"I am about ready to break down and buy a pair of 208's and build Martin's (super simple ) BR design as so many other people have made them and been quite happy with them."

You will have the exact same problem with the 208 as you have now with the FE-206E. In my opinion they both require a filter to work well in a BR (or ML TL) enclosure. Before buying the 208's, why not try my Lowther ML TL with the FE-206E. You will need to increase the length of the port to six inches and add a correction circuit. The circuit that people are using is the same Zobel as my Lowther design with a 3 mH inductor in parallel with a 6-10 ohm resistor as a BSC circuit. The value of the resistor needs to be adjusted to mesh with the damping factor of your amp (lower for a tube, 10 ohm for a SS), your room, and your personal taste in bass response. Play with the value until things sound right. I have heard very positive feedback on this combination.

Martin

Martin is a great resource, and far more knowledgeable about these things than me. My 2 cents on what he suggested is as follows:
increasing the port length to 6 inches will flatten the response below 250 HZ, but will attenuate it dramatically. The filter will basically then attentuate the response for the HZ over that. The result:
a flatter response, but also MUCH reduced sensitivity. IF you are running tube amps, with low watts, this may not be a good idea. If you are using solid state, and power is not an issue, then you can try it. However, to me, sensitivity means more than just low watts, it means greater dynamics and more presence as well.

Also, I personally feel that adding electronics to the speaker is somewhat at odds with why we are sticking to a single driver design in the first place....i mean why not just go with a multi driver setup?

Why don;t you wait till we heaar it, and then decide? Again, i think too many of us get caught up in the frequency extension game, and miss out on why we have single driver setups to begin with.
I left you a message, with my number. Call me when you can.
thanx
-akhilesh

Phil's little speakers sound great, and they're a single driver Fostex in a bass-reflex box. He purchased them from that fellow in St. Louis. Nothing to 'em - 8" driver in a simple ported box and no electronic components 'cept the driver.

But aren't there some Fostex drivers that are commonly used without additional components in certain cabinets? I don't have any experience with Fostex drivers, but I could have sworn I'd seen some reputable implementers making systems with them that worked pretty well using only acoustic EQ from the cabinet.

There are many designs for Fostex drivers that don't use the additional filter that I use on all of my designs. But for BR type enclosures, and this includes TL's and TQWT's, I think that a little filtering really helps the SPL balance of the speaker and provides a great improvement. My personal opinion is that adding a filter corrects more problems then it creates. Yes, you loose some efficiency but the improved integration of the bass with the mid and high end is well worth this small negative. Many people will argue and resist trying the filter. I have had many private e-mail discussions with skeptics, but when they try the filter (it is easily reversible) almost every response is positive and the filter stays. You can over do the filter by using too large of a resistor value and then the life will be sucked out of the music. It takes some tweaking and listening.

The common arguement is that a minimalist system is the best and only way to true hifi. Very low wattage SET amp and a straight connection to the driver with no passive components. If it works for the individual that is great. My opinion is that people using these types of amps really paint themselves into a corner, there is no flexibility in the speaker design and the low power of the amp is dictating the entire system. I have played my Lowther ML TL's for a number of people using a solid state amp and have received very few real significant criticisms. Many were shocked at the clarity and range of the response.

My advice to anyone with a full range driver is to try the filter and see if it improves the system. It will need to be tweaked to get it just right. It is a relatively cheap and easily reversible modification. If you run out of power with a SET amp, borrow a solid state unit and see what can be achieved. Then decide. If you don't try you will never know.

Martin

PS TNT-Audio has an interesting article this week that is relavent to this discussion.

I use the 206E in a 1.3L bass reflex cabinet made by David Dicks (single driver, no crossover or filter). More information at http://www.oldhifi.com/fostex.html (be forewarned, there are a lot of pretty bold claims made on the site - David loves these drivers, although he loves Lowthers more - I chose the Fostex drivers after a side-by-side comparison at David's house in St. Louis).

You definitely lose some low-end with this configuration, and I'm not sure any cabinet or filter combination is really going to change this (David sells bigger cabinets to extend the bass marginally). At the same time, I am really pleased with the overall presentation. On small ensemble stuff (particularly acoustic, jazz, classical) these speakers really sing. If you want really extended bass you probably aren't going to be happy with any single driver (David says as much near the end of his site, recommending Hsu subwoofers for those who miss the really low frequencies). I don't know how low they measure flat, but they usually measure somewhere around "that sounds freaking awesome" using the only tools I own (ears), which is good enough for me. On a related note, you should hear "rub a dub dub, three men in the tub" on the tubes - it's like you are actually there making candlesticks...

Someday (I'm figuring around 2025) I'm going to build some real speakers (7Pi horns) and really rock the Casbah.

My personal philosphy with single speaker design is to minimize electronics for the majority of the spectrum. While one can get drivers (like Lowthers or Fostexes) that are offer good frequency extension, ther eare other factors like tone. I am partial to the "tone" of older alnico drivers (from the 1960s & 1970-s). This means that in the higher ranges and the really low ranges, i have to play games like supertweeters, and (so far not tried but will soon) : subwoofers.

Also, I use only tube amps (cheap tube amps with less than 10 watts per channel power).

However, different people have different approaches: I know MArtin has done great work in actually building lots of enclosures for single drivers.. and trying different methods to compensate for their weaknesses. I thought about building a horn or long pipe, but decided I wanted coherence, and to me, as a layperson, if the bass is coming from behind the cabinet, it lacks that "single driver magic".
Anyway, this is a deeply subjective & personal issue, and each of us has to find our own place!
-akhilesh

So I ask myself, self, why does everyone worry so much about this? People love the presentation of single driver speakers, they love the high efficiency; they have a problem when using a crossover to another driver, but still long for something more, be it bass or high treble.... I use very inefficient speakers driven by 3.5 watt mono amps; I have a Richter Scale crossover that allows me to get away with this. I have dynamics; I get to listen to my favorite speakers and I have very refined bass. Get yourself a crossover that allows you to correct the low end, (it also has a frequency anlyzer and contouring ability). We can have our cake and eat it too.