Well, if you already have them, that is something different. MDF is cheap, so it is worth building some boxes to try them out. 
Another alternative would be to stuff your ports and gain more usable range for the sub. You've said SPL isn't an issue, but after working hard for max extension I am now wondering myself if it isn't a good idea to consider max SPL more at these low frequencies.
Shiva 90L sealed F3 is 31Hz.
Another alternative would be to stuff your ports and gain more usable range for the sub. You've said SPL isn't an issue, but after working hard for max extension I am now wondering myself if it isn't a good idea to consider max SPL more at these low frequencies.
Shiva 90L sealed F3 is 31Hz.
thanks guys!
a friend of mine put the parameters of the visaton in LspCAD. de program suggested twin boxes of 138 liters, ported at 25.4 hertz.
i don't know the F3. could someone estimate the F3 with these values i gave above?
i guess this should give me reasonably deep bass, won't it? The box sure will be large, but i don't really mind. for all of you to know which woofer we are talking about, i've pasted some info from www.thielesmall.com below:
Brand Visaton
Model W 300 S 8 Ohm
Description
Range / type Woofer,
Typical use Undetermined
Recomended enclosure
Series
Manufacturer
Order nr 9041
Production status Active 2004
Nom. diamerer [inch] 12
Vas [Liters] 340
Qts 0,32
Qes 0,39
Qms 1,8
Fs [Hz] 22
Sensitivity [dB] 92
Max Power [W] 150
Power definition 150 RMS, 200 max
Lower freq [Hz] 22
Upper freq [Hz] 1000
Rec. Filter freq [Hz]
xmax [mm] 14
Moving mass [g] 57
Disp area [m2] 0,0507
Disp Vol [cm3]
xdamage [mm]
Air gap [mm] 8
Coil height [mm] 18,5
Coil diameter [mm] 50
Cms [mm/N]
Rms [N*s/m]
Magnet weight [gr]
Magnet height [mm] 0
Magnet diameter [mm] 140
Magnet material -
Re [ohm] 6,6
Z [ohm] 8
L [mH] 1,8
Bl [Tm] 11
Magnetic flux [Wb] 1,4
Flux density [T] 1,1
Outer diam. [mm] 332
Bolt circle [mm]
Nr of bolts [Nr]
Cutout [mm] 280
Weight [Kg] 4,5
Height [mm]
Depth [mm] 134
a friend of mine put the parameters of the visaton in LspCAD. de program suggested twin boxes of 138 liters, ported at 25.4 hertz.
i don't know the F3. could someone estimate the F3 with these values i gave above?
i guess this should give me reasonably deep bass, won't it? The box sure will be large, but i don't really mind. for all of you to know which woofer we are talking about, i've pasted some info from www.thielesmall.com below:
Brand Visaton
Model W 300 S 8 Ohm
Description
Range / type Woofer,
Typical use Undetermined
Recomended enclosure
Series
Manufacturer
Order nr 9041
Production status Active 2004
Nom. diamerer [inch] 12
Vas [Liters] 340
Qts 0,32
Qes 0,39
Qms 1,8
Fs [Hz] 22
Sensitivity [dB] 92
Max Power [W] 150
Power definition 150 RMS, 200 max
Lower freq [Hz] 22
Upper freq [Hz] 1000
Rec. Filter freq [Hz]
xmax [mm] 14
Moving mass [g] 57
Disp area [m2] 0,0507
Disp Vol [cm3]
xdamage [mm]
Air gap [mm] 8
Coil height [mm] 18,5
Coil diameter [mm] 50
Cms [mm/N]
Rms [N*s/m]
Magnet weight [gr]
Magnet height [mm] 0
Magnet diameter [mm] 140
Magnet material -
Re [ohm] 6,6
Z [ohm] 8
L [mH] 1,8
Bl [Tm] 11
Magnetic flux [Wb] 1,4
Flux density [T] 1,1
Outer diam. [mm] 332
Bolt circle [mm]
Nr of bolts [Nr]
Cutout [mm] 280
Weight [Kg] 4,5
Height [mm]
Depth [mm] 134
My friend's program suggested to use 17.8cm of the the 10.4 cm diameter PVC-pipe i had lying around. according to the formula i found on www.diysubwoofers.org the length of the port should be 21 centimeters! why do these values not correspond?
