Now that I got a pair of fe206e, which type of enclosure should be best for this driver. I'm looking into getting the most bass out of it. Would the Back loaded horn type of enclosure recommended by fostex good enough? I'm lost. Please help.Thanks.
How much is enough? A question that has puzzled many a human since mastodons called to each other across primeval swamps.
The answer is that there's no simple answer in all honesty. Sorry. However, a few views.
The Fostex horns are good. Very good. Much better than some might lead you to believe. But you're never going to get subterranean bass out of them -figure on about an F3 of 50Hz, with a bit more from room gain, depending on the size of your listening room. The Jerricho horn has also had some good comments, and looks superficially at least a little more attractive (the 206 horn doesn't have the looks of the 208esigma horn IMO) but I suspect the Fostex horn will put out more in the bass regions.
I'd forget reflex-loading with these drivers -the 45l box Fostex recommends is punchy, but has no real bass -reminds me of a pair of Linn Kans with the bonus of not requiring the output power of the Hoover Dam to say boo to a goose. Not much action under 120Hz in room.
Other designs -have a look at Martin King's site for a straight mass-loaded transmission-line using this or the FE207E driver. It won't work as well as the 207E -the 206 needs a heavy dose of contour filtering to bring the top end into line; it's just not as well suited to other cabinets as the 207E. But this is a good one. Probably the best you'll come across, though you'll sacrifice efficiency unless you use active rather than passive equilisation. Not a major issue unless you're running SET amps. This design would be my choice.
One other option for serious bass -bit of a wild-card this: you could try an enlarged version of Terry Cain's BIB TQWT box. Try this as a starting point: height 66", depth 16", width 9 1/2". External dimensions assuming 3/4" build material. Sm = 3Sd . Driver at 42" from the base. Stuff the area above the driver in the first portion of the line, and add a little wadding in the base. Internal sloped baffle ends 7" above base and 7" from inside of the rear baffle. I've kept So = 0 as I suspect the FE206E will need the extra gain. Use the filter from Martin's 206E / 207E MLTL. Frequency response on a sim will not be pretty. In fact, it's downright ugly. But these measure a lot better in room than MathCad predicts -I know, because I've tried it, in response to a challenge from Terry elsewhere, and they did. I had to eat a lot of humble pie. (chomp). Most impressive. I dislike So = 0, but with these drivers, you'll probably need it. Frequency response will have a bit of ripple though. Then again -you said you wanted bass? With these, I'd expect an F3 of about 25 - 30Hz with room gain, depending again on your room size. Deep enough? ;-)
I would go for the back loaded horn. Myself I finished monday a Back loaded horn with the FE108E Sigma. Great bass output. And this is only a 10cm driver. I was worried that the bass was to boomy, but that isn´t the case.
An alternative is a TQWT, but the output in the frequentie between 100-500 HZ is less then by a horn, so the mid wil sound to loud. Also you wil need a passive correction filter. Al these components wil give lost of clarety and detail ( or you will have to buy expensive components at almost the price of your units). Myself I never heard a TQWT, they say the base wil sound deeper, but the output is less. For example: a man who had the same horns with the FE108EZ compared those with his new TQWT´s whit the FE167E. The bass was less!!!! Realise that the unit is much bigger!!!
It´s funny because I also considerd building with the FE206E, but I decided for the FE108EZ, because I play in a small room and do not have to play loud. So I went for the most natural sounding unit in mid and high frequenties.
I have a link with another back loaded horn. it is a lot smaller than the fostex desing. If I have to pick a design other then the original Fostex plans, I would build those: http://home.hetnet.nl/~geenius/Solo206.html
Succes with your project
well explained Mr. Scottmoose. Thanks. Unfortunately I don't really fully understand what you trying to explain. My knowledge in speaker building is rather limited. This would be my first speaker project so be patience with me.
Alexander. thanks for the link.
Some quick explanations! Sorry about making assuumptions there! (You'll probably know some of these) These are rough & ready comments, but they'll serve as a introductory guide.
F3 is the point below which response (ie volume) from a speaker falls away rapidly.
So is the area of the closed end of a transmission line. Sm is the area of the open end. (or rather, the end which has some form of opening in or near).
