germpod said:
Easy: the mid Vas & Qt of the 167 mean an internal footprint of 144in^2 to get the cab volume optimised right, and if you're going for a BIB, you want to do that, or you'll loose a lot of their performance benefits. Unfortunately, they physically won't fit my room, which has to serve as an office as well.
OzMikeH said:
My 167s were accurately measured & pair-matched by Dave; the T/S parameters he provided are more accurate than the Fostex claimed data. The two different CSAs you mention above are for two different drivers, the 167 (144in^2) and 208ESigma (106.54in^2). That's why they're different. Although the 208 is substantially larger than the 167, it needs less Vb. The footprint would be smaller anyway, as it's got a lower Fs, so the cabinet is taller.
The stuff I did on Zillaspeak is mostly obsolete. Ignore the dimensions and just use GM's T/S based alignment. I haven't discussed it with Jeff (Godzilla) because I haven't had time to do anything about it yet. They'll still work, just not as well.
The stuff I did on Zillaspeak is mostly obsolete. Ignore the dimensions and just use GM's T/S based alignment. I haven't discussed it with Jeff (Godzilla) because I haven't had time to do anything about it yet. They'll still work, just not as well.
Re: fe208 es enclosure
More research needs doing, but the addition of a karlson slot to the BIB is a suggestion for reducing the ripple in a BIB. I just read a (1960s) paper that GM pointed to and indeed in theory it should do exactly what is intended. Exact shape & size is still open to exploration.
dave
dondiba said:
More research needs doing, but the addition of a karlson slot to the BIB is a suggestion for reducing the ripple in a BIB. I just read a (1960s) paper that GM pointed to and indeed in theory it should do exactly what is intended. Exact shape & size is still open to exploration.
dave
>>> The stuff I did on Zillaspeak is mostly obsolete. Ignore the dimensions and just use GM's T/S based alignment. I haven't discussed it with Jeff (Godzilla) because I haven't had time to do anything about it yet. They'll still work, just not as well.
Say it isnt so... Well, at least the dims and charts are there for some fine sounding BIBs. I put GMs formula on the How to Build a BIB page so everyone doesnt have to look far to find it:
http://www.zillaspeak.com/bib-howtobuild.asp
Happy building,
Godzilla
Say it isnt so... Well, at least the dims and charts are there for some fine sounding BIBs. I put GMs formula on the How to Build a BIB page so everyone doesnt have to look far to find it:
http://www.zillaspeak.com/bib-howtobuild.asp
Happy building,
Godzilla
OK, that was a bit of an exaggeration. Some are pretty close, which is a start. That's progress for you though. What Greg has done in coming up with his T/S based alignment is pretty much the biggest step forward in pipe-horn design since they were first introduced, removing almost all the guesswork from the Vb calculation. That's just one alignment of course, but as it's the one Greg favours, I reckon we can take it that it's as good as it gets for this sort of cabinet.
What I'll try to do is model a good selection of drivers using this alignment, with some dimensions, and get them across to you. I'm also working up an Excel sheet based on a couple of the existing ones (as driving Excel is not what Scott's are designed for) which will include all the neccessary calculations.
That's just one alignment of course, but as it's the one Greg favours, I reckon we can take it that it's as good as it gets for this sort of cabinet. What I'll try to do is model a good selection of drivers using this alignment, with some dimensions, and get them across to you. I'm also working up an Excel sheet based on a couple of the existing ones (as driving Excel is not what Scott's are designed for) which will include all the neccessary calculations.
bib dimensions for 208es
Hi,
using provided informations on zillaspeak and Sm given by GM :
Sm : 106,54 in^2
L : (Fs = 42 Hz), L = 161,43 in
folded height (L/2) = 80,71 in
Z : 161,43 * 0,217 = 35,03 in
if width = 9 in, then deep = 11,84 in (maybe useful for a deep
driver = 4,21 in)
a,b, c = deep/2 : 5,92 in
this will be very tall !
regards
Dondiba
Hi,
using provided informations on zillaspeak and Sm given by GM :
Sm : 106,54 in^2
L : (Fs = 42 Hz), L = 161,43 in
folded height (L/2) = 80,71 in
Z : 161,43 * 0,217 = 35,03 in
if width = 9 in, then deep = 11,84 in (maybe useful for a deep
driver = 4,21 in)
a,b, c = deep/2 : 5,92 in
this will be very tall !
regards
Dondiba
I have cardboard cutouts of the 208.BIB outline stuck to the wall right now, and they are not that bad at all, I'm quite surprised and pleased to report.
I have sort of settled on 9" interior width as having a good aspect ratio to height. The driver overall is 9" so will take up most of the baffle area, including 1.5" for side panel widths. I think the concentric baffle thang here is a good idea for aesthetic purposes as it breaks up the vertical line, and lessens perceived height, or size, and draws attention to itself, to the midline height. The perceived height is far greater without that round in the middle.
I also found really nice quality S2S 3/4 13pp Birch at Home Depot Audio today, in 4 X 8 blanks. On sale, no less. $34. ea. I found two I like, and they are coming tomorrow. Next I want 1-1.5" burled clinkers, hopefully Cherry, or Apple, for the round baffles. This is going to take time. Long after the carcasses are burned on the beach will the 208's be permanently mounted to the baffles. I envision shellac'd Birch, with oiled burl concentric baffles on these.
