168-167.asp
The shape of the response you got is similar to what i get in WinISD for simple ported boxes.
The shape of the Voigt is timeless and our kids will be building similar speakers with newer full range drivers well into the future. They will probably laugh we only got down to around 50 or 60hz.
Much appreciation. You've confirmed on paper what i will build wont be a total flop... i was going to build it anyways... but you soothed my apprehension and actually got me excited about this project.
I will place these about 2 to 4" from the back wall and warm up that bass a little too. How nice it should sound!
Pine is great. My last project with the TB Bamboo's cracked front and back tho when screwing in the drivers. I did drill holes prior to screwing and it still cracked. I think it may have had something to do with the fact the wood was really not flat and forced into place with many clamps... causing stresses in the wood. In the end i filled the cracks and stained them black.
http://www.zillaspeak.com/Bamboo.asp
I still prefer pine tho and hear beneficial sonic contributions compared to similar designs i've built using mdf or particle board.
Thanks again for providing a neat chart!
Godzilla
You're welcome. If you want to use it, by all means -glad to help where I can. Impressive set of speakers you have there BTW!
Yeah, I like pine. Bit of a pain when fastening drivers -pehaps some rubber gaskets or washers might help if you bolted the driver in place rather than screwed it in? I haven't used it as much I'd like, as trying to get hold of anything apart from MDF round here is a nightmare. Good for horns I believe. Suffice to say, if I built a horn, pine would be my first stop.
Cheers
Scott
Yeah, I like pine. Bit of a pain when fastening drivers -pehaps some rubber gaskets or washers might help if you bolted the driver in place rather than screwed it in? I haven't used it as much I'd like, as trying to get hold of anything apart from MDF round here is a nightmare. Good for horns I believe. Suffice to say, if I built a horn, pine would be my first stop.
Cheers
Scott
BR vs. BLH
Let me try to show this from a different angle. Scott, are your simulations done assuming 1W input power? Can you, please, post the cone displacement (excursion)?
One of the main problems with ported box is that below Fb the driver is totally undamped. Excursion goes through the roof very fast as frequency goes down. The Xmax of this driver is only 1.3mm one way. At 40 Hz it will bottom out at 2W input power in so nicely looking modled box, producing max SPL of 84 dB.
I am not that familiar with ML-TL design yet (getting there...), but AFAIK, there is the cone displacement plot in Martin's worksheet. Scott, can you check in your model where it will hit the excursion limit in that design?
Anyway, in a BLH high excursions are not required from the driver: the horn works, basically, as a trasformer. What's needed is high speed. To get this you've got to have as high a BL as possible, which means huge magnet. Huge magnet results in low Q. At least this is my understanding that low Q is a result of a design aimed at horn enclosure and not the other way around: low Q drivers are only sutable for horns.
As a matter of fact, low Q drivers with high excursion limits make the best subwoofers for ported enclosures. Low Fs also helps in this case.
I am working right now on a design of a BLH for new Hemp 8" driver, with Q around .5 and beleive it makes for a better final result than FE106 with half the Q. In Martin's article on the advanced design of the BLH there is a chapter, where he shows the benefits of higher Q.
Vadim
Let me try to show this from a different angle. Scott, are your simulations done assuming 1W input power? Can you, please, post the cone displacement (excursion)?
One of the main problems with ported box is that below Fb the driver is totally undamped. Excursion goes through the roof very fast as frequency goes down. The Xmax of this driver is only 1.3mm one way. At 40 Hz it will bottom out at 2W input power in so nicely looking modled box, producing max SPL of 84 dB.
I am not that familiar with ML-TL design yet (getting there...), but AFAIK, there is the cone displacement plot in Martin's worksheet. Scott, can you check in your model where it will hit the excursion limit in that design?
Anyway, in a BLH high excursions are not required from the driver: the horn works, basically, as a trasformer. What's needed is high speed. To get this you've got to have as high a BL as possible, which means huge magnet. Huge magnet results in low Q. At least this is my understanding that low Q is a result of a design aimed at horn enclosure and not the other way around: low Q drivers are only sutable for horns.
As a matter of fact, low Q drivers with high excursion limits make the best subwoofers for ported enclosures. Low Fs also helps in this case.
I am working right now on a design of a BLH for new Hemp 8" driver, with Q around .5 and beleive it makes for a better final result than FE106 with half the Q. In Martin's article on the advanced design of the BLH there is a chapter, where he shows the benefits of higher Q.
Vadim
kifeinthesink said:
I've never heard the FE208ESigma. However, the ESigmas generally have more detail in the midrange, as well as being smoother, and they don't have the unpleasent resonances a whizzer-cone can cause.
