All sounds good to me except for the ceiling loading since once a reflective surface moves away from the perpendicular, loading rapidly decays away same as room modes [AKA 'slap' echo] will when angled away from the sound wall, so probably not enough loading to matter. Best then to floor load. This is easy to test, just tilt a speaker back and by about 12 deg the bass should have rolled off considerably.
GM
This very interesting thread made (forced) me to buy 250 lbs of plywood yesterday.
I know this is about fullrange drivers but since its a BIB i hope this is a good place to show it.
Johannes.
I know this is about fullrange drivers but since its a BIB i hope this is a good place to show it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Johannes.
Yes, wish all the various BIBs were in this thread, then [re]searching would be a 'breeze' using the thread search feature.
Note that the folded horn is a little short for typical ceiling loading, so you may need a 'tophat' to extend it higher to somewhat mass load it if you have problems with too much excursion.
GM
Just had a thought. If i knew the ts parameters of the 5 1/4" midwoofer in my DM302 i could build a bib if it was suitable.
but it might just be as easy to buy some drivers and build a bib for them.
I searched this thread for a formula to design one of these but to no avail.
Can someone point me to such a formula, cant seem to find one anywhere.
Btw im doing all this from a motorola droid 3 cellphone so my browser is not the usual firefox/ie fare.
but it might just be as easy to buy some drivers and build a bib for them.
I searched this thread for a formula to design one of these but to no avail.
Can someone point me to such a formula, cant seem to find one anywhere.
Btw im doing all this from a motorola droid 3 cellphone so my browser is not the usual firefox/ie fare.
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Yes I saw yesterday that Z' was having some problems at expects things to get righted soon. Any of us should be able to attach the .xls file. I use Open Office free desktop suite and it loads fine for me.
I have the iteration called BIB Calculator V1. Others could say if later versions are available from them.
lon@athenet.net
FYI, example calculation: http://www.diyaudio.com/forums/full...se-fostex-craft-handbooks-80.html#post1229324
GM
GM
Ok, thx for the link.
wanna see if i understand what im looking at.
its the specs of the bib
Vb is box volume
L is lenght of the line
Sm is surface area of the mouth
i guess the position of the driver along the line and dimensions of the line are given by formulae set up in the sheets.
I also gather its a result of the specs vas qts and fs.
wanna see if i understand what im looking at.
its the specs of the bib
Vb is box volume
L is lenght of the line
Sm is surface area of the mouth
i guess the position of the driver along the line and dimensions of the line are given by formulae set up in the sheets.
I also gather its a result of the specs vas qts and fs.
You're welcome!
Vb = 20*Vas*Qts^1.25
Again, the driver location can be varied somewhat from its L*0.217 down to around L*0.434 according to Scott [by way of MJK?].
Vas can be in liters, ft^3, etc.; just be sure to use the appropriate speed of sound [SoS] in ft, m, etc. to get the right path-length [L]. The SoS varies depending on the program used, with ~344 m/sec being the average.
Regardless, the difference from low to high in a such a long pipe isn't obviously audible plus getting decent floor or ceiling loading is much more important, so the Fs/2 tuning is somewhat flexible unless the desired ‘L’ is longer than the driver’s theoretical low corner frequency [Fl = Fs*Qts/2]. Even then it may not matter, but haven’t experimented with, or read of any research done, though Prof. Leach’s horn math implies we must rethink how the driver must be loaded.
GM
Attachments
'Sunk the hook' in another one, did we? 
Have you seen this? http://www.quarter-wave.com/General/Fostex_FE-167E_BIB_Design.pdf
F3 is just the half power point of the resonant system. Fl and its reciprocal, Fh, define the driver's impedance/loading BW where Fs is the mean.
GM
Have you seen this? http://www.quarter-wave.com/General/Fostex_FE-167E_BIB_Design.pdfF3 is just the half power point of the resonant system. Fl and its reciprocal, Fh, define the driver's impedance/loading BW where Fs is the mean.
GM
You know? I read that paper a couple months ago found it intriguing but forgot about it because i didnt know what it meant.
Is he talking about how to refine sims by quantifying non coincident drive/terminus points?
If so how would they be added to a sheet? What equation would be relevant?
Is he talking about how to refine sims by quantifying non coincident drive/terminus points?
If so how would they be added to a sheet? What equation would be relevant?
A couple of quick questions before I start ordering components for my BiB build:
1) I intend to get a set of Fostex ~6.5" drivers from Dave at Planet 10 Hifi, pre-modified. I had the FE166En in mind, but apparently he still has a few FE167E in stock, which would be slightly cheaper. Does anyone have a suggestion as to whether one would perform better than the other in this enclosure?
2) Despite going over the entire thread, I haven't found a definitive answer to what an optimal ceiling-to-mouth distance would be. The stock specs for the 166En make this distance 31" for my eight foot ceiling. By adjusting the Fs in the spreadsheets, I can bring this to about 25", without raising the speaker too high for my listening position. Would these perform at nearly the same level, or would somewhere within the range be "optimal", by theory?
Thanks in advance, everyone!
1) I intend to get a set of Fostex ~6.5" drivers from Dave at Planet 10 Hifi, pre-modified. I had the FE166En in mind, but apparently he still has a few FE167E in stock, which would be slightly cheaper. Does anyone have a suggestion as to whether one would perform better than the other in this enclosure?
2) Despite going over the entire thread, I haven't found a definitive answer to what an optimal ceiling-to-mouth distance would be. The stock specs for the 166En make this distance 31" for my eight foot ceiling. By adjusting the Fs in the spreadsheets, I can bring this to about 25", without raising the speaker too high for my listening position. Would these perform at nearly the same level, or would somewhere within the range be "optimal", by theory?
Thanks in advance, everyone!
Dobbykins,
I made a BIB for a friend with the FE166EN and it worked very nicely; no experience with FE167E though, maybe others can comment. The ceiling is at 9' at my place, and IIRC the BIB with FE166EN is 64.5" tall - had no problems with them - but please note, you need to place them near corners for good bass output. I had them at my place for some time, and must say, they were very pleasing to listen.
I made a BIB for a friend with the FE166EN and it worked very nicely; no experience with FE167E though, maybe others can comment. The ceiling is at 9' at my place, and IIRC the BIB with FE166EN is 64.5" tall - had no problems with them - but please note, you need to place them near corners for good bass output. I had them at my place for some time, and must say, they were very pleasing to listen.