Very definitely nothing exalted here: Scott's first law states that any person who considers themselves to be an expert on any subject isn't one.
Assuming 3/4in build material, it's not far off Martin's old MLTL box for (primarily) the FE207E. There are arguments for having the lower Q driver & then compensating for the over-damping though, which has probably been done to some extent -without knowing exactly what the internal filter is (component values, topology) & how / if the drivers have changed in spec. over time we can't be certain.
For whatever it's worth, I do have a couple of suggestions. As-is, assuming a voltage source amplifier like the Naim & the factory driver data, as far as alignment goes you'd probably want about 4ohms in series to start balancing things out in 1/2 space, and probably about 2.5ohms with them in / near corners. The existing filter is probably providing some / all of this already, although that may be a secondary effect; if you can give us the values / circuit topology & components, we'll have a better idea. You could probably lose an inch off the duct length. The damping as-is looks to have a piece of panel (not acoustic) damping on the rear wall behind the driver, with the upper volume empty & the lower stuffed. That's usually the reverse of how you'd normally do it -lightly stuffing the upper portion (ensuring it's not in physical contact with the driver) tends to be preferable. An alternative would be to lag out the top, back & one sidewall with OC-703 or similar 3lbs / ft^3 rated rigid fibreglass, 1in Ultratouch, SAE-F10 rated soft-wool felt or equivalent & adjust as preferred from there.
Assuming 3/4in build material, it's not far off Martin's old MLTL box for (primarily) the FE207E. There are arguments for having the lower Q driver & then compensating for the over-damping though, which has probably been done to some extent -without knowing exactly what the internal filter is (component values, topology) & how / if the drivers have changed in spec. over time we can't be certain.
For whatever it's worth, I do have a couple of suggestions. As-is, assuming a voltage source amplifier like the Naim & the factory driver data, as far as alignment goes you'd probably want about 4ohms in series to start balancing things out in 1/2 space, and probably about 2.5ohms with them in / near corners. The existing filter is probably providing some / all of this already, although that may be a secondary effect; if you can give us the values / circuit topology & components, we'll have a better idea. You could probably lose an inch off the duct length. The damping as-is looks to have a piece of panel (not acoustic) damping on the rear wall behind the driver, with the upper volume empty & the lower stuffed. That's usually the reverse of how you'd normally do it -lightly stuffing the upper portion (ensuring it's not in physical contact with the driver) tends to be preferable. An alternative would be to lag out the top, back & one sidewall with OC-703 or similar 3lbs / ft^3 rated rigid fibreglass, 1in Ultratouch, SAE-F10 rated soft-wool felt or equivalent & adjust as preferred from there.
It’s interesting that this and another thread about using Fostex 206nv popped up at the same time and the use of Martin’s MLTL seems to be the focus of discussion. I’ve wanted to try it for a while.
One thing that hasn’t been mentioned I think is that Martin originally designed his MLTL for the Lowther DX series drivers.
He modeled the cabinet in MathCAD, and actually built it, tested it and tuned it with a correction network for the Lowthers.
On his page devoted to the Fostex version of his MLTL (which has the same exact dimensions…albeit with different vent specifications) he notes that he considers it a “virtual” project because he never built and heard it himself with the Fostex drivers.
The Fostex MLTL was an accommodation and adaptation of the original Lowther MLTL design for the many people that were reaching out to him with inquiries about using the Fostex drivers in his design.
Martin obviously spent the time to “re-tune” the plans in a manner that he felt was sufficient (who better?).
Just some food for thought as the OP seems interested in trying other drivers in the nice cabinets he lucked out on.
Lowthers would seem to be a good option for these cabinets. They are definitely more expensive than Mark Audio drivers…and not everyone's cup of tea it seems.
I had an interest in them, but not enough to pay retail. I sought out good used drivers.
Just another option.
One thing that hasn’t been mentioned I think is that Martin originally designed his MLTL for the Lowther DX series drivers.
