Hi,
I have some free time, couple sheet of MDF and a driver I want to use. There is still no enclosure type I would prefer although this design inspired me quite a lot. Is a transmission line achievable with my driver?
12inch, Unknown brand
Vas 125.61L
Qms 1.74
Qes 0.36
Qts 0.30
FS 36.5
…what type enclosure should I choose?
I will be please to ear your opinions
I have some free time, couple sheet of MDF and a driver I want to use. There is still no enclosure type I would prefer although this design inspired me quite a lot. Is a transmission line achievable with my driver?
12inch, Unknown brand
Vas 125.61L
Qms 1.74
Qes 0.36
Qts 0.30
FS 36.5
…what type enclosure should I choose?
I will be please to ear your opinions
First off, with a 36.5Hz Fs/lowish Q it's not going to be a subwoofer. You need Sd to calculