The small Fostex bass reflex loaded thing does not work as horn. Mouth area of 225 cm2 is on par with a smaller midrange horn, so it is flared pipe.
From 1 kHz it gently slopes down 10 dB by 200 Hz, so it is bass light, below 60 Hz it falls rapidly. On top of that it has a dip between 90-180 Hz reaching -10 dB at 130 Hz. All can be read in Klang & Ton 2012/2
The thing is that if you build backloaded bass horn much smaller than the Jericho it will despite its "horny appearance" not work as horn (Flare and mouth area mostly) but as a quarter wave resonator (length dominated). So if you really want a horn accept that is has to be big, hybrids, pipes and BR can be smaller and might be good enough output wise in your room.
From 1 kHz it gently slopes down 10 dB by 200 Hz, so it is bass light, below 60 Hz it falls rapidly. On top of that it has a dip between 90-180 Hz reaching -10 dB at 130 Hz. All can be read in Klang & Ton 2012/2
The thing is that if you build backloaded bass horn much smaller than the Jericho it will despite its "horny appearance" not work as horn (Flare and mouth area mostly) but as a quarter wave resonator (length dominated). So if you really want a horn accept that is has to be big, hybrids, pipes and BR can be smaller and might be good enough output wise in your room.
The Fostex 126 cabinet is rubbish IMO, although the small terminus area is just one of its problems. The whole design IMO is simply poor. I know what they were trying to do, but it doesn't work well enough. I gather they burn well though. 
From my POV, I just call anything that expands toward the terminus a horn since whether Fc = F0 (i.e. whether they're impedance matched down to their QW cutoff frequency) or not, they all have something in common: the presence of some degree of 1/2 wave resonant behaviour. Providing the designer is aware of what occurs when terminus CSA is progressively compromised compared to the ideal, it's not a big deal, or doesn't have to be. Most back horns that do not employ corner loading, and quite a few of those too, are compromised in some way or other; it's usually just a matter of degree.
From my POV, I just call anything that expands toward the terminus a horn since whether Fc = F0 (i.e. whether they're impedance matched down to their QW cutoff frequency) or not, they all have something in common: the presence of some degree of 1/2 wave resonant behaviour. Providing the designer is aware of what occurs when terminus CSA is progressively compromised compared to the ideal, it's not a big deal, or doesn't have to be. Most back horns that do not employ corner loading, and quite a few of those too, are compromised in some way or other; it's usually just a matter of degree.
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It's been a while but I wanted to give an update. After a busy last few months I'm finally ready to return to this project. After much searching and reading what others have had to say about the BK-12, BK-16, and BK-20, it sounds like these wouldn't be a great performers compared to other designs. While easy to build, I really don't want to waste my time with something that just won't work all that well.
So I've moved on to considering others. I've looked at the Austin series of horns and I'm impressed with their performance but they are aesthetically ugly, so they're out. Other than that, not much has appealed to me except for the so called "big vent reflex" cabinets like the Replikon. Unfortunately, all the designs are now completely outdated, as none of the drivers are available. Anyone have any recent BVR designs? I've seen the "half Chang," but there doesn't seem to be any plans available, and the one set I did find performed poorly.
So I've moved on to considering others. I've looked at the Austin series of horns and I'm impressed with their performance but they are aesthetically ugly, so they're out. Other than that, not much has appealed to me except for the so called "big vent reflex" cabinets like the Replikon. Unfortunately, all the designs are now completely outdated, as none of the drivers are available. Anyone have any recent BVR designs? I've seen the "half Chang," but there doesn't seem to be any plans available, and the one set I did find performed poorly.
If I've got my dates right, the original Chang family was archived even before the major revamping of the Fostex FE line up a couple of years ago now.
Scott has come a long way with his designs in the past 5 years - as I can attest having built quite a few of the very wide range of his catalog.
It's probably time to revisit the basic starter questions of application / venue, as well as to ask if in the intervening 4 months or so, have you had the opportunity to hear any systems similar to what you envision?
I am not sure you should rule out the BK-12 as a poor performer but if you are looking for a small BLH for a small room, the FH3 is probably your best other alternative.
I wouldn't take that video as any indication at all, except that the speakers are capable of making sound - you'd have to work very hard to make the FE126Ens sound that bad when they're in the same room as you.
Does the cabinet have to be floor-standing?
The new Alpair 12Ps in smallish ported boxes are rather good, and would (I suspect) provide more low end than a FE126 could ever muster. A full-sized floorstander would provide dig lower still, but would mean a more complex build.
What're you planning on using these speakers with? (in terms of music and amplification)
Chris
For your smaller room I would recommend the relatively recent FFxx5WK series in bass reflexes, or Markaudio speakers in one of the many designs for them.
These will give decent bass relative to the box volume. Your room will not be dominated by speakers.
I also think that these speakers sound noticeably more refined and tonally richer than any of the FExx6En series.
Next week I should have FF125WK ready in compact BR boxes, to be used in a small room with a tube amp, will give impresisons then.
I also have a pair of Markaudio A12P ready for a more ambitious project, to replace my main speakers. These were truly amazing in a listening session within rather big "superpensil" boxes (which in principle weren't designed for them, yet the combination works well). Having heard many speakers, it was obvious that serious money has to be spent to get a significant sound quality upgrade over the A12P in a suitable enclosure.
These will give decent bass relative to the box volume. Your room will not be dominated by speakers.
I also think that these speakers sound noticeably more refined and tonally richer than any of the FExx6En series.
Next week I should have FF125WK ready in compact BR boxes, to be used in a small room with a tube amp, will give impresisons then.
I also have a pair of Markaudio A12P ready for a more ambitious project, to replace my main speakers. These were truly amazing in a listening session within rather big "superpensil" boxes (which in principle weren't designed for them, yet the combination works well). Having heard many speakers, it was obvious that serious money has to be spent to get a significant sound quality upgrade over the A12P in a suitable enclosure.
Thanks for the responses guys. I am primarily planning on using these with a Crown D-45 amp, mostly for light rock and jazz music. My primary reason for deciding on a backloaded horn is that I'm looking to try something new and different. I have heard bass reflex boxes and know what they sound like, but I've never heard a single-driver BLH or BVR. This is my whole reason for embarking on this project. I find it very interesting.
That being said, I want to make sure I select a good design to work with. With all the designs and discussion out there it's hard separate the signal from the noise and choose which one to build. Like I said, I'd hate to build an underperforming cabinet and be put off completely from pursuing this further. But maybe I worry too much and I should just hurry up and build something!
That being said, I want to make sure I select a good design to work with. With all the designs and discussion out there it's hard separate the signal from the noise and choose which one to build. Like I said, I'd hate to build an underperforming cabinet and be put off completely from pursuing this further. But maybe I worry too much and I should just hurry up and build something!
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The Fote might well tell you all about your amps shortcomings... andfew of them need that much power.
dave
If you are looking for a compact back loaded horn, the Cornu spiral horn cannot be beat in terms of size, and I believe it is a true horn - the one I made has a 24x expansion ratio. Modifying the design to skip the middle separator panel and using alternate materials other than wood lets one make it quickly and easily. I scaled mine down to 20 inches square by 2.38 in deep and driving with a 3.5 in Vifa TC9FD.At this size, the longest horn path still should reach down to 61 Hz. It sounds amazing, you just cannot believe the open spacious full bodied sound from this tiny driver. If anyone is interested in this easy DIY build, see this thread: http://www.diyaudio.com/forums/construction-tips/223313-foam-core-board-speaker-enclosures-6.html
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