hey everyone,
i have got my subwoofer design ready and it equals out to 54 litres in volume and tuned to 35 hz
i have 2 x 10inch Response XL subwoofers and the specs are (i think this is what is required?)
FS:24.38
QTS: .299
Vas: 73.19
QES: .337
im not sure what the size of my port should be? winisd gives me the length required for the diameter of my choosing. Does it matter what diameter i choose for my enclosure (its a vented enclosure btw)
also what effects would having 2 ports be on my enclosure?
thanks,
lach
i have got my subwoofer design ready and it equals out to 54 litres in volume and tuned to 35 hz
i have 2 x 10inch Response XL subwoofers and the specs are (i think this is what is required?)
FS:24.38
QTS: .299
Vas: 73.19
QES: .337
im not sure what the size of my port should be? winisd gives me the length required for the diameter of my choosing. Does it matter what diameter i choose for my enclosure (its a vented enclosure btw)
also what effects would having 2 ports be on my enclosure?
thanks,
lach
If the port is too small it will start compressing sooner. At resonance frequency most sound comes via ports. In your case use as large (in diameter and length) ports as you can fit into box. Latest Genelec woofers for an example use large sprilar shaped ports inside the cylindrical boxes.
would a Flared Speaker Port - 58mm dia x 120mm Long x 1 be adequate for my enclosure?
Winisd is giving me this Mach reading which goes red when i punch in a singular 58 mm in diameter port. It also wont let me chooose the port length? is this because the port diameter and length both adhere to a specific rule ?
also, can winisd properly calculate dual ports properly? because it says i can put 2 x 2" ports in and it will work out just fine.
and do the ports count as part of the volume of the speaker box? i remember reading somewhere that the port volume must be added to the total volume when calculating the measurements?
lol one last question. Do flared ports require an extra formula or are they just the same as normal ports?
thanks,
lach
Winisd is giving me this Mach reading which goes red when i punch in a singular 58 mm in diameter port. It also wont let me chooose the port length? is this because the port diameter and length both adhere to a specific rule ?
also, can winisd properly calculate dual ports properly? because it says i can put 2 x 2" ports in and it will work out just fine.
and do the ports count as part of the volume of the speaker box? i remember reading somewhere that the port volume must be added to the total volume when calculating the measurements?
lol one last question. Do flared ports require an extra formula or are they just the same as normal ports?
thanks,
lach
Lach O'Sullivan said:
Qts = .299 that is suspicious. usually accuray to 2 decimal places is hard. i think we should read this as 0.3 (+/- 10%).
i'd use teh largest dia port that can safely fit in my box and then add 10% for good measure. one can cut a port to size. many years ago when i was "into" bass reflex boxes I used to build many ports if the design said 6" I'd build ports from 4 and 8" ports too. then tune by ear. there are other ways like flling the port with a open cell foam damper or straws to tune ports too.
Two ports are good, the area adds together (can't remember exact details) and effectively you get the same effect as having one larger diameter port (length increases too, just as it does if you increase the diameter of a single port).
I think speaker workshop will give you the correct length for each port if you use two, but its been a few years since I did my dual ported box, so I can't remember which program I actually used.
I used 70mm pvc pipe, but make sure you use the inside diameter of the port when you do the simulation, with pvc pipe the diameter refers to the outside, 70mm is actually closer to 65mm internal diameter.
Not sure about flared ports, I imagine the flare affects the volume to a degree, but whether it is significant or not, I don't know.
Regards,
Tony.
I think speaker workshop will give you the correct length for each port if you use two, but its been a few years since I did my dual ported box, so I can't remember which program I actually used.
I used 70mm pvc pipe, but make sure you use the inside diameter of the port when you do the simulation, with pvc pipe the diameter refers to the outside, 70mm is actually closer to 65mm internal diameter.
Not sure about flared ports, I imagine the flare affects the volume to a degree, but whether it is significant or not, I don't know.
Regards,
Tony.
Hi Lach
I couldn't agree more. For your box, a good starting point would be to use a 2.5inches dia PVC tube and cut lengths of 2", 3", 4", 5" 6" as navin has mentioned.
If you happen to have Eagles "Hell freezes over", play Hotel California. There is a nice 40Hz there. This is the frq where you begin to feel some vibration. Change the tubes until you like the sound in your room.
BTW, this is for 1 pc of 10" Response in a 54L box with 1 port.
Cheers
I couldn't agree more. For your box, a good starting point would be to use a 2.5inches dia PVC tube and cut lengths of 2", 3", 4", 5" 6" as navin has mentioned.