I have sort of settled on 9" interior width as having a good aspect ratio to height. The driver overall is 9" so will take up most of the baffle area, including 1.5" for side panel widths. I think the concentric baffle thang here is a good idea for aesthetic purposes as it breaks up the vertical line, and lessens perceived height, or size, and draws attention to itself, to the midline height. The perceived height is far greater without that round in the middle.
I also found really nice quality S2S 3/4 13pp Birch at Home Depot Audio today, in 4 X 8 blanks. On sale, no less. $34. ea. I found two I like, and they are coming tomorrow. Next I want 1-1.5" burled clinkers, hopefully Cherry, or Apple, for the round baffles. This is going to take time. Long after the carcasses are burned on the beach will the 208's be permanently mounted to the baffles. I envision shellac'd Birch, with oiled burl concentric baffles on these.
http://youtube.com/watch?v=HSE582c0hXg
Scott, it makes me laugh how you like Gwen so much. Not sure if you get the David Letterman Show where you live. If not, watch this video. After her song Letterman interviews her and its pretty funny to see how hes so clearly attracted to her.
BIBs have a way of blending into the room without being visually overpowering. My five and a half foot BIBs seem to fit right into a pretty small room. Small footprint... BIG sound.
Godzilla
Scott, it makes me laugh how you like Gwen so much. Not sure if you get the David Letterman Show where you live. If not, watch this video. After her song Letterman interviews her and its pretty funny to see how hes so clearly attracted to her.
BIBs have a way of blending into the room without being visually overpowering. My five and a half foot BIBs seem to fit right into a pretty small room. Small footprint... BIG sound.
Godzilla
Hmm, I believe it's an exponential one
I was reffering to a smooth curve, I have found that influences on thermal dissapation affect the curve and can sometimes affect the curve by influencing energys that cause a deviation in the curve.
Example! if you place a lower/hotter temperature mass near another mass there is an exchange in energy. They try to become an equil in temperature, as they attempt to normalize to a given state one mass rises in temperature the second( the emmiter) loses temp, its a dance between emmiter and reciever. The gradient of energy exchange is dependant on the mass difference and the distance as well as the initial difference of temperatures between the two masses.
Thats why its never a smooth curve between the two masses.
ron
I was reffering to a smooth curve, I have found that influences on thermal dissapation affect the curve and can sometimes affect the curve by influencing energys that cause a deviation in the curve.
Example! if you place a lower/hotter temperature mass near another mass there is an exchange in energy. They try to become an equil in temperature, as they attempt to normalize to a given state one mass rises in temperature the second( the emmiter) loses temp, its a dance between emmiter and reciever. The gradient of energy exchange is dependant on the mass difference and the distance as well as the initial difference of temperatures between the two masses.
Thats why its never a smooth curve between the two masses.
ron
Hi Folks,
Been a while since I've posted but I've been lurking..... I got a question for you.
What about the fostex f200A, it is about the same price as a fe208 plus tweeter. Has got great bass and good highs, not as sensitive though and is probably designed for a bass reflex. But what about in a BIB?
Cheers Stroop
Been a while since I've posted but I've been lurking..... I got a question for you.
What about the fostex f200A, it is about the same price as a fe208 plus tweeter. Has got great bass and good highs, not as sensitive though and is probably designed for a bass reflex. But what about in a BIB?
Cheers Stroop
Godzilla said:
Ah, Gwen's great. Very obviously a good business brain there, she doesn't take herself too seriously, and musically she's cleverer / more creative than she's often given credit for. Not really to my taste, but it's very slick. That she's rather easy on the eye is a plus point too.
I liked her as Jean Harlow best. However...Yeah, plus point (for a lot of drivers) is that this load doesn't take up much floor-space & the scale of the sound makes box speakers just quietly pack their bags & leave the room. Not a bad combination methinks.
stroop said:
Yep, it'd work. Just follow the T/S based alignment GM came up with & you can't go wrong. I suspect it might be a trifle large though...
dmason said:
Hi,
i did not plan to use this concentric baffle thang as it means more complicated woodwork but i think i will be obliged to do so because :
the available "deep" at the Z level it'll be only 2,5", for needed 4" (driver's deep)
should the wood ring be about 2" ahead the front baffle, so a 2" thick wood panel must be used for opening 2 concentric holes : rather tricky (for me)
BTW,would the ripple come also from the fact that the rear panel
is so close to the driver in BIB?
and would'n this thang "suffocate" the rear wave from the driver, as the total thickness behind the driver will be 2 3/4 "?
regards
dondiba
dondiba said:
Why not just use a rectangular blanking plate if you find a circle difficult to manage?
dondiba said:
Not really, the ripple in the response is caused by the acoustic-impedance mismatch at the mouth. The major issue with the proximity of the sloping internal baffle is the potential for reflections back through the cone. That's why you must make sure there is some damping material behind the driver. There's little 'suffocation' going on: remember, as an end-loaded horn, the wave is simply expanding. There's some blockage by the magnet & frame etc, just as in other cabinets, but it's not usually an issue if you're careful & space the driver out etc.
Hi,
here after a dirty drawing of the enclosure
sketched according to your advices (special thanks to Scottmoose)
the sketch do not look pretty (done with "paint" ) but it seems to fit the driver
i don't kow if it is still a BIB, but sound matters first
and when adding a tweeter, it could help
regards
dondiba
here after a dirty drawing of the enclosure
sketched according to your advices (special thanks to Scottmoose)
the sketch do not look pretty (done with "paint" ) but it seems to fit the driver
i don't kow if it is still a BIB, but sound matters first
and when adding a tweeter, it could help
regards
dondiba
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