zek said:
zek said:
Greets!
Yes, it's technically wrong. For that matter, every BIB that's not exactly proportional to the original is technically wrong, but then we can't accurately sim the original AFAIK (at least with MJK's WSs), so which to choose to build? I chose to base all sims as close as practical to a true linear taper and post dims that I believe comes closest to theoretically matching it, but not having built/measured one, I don't know for sure if I'm right. What I do know from experience is that the pipe is big enough and the room will change the response enough that it's pretty much academic IMO and the limited feedback we've gotten so far supports it.
Same for the folding dims. Originally I was just going to ignore the baffle thickness since depending on how the cab's assembled would either affect the folded length calculation and/or the depth calculation, so in the end I just added it to 'Sm' figuring it was acoustically insignificant and would keep folks from asking me why I didn't factor it in, but I forgot to 'hide' the formulas to cover up my math 'error'.
That said, I'm a little confused with your math in that 'd' is considered to be ~zero in a BIB, so has no bearing on depth, and 'Sm' is initially an area dimension since we are deriving a width and depth from it using a ~1:1.4142 ratio.
GM
Hi GM,
`d` in my math is the same as `D` in yours math and can not be zero because throat area is Sm=D*W or as I wrote Sm=d*W because depth of enclosure are not the same as depth of throat.
Depth of enclosure D=d+t, where `t` is inner baffle thickness and `d` is throat width (see my sketch here)
W= width of throat is the same as width of enclosure
Of course we are talking about inside dimensions of enclosure.
`d` in my math is the same as `D` in yours math and can not be zero because throat area is Sm=D*W or as I wrote Sm=d*W because depth of enclosure are not the same as depth of throat.
Depth of enclosure D=d+t, where `t` is inner baffle thickness and `d` is throat width (see my sketch here)
W= width of throat is the same as width of enclosure
Of course we are talking about inside dimensions of enclosure.
Hi Zek, you might have misunderstood a bit; your math is actually in agreement with Greg's. I think you've mistaken 'throat', or So, which is the beginning of the horn, for the 'terminus' of the horn, which is Sm.
The BIB is an So=0 horn: the throat, or start of the horn, comes to a point, and has no surface area. It therefore has no effect on overall internal depth. The internal enclosure depth D=Sm/W+IB where Sm is the area of the terminus of the horn, W is the internal enclosure width and IB is the thickness of the internal baffle.
Cheers
Scott
The BIB is an So=0 horn: the throat, or start of the horn, comes to a point, and has no surface area. It therefore has no effect on overall internal depth. The internal enclosure depth D=Sm/W+IB where Sm is the area of the terminus of the horn, W is the internal enclosure width and IB is the thickness of the internal baffle.
Cheers
Scott
Lowther DX3 and Thanks
Scott,
Thankyou so much for the numbers for the DX3...
But I am torn as to which set of numbers to use...javascript:smilie('
')
Set one:
LL: 128 inches
Zdriver: 25.6 inches
Sm: 118.25 sq. in.
OR
Set two:
LL: 120 inches
Zdriver: 25.2 inches
Sm: 220 sq.in.
4 0hm series resistor
And lastly:
LL: 138 inches
Zdriver: 30 inches
Sm: 220 sq.in.
2 ohm series Resistor
There is a fairly large difference between all three...
Which set shold I use for the DX3?
Thank you for your Help...javascript:smilie('')
Phil
Santa Fe
Scott,
Thankyou so much for the numbers for the DX3...
But I am torn as to which set of numbers to use...javascript:smilie('
')Set one:
LL: 128 inches
Zdriver: 25.6 inches
Sm: 118.25 sq. in.
OR
Set two:
LL: 120 inches
Zdriver: 25.2 inches
Sm: 220 sq.in.
4 0hm series resistor
And lastly:
LL: 138 inches
Zdriver: 30 inches
Sm: 220 sq.in.
2 ohm series Resistor
There is a fairly large difference between all three...
Which set shold I use for the DX3?
Thank you for your Help...javascript:smilie('
')Phil
Santa Fe
Hi Phil
Well, the third of the sets you mention are GM's suggested dims for the DX2, not the DX3, so that narrows it down to the first or second. I came up with the first, GM the second. Either should work very well, so it's up to you really. The plots suggest the first, despite having a much smaller footprint, gives away little to the larger second one. I re-checked both just to be sure using the measured T/S parameters for the DX3 off Martin King's site. That's a massive difference in Vb, but the responses are quite similar. Just goes to illustrate the point GM made about 50 pages ago: within reason, it's very difficult to have too large a speaker enclosure -if it's a bit under-damped, then add damping, either electrical, or to the cabinet. Small boxes are not nearly so forgiving of changes. In fact, they're extremely unforgiving in comparison. I increasingly wonder if we make life harder and more complicated than it has to be nowadays.
