Enclosures for Fostex FE206 ESR + T90A-EY

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Gentlemen,

Sorry for the newbie questions, but I am trying to make sense of different pieces of information I have collected on the net and on this site regarding enclosures for Fostex FE206 drivers.

I recently received as a gift a pair of Fostex FE206 ESR and T90A -EY and I am trying to find relatively simple enclosures to build so I can use these speakers. I use different type of amps, mosfet and old (rebuild) quadII's. I haven't built any Hifi gear for the last 15 years and I am not very technically oriented.

1) Is the recommended enclosure for the FE206E as presented on the fostex site been tried with the FE206 ESR by someone ?

2) Would there be tested alternative and simple designs one might suggest ? WAF is not an issue.

3) My woodworking skills are somewhat limited. The most complex cabinets I ever built were a onken-mahul design with a set of Focal drivers. This was 15 years ago. Still working and enjoyable.



Kind regards,
Sierra
 
I would say that reading from the experience of some diyaudio members, especially No Xo, a noob may probably be best off with the recommended 206ESR enclosure since these drivers seem hard to tame but in the end fare pretty well after plenty of break-in time. For other enclosures expect a LOT of tweaking damping tweaking undamping tweaking redamping,...well you get the point right? It might be a lot of fun to do though.
 
Simple to build: look no further than here: www.quarter-wave.com and go to the projects section. You'll see the virtual project in there. Do not attempt this design without the circuit though, or you'll end up with 0 bass.

If you want a horn, then I'd go for the Dallas II, which you'll find in the horn gallery section of www.fullrangedriver.com, or Onur's double horn, which is here: http://www.yildiz.edu.tr/~ilkorur/speaker/fostex_fe206e.htm

Both are worth looking into -the latter will need some series resistance though. Bit harder to build, but better than the standard Fostex enclosure.
 
Sorry; I mis-read the fact that your drivers are 206ES-R. A gift? Wish someone would give me a pair! (though I was a little disappointed that they have a ferrite magnet, rather than an enlarged version of that wonderful cobalt-lathanum motor the 166ES-R had. Oh well.)

The Dallas II and Onur's horn would both need modifying to get the ES-R working with them, so I'd probably forget those, and go with either the Fostex factory ES-R horn (NOT the standard FE206E version), or the BIB if you have the ability to corner load the thing, or at least a rear wall, and don't mind a very tall enclosure. I've been fooling around with possible alternative horn ideas for this driver on and off as it's really very special, but I haven't finished them yet. Will try to get one completed today & get some suggested dimensions up here.

Best
Scott
 
Right, here's one idea for the 206ES-R. It's of the type GM calls a Big Vent Reflex, similar to a Replikon, and is a double horn to reduce the footprint somewhat. I'll leave the exact layout to anyone mad enough to want to build it, as I'm lousy at drawing I'm afraid. It's a bit of a monster too, but I like the potential response. It won't be exactly like this, as the upper mouth will not see the same reflection boundary condition as the lower. Still, there seems some potential here.

Approximate external dimensions assuming 3/4in build material. It'll be about 12.25in wide, 14.25in deep & 75in tall, give or take.
CC is 12in deep, 23.75in tall, 10.75in wide. The horn throats are at the rear of the chamber, exiting in the vertical plane. Each throat =0.2Sd. Each horn is 40in long. Each mouth =8.2Sd. The FR plot assumes the enclosure is unstuffed. A little series resistance will be a good idea -not sure about baffle-step. Thoughts anyone?

Have fun
Scott
 

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Gentlemen,

Thanks for your very prompt answers. I will probably do the ML-TL or the BIB enclosures before I start to play around with other designs. One of these simpler designs would also allow me to break-in the speaker until I move to more complex designs.

One question about the BIB enclosure you might be able to answer straight away : I have seen on the ZillaSpeak website the characteristics for my specific fostex driver and some formulas to calculate the dimension of the BIB box.

