doggy, push it into a corner, youll get even lower bass!(and more of it!)
and another question i couldnt find an answer to. Does the BIB help control excursion any more than say a dipole? i dont know what this is called...if i were to make a name for it i would call ti resistive damping or something... but you understand what i mean, eg a sealed box reduces excursion at low frequencies compared to just the free air speaker. Is this also true of the BIB? if it is, i can imagine getting come pretty serious SPL out of them.
and another question i couldnt find an answer to. Does the BIB help control excursion any more than say a dipole? i dont know what this is called...if i were to make a name for it i would call ti resistive damping or something... but you understand what i mean, eg a sealed box reduces excursion at low frequencies compared to just the free air speaker. Is this also true of the BIB? if it is, i can imagine getting come pretty serious SPL out of them.
Scott, can you please help me with the BIB dimensions for a 6.5" driver having the following T/S parameters:
Re 3.7 Ohms
Sensitivity 91.5 db
Power 80 watts
Fs 37.5 Hz
Qms 1.52
Qes 0.28
Qts 0.24
Vas 25.6 Ltrs
Mms 17.4 g
Cms 1036.1 uM/N
Sd 0.0132 M 2
BL 7.31 TM
X-max 5 mm
Le@ 1kHz 0.53mH
Frame dia 167 mm
Cutout dia 147 mm
Depth 75 mm
Krm 1.370 mOhms
Kxm 17.805 mH
Erm 0.818
Exm 0.599
Box Rec 6 ltrs vented 1.5’ dia x 5.5’ L
Many thanks,
Re 3.7 Ohms
Sensitivity 91.5 db
Power 80 watts
Fs 37.5 Hz
Qms 1.52
Qes 0.28
Qts 0.24
Vas 25.6 Ltrs
Mms 17.4 g
Cms 1036.1 uM/N
Sd 0.0132 M 2
BL 7.31 TM
X-max 5 mm
Le@ 1kHz 0.53mH
Frame dia 167 mm
Cutout dia 147 mm
Depth 75 mm
Krm 1.370 mOhms
Kxm 17.805 mH
Erm 0.818
Exm 0.599
Box Rec 6 ltrs vented 1.5’ dia x 5.5’ L
Many thanks,
Ok there are already a few questions being asked here but I think I'll push my luck and ask another one. This will most likely seem stupid but thats ok because when it comes to math I feel stupid
When you model the BIB and lets say (random) you get, 50''H x 6''W x 8''D internal dimentions, do you have to increase for the internal divider? So if I was to build out of 3/4'' would the depth now have to be 8.75''? Dave
When you model the BIB and lets say (random) you get, 50''H x 6''W x 8''D internal dimentions, do you have to increase for the internal divider? So if I was to build out of 3/4'' would the depth now have to be 8.75''? Dave
Looks like you're on the right lines to me.
See my post #909
http://www.diyaudio.com/forums/showthread.php?postid=945862#post945862
See my post #909
http://www.diyaudio.com/forums/showthread.php?postid=945862#post945862
Samuel Jayaraj said:
Coming up in the next half hour.
DaveCan said:Ok there are already a few questions being asked here but I think I'll push my luck and ask another one. This will most likely seem stupid but thats ok because when it comes to math I feel stupid
Best way of looking at it is like this. When you have the required area of the mouth, determine your prefered W x D dimensions, preferably using the formula Greg advises to maintain the optimum expansion of the horn. Then, if you are using 3/4in material, add 2 1/4in to the mouth depth you have just established, which will give you the total, external depth of the enclosure.
Well, although, according to Martin King (www.quarter-wave.com) and others, a horn could care less about the driver's diaphram area providing the other driver parameters do not change, by doubling the number of drivers, you double Vas. Therefore, you need to double the cabinet Vb, or the bass will rapidly roll off.
You also need to consider where you'd put them. 2 drivers mounted on the front baffle, even if very close together = a very bad idea. Massive lobing will be the instant result, with consequent dramatic decrease in HF, so you'll need electronic eq to bring it into line.
Hope that helps
Scott
You also need to consider where you'd put them. 2 drivers mounted on the front baffle, even if very close together = a very bad idea. Massive lobing will be the instant result, with consequent dramatic decrease in HF, so you'll need electronic eq to bring it into line.
Hope that helps
Scott
Sam, here's the BIB dims you wanted.
Line length 145in
Zdriver 33in
Sm=58.5in^2
Just to let you guys know, I'm currently working on some dedicated BIB bass extenders. Jeff (Godzilla) is away for a long weekend, so they won't be up on the site for a week or so, but they'll be worth waiting for. A few others should appear too; particularly those Greg's done recently, which haven't yet made their way onto the pages.
Regards
Scott
Line length 145in
Zdriver 33in
Sm=58.5in^2
Just to let you guys know, I'm currently working on some dedicated BIB bass extenders. Jeff (Godzilla) is away for a long weekend, so they won't be up on the site for a week or so, but they'll be worth waiting for. A few others should appear too; particularly those Greg's done recently, which haven't yet made their way onto the pages.
Regards
Scott
Attachments
I think Greg's done a couple of Lowthers about 30 pages back. It's about time I did one though, so here's one for your DX3s, using the parameters off the Single Driver site -the ones on Lowther's own site are worth about as much as the ink on a £1 note (removed from circulation 1985).
Line length 128in.
Zdriver 25.6in
Sm=118.25in^2
I want to know what these sound like, so get that saw fired up!
Best
Scott
Line length 128in.
Zdriver 25.6in
Sm=118.25in^2
I want to know what these sound like, so get that saw fired up!
Best
Scott
Attachments
Bing Yang said:
You could make a BiB bipole. I think the the attached approach would work.
The first is just two standard BiBs back to back with the common wall removed.
The second merges two unequal length BiBs. This could have the advantage of having the peaks in one BiB filling in the valleys of the other. It would take some simulations to find the right combinations of lengths to do this.
This is just an idea, I've not built it.
Attachments
Many thanks as always Greg, why it didn't occur to me to use those on Martin's site I don't know. I must be loosing it.
Here's a plot for Greg's DX2 cabinet:
Line length 138in
Zdriver 30in
Sm=220in
2 ohm series resistance
On a different note, for general interest, if anyone likes some of the now unavailable books on audio -particularly amps, but other stuff too, have a look here: http://www.pmillett.com/tecnical_books_online.htm
Here's a plot for Greg's DX2 cabinet:
Line length 138in
Zdriver 30in
Sm=220in
2 ohm series resistance
On a different note, for general interest, if anyone likes some of the now unavailable books on audio -particularly amps, but other stuff too, have a look here: http://www.pmillett.com/tecnical_books_online.htm
Attachments
Just one more question with regard to the BIB dimensions for the Fostex 168EZ Sigma.
Using the Excel sheet provided by GM, I get H=64", D=10.299" & W=7.210".
However, Ray Collins who has already constructed his BIB for the same driver used H=64", D=11.00" & W=6.75".
Which of the above is the most optimal dimensions? My guess is the one provided by GM's worksheet.
Using the Excel sheet provided by GM, I get H=64", D=10.299" & W=7.210".
However, Ray Collins who has already constructed his BIB for the same driver used H=64", D=11.00" & W=6.75".
Which of the above is the most optimal dimensions? My guess is the one provided by GM's worksheet.