He modeled the cabinet in MathCAD, and actually built it, tested it and tuned it with a correction network for the Lowthers.
On his page devoted to the Fostex version of his MLTL (which has the same exact dimensions…albeit with different vent specifications) he notes that he considers it a “virtual” project because he never built and heard it himself with the Fostex drivers.
The Fostex MLTL was an accommodation and adaptation of the original Lowther MLTL design for the many people that were reaching out to him with inquiries about using the Fostex drivers in his design.
Martin obviously spent the time to “re-tune” the plans in a manner that he felt was sufficient (who better?).
Just some food for thought as the OP seems interested in trying other drivers in the nice cabinets he lucked out on.
Lowthers would seem to be a good option for these cabinets. They are definitely more expensive than Mark Audio drivers…and not everyone's cup of tea it seems.
I had an interest in them, but not enough to pay retail. I sought out good used drivers.
Just another option.
I'd be a mite wary about the Lowthers. Nothing against them, and if you select carefully, the basic response balance should be decent. However -those units tend to compress quicker than the Fostex, so depending on where your priorities lie, the LF dynamic range may end up getting a bit more clipped. YMMV as always.
Well I exalt your enviable modesty instead. Thank you!
...all of which I will implement gladly and appreciatively, however just want to first clarify that this advice concerns replacing/upgrading the drivers to the MA-200s versus squeezing the last few ounces/mls from the fostex fe206e units. Also, in which case, I was planning/hoping to remove any network whatsoever from the path between driver and amplifier, as I've done with the Fostexes, which seemed to be the tweak that transformed them up into the addictive fixation they've since become. But, whatever the modest maestro recommends shall be law. Happy to chop an inch from the ports as well.
And, here's the (presently bypassed) network:
Hope that helps!
Also, my dimension illustration may not have been clear, as it is indeed the upper portion of the x-brace that is padded (about 6" or so above the brace), whereas the bottom portion is a wide open box. Do you still recommend adding some of those insulation options for additional damping to compensate for the MA-200's parameters?
I assumed that squishy panel was to absorb energy from the rear of the driver, perhaps along the same lines of the popular felt'ening of the basket's legs to prevent reflected sound projecting through the paper cone.
Yep! Was considering that route as well, though it didn't necessarily (from online impressions fwiw) seem to suit my music tastes of largely dynamic rock/jazz/electronica in the way I've heard the MAs excel at. Plus, cost 🙂 Definitely chewy food for thought though, and maybe a future experiment if I come across an affordable used pair, though the MA option seems to anecdotally check the right boxes for my preferences, at least for the immediate direction I'm intrigued to go. Appreciated!
Finally, I was considering (at the advice of the previous owner, who also came into them in a mysterious, second-hand fashion) adding mass to the cabinets since, for the size they are, they do feel a bit light (30 lbs maybe?). Not sure exactly how, and maybe that's just legacy, naturally-heavier multi-way speaker thinking.
@AirPlur
Getting Fostex 206e to work in that MLTL cabinet requires a high output impedance amplifier (tube, or Pass F2 or similar). If you don't have one...Did you try to connect a high power resistor in series with + lead, between the amp and the speaker? If you don't have the resistor, you may even try a filament lightbulb, (300w, 110 v) if you still have one around...
Getting Fostex 206e to work in that MLTL cabinet requires a high output impedance amplifier (tube, or Pass F2 or similar). If you don't have one...Did you try to connect a high power resistor in series with + lead, between the amp and the speaker? If you don't have the resistor, you may even try a filament lightbulb, (300w, 110 v) if you still have one around...
As soon as someone is able to sell me it (them)! Ideally, with the neato dots of science on them.
You have two options: either use that box with another driver (MA - this seems what you would like to do).
Or, use the Fostex with another, proper cabinet (Vulcn or Kirishima).
Or both 😀
I was just suggesting that you try a resistor trick, to see if that will give you a more pleasant sound, before spending money on another set of drivers...
I'll check on MA200 in the morning.