There is a last point to consider BTW -a very important one. If you went for the first set of dimensions, you wouldn't be able to say you have your Lowther's in an enclosure designed for them by Greg Monfort. And that, IMHO, counts for a lot.
Regards
Scott
Well, the third of the sets you mention are GM's suggested dims for the DX2, not the DX3, so that narrows it down to the first or second. I came up with the first, GM the second. Either should work very well, so it's up to you really. The plots suggest the first, despite having a much smaller footprint, gives away little to the larger second one. I re-checked both just to be sure using the measured T/S parameters for the DX3 off Martin King's site. That's a massive difference in Vb, but the responses are quite similar. Just goes to illustrate the point GM made about 50 pages ago: within reason, it's very difficult to have too large a speaker enclosure -if it's a bit under-damped, then add damping, either electrical, or to the cabinet. Small boxes are not nearly so forgiving of changes. In fact, they're extremely unforgiving in comparison. I increasingly wonder if we make life harder and more complicated than it has to be nowadays.
There is a last point to consider BTW -a very important one. If you went for the first set of dimensions, you wouldn't be able to say you have your Lowther's in an enclosure designed for them by Greg Monfort. And that, IMHO, counts for a lot.
Regards
Scott
Lowther DX3 and Thanks
Well Scott,
I guess I'll simply built both cabs and let my ears make the call.
Either way I'm am quite sure they both will be wonderful and happy.
I'm think too that I might buy a DX4 and give the DX3 to my friend Robert. (Well not exactly "GIVE")...Dollars will be exchanged within the "giving".
So, I thank you and GM for the numbers...I shall honor them well.
Photos will be forthcoming.
Peace
Well Scott,
I guess I'll simply built both cabs and let my ears make the call.
Either way I'm am quite sure they both will be wonderful and happy.
I'm think too that I might buy a DX4 and give the DX3 to my friend Robert. (Well not exactly "GIVE")...Dollars will be exchanged within the "giving".
So, I thank you and GM for the numbers...I shall honor them well.
Photos will be forthcoming.
Peace
In my humble opinion, there are two considerations..
1) A difference from "optimal" load will make a difference.
2) The FE166-esr is in my opinion the most musical wideband driver I have heard, and therefore deserves audition in the optimal load. If you have to wait to buy another blank, I strongly feel it is worth waiting for.
My ears salivate for the hearing of FE166esr in a BIB. I think this driver in a BIB with a fine SET pairing is where I wanna be. I regret selling my Fostex Rx 166 horns. Blumenco has them in a BIB, I believe, perhaps he can wax poetic on the matter.
1) A difference from "optimal" load will make a difference.
2) The FE166-esr is in my opinion the most musical wideband driver I have heard, and therefore deserves audition in the optimal load. If you have to wait to buy another blank, I strongly feel it is worth waiting for.
My ears salivate for the hearing of FE166esr in a BIB. I think this driver in a BIB with a fine SET pairing is where I wanna be. I regret selling my Fostex Rx 166 horns. Blumenco has them in a BIB, I believe, perhaps he can wax poetic on the matter.
Hi dmason,
the differance in volume between the squeezed version and original will be 1.3 gallons (5liters). From what I've read in this thread the Bib's are quite forgiving. I wonder how far you can stretch dimensions before the "optimal load " goes sour. I'm reluctant to fork out 100$ for one more board, but neither want crappy sound.
From what I've read Bluemenco is very satisfied with his 166-ESR BiB's, words like magic and eerie comes to mind.
the differance in volume between the squeezed version and original will be 1.3 gallons (5liters). From what I've read in this thread the Bib's are quite forgiving. I wonder how far you can stretch dimensions before the "optimal load " goes sour. I'm reluctant to fork out 100$ for one more board, but neither want crappy sound.
From what I've read Bluemenco is very satisfied with his 166-ESR BiB's, words like magic and eerie comes to mind.
Tachyon said:
Why does that not surprise me? These big, simple corner horns really do work. Give them a decent driver and they sing. I'd love to hear a pair with ES-Rs.
