I'm making a speaker with two Tang Band W4-1320SF 4" Bamboo Cone drivers (http://cgi.ebay.com/Tang-Band-W4-13...ihZ018QQcategoryZ3276QQtcZphotoQQcmdZViewItem) and was wondering what the minimum enclosure volume would be that still maintained reasonable sound quality? Pretty much I want to make the speaker as small as possible. Sorry if this is a little vague, but I've never built speakers before and have a very limited understanding of this stuff. Please ask me to elaborate if necessary.
They have the recommended cabinet right there on the eBay page. If you want it to sound half-way decent, it might be best to stick with what they provide as a first project.
Ok I guess I should have mentioned that this is for a portable boombox type thing (with an emphasis on the portable). I don't really want to have masses of empty space making it bigger than it needs to be...unless it's really necessary...
revans said:
Those are reasonable drivers to play with, but no matter what you do, you won't get much sound below about 80Hz. And, if you try to reduce the size of the box, you won't get that either.
I can't see the drawings on the eBay sight from work, but you are best to go with a 4 litre box for these if you're going to make a vented pair of boxes. The internal dimensions would be 4 inches wide (10cm) 6 1/6 inches deep (15.5cm) and 10 inches high (25.4cm). Port should be (if it's round) 1.5 inches diameter (3.8cm) and 4 inches long (10cm). If it's going to be a slot port (ie. the full width of the speaker - 10cm) then it should be .45 inches high (or 1.15cm).
If you try to make it smaller, then the driver is unable to work sufficiently well against the volume of air in the box to be able to make sound in the lower resgisters. And is unable to excite the resonater (the port) to be able to get that to work either.
To get something to work in a smaller volume, you'd need to look at something with a lower Qts or Vas. Or just live with the larger, better sounding, speakers.
What were you intending to drive them with? These could do with some good amplification. They might be better suited to a home (or PC) environment than as a 'boom box'.
I was going to use an Amp6-Basic to drive them. Apparently that's the weapon of choice in these areas...
revans said:
Should be a good match. The speakers on the 41hz website with the amp6basic board are about the same size I'm suggesting (mine would be a little thinner, and a bit deeper, and maybe a little less tall - not sure on the height).
So you reckon in the name of sound quality it wouldn't be wise for the size of each speaker's enclosure to be smaller than what you specified?
Oh I was just thinking, if I was to put both the Tang Bands together in one enclosure, would the volume of the enclosure then need to be double that of a single speaker enclosure? Or is there some reason that this wouldn't be the case?
E.g. The volume of a 10x15.5x25.4cm enclosure (Cloth Ears recommendation) is 3937 cubic cm, so with two drivers volume would be ~8000 cubic cm
E.g. The volume of a 10x15.5x25.4cm enclosure (Cloth Ears recommendation) is 3937 cubic cm, so with two drivers volume would be ~8000 cubic cm
Your thinking is exactly right - double the drivers, double the volume. Except that you would get some pretty interesting effects if you were trying to use them as a stereo.
You could build an 8 litre enclosure, but with a board right down the middle - you wouldn't get much stereo effect, but your drivers wouldn't interract with each other. If you used 12mm plywood, you could make a box that is 53.2cm long (including the walls at each end and one in the middle), 12.4cm high (including the walls again) and 19cm deep (yes, with the walls). If you mounted the drivers at each end of the front face, you'd have about a 40 distance between the centres - and you'd get stereo for about 2 metres in front of the box (maybe more).
But, if you did it this way, you wouldn't be able to separate them if you wanted to. I'd suggest building 2 boxes and looing at a good way of hooking them together when you wanted to move them around.
You could build an 8 litre enclosure, but with a board right down the middle - you wouldn't get much stereo effect, but your drivers wouldn't interract with each other. If you used 12mm plywood, you could make a box that is 53.2cm long (including the walls at each end and one in the middle), 12.4cm high (including the walls again) and 19cm deep (yes, with the walls). If you mounted the drivers at each end of the front face, you'd have about a 40 distance between the centres - and you'd get stereo for about 2 metres in front of the box (maybe more).
But, if you did it this way, you wouldn't be able to separate them if you wanted to. I'd suggest building 2 boxes and looing at a good way of hooking them together when you wanted to move them around.
Yeah, I think I'll go with trying to use two 10x15.5x25.4cm boxes. However, could I adjust this so that the volume is the same, though with changed dimensions?
I've managed to pack the electronics for my boombox into ~24x14x14cm box so I just need to arrange that with the speaker boxes in one package...
I've managed to pack the electronics for my boombox into ~24x14x14cm box so I just need to arrange that with the speaker boxes in one package...
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Hey, what if I was to mount the speakers in one enclosure in a isobaric fashion? I just read this:
EDIT: Ok furthermore, I just discovered and used this calculator here: http://www.carstereo.com/help/Articles.cfm?id=17 which took all that electro mechanical jargon and gave me a required internal volume of 0.088 cubic feet for two speakers mounted isobarically. This is far better for my design needs...can I rely on this...?
If I mounted the speakers magnet to magnet, how low a volume could I then achieve?
EDIT: Ok furthermore, I just discovered and used this calculator here: http://www.carstereo.com/help/Articles.cfm?id=17 which took all that electro mechanical jargon and gave me a required internal volume of 0.088 cubic feet for two speakers mounted isobarically. This is far better for my design needs...can I rely on this...?
Hi,
Isobaric is essentially creating one driver out of two,
you cannot use it for a left and right pair of speakers.