The 206 is fine in that box if a/ you like it (most important factor -you're the one listening to it after all), and b/ any compensation necessary for the loading / alignment is applied -although this also relates back to point a/
To be honest, it's not a 'natural' fit, but you can make it that way if you don't mind some dynamic compression, since the 206 is technically a 'horn driver' in terms of being highly (over) damped & was largely designed with the intention of being on the end of a typical SET etc. amplifier, or with equivalent compensation. Speaking generally, one ye olde technique a good friend often suggests is that if you haven't got that is to wire a pot in series with the speaker & adjust until you've got the balance you like. Measure the resistance, remove & replace with a power-resistor of suitable rating, or better, a grid of small metal films built up to the necessary value & power-handling.
The 206 is fine in that box if a/ you like it (most important factor -you're the one listening to it after all), and b/ any compensation necessary for the loading / alignment is applied -although this also relates back to point a/
To be honest, it's not a 'natural' fit, but you can make it that way if you don't mind some dynamic compression, since the 206 is technically a 'horn driver' in terms of being highly (over) damped & was largely designed with the intention of being on the end of a typical SET etc. amplifier, or with equivalent compensation. Speaking generally, one ye olde technique a good friend often suggests is that if you haven't got that is to wire a pot in series with the speaker & adjust until you've got the balance you like. Measure the resistance, remove & replace with a power-resistor of suitable rating, or better, a grid of small metal films built up to the necessary value & power-handling.
Super appreciated, and maybe I'll try to do something else with the Fostexes that could incorporate all of these tweaks 🙂
Thank you sir!
I'll be forever grateful to the fe206e drivers for infecting me with the bug and exposing a jaded audiophile/musician to the splendor of full-range single-driver audio (is there any easy acronym for this configuration?), but the overall voicing just isn't my preference.
Also, I think the longer term plan could be to build/source a bespoke cabinet for the MAs (Frugal-Horn, Pencil, that really tall one named after a mountain i can't recall), so the current cabinets may just be a holdover until I'm able to give them the home they deserve. And have some fun with them in the meantime🙂
And / or use a 10 band equalizer to add some bass, cut the highs, take care of baffle step, etc.
Won't help with floor bounce though, nor very narrow cone resonances.
The 206e has a climbing response, and that is before putting it on a 10" wide baffle (less bass @ 450, even less @ 225hz), but the mltl maybe can create some bass pipe harmonics to fill in the bass.....................
Past 4khz can be knocked down by sitting off axis, but not the 1.5 - 4khz area.
Also, take note if they sound better to your ears 5', 7' or 10' away..................
Within their limits of music / distance / volume, full range drivers can be magical.
or better yet, relaxing......
You can tweak them in passively, sell them for the same $$ to someone else, or sell the drivers on fleabay and put different 8's in the boxes, like the seas fa22rcz ($212 each).
https://josephcrowe.com/blogs/news/seas-fa22rcz-8-fullrange-driver
"subjective listening uh this driver is significantly better than the fostex fe 206 en in terms of overall clarity and smoothness. The treble i would say is on par with a really good dome tweeter or even a pure ribbon tweeter which is quite surprising. I would say it's very similar to the smaller mark audio drivers like the alpair 7.3 in an 8 inch format."
I don't think I am brave enough to cut the dust cap off to install a phase plug, eventhough I am sure it would sound better.............
Won't help with floor bounce though, nor very narrow cone resonances.
The 206e has a climbing response, and that is before putting it on a 10" wide baffle (less bass @ 450, even less @ 225hz), but the mltl maybe can create some bass pipe harmonics to fill in the bass.....................
Past 4khz can be knocked down by sitting off axis, but not the 1.5 - 4khz area.
Also, take note if they sound better to your ears 5', 7' or 10' away..................
Within their limits of music / distance / volume, full range drivers can be magical.
or better yet, relaxing......