Contour filtering: it's a passive set of components -typically an inductor and a resistor that sit between the amplifier and the speaker drive-unit. It serves to smooth the sound by reducing levels in specific parts of the frequency range. Some people panic about putting passive components there; providing it's done properly; it's not a problem and will not corrupt or damage the sound. You won't need expensive 'audio-grade' components either: they're usually (not always) a con with no better (and frequently worse) measured performance over good-quality standard components. It sounds frightening, but really all you need is the two items per speaker: the inductor and resistor, which isn't difficult.
A TQWT is a Tapered Quarter Wave Tube. They're sometimes known as a Voigt Pipe. Have a look here:
I'd normally say DO NOT build this design -oddly enough, the FE206E is probably a better match for it as it stands than than any other driver I can think of, including the Lowther's it was supposedly designed for, though it'd need some heavy filtering. I'd still reduce the port area a bit though. A 4" x 4" round port would probably be a start.
The BIB I was referring to in its original form resides here:
The pictures speak a thousand words. It's a tall rectangular box, open at the top, with a sloping internal baffle that extends from the top of the front panel to just beyond the centre-line of the box, near the bottom. However, you need to modify the dimensions to use the FE206E as the original design shown in the link is for smaller drivers up to about 6" Try the sizes I mentioned in the earlier post -these should be a good starting point; it's dead-easy to build and produces more bass than you'd believe (good quality bass too).
A straight MLTL is a straight Mass-Loaded Transmission Line. it looks like a bass-reflex (i.e. ported) floor-standing box externally, but it behaves differently. The design I was thinking about is here:
Alexander -I suspect the reason that the man you mention comments on the poor bass of his TQWT is that they haven't a proper contour filter on them -a common problem I fear. Check Martin's site for his modification to his own ML-TQWT project with a different filter, and the sudden improvement in bass performance (if you haven't seen it; here's the link:
See the 'recent design improvements' page.)
Horn is the way
If you want to keep things simple, the Fostex design horn is way to go. It seems a bit daunting at first when you look at the plan, but it's really quite simple to put together.
You will not get really low bass (as in subwoofer), but you will have plenty of tight, punchy, fast bass (any acoustic instrument will sound lifelike, even the doublebass).
If its not enough, try a 4 to 10 Ohms non-inductive resistor in the circuit (between + out on the amp and the + in on the speaker). Makes for a cheap, simple and very inexpensive Eq circuit.
Thanks Mr Robertg. Most probably I'll go for the fostex design horn as recommended since that all enclosure detail are provided for simplicity but I'll still try other types of enclosure if it is better.
Scottmoose, What do you think of the back loaded horn recommended by fostex. Will I get a decent low freq. response from this enclosure. Construction of enclosure shouldn't be a problem since I had my carpenter getting it done. Another thing is that I do not intend to use other passive components with the driver. Hopefully I'm gettin' the right driver. what you think of the fe206e frankly? My first intention is go for the fe208 sigma but then I ended up gettin this fe206e which I found not much info on the net regarding good enclosure for this driver. Rather dissappointed. Thanks for the detail explaination.
The FE206E is a good driver. Very good as it happens. That large (OK, VERY large) motor and banana-pulp cone are extremely impressive, especially for the reasonable price. Relax in the knowledge you have one of the best 8" drivers available. I personally favour its FE207E cousin, simply because my major interest lies with transmission-line speakers not horns, and it's better suited to these than the 206E, which was designed from the outset for horn-enclosures, like the more expensive, and in some ways inferior 208ESigma.
Of the plans available on the web, bearing in mind your requirements, interest, drivers, and it being your first project, I'd go with the factory horn design. It's often unfairly dismissed because of all the right-angles in the construction: they're actually there for a reason, not just to ease construction - they act as diffusors, and also, as Terry Cain points out, to allow a longer horn-length for a given box-size. I expect you'll get around 50Hz out of it, depending on room-gain and room size. Not spectacularly deep, but not bad at all. I've built the FE103E horn in the past, and liked it a lot. Fostex know what they're doing.
Out of interest -anyone out there tried the 206E in the 208ESigma horn? If so; what mods were needed? If it works well, I'd go for that -its a little easier on the eye.
TL and Horn Comparison for FE-206E
Why don't you have a look at my TL and Horn comparison for Fostex FE-206Es. It may ease thing up fo you. You can reach them from the link below and then clicking Fostex FE-206E link.
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