yes I know BR is ported
but it will only cause phase problems
no need when going 3way
acoustic 'resistance'
but it will only cause phase problems
no need when going 3way
acoustic 'resistance'
Never built an aperiodic enclosure but the vents come in a certain size and according to some guidelines you use one or more of the same size.
Back in the '80s Dynaudio was one maker of aperiodic boxes (at the time they were still selling drivers to us diy'ers including the vents) and their larger speakers had 3 or 4 of those vents. How to actually make the correct decision on vent number I sadly do not know. Sorry!
Back in the '80s Dynaudio was one maker of aperiodic boxes (at the time they were still selling drivers to us diy'ers including the vents) and their larger speakers had 3 or 4 of those vents. How to actually make the correct decision on vent number I sadly do not know. Sorry!
I would
or, if stuffed relatively heavy you would have something like aperiodic acoustic valve
Using your linked calculator for SB Acoustics driver specs:
FS 27Hz
Vas 94 Liters
Qts 0.41
Bass reflex tube should have at least 1/3 of the driver: 0.068 cm for 1 BR
Results are:
Cabinet volume in litres: 75 Liters
Cut-off frequency f3 (-3dB) in Hz: 30 Hz
Cut-off frequency f8 (-8dB) in Hz: 24Hz
Efficiency in dB (1W/1m): 89 dBs
Length of bass reflex tube(s) in cm: = 0??????
No of bass reflex tubes: 1 tube
Total area of bass reflex tube(s) in cm2: 0??????
Ql: 7 ??????
Please help: sorry my ignorance I don't understand why lenght of tube BR is 0, total are BR tube is 0 and don't understand what's Ql? the results says that the drivers isn't flat till 20Hz, right?
TIA
For 1 SB 23NRSX45-8:
Vb = 75L
Fb = 26Hz
F3 = 27Hz
F10 = 20Hz
Port inside diameter = 7.65cm (3")
Port Length = 26.86cm
Stuffing = walls covered
xmax is not exceeded until 100dB 1W/1M at about 23Hz.
Port size and Vb can be slightly adjusted if desired. Actually, there any number of different ways to tune this - this is just one.
Port Volume (L) = (pi*r^2*l)/1000, where r = 1/2 the outside port diameter (cm), and l = the length inside the cabinet (cm) (divide by 1000 because 1L = 1000cm^3)
Be sure that Vb of 75L excludes the volumes of the port, driver, bracing, xo's, etc.
Here's what the response looks like:
Vb = 75L
Fb = 26Hz
F3 = 27Hz
F10 = 20Hz
Port inside diameter = 7.65cm (3")
Port Length = 26.86cm
Stuffing = walls covered
xmax is not exceeded until 100dB 1W/1M at about 23Hz.
Port size and Vb can be slightly adjusted if desired. Actually, there any number of different ways to tune this - this is just one.
Port Volume (L) = (pi*r^2*l)/1000, where r = 1/2 the outside port diameter (cm), and l = the length inside the cabinet (cm) (divide by 1000 because 1L = 1000cm^3)
Be sure that Vb of 75L excludes the volumes of the port, driver, bracing, xo's, etc.
Here's what the response looks like:
Attachments
I can't get BR tube of 3" 7.65cm, can I use two BR tubes in other standard size?
I can get 85mm adjustable lenght 125-275mm MBR-80M - Bass reflex tube 54cm² - Europe Audio
I can get 85mm adjustable lenght 125-275mm MBR-80M - Bass reflex tube 54cm² - Europe Audio
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If Vb is actually 75L, that port will do fine. You will need the full length, 274mm.
If I wanted to go the extra mile (or km), I would probably consider doubling up the thickness of your front baffle and go with 19mm thick bracing of good quality plywood instead of MDF, but you may need to change cabinet dimensions and/or the port if you do so. Otherwise, your plans look correct and sufficient, but you should do an accurate calculation of the net internal volume to be sure of the port length.
I would also suggest when you route out the chamfer for the driver on the rear of the front baffle that you do not cut out the material where the screws/bolts go. So you get something like the picture below, although the 45 degree chamfer that I think you did for your mid is preferable.
If I wanted to go the extra mile (or km), I would probably consider doubling up the thickness of your front baffle and go with 19mm thick bracing of good quality plywood instead of MDF, but you may need to change cabinet dimensions and/or the port if you do so. Otherwise, your plans look correct and sufficient, but you should do an accurate calculation of the net internal volume to be sure of the port length.
I would also suggest when you route out the chamfer for the driver on the rear of the front baffle that you do not cut out the material where the screws/bolts go. So you get something like the picture below, although the 45 degree chamfer that I think you did for your mid is preferable.
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