Fostex FE206ES-R
L = (Line length) 161.5"
Zdriver = Driver 32.5" down from sealed end of cabinet
Sm = 139.125"^2

From the drawings, it seems that Zdriver and So is the same variable but under two different names : distance from the center of the driver to the top end of the cabinet ? True ?

From the Sm variable also called terminal area (=width x depth), how do you calculate the other dimensions ?

Do you start by taking a reasonable width for the cabinet that allows you to fix the speaker properly (let's say 12" width) and then calculate the depth (in this case, using Sm=139.125, the depth would be around 11.6") ?

Then from the depth, how do you calculate the other dimensions ? The explanation for the line length is a bit unclear to me.

May be there are some sources of information you might know I could look up ?

Greetings,
Sierra
 
Hi!

The MLTL will probably need some modifying for the ES-R driver as it's parameters are different to the standard FE206E. If you want me to, I'll come up with one in MathCad for you. However, although it's perfectly possible to use these drivers in resonant TL enclosures, IMO, they're best in some form of horn.

Re the BIB.

The correct term is Zdriver (the 'So' labelling on the lower diagram is wrong, Jeff hasn't had time to change it yet), and you are quite correct: it's the distance of the driver centre from the sealed end of the line.

The WxD dimensions of Sm are an interesting question, as there is some room for experiment here. However, in your case, with ES-Rs, I'd stick as close as practical to the correct conical horn profile, so, rounding the dimensions GM's nifty little spreadhseet provides to the nearest sensible numbers, I'd go for an internal width of 10in, and an internal depth of 14in. Terminate the internal baffle 7in from the front and rear cabinet walls, & the same distance from the cabinet base. Greg and I when we calculate the area of the open end use nominally 'ideal' figures, which are not always practical in the real-world -you can round them to the nearest / easiest figure without audably affecting the response.

The exact height of the enclosure can be calulated using another spreadsheet which calculates the radius of the curve at the bottom of the enclosure. In your case, a box 82in tall, excluding the base, will get you spot-on. I keep meaning to ask Jeff if he could include these on the BIB pages he's hosting as they're useful little tools. An FE206ES-R BIB? That thing will thunder.

Hope that's of use
Scott
 
FE206ES-R in ML-TL

Well I have some FE207E's in an ML-TL which I like a lot.
However I also have some FE206ES-R's waiting for me to build a cabinet. I was thinking about putting them into the ML-TL this weekend - and tweaking the BSC circuit a bit.

One concern is that I don't think the mounting holes are going to line up - and I would hate to bugger the ML-TL's just because I'm anxious to put the ES-R's to work.

I've been following the various conversations on these drivers across the full range forums - and really the design I want to try is the k-slot loaded horn design of RCA-Fans from the audio asylum. Just because they look so d**m good - and relatively simple to build.

Steve in Vancouver
 
FE 206 ES-R in BIB

Scottmoose,

Since you are the official spreadsheet guru, I will go with your calculation for the FE 206 ES-R in the BIB :

In summary, for those who don't want to go through the whole thread, the internal dimensions are:

Total height = 82 inches
Z driver = 32.5 inches
Width = 10 inches
Depth = 14 inches
Distance from the bottom of the inclined panel to front panel, rear panel and base = 7 inches

I would welcome any feedback and experience on the best way to build the cabinet. I was thinking of birch plywood (30 mm thickness +/- 1.25 inches) with just "biscuits" and glue for the vertical and inclined panels and a removable "base box" fixed with screws to the cabinet and filled with a mixture of lead shots and a silicone type compound which - when dry- looks very similar like the sealant you use around your bathtub. I used this before. It has a good density and it is pretty stable with age.

I will look around for some posts on the type of filing you use and where.

But before starting the build, I have to figure out how and where to fix the T90 A-EX. Don't know if this needed at all. Probably better to experiment without it first and see what comes out before drilling the box again.