OK, low Q drivers in box enclosures. Well, they don't naturally work as well as higher Q drivers -they have more motor strength, and the result is that in a box enclosure, they are over-damped. However, adding some series resistance sorts that problem out. Also useful if you run a transistor amplifier which have a high damping factor, and thus over-damp most full-range units with their big magnets and hyper-light cones. Tube amps, with their low damping don't have this problem.
Re: BR vs. BLH
Sim is done at 1w. Woofer displacement shown below. As you can see, it's not bad. This is basically very similar to Martin's Vitual MLTL Project for the FE206/7E which have similar excursion capabilities. I've never had a problem with mine. They're not ideal for reproducing Motorhead of course, but against that, they go much lower for a much smaller box-size, and usually have a smoother response. Not that I'm denying horns their due -I have a pair of Terry Cain designed rear-leaded Voigt style corner horns / giant TQWTs terminating in free space with FF165Ks (Xmax 0.3mm) that are very good indeed.
That said -I like the higher Q drivers too: as Martin notes, and you have found out, they have some benefits, even in horns. I gave up worrying about the Q of the driver a while back, unless it's over around 0.5, in which case it's probably best in a huge sealed box or on an open baffle.
Cheers
Scott
VadimB said:
Sim is done at 1w. Woofer displacement shown below. As you can see, it's not bad. This is basically very similar to Martin's Vitual MLTL Project for the FE206/7E which have similar excursion capabilities. I've never had a problem with mine. They're not ideal for reproducing Motorhead of course, but against that, they go much lower for a much smaller box-size, and usually have a smoother response. Not that I'm denying horns their due -I have a pair of Terry Cain designed rear-leaded Voigt style corner horns / giant TQWTs terminating in free space with FF165Ks (Xmax 0.3mm) that are very good indeed.
That said -I like the higher Q drivers too: as Martin notes, and you have found out, they have some benefits, even in horns. I gave up worrying about the Q of the driver a while back, unless it's over around 0.5, in which case it's probably best in a huge sealed box or on an open baffle.
Cheers
Scott
Attachments
Greetings to all,
I have purchased a pair of S/H FE 208 E Sigma and I would like to build a relatively simple box for it.
Here is an extract of scottmoose #6 post:
"This enclosure is 42" tall, 9.5" wide, 11" deep. The centre of the driver is 11.25" down from the internal top. The port is 4" wide, and 2" long, and is located 4" up from the internal bottom. 0.25lbs ft^3 stuffing is assumed from the top of the enclosure to 12" from the base".
Just to cross-check everything before I start to order and cut wood panel : All dimensions are internal and the port is round : diameter of 4", 2" long and 4" from the internal bottom ??
If someone can confirm this, this would be great....
thanks,
Sierra
I have purchased a pair of S/H FE 208 E Sigma and I would like to build a relatively simple box for it.
Here is an extract of scottmoose #6 post:
"This enclosure is 42" tall, 9.5" wide, 11" deep. The centre of the driver is 11.25" down from the internal top. The port is 4" wide, and 2" long, and is located 4" up from the internal bottom. 0.25lbs ft^3 stuffing is assumed from the top of the enclosure to 12" from the base".
Just to cross-check everything before I start to order and cut wood panel : All dimensions are internal and the port is round : diameter of 4", 2" long and 4" from the internal bottom ??
If someone can confirm this, this would be great....
thanks,
Sierra
Ye gods, this was 15 years back. With the benefit of another decade & a half, I wouldn't be too inclined to use the ESigma in this way. It will work (assuming I didn't make a complete Horlicks of it back then), but power-handling will be limited, and it will likely need to be positioned close to a front wall to avoid needing some EQ.
Thanks Scottmoose !!
Your feedback is dearly appreciated... I haven't started to cut the panels.
With 15 years more under the belt (no pun intended), what would you do with the FE208e∑ then ??
At the time, there was a Fostex recommended enclosure and also a design from the magazine "Hobby Hifi" called BK208. Both were BLH. I enclose the files.
I am open to any suggestions... these two drivers are New Old Stock and they do deserve a box and a decent tweeter....
Don't know if this driver would work on a open baffle...
Thanks for your help,
Sierra
Your feedback is dearly appreciated... I haven't started to cut the panels.
With 15 years more under the belt (no pun intended), what would you do with the FE208e∑ then ??
At the time, there was a Fostex recommended enclosure and also a design from the magazine "Hobby Hifi" called BK208. Both were BLH. I enclose the files.
I am open to any suggestions... these two drivers are New Old Stock and they do deserve a box and a decent tweeter....
Don't know if this driver would work on a open baffle...
Thanks for your help,
Sierra
