Greets!
Sure! Dual drivers will be up to 6 dB louder and require 2x the pipe Vb, while compound drivers will dramatically reduce the required pipe Vb, which is only a 'good thing' with drivers that require huge cabs. Also, due to depth limitations they will have to be clamhell mounted, relegating them to sub duty.
Yes, though its placement will make it impractical AFAIK unless mounted internally like Danley Soundlab's Tower Of Power sub.
GM
Sure! Dual drivers will be up to 6 dB louder and require 2x the pipe Vb, while compound drivers will dramatically reduce the required pipe Vb, which is only a 'good thing' with drivers that require huge cabs. Also, due to depth limitations they will have to be clamhell mounted, relegating them to sub duty.
Yes, though its placement will make it impractical AFAIK unless mounted internally like Danley Soundlab's Tower Of Power sub.
GM
Talking of dual drivers I have a set of drivers/crossovers for a pair of Ariels (MTM) sitting around and was thinking of puting them in a BIB. I had assumed from what I had read that means doubling the mouth area to effetively double the volume to allow for the Vas being doubled. Length would stay the same for that driver??
Regards driver position, distance from top of cab - would you use the mid point between the drivers?
Cheers
Regards driver position, distance from top of cab - would you use the mid point between the drivers?
Cheers
Calling Jim......... How big did your box actually end up?
I've been working out the dimensions to make best use of the sheets, and after calculating
the height am a bit intimidated by the size of these things... exterior dims: 12.8"W x
20.25"D x 82.7"H javascript:smilie('
') [allowing for a base in proportion].
The height of my ceilings is only 94.5". As the walls and ceiling form the mouth of the horn,
is there enough space for this to work properly?
Way back somewhere in this thread I thought it was decided that cab height was half line
length [or at least pretty close]. But thinking back it may have been more a rule of thumb
for smaller drivers.
I've managed to keep the internal ratio to 1.414, and will increase the front and rear baffle
thickness to 25mm [1"]. Are any braces needed in there, or does the internal baffle suffice?
This is a big box! Just need to know if it's too close to the ceiling.
Thanks again, John.
I've been working out the dimensions to make best use of the sheets, and after calculating
the height am a bit intimidated by the size of these things... exterior dims: 12.8"W x
20.25"D x 82.7"H javascript:smilie('
') [allowing for a base in proportion].The height of my ceilings is only 94.5". As the walls and ceiling form the mouth of the horn,
is there enough space for this to work properly?
Way back somewhere in this thread I thought it was decided that cab height was half line
length [or at least pretty close]. But thinking back it may have been more a rule of thumb
for smaller drivers.
I've managed to keep the internal ratio to 1.414, and will increase the front and rear baffle
thickness to 25mm [1"]. Are any braces needed in there, or does the internal baffle suffice?
This is a big box! Just need to know if it's too close to the ceiling.
Thanks again, John.
copperhead said:Calling Jim......... How big did your box actually end up?
I've been working out the dimensions to make best use of the sheets, and after calculating
the height am a bit intimidated by the size of these things... exterior dims: 12.8"W x
20.25"D x 82.7"H javascript:smilie('
The height of my ceilings is only 94.5". As the walls and ceiling form the mouth of the horn,
is there enough space for this to work properly?
Way back somewhere in this thread I thought it was decided that cab height was half line
length [or at least pretty close]. But thinking back it may have been more a rule of thumb
for smaller drivers.
I've managed to keep the internal ratio to 1.414, and will increase the front and rear baffle
thickness to 25mm [1"]. Are any braces needed in there, or does the internal baffle suffice?
This is a big box! Just need to know if it's too close to the ceiling.
Thanks again, John.
Hi John, I'n not an expert, But where did you get 82,2" H for Hemp?
Considering the Dims on Zilla site, if you use
L= 150.5
Sm = 200"^
So = 30.1
my results considering GM and Scottmoose suggestion are:
D = 17.25" (a bit more deep) int.
W= 11.55" int.
H= 77.1" int. (considering semicircle lenght)
H external = 78.1
So = 30.74
You can also try GM dims
L= 140
Sm= 303"^
So =30
and I got
D= 21" int
W=14.45" int
H = 72.26"
H external 73.26"
So= 30
Maybe GM could explain well the maximum distance from the ceiling and its interaction. But I think you can play with the position from corners and rear walls to balance the response. Anyway, having the mouth closer to the ceiling it's more or less like an inverted BIB using the floor....
Ciao.Fab
Well, I did say they'd be a little large... The line length is not exactly length /2, but that gets you close enough, though there's an excellent spreadsheet available on the thread & elsewhere that makes a good partner to Greg's that helps you calc the exact cabinet height for a given line length.