Greetings from Geneva,
Sierra
 
Dunno about the worksheet guru bit, though I'm a massive supporter of Martin King and his work. I do my best anyway.

Yep, dimensions are all correct, and your proposed construction method and materials spot on. The only alternative I can think of would be to laminate 1/2in particle board to 3/4in birch ply, though that's a lot more involved of course. Big enclosure this one.

One point that's only just occured to me though is that with the theoretically ideal conical expansion, that huge magnet very probably isn't going to clear the sloping internal baffle. If you want to stick with the 'ideal' expansion, you'll need some form of false baffle, like the one Terry Cain uses, to mount the driver on. Get some nice hardwood about 1 - 1 1/2in thick, and about 6 -7 in wider than the driver, and get the local cabinet maker to shape it on his lathe, if you can't do it yourself.

Alternatively, you could depart from the ideal theoretical expansion slightly and go to dimensions which will allow the magnet to clear the baffle naturally. 9in wide x 15.5in deep should do it. (excluding the build material). Terminate the internal baffle 7.75in from the internal front, base and rear walls.

Stuffing is rather room-dependant. I usually start by stuffing the point above the driver lightly, and putting a 1in layer on the base. After that, I wait until they are in the room, and adjust their position, and the amount of stuffing from there.

I'd hang fair on the tweeter until you've heard the drivers without it. You could try it in a pod, or perhaps rear-firing as TC does with his double BENs and Super Abby respectively.

Hope this is of use
Regards
Scott
 
206es-r

Actually, I think that the 206esr does have the cobalt lanthanum magnet. it is a ferrite magnet type, just like the 166esr was. the cobalt in the mix makes it a special ferrite magnet. there are many ways of mixing the magnet metals as alloys.

look around on the japanese sites. they cite lanthanum cobalt. though admittably, there seems to be confusion about this all over the web (what's new?).

Ill put it this way, the 206esr sounds "lanthanum cobalt" to me. just like alnico has its own sound and straight up ferrite has its own sound.

anyways, I will be building the recommended enclosure out of void free baltic birch, 18mm soon. I tried to find luaun core material, to no avail. oh well. birch sounds great and is of good specific gravity.

I bought the t90aex, the p208 brass ring, I got the brass tweeter stand, fostex cs .47 cap. and a nice attenuator.

adding up to nearly 2000 bucks in parts, these things will be a huge expenditure in parts, time, etc, especially for a lowly college student like me.

about the BIB - when i built the 166es-r BIB, I like it for everything as a balanced whole. there is little problem with lower frequency resonances in this enclosure.

it does have front baffle resonance issues. they are not distracting, but they do muddy the sound a bit. I consider it to simply be a tradeoff of this enclosure in general. use the right wood for the driver, and it might help... in the end, it is a very acceptable compromise, I feel. however, the lightining speed of the 166 I know is there is a smidgen not as obvious as I would desire. i am a bit more of a detail freak than some, but not others. most people hear this speaker and conclude it to be the most detailed they have ever heard. and in many respects, it is the most detailed i have heard. it kinda does everything well. it needs the right room though. reflectivity is highly desirable. we do not want to shake the floors, instead the ear drums. it relies a little too heavily on the room making the bass for my tastes, actually. course, I do not have the right room for them. in older, plaster ceiling, plaster wall, wooden floor homes, they do disco bass. in my apartment, with crappy acoustic ceiling tiles, low pile carpet and less than solid construction, I have to eq it back in...

so before one builds the 206esr bib enclosure we must consider this perhaps?

most of the orthodox (long path) front mouth opening blh end up being installed in a room. they need a certain amount of damping to fit into their acoustic environment. this is frequently to take a 150hz or so bump in response, but that can vary, depending on construction material, amps, room, state of mind, etc. this takes a while to determine. it is nearly impossible for the layman to determine reliably, let alone control. it is still hard for me to determine.