Where did Greg's post go? I dunno, must've been quick, 'cause I didn't see it at all. Strange. Anyway, Vb is the internal volume of the enclosure. While I'd agree with Dan that the ES-R deserves the best, a small difference shouldn't be too drastic, as the response is altered by the room anyway. Attached is a rough 1/2 space plot for the ES-R in the smaller cabinet.
Regards
Scott
Attachments
Thanks Scott!
You did the plot without me asking, great! Comparing the two there seems to be minimal if any difference, so I'll happily go along with the smaller design
I'm really looking forward to hear the BiB's when they are ready, work will start this weekend. More info and pics later. The drivers have been playing in another temporary construction for 4 months now and they are getting sweeter every day!
Strange with post's dissapearing, anyway, I always copy and paste my text so GM's post was saved on my "scrapboard".
"Greets!
They are only 'forgiving if there's enough boundary gain, but the sim appears to assume no series R, so you could be left wanting up to 2x more Vb if you have to use it to flatten its in-room response, especially if you start out 'short'.
If you don't need any though, a 5 L (~5%) reduction shouldn't make much of a difference.
GM"
You did the plot without me asking, great! Comparing the two there seems to be minimal if any difference, so I'll happily go along with the smaller design
I'm really looking forward to hear the BiB's when they are ready, work will start this weekend. More info and pics later. The drivers have been playing in another temporary construction for 4 months now and they are getting sweeter every day!
Strange with post's dissapearing, anyway, I always copy and paste my text so GM's post was saved on my "scrapboard".
"Greets!
They are only 'forgiving if there's enough boundary gain, but the sim appears to assume no series R, so you could be left wanting up to 2x more Vb if you have to use it to flatten its in-room response, especially if you start out 'short'.
If you don't need any though, a 5 L (~5%) reduction shouldn't make much of a difference.
GM"
Thanks for the plott, Scott. Every picture tell a story. That one says to me that the reduced CSA load will work fine, but I also perceive that there will be lost the throati-ness that comes with that extra reach of 5 cycles or so before the illustrated roll off of the "optimal" load, optimal being in quotation marks.
I say life is short, blow a hun on another blank, and get the most out of those magical drivers! Either way the expected reaction will go something like:
I bet the GC/tube pre combo would be astounding!!
"These things do work." In my opinion, and I believe that of Scott, ..that one of the amazing, almost alchemical bonuses of the whole BIB thing is the lower register has a presentation that is almost indistinguishable from dipole, -- the money zone of open baffled magic, and THE hardest part to attain. Build BIB's and love OB bass, truth being stranger than fiction. This makes the BIB about the best speaker compromise of all IMHO.
And Happy 4th of July to all our American friends, Happy Canada Day to our Northern friends, and Happy Weekend to our BIB colleagues from Ankara to Zingali.
I say life is short, blow a hun on another blank, and get the most out of those magical drivers! Either way the expected reaction will go something like:
I bet the GC/tube pre combo would be astounding!!"These things do work." In my opinion, and I believe that of Scott, ..that one of the amazing, almost alchemical bonuses of the whole BIB thing is the lower register has a presentation that is almost indistinguishable from dipole, -- the money zone of open baffled magic, and THE hardest part to attain. Build BIB's and love OB bass, truth being stranger than fiction. This makes the BIB about the best speaker compromise of all IMHO.
And Happy 4th of July to all our American friends, Happy Canada Day to our Northern friends, and Happy Weekend to our BIB colleagues from Ankara to Zingali.
Tachyon said:
Greets!
I deleted it because it was a first draft that when I clicked on 'preview' it timed out and I couldn't access the forum for awhile, and when I finally could, it gave me the 'thanks for posting' notice. For whatever reason, for several days now I've had only very limited access to the forum, with no access most of yesterday until mid-morning here.
Anyway, my first drafts are usually just 'knee jerk' reactions to Qs without giving any thought to any potential ramifications or technical correctness, so rarely worth posting.
FWIW, here's my ~ready for 'prime time' response:
Greets!
They are only 'forgiving' if there's enough boundary gain and the sim appears to assume no series R, so you could be left wanting up to 2x more Vb if you have to use it to flatten its in-room response, making a 5 L (~5%) reduction seem insignificant. That said, $100 is a bit much for ~5 L, so I guess it boils down to how much tunability you're willing to afford now and whether or not you're willing to make new, larger cabs later if need be.
GM