Chris -funny you should mention an Ariel BIB. I did a cabinet for these a while back, but I can't find it anymore, so I re-ran the sim:
Line length 112in
Zdriver 24.5in
Sm=64.0625in^2
The line length is not exactly length /2, but that gets you close enough, though there's an excellent spreadsheet available on the thread & elsewhere that makes a good partner to Greg's that helps you calc the exact cabinet height for a given line length.Chris -funny you should mention an Ariel BIB. I did a cabinet for these a while back, but I can't find it anymore, so I re-ran the sim:
Line length 112in
Zdriver 24.5in
Sm=64.0625in^2
Attachments
Hi Fab,
The internal height of the cab I calculated as 80" [if line length is a path bisecting the front and
internal baffles, a semi-circle around the bottom of the internal baffle, plus the thickness of that
baffle, then upward, bisecting internal and rear baffles.]
I included a 3/4'' base that would be included inside of the cab, [if that makes sense, that would
be temporarily screwed in place as per Scotts' recommendation], and then that whole thing
sitting on a 2" granite or marble base.
I don't think I screwed up the measurements.
John.
The internal height of the cab I calculated as 80" [if line length is a path bisecting the front and
internal baffles, a semi-circle around the bottom of the internal baffle, plus the thickness of that
baffle, then upward, bisecting internal and rear baffles.]
I included a 3/4'' base that would be included inside of the cab, [if that makes sense, that would
be temporarily screwed in place as per Scotts' recommendation], and then that whole thing
sitting on a 2" granite or marble base.
I don't think I screwed up the measurements.
John.
copperhead said:
Hi John,
I don't know.... I'm putting on paper my BIB, but before that, I've tried to draw the dims straight on the plywood 1:1 scale to measure and check the dimensions. Start with L/2 and placed the internal baffle with different thickness wood, I measured very little difference between the oblique line and the straight one (not even 5mm!). Then I considered the semicircle path and made the adjustment...
So I consider 80" internal much longer than it should be....
It make sense that your speakers rise up using the marble bases, but be aware of marble and similar, in my experience when I tried granite and marble under my turntable, the sound got worse! And it was possible to hear different sound from different marbles. So I turn ed to thick plywood instead, as long as a friend of mine made some astonishing platforms.
Cheers.
Ciao. Fab.
Hi Fab,
I got an internal depth of 17.58", internal baffle 8.79" from front back and base.
The internal baffle came out to 71.44" long. Your right the oblique angle is only a fraction
longer. 71.3" + 8.79" = 80.09". I was going for a heavier base on Scotts' suggestion.
I don't have any experience of marble or granite but it had seemed like a good idea.
Plywood is easier and cheaper.
John.
I got an internal depth of 17.58", internal baffle 8.79" from front back and base.
The internal baffle came out to 71.44" long. Your right the oblique angle is only a fraction
longer. 71.3" + 8.79" = 80.09". I was going for a heavier base on Scotts' suggestion.
I don't have any experience of marble or granite but it had seemed like a good idea.
Plywood is easier and cheaper.
John.
copperhead said:
I see, I do a different calc.
L= 150.5 so H = 75.25
Circle radius = W/4= 17.58/4= 4.4(circa)
Semi circle lenght = 13.8"
Difference from L/2 lenght = L/2-[(W/2)+(SemiC/2)] = 1.89"
Effective lenght = L/2 + 1.89" = 77.14 internal.
Assuming the sloping line more or less equal, that measure is the same for both.
So internal corrected H= 77.14"
I think it works like this if I've not misunderstood GM and Scott suggestions.
Considering marble and granite, if you have some spare at home you can try. I don't know if they bahave with speakers like turntables instead, certainly they look sritking good, I know... I'm not going to try when I'll build my BIB because I will use the platforms I own which work preatty well.
Ciao.Fab.
Re: Re: From Zaph
I have a number of B3S's around for various uses. Based on the MTM line of thought and the above starting point for the associated BIB:
2 drivers, 50sqin throat, same line length, and the Zdriver would be the center of the two drivers?
Hoping this will make a nice small room jazz/folk speaker for lower level listening.
Regards.
Scottmoose said:
I have a number of B3S's around for various uses. Based on the MTM line of thought and the above starting point for the associated BIB:
2 drivers, 50sqin throat, same line length, and the Zdriver would be the center of the two drivers?
Hoping this will make a nice small room jazz/folk speaker for lower level listening.
Regards.
Hi John,
yes, Hemp BIB are really big and should sound great! (according to GM thought in this post http://www.diyaudio.com/forums/showthread.php?postid=990418#post990418)
You're luky to have place for a real BIB!
As far as I finished coating the wood floor in the basement I'll start to build my BIB, smaller, but hope it'll sound great either!
Ciao.Fab.
yes, Hemp BIB are really big and should sound great! (according to GM thought in this post http://www.diyaudio.com/forums/showthread.php?postid=990418#post990418)
You're luky to have place for a real BIB!