reviewing some lessons - square during construction is vital. break in is vital. proper damping inside and outside the horn is vital. placement is important. amps are important. cables are important. that is all I can think of here.

when tuning back horns, I arrive at an idea of nothingness eventually. to make the speaker sound like nothing (at least as much as it can). this is showing of a lack of ego of the speaker builder (as opposed to "listen to THAT frequency region!"), a settled nature of components, and a peaceful mind. my only goal is balance. compromise. sometimes, in this country, with that goal, I feel very alone.

in thinking of the large orthodox front mouth blh it is hard to think of them as having alot of economy, simplicity, smallness, or an ease of distribution.

in their problem (lower vocal resonance), they gain super powerful and disappearing bass. with a horn, there are various amounts of LOADING. loading with room, loading with the horn, acoustic impedance, etc. it does not stop and all values are floating. ahh! the goal is to tune the resonance out to the point that it does not distract, while maintaining enough bass. given that many rooms resonate in the 180hz and below region, this can add to the complexity of the situation. it is the same with the super tweeter.

In single driver speakers, the horns we place on top and bottom I like to relate to salt in a food dish - it is a flavor enhancer, and should not be tasted as salt itself. course, everyone has their own tastes here. some people really want to HEAR that 500 dollar super tweeter... hence the complex nature of any of us here giving any "solutions" to each other. only relating experiences and learning from our own and those of others.

hence the complex nature of creating especially these more state of the art horns as product... how many reviewers are going to remove the driver and tweak with damping for half a week? when their conclusions are kinda subjective annyways? how many customers are going to open their horns and peer into their souls? and their own souls to find the answers only to find out that there are none.

there are ways around this that I will not go into here. everyone has their own way of slicing the pie.

I am choosing to build the long path horn of orthodox nature as I consider it to be the best match for this driver.

also, there is the problem with BIB as having a huge front baffle that resonates in the upper regions and muddies sound there somewhat, especially with these higher speed drivers, mass loading via brass, double thick ply, or both is important.

if detail is not the final goal, concentratiing on getting good tone out of the cheaper drivers is ultimately a more worthwhile pursuit.

it is all tradeoffs. for most people, and most DIYers, I think that BIB is really the best solution. we read up on that current forum. the ones I want to try is a large mouth 168EZ, and the larger 103e.

I dunno, I am full of opinions. probably full of crap too. I hope y'all can learn from this and also refute me and teach me a bit.

one site I found particularly helpful with this driver is the spi sound plaza. the japanese version has some updates on the 206es-r driver and the t90a ex. get google to translate it for you, drink a few beers, invite some audio freinds over, and have fun reading it!

well, from out here walla walla,

Clark
 
I stand corrected re the magnet.

Perhaps something like 3/4in classic core with it's 2, 1/8in MDF internal substrates and ply external layers would be the best solution for building, if you can get hold of it. Mind you, I don't exactly think you and TC need any suggestions from me about build materials! Doubling the front and rear panels on the BIB works well -my 165's cabinet has just this; a 3/4in layer of MDF laminated to an internal 1/2in layer of chipboard. Also gives the driver a bit more breathing room if it's tight to the sloping baffle, providing you over-size the cut-out on the inner layer or bevel it. A false baffle could also help kill some of that panel resonance.

You're right about the BIB being room-dependant -ye olde style construction is best; a ceiling with acoustic tiles doth not a happy combination make, as you so rightly say.

I do like the BIB as a design though over most 'normal' long-path length horns. Long most of them may be -but not long enough though. Unlike most, the BIB gets to 1/2 wave. Of course, you then have to compromise mouth size with Vb to get the load right, so as Greg is fond of saying, no free meals here! They do get a heck of a lot of gain though in the LF, being so long.