www.diysubwoofers.org :
Lv = (23562.5*Dv^2*Np/(Fb^2*Vb))-(k*Dv)
where,
Dv = port diameter (cm)
Fb = tuning frequency (Hz)
Vb = net volume (litres)
Lv = length of each port (cm)
Np = number of ports
k = end correction (normally 0.732)
www.diysubwoofers.org :
Lv = (23562.5*Dv^2*Np/(Fb^2*Vb))-(k*Dv)
where,
Dv = port diameter (cm)
Fb = tuning frequency (Hz)
Vb = net volume (litres)
Lv = length of each port (cm)
Np = number of ports
k = end correction (normally 0.732)
i absolutely agree
thats why i wrote the higher the crossover frequency, the steeper it should be, and more carefull the sub placement
if placed right next to the main speakers, no problem whatsoever no matter what crossover frequency
i have copy of someones phD thesis on subwoofers/satelites and localization issues, the ideal crossover frequency is 150 Hz assuming correct sub placement
it is logical to place sub as close to main speakers, make no sence to put it behind your back, no matter how low you cross it
there are not only localization issues but phase issus as well, therefore the best placement is as close to mains
the benefit of crossing higher (assuming correct sub placement) is releaving main speakers from low frequencies thus lower midrange distortion, higher spl for dedicated woofer can handle much more power...i tried all different combinations, this is the one which worked best for me: after the volume control split the signal at 150 Hz, use low power preferebly single ended classA amp for satelites, dedicated high current sub amp with selectable crossover fr. and volume for sub, play with those two setting till the sub disappears and bass becomes integrated with mains
i intend to make a subwoofer in the REL manner. connecting the sub at speakerlevel to the poweramp. REL subwoofers have no high pass, as the main speakers are not supposed to be relieved from the bass. the subwoofer should only take over from where the natural roll off of the speaker starts.
how could i tune the box for the sub to be more efficient at the lowest frequensies. this may be at the expense of sensitivity at higher frequensies.
what happens in general when you make the box larger?
and what generally happens when you change the length and diameter of the reflex-pipe?
how do you determine what frequensie the port should be tuned at?
how could i tune the box for the sub to be more efficient at the lowest frequensies. this may be at the expense of sensitivity at higher frequensies.
what happens in general when you make the box larger?
and what generally happens when you change the length and diameter of the reflex-pipe?
how do you determine what frequensie the port should be tuned at?
A larger box give better low frequency response.
A longer port in a given box will tune the box lower, so better low frequency response.
A larger port is needed for larger subs.
You tune the port according to what you want your sub sounds like.
You tune around Fs for compromise between low frequency response and high sensivity in the 30 Hz range, it's also a compromise between flat response and boomy response.
Higher than Fs will give higher sensivity and poor low frequency response, it will be boomy.
Lower than Fs will give lower sensivity, but maximum flatness in room response and good low frequency response. You can't go too low, or your frequency response curve will look ugly. You'll have a point between Fs and the tuning of the port where the bass response will be poor.
A longer port in a given box will tune the box lower, so better low frequency response.
A larger port is needed for larger subs.
You tune the port according to what you want your sub sounds like.
You tune around Fs for compromise between low frequency response and high sensivity in the 30 Hz range, it's also a compromise between flat response and boomy response.
Higher than Fs will give higher sensivity and poor low frequency response, it will be boomy.
Lower than Fs will give lower sensivity, but maximum flatness in room response and good low frequency response. You can't go too low, or your frequency response curve will look ugly. You'll have a point between Fs and the tuning of the port where the bass response will be poor.
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