You need 0.08 cubic feet sealed per left and right driver.
Approximately double that for a vented version, which is best built
as 6th order - including an active high pass filter with Q ~ = 2 at
at a lower port frequency - say 60Hz. The active filter can be
built into the input and feedback loop of the power amplifier.
🙂/sreten.
Isobaric is essentially creating one driver out of two,
you cannot use it for a left and right pair of speakers.
You need 0.08 cubic feet sealed per left and right driver.
Approximately double that for a vented version, which is best built
as 6th order - including an active high pass filter with Q ~ = 2 at
at a lower port frequency - say 60Hz. The active filter can be
built into the input and feedback loop of the power amplifier.
🙂/sreten.
yes, you can use isobaric loading.
It will save ~2L per enclosure, but will waste the volume required to mount the second driver. Maybe a net saving of 1L per box.
To offset this slight advantage you need to buy and carry around 4drivers.
The battery will have to power 4 drivers and run out of charge twice as fast.
It will save ~2L per enclosure, but will waste the volume required to mount the second driver. Maybe a net saving of 1L per box.
To offset this slight advantage you need to buy and carry around 4drivers.
The battery will have to power 4 drivers and run out of charge twice as fast.
I would make spheres to put them in:
Many ways to make them, including:
http://www.susan-parker.co.uk/susan-speaker-sphere.htm
As mentioned: (2) 4" drivers are not able to push enough air ( VD ) to produce bass below 80Hz without excursion limiting.
They can sound very nice with a subwoofer for very compact sound, but again we are not talking high SPL.
Syd
Many ways to make them, including:
http://www.susan-parker.co.uk/susan-speaker-sphere.htm
As mentioned: (2) 4" drivers are not able to push enough air ( VD ) to produce bass below 80Hz without excursion limiting.
They can sound very nice with a subwoofer for very compact sound, but again we are not talking high SPL.
Syd
Ok so screw the isobaric loading 
I guess I'll be going back to the standard "one ported enclosure per speaker" method 😀
Tang Band's suggested enclosure is 16.1x20.1x26.1cm while Cloth Ears suggested a 10x15.5x25.4cm enclosure per speaker. Would I be able to reduce these dimensions at all, even by a centimetre or two? i.e. What would be the size limit you guys would reasonably reduce the enclosure to?
I guess I'll be going back to the standard "one ported enclosure per speaker" method 😀Tang Band's suggested enclosure is 16.1x20.1x26.1cm while Cloth Ears suggested a 10x15.5x25.4cm enclosure per speaker. Would I be able to reduce these dimensions at all, even by a centimetre or two? i.e. What would be the size limit you guys would reasonably reduce the enclosure to?
Hi,
Isobaric is silly because you could simply choose a 4 ohm driver
with the equivalent parameters of the compound isobaric driver.
Taking sealed as the "standard" volume, an isobaric arrangement
would be ~ half the volume sealed or ~ the same volume vented.
One driver vented is going to be ~ twice the sseled volume.
If your going vented you will need to include a highpass bass filter.
Consequently a 6th order alignment begins to look attractive.
For the flat vented responses you'll need a butterworth bass filter
(Q=0.7) set say 20% below the port tuning frequency. The red trace
shows an alignment you could use with a high pass filter set to 60Hz
but a higher peaking Q than Butterworth, usually Q=1.5 to 2.0.
🙂/sreten.
FWIW is these volumes are too big simply choose another driver.
The TB's do not appear to be particualarly good value.
These drivers sealed + mini tweeter are a possibility :
http://www.madisound.com/catalog/product_info.php?cPath=45_241_309&products_id=8470
Isobaric is silly because you could simply choose a 4 ohm driver
with the equivalent parameters of the compound isobaric driver.
Taking sealed as the "standard" volume, an isobaric arrangement
would be ~ half the volume sealed or ~ the same volume vented.
One driver vented is going to be ~ twice the sseled volume.
If your going vented you will need to include a highpass bass filter.
Consequently a 6th order alignment begins to look attractive.
For the flat vented responses you'll need a butterworth bass filter
(Q=0.7) set say 20% below the port tuning frequency. The red trace
shows an alignment you could use with a high pass filter set to 60Hz
but a higher peaking Q than Butterworth, usually Q=1.5 to 2.0.
🙂/sreten.
FWIW is these volumes are too big simply choose another driver.
The TB's do not appear to be particualarly good value.
These drivers sealed + mini tweeter are a possibility :
http://www.madisound.com/catalog/product_info.php?cPath=45_241_309&products_id=8470
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@ Sreten: I actually picked the Tang Band's for US$70.00, not the $129.99 buy now price up on ebay. The reason I got them is because thy have free shipping, and without that getting speakers all the way down to NZ where I am is ridiculous. (>$50)
Also @ sreten: To be honest I'm new to this stuff and barely understood half of what you just said...😀...However, I do understand that typically sealed enclosures are smaller than ported, which means sealed may be a better option for me...?
Also, in the throes of internet research, I saw that polyfill can be used to "fool" speakers into thinking their enclosures are bigger than they actually are. If I used polyfill how much further could I reduce the size of the enclosures?
Also @ sreten: To be honest I'm new to this stuff and barely understood half of what you just said...😀...However, I do understand that typically sealed enclosures are smaller than ported, which means sealed may be a better option for me...?
Also, in the throes of internet research, I saw that polyfill can be used to "fool" speakers into thinking their enclosures are bigger than they actually are. If I used polyfill how much further could I reduce the size of the enclosures?
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