As far as I finished coating the wood floor in the basement I'll start to build my BIB, smaller, but hope it'll sound great either!
Ciao.Fab.
ChrisMmm said:
Greets!
Correct.
Right.
Theoretically, yes, but shifting the driver 'module' a bit to make them fit shouldn't be a problem, and of course the XOs will be off unless you replicate the Ariel's baffle width/shape and place the BIBs well away from any walls/corners, negating some of its benefits unless floor loaded.
GM
copperhead said:
Greets!
When you use the SQRT(2) width/depth ratio, the length is divided by 2.
My (lack of) math skills precludes me from calcing the optimal mouth/ceiling distance (I have to draw it out to scale
), but the ideal AFAIK for corner placement is that it ~continues the pipe's expansion rate, i.e. if its CSA doubles every 20", then ideally the mouth/ceiling gap would be 20" or multiples of 20". Any nearer and you theoretically get some 'floor' mass loading, ergo with a greater gap there's reduced loading, like when rapidly flaring a vent. For other locations, the vent rule-of-thumb (ROT) of at least 3x the mouth's (effective) radius is sufficient. If it sounds too 'boomy' due to being too close, you can always scallop out the mouth like T.C. did on his recent floor loading model to relieve the pressure.
GM
McFaBs said:
Greets!
Maybe I drew it out and/or did the math wrong, but I approached it from an expansion rate POV like any other horn folding. A 3D CAD program construction will 'tell the tale', but I don't have either the software or skills to confirm it.
WRT using a rigid/massive base, this is the last thing you want supporting it since it will cause strong reflections back to the driver/throat, requiring what I consider excessive stuffing/damping in the pipe. Really, the bottom should in theory be made of a relatively lossy material since the floor will be plenty rigid enough even if it's a 'floater' (suspended), and if wall loaded, then the back should be also. From this it follows that if corner loaded, then the bottom and the two corner sides should be lossy to damp down unwanted harmonic energy.
GM
I wasn't suggesting the base itself should be granite guys -sorry for causing any confusion. I'm completely with Greg on that one. That's why we put the 1in or better layer of damping on the base -to kill reflections back up the line.
The granite etc. was a suggestion for a plinth to stand the cabinet on if your floor happens to be a pain. In my case, floors are suspended (ha! it's chipboard over beams!) and it vibrates something chronic unless drastic measures are taken. A massy stone plinth is the best way I know of, unless you fancy building a couple of sandboxes. I tried out a few different coupling methods from cabinet to plinth a while back, and finally settled upon 3 semi-spherical cork feet I bought from the local independent DIY store: very effective. Not sure exactly what they're originally intended for, but this is a very good use. Blu-Tak or similar applied in sheets to the cabinet base, then stuck down is also pretty good.
The granite etc. was a suggestion for a plinth to stand the cabinet on if your floor happens to be a pain. In my case, floors are suspended (ha! it's chipboard over beams!) and it vibrates something chronic unless drastic measures are taken. A massy stone plinth is the best way I know of, unless you fancy building a couple of sandboxes. I tried out a few different coupling methods from cabinet to plinth a while back, and finally settled upon 3 semi-spherical cork feet I bought from the local independent DIY store: very effective. Not sure exactly what they're originally intended for, but this is a very good use.
Blu-Tak or similar applied in sheets to the cabinet base, then stuck down is also pretty good.
Greets!
For either 'trampoline' (really 'springy' suspension) or rigid (concrete slab or similar) floors, I recommend viscuous damped springs for the former and small mechanical business/manufacturing machine iso-feet or similar for the latter.
FWIW, since iso-feet can cost more than the speakers, an effective 'el cheapo' solution is a regular bike tire innertube for lighter speakers and trailer tire size for bigger/heavier ones formed into an appropriate size open top base, then use a hand pump to inflate it as required.
Unfortunately, the only really cheap option for 'trampoline' floors I know of is to suspend the speakers from the ceiling with rope. Making macramé speaker, TT, etc., hangers was popular around here back in the 'bad old days' of minimal/~non-existant building codes.
GM
For either 'trampoline' (really 'springy' suspension) or rigid (concrete slab or similar) floors, I recommend viscuous damped springs for the former and small mechanical business/manufacturing machine iso-feet or similar for the latter.
FWIW, since iso-feet can cost more than the speakers, an effective 'el cheapo' solution is a regular bike tire innertube for lighter speakers and trailer tire size for bigger/heavier ones formed into an appropriate size open top base, then use a hand pump to inflate it as required.
Unfortunately, the only really cheap option for 'trampoline' floors I know of is to suspend the speakers from the ceiling with rope. Making macramé speaker, TT, etc., hangers was popular around here back in the 'bad old days' of minimal/~non-existant building codes.
GM