You can tweak them in passively, sell them for the same $$ to someone else, or sell the drivers on fleabay and put different 8's in the boxes, like the seas fa22rcz ($212 each).
https://josephcrowe.com/blogs/news/seas-fa22rcz-8-fullrange-driver
"subjective listening uh this driver is significantly better than the fostex fe 206 en in terms of overall clarity and smoothness. The treble i would say is on par with a really good dome tweeter or even a pure ribbon tweeter which is quite surprising. I would say it's very similar to the smaller mark audio drivers like the alpair 7.3 in an 8 inch format."
I don't think I am brave enough to cut the dust cap off to install a phase plug, eventhough I am sure it would sound better.............
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Actually, the 206E does flatten out at 15 degrees from about 1.35KHz, as you'd expect with an OA piston corner of 676Hz and a VC point source, with the whizzer helping off-axis consitency above the 3.13KHz VC point source corner.
I like the Seas, although it has rather different loading requirements to the old 206E and although I'd call its HF (and the 206E's) decent in the context of this sort of driver, especially if adjusted via electrical or mechanical preference, I certainly wouldn't put its HF quality on a par with a quality dome tweeter such as some of Seas's own, SB's Satori range, some of Scan's units etc. They do score in other ways, so as always it's swings & roundabouts depending on where your priorities lie, but out & out HF linearity isn't one of them.
I like the Seas, although it has rather different loading requirements to the old 206E and although I'd call its HF (and the 206E's) decent in the context of this sort of driver, especially if adjusted via electrical or mechanical preference, I certainly wouldn't put its HF quality on a par with a quality dome tweeter such as some of Seas's own, SB's Satori range, some of Scan's units etc. They do score in other ways, so as always it's swings & roundabouts depending on where your priorities lie, but out & out HF linearity isn't one of them.
Okay -having looked at Martin's old Lowther / 206 / 207 box: the MA200M will go in, with a few caveats. As-is, it's underdamped and tuned slightly high. You can increase the duct length by an inch from standard to lower Fb, which will help. Even with the heavy flare, I'm alergic to ducts longer than that, especially on the front baffle since there's a risk of 1/2 wave modes developing, so that's about as far as I'd suggest going. If there's still some apparent peaking around Fb you could either add some more damping below the brace, down to the level of the duct, or (easier) just damp out the duct with layers of grill cloth using the old click test:
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I've never, in my 40 years of using my ears to enjoy reproduced music, encountered a more finicky, directional set of speakers, where not just the distance or height of my head makes a make/break difference but also the angle of my head. I was expecting to have placement be a more involved process than usual based on what I'd read, but once I found a sweet spot (there may be other, better ones I'll discover after some additional room treatments) it was well worth the effort.
Same.
Huzzah! Thx for verifying, and what a neat trick re the click test. Glad I never toss grille cloth when I'm discarding speaker grilles when doing my "Ammoflage" charity speakers (about USD $100k raised so far, but I digress). Either way, sounds like some manageable experimentation that can be managed sans workshop tooling.
Oh, one question...is it advisable to flange out the driver hole as shown in the recommended MA website enclosure instructions? I may have to add a 1/4" of diameter to accommodate the MAs, and "while I'm in there" was wondering if that would be worth doing (somehow) as well.
Also, Madisound let me know they have some MA-200s arriving soon, so it's all coming together🙂
Thanks again everyone, and especially @Scottmoose @planet10 for the guidance!
In that sense, anyone want a good deal on a pair of cherry, well broken-in Fostex drivers for their horn-loading speaker project? 😉
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Oh yes definitely will flush-mount. Was wondering if I should also flare out the backside of the hole diagonally, as shown here, or if that's more a marginal "nice to have" i.e. I don't need to go out and purchase a specialty tool to accomplish it in order to do the drivers justice 🙂
If you're going to go to all this trouble (yes chamfer the hole) you should first obtain the phase plugs from planet10 and install them in the 206 drivers imo. You will probably hear the lack of baffle step correction as midrange shout no matter what new drivers you put in. Your situation will not be much different, but you won't have phase plugs.