Hi Creeper, thanks for the interest. No JTM clone. Because I only listen at 70dB, a single driver speaker is practical for the way I listen. Furthermore because they beam above 3-4kHz, I don't have problems anymore with boosts in HF from wide dispersion drivers reflecting around the room. And this happened with every speaker I tried, even the soft dome ones.
This speaker has just the single 4" driver (no whizzer) in a box with no T-L. I have my current Tang-Band 871s 3" paper driver against the wall. Measures flat to only 80hz which does not cut it. I don't know if the new speaker will be sealed or vented. Will have to see how much bass it produces sealed. As Sean wrote, less bass but greater *extension* because of more gradual LF rolloff. If I tuned the box to 70Hz bass may drop off fast below the 70Hz and so a sealed box will give less bass at 70hz but more bass at 30 hz. No big deal to put in a vent later.
Fostex has such low x-max (usually .35mm) that I don't see adequate bass. They seem to start rolling off at 200hz vs. the 3mm x-max Tang-Band's 100hz. Also some have mechanical Q as high as 8.5. Maybe they sound good but the ones I've heard sounded bright. I think partially from the lack of bass and partially from ringing of high Q driver.
I was considering the FR-125 from www.creativesound.ca but I don't need 9mm xmax when the speaker is against the wall. Also because of the bass output, No (Musical power) is only .242% and SPL is 85 dB while the Tang-Band is .501% and 89dB. Not high efficiency but without an x-over still plays quite loud on low power. I guess the x-over on the Mission speakers (with some sort of bass boost circuitry) lowered *effective* efficiency to 2-4dB lower than x-overless speaker.
So this is the best I've come up with on paper. The Tang-Bands are only ~$32 each and my speaker design has a removable front and back panel sealed with foam tape. They will sort of look like Epos. I'm getting extra front panels so I can just drill out a front panel for a different driver hole, drop the new front panel in the speaker cabinet and voila - new speaker. Or may go with a standard 2-way front panel which I can drop in if I get tired of a single driver.
After this, I would like to build an amp3 kit from 41hz.com. Costs $25. I think the T-amp will complement a warm sounding driver like the Tang-Band very well. T-amps are said to have good detail and stereo separation but can sound thin, and bright from HF garbage. Single driver don't have much HF extension to begin with so I don't see this as a problem.
This is just my opinion, but I see a lot of people (myself included) moving away from hi-rez metal tweeters, etc. towards "lower res" vinyl, tubes, etc. Until a stereo can remove ALL the HF distortion from the electronics, power supplies, cables, power from the wall, you're listening to a lot of HF garbage along with the HF music. So hence the move away from this type of high resolution. Where I differ is the thought of "why spend a lot of money for "low rez"?" My single driver speaker tends to have a tube-like/ vinyl-like sound quality. And I'm not paying for the high rez of B&W. Or high price tubes and vinyl to subsequently reduce the resolution. I'm not worried about the nice tonality of tubes and vinyl, doesn't matter so much to my ears. Plus I still have the convenience of CD's where I burn all my favorite songs onto one CD so I don't have to switch every 10 minutes.
The realy cool thing is this $32 pre-built remote control kit with motorized volume pot I found. So I can have remote volume on the power amp for $32. Not some stupid $350 rip-off priced Creek unit. No pre-amp which is a problem but my CDB puts out 2v so it's not as bad as some others.
This is more fun than audio just being a money hobby where all it comes down to is saving up money for the next purchase, IMHO.