I remember Terry suggesting in a discussion re the FE166ES-R a while back that it's possible to double the factory horn -keep the CC the same volume or fractionally larger, and possibly reduce the total throat CSA somewhat, so you could probably do the same with the Factory FE206ES-R horn. Of course, the flare rate will be changed due to the doubling of the mouth CSA. How that'd work out I don't know -horns are not my field. It's certainly not the normal way to go about designing a double horn, but if TC says it's possible, then it must be. Draw your own conclusions on that one!
 
yup

yeah, I love the BIB as a concept, an actualization, and as an artistic entity.

seriously, the bib just sounds good, in that oh my god what is happening sort of way.

yeah, a double horn for the esr would be pretty killer. as a shameless plug, cain and cain does do custom double horns, big and small. I happen to have a pair actually....

the esr would shoe horn ( heyuk heyuk) into the large double horn easily. monster bass would result.

damnit if i havn't seen god through the 8 inch sigma drivers in those cabinets. course, they are expensive and ungodly large.

eh.

double horn would need the smaller throat area, smaller cc, etc. fewer folds. it would sound nice. a hard beast to tame though.

well, see y'all in a bit. any advice as to how to upload photos?

thanks

Clark
 
Simplest way, providing they're not too big, is to go to browse on the reply screen and navigate to whereever it happens to be on you HD. Then click open. When you post your reply, it should be attached. There's ways and means of ataching several to one post, but how, I'm not sure though, never having needed to do it myself.

You have some double horns of the C&C variety. Why does this not surprise me? I am currently a strange shade of green. Envy. Pure envy. Custom ones as well -I should really have guessed, though I didn't know for certain that was the case.

The sim I did on the first page was for a 206ES-R double horn, of the large CC, short path-length type (think double Replikon). Just a different approach really. I quite like them. I'm currently fooling around with one for the FE126E as well, which I might actually have to build -the sims look pretty good so far.

Cheers
Scott
 
...
Actually, I think that the 206esr does have the cobalt lanthanum magnet. it is a ferrite magnet type, just like the 166esr was.

FWIW, eifl export still has a pair of the limited edition FE208ES for $400. This is one extends up to 20kHz and is more efficient than the standard 208EZ. Dual magnets may neccesitate a 'false baffle' fora BIB. The T/S was published before in Fostex Japan's website, but I guess Koji still has the accompanying documents for these.

image200004153.jpg
 
Brass rings with Fostex FE-206 ESR ?

A quick couple of questions regarding the brass rings that fostex sells for the FE208E sigma and that fit the FE-206 ESR :

1) I will be building the box next week (see previous post on the design) and the clearance between the back of the speaker's magnet and the inclined panel is extremely small. Does it make sense to invest in the brass rings that Fostex sells to get more clearance or does it creates some anomalies (see blumenco's post)

2) For the cap and coupling with the T90 AEX, shall I go with a .33 mfd or .47 mfd ?

Cheers,
Sierra
 
Sierra, I have played with both a .47 and .33mfd cap and to me the .33 cap blends the T90AEX with the FE206ESR the best. I built the Fostex recommended horn for the FE206ESR and did not like it at first. It took much break in and alot of good advice regarding stuffing and damping before I started to enjoy them. Bluemenco and Kloss` posts were of great value to me. Add stuffing, listen then remove some and listen more. Add some back, then listen more and continue the process until YOU like the sound in YOUR room. I am a newbie, or what I would call a greenhorn (a horn builder who lacks knowledge and expirience), but this was a very satisfying process and I learned alot. Now I`m beginning to learn the ins and outs of tube rolling and the effect they have on these horns. Build some horns and you`ll have something to play with for years. This is a great hobby.
 
Thanks No Xo.


I am currently planning to build the BIB / TQWT enclosure and not the recommended fostex enclosure for the FE 206 ESR. Simpler for me to do as I have no access to a good workshop.

I will try the .33 cap as per your recommendation and take it from there.

I was also planning to fix the loudspeaker on the enclosure using a wooden ring (similar to Cain & Cain system) but since I can get the fostex brass rings at a reasonable price, I was wondering if anyone had experimented with them.
 
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