If you happen to have Eagles "Hell freezes over", play Hotel California. There is a nice 40Hz there. This is the frq where you begin to feel some vibration. Change the tubes until you like the sound in your room.
BTW, this is for 1 pc of 10" Response in a 54L box with 1 port.
Cheers
i use the stereophile test CD and my ears. about all i need. if ti sounds good who ares how it measures right? over the years you understand what modification do what.
>i have got my subwoofer design ready and it equals out to 54 litres in volume and tuned to 35 hz
>i have 2 x 10inch Response XL subwoofers and the specs are (i think this is what is required?)
FS:24.38
QTS: .299
Vas: 73.19
QES: .337
====
Based solely on these specs, 54Hz is slightly too small/tuned too high for two drivers. Also, it's a good idea to allow for a bit of VC heating since subs tend to run a little hot, so I recommend going a bit bigger/tuned lower, ~2.84ft^3 (80.42L)/29Hz as a starting point.
====
>im not sure what the size of my port should be? winisd gives me the length required for the diameter of my choosing. Does it matter what diameter i choose for my enclosure (its a vented enclosure btw)
====
Ideally, you want the vent mach to be limited to 5% at rated output so that it doesn't audibly 'chuff'. often this means long vents that have their own pipe resonances that can comb filter with the main's output so there's a point of diminishing returns WRT size/length/vent mach.
====
>also what effects would having 2 ports be on my enclosure?
====
Makes the vents even longer than a single one of the same cross sectional area due to greater friction. The smaller diameter pipes will have higher frequency/lower amplitude harmonics than one big pipe though.
Anyway, where possible, I like to use the cab (tower design, AKA ML-TL or ML-TQWT) to help with the venting since it makes the vent shorter than in a typical BR, so for my suggested Vb/Fb (inside dims): 34.5" (876.3mm) x 15.187" (385.75mm) x 9.38" (238.25mm) with the drivers centered in a bipolar layout, and proportionately adjust width/depth if required due to driver depth. Touching motors is fine, and acts as shielding as a side benefit.
I recommend starting with a 4" 101.6mm) diameter x 8" (203.2mm) long vent and go up to 12" 304.8mm) to see what works best in your room/location.
GM
>i have 2 x 10inch Response XL subwoofers and the specs are (i think this is what is required?)
FS:24.38
QTS: .299
Vas: 73.19
QES: .337
====
Based solely on these specs, 54Hz is slightly too small/tuned too high for two drivers. Also, it's a good idea to allow for a bit of VC heating since subs tend to run a little hot, so I recommend going a bit bigger/tuned lower, ~2.84ft^3 (80.42L)/29Hz as a starting point.
====
>im not sure what the size of my port should be? winisd gives me the length required for the diameter of my choosing. Does it matter what diameter i choose for my enclosure (its a vented enclosure btw)
====
Ideally, you want the vent mach to be limited to 5% at rated output so that it doesn't audibly 'chuff'. often this means long vents that have their own pipe resonances that can comb filter with the main's output so there's a point of diminishing returns WRT size/length/vent mach.
====
>also what effects would having 2 ports be on my enclosure?
====
Makes the vents even longer than a single one of the same cross sectional area due to greater friction. The smaller diameter pipes will have higher frequency/lower amplitude harmonics than one big pipe though.
Anyway, where possible, I like to use the cab (tower design, AKA ML-TL or ML-TQWT) to help with the venting since it makes the vent shorter than in a typical BR, so for my suggested Vb/Fb (inside dims): 34.5" (876.3mm) x 15.187" (385.75mm) x 9.38" (238.25mm) with the drivers centered in a bipolar layout, and proportionately adjust width/depth if required due to driver depth. Touching motors is fine, and acts as shielding as a side benefit.
I recommend starting with a 4" 101.6mm) diameter x 8" (203.2mm) long vent and go up to 12" 304.8mm) to see what works best in your room/location.
GM
subwoofr
My prog comes up with :
1- 2x10 spkr in 54L box with 30 hz tuning better than 35hz.
It will F3 @ 28hz and needs a 2 7/8 dia. port 8 1/8 long.
Two ports are not needed here and would be noisier.
If you want dual flanged ports, Parts Express has all instructions for thiers.
Check out my prog. on my web if you are planning on a lot of DIY
http://users.zoominternet.net/~dbaudio
My prog comes up with :
1- 2x10 spkr in 54L box with 30 hz tuning better than 35hz.
It will F3 @ 28hz and needs a 2 7/8 dia. port 8 1/8 long.
Two ports are not needed here and would be noisier.
If you want dual flanged ports, Parts Express has all instructions for thiers.
Check out my prog. on my web if you are planning on a lot of DIY
http://users.zoominternet.net/~dbaudio
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