Several years ago, I purchased a pair of Fostex FE207e drivers and proceeded to build a pair of MJK's Project 05 ML-TL. After settling on the right BSC values and adding a pair of Planet10's phase plugs, I was quite happy with the results.
Now, I'm settled in for a good while, and have no intentions of moving anytime soon (I used to move a lot). The frequent moving has not been kind to my cabinets, and I'm thinking it's time to build something else. Herein lies my question: What to build for these 207's? I've read the entire Half-Chang thread, and a good part of the Chang thread, but can't seem to locate the plans anywhere. It looks like most current efforts are understandably focused on drivers that are currently available.
So, I'll ask. What cabinet would/have you used or recommend to get the most out of the 207's? What have your experiences been?
Thanks
Now, I'm settled in for a good while, and have no intentions of moving anytime soon (I used to move a lot). The frequent moving has not been kind to my cabinets, and I'm thinking it's time to build something else. Herein lies my question: What to build for these 207's? I've read the entire Half-Chang thread, and a good part of the Chang thread, but can't seem to locate the plans anywhere. It looks like most current efforts are understandably focused on drivers that are currently available.
So, I'll ask. What cabinet would/have you used or recommend to get the most out of the 207's? What have your experiences been?
Thanks
What do you want mid or bass?!
If mid use it as a mid with a woofer/sub in a 2 way configuration.
If as a bass/full driver you have to test various designs but from simulation I would give a go to the (BR) 30/32 L , 40Hz tuned (or 35L/42Hz as in the example below). Consider this an example/test only, I never tried it before.
http://www.madisound.com/pdf/fostexdrivers/FE207E.pdf
I don' have at the moment any link to a 2-way (+ woofer), but they have been posted here at diyAudio often.
Related:
Philips 9710/
video for different driver Fostex F120A
Fostex F120A FT90H - YouTube
If mid use it as a mid with a woofer/sub in a 2 way configuration.
If as a bass/full driver you have to test various designs but from simulation I would give a go to the (BR) 30/32 L , 40Hz tuned (or 35L/42Hz as in the example below). Consider this an example/test only, I never tried it before.
http://www.madisound.com/pdf/fostexdrivers/FE207E.pdf
I don' have at the moment any link to a 2-way (+ woofer), but they have been posted here at diyAudio often.
Related:
Philips 9710/
video for different driver Fostex F120A
Fostex F120A FT90H - YouTube
The 35 liter BR box with 80 mm dia x 180 mm port from Fostex appears to have a recessed bass shelf, possibly because the volume is too small and the tuning too low. I think, you will have a more balanced bass shelf (with small low bass bump) with a larger box and higher tuning frequency (60 liters @45 Hz). However, I think a MLTL or BLH is needed to really take advantage of this driver.
So, I've been out of the loop for quite a while here, and had to familiarize myself with BIB. I've come across MJK's write-up "Fostex FE-167E Full Range Driver in a Bigger is Better Enclosure" which lead me to zillaaudio as well as Terry Cain's article at the single driver website.
Obviously I have some more reading to do, but how critical are the corners to this implementation? My current listening area is approx 12' x 18' with 8' flat ceiling, and my speaker placement is midway along the long wall, spread about 7' apart. To utilize the corners would require a wholesale rearrangement of the room....not impossible, but difficult.
The BIB will still work fine without corner loading if you have it near a wall you will get wall and ceiling bass enhancement. As the BIB for this driver will be quite tall - you will be close to the ceiling anyhow. The BIB calculator says the box is 87 in tall x 11.5 in wide x 14 in deep (ext dim). This puts you within 9 inches from the ceiling - definitely will get lots of ceiling bass enhancement. This is a relatively slender cabinet due to the low Qts and moderate Vas. If you have the room and the WAF, BIB is the way to go. You might try flattening the BIB to make a FIB and mount the driver on the longer 14 in wall if there is room. A FIB can be made by changing the aspect ratio to 6 in deep x 25 in wide (internal dim) (preserves CSA) and placing the speaker next to wall where it hardly takes up any floor space. It could be made to look like a built-in wall column and painted to match wall trim.
Corner loading in most rooms just means it will increase low distortion power handling below ~100 Hz with ~1 mm Xmax drivers and reproduce the lowest pipe organ symphonies with a bit of authority with higher Xmax rated drivers.
As already noted, the standard BIB will be tall enough to get good ceiling loading, but the trade-off may be a too high a driver position, so inputting a higher Fs to lower it will of course reduce ceiling loading and where the corners become a good plan, though a simple rectangular 'top hat' can be added for mid-wall positioning to help somewhat.
I'm also a big proponent of wide, flat cabs to keep from having to use any baffle step compensation [BSC] as an acceptable trade-off to maintaining a relatively smooth transition through the fold.
GM
I fully agree with GM's arguments.
Build my BIB's in 2008 for lowther dx3 ; reduced size : 30x47x157cm outside dimensions.
Wasn't pleased with the sound of the lowthers , even with BSC.
Put the FE207's in and Great result , even without BSC.
They def. need Corners or at least a side wall!
Good luck with your choice!
Build my BIB's in 2008 for lowther dx3 ; reduced size : 30x47x157cm outside dimensions.
Wasn't pleased with the sound of the lowthers , even with BSC.
Put the FE207's in and Great result , even without BSC.
They def. need Corners or at least a side wall!
Good luck with your choice!
Yes, I agree. Currently my 207's are in MJK's Project 5 (MLTL) with BSC and phase plugs from Planet10, and they do sound good, especially with jazz and acoustic music. Vocals, especially female, are magnificent.
As I mentioned earlier, I used to move frequently, and I didn't have the forethought to install a variable BSC. Rather, I settled on a moderate value for the setup they were originally designed for. To compensate for room irregularities when I would relocate, I implemented a digital room correction filter (using BruteFir to apply the filter before the flac stream is sent to the Squeezebox). The results are significant, but it is a real pain to measure the room response and generate the filters every time I moved or redecorated. Also, the DRC obviously doesn't work when I use an analog source, but that doesn't stop me.
I am intrigued by the BIB's and have some more reading to do, but that particular thread is HUGE! I am still curious about the Chang/Half-Chang as well. Can anyone offer a subjective comparison between these?
Also, the link to the BIB designs on zillaaudio.com is dead. Is it possible that this info is currently being hosted elsewhere and I just haven't found it yet?
The BIB calculator is rather hard to find in that massive thread. I re-posted GM's spreadsheet here: http://www.diyaudio.com/forums/full-range/233720-just-found-bib-design.html#post3446640
Thank you! That helps a lot.
OK, after spending many hours reading through the forum and linked material, I've decided to give BIB a go. Budget is tight at the moment, and three sheets of good plywood is not inconsequential, so I'll need to save some nickels for a while. In the meantime, I have some more decisions to make and could use some guidance.
I like the FIB concept, and I do have the room for the 14", but the 25" implementation would interfere with the windows. Also, In considering the "wall column" implementation, I got to thinking about positioning. Currently, my MLTL's are significantly toed in, so they cross directly in front of the listening position. Would this also be necessary with the BIB? If so, that may make the "wall column" less desirable?
Also, I had a good read through Bob Brine's thread "A cabinet out of thin material". As big as these cabinets are, they will be quite heavy if constructed from 3/4" plywood, or even heavier if I cheap out and go with MDF. I wonder how these BIB's might respond to a thin/lighter cabinet, say maybe 1/4" plywood attached to 1/2" expanded polystyrene or some such? Thoughts?
If pressed to reduce cost, I might use OSB for the back, bottom, and divider board--no real need for beautiful veneers there.
There are differing opinions regarding build materials, with strong feelings both for and against MDF. Personally, I'm a plywood kinda guy. Don't want anything to do with MDF.
As always: YMMV
Cheers, Jim
There are differing opinions regarding build materials, with strong feelings both for and against MDF. Personally, I'm a plywood kinda guy. Don't want anything to do with MDF.
As always: YMMV
Cheers, Jim
BBC have publications regarding thin walled cabinets. I have done an interpretation of their designs (http://www.diyaudio.com/forums/multi-way/228670-one-bc-homage-classic-vintage-design.html)
OSB is light but a bit scruffy with its uneven surface and tendency to fray at the edges.
OSB is light but a bit scruffy with its uneven surface and tendency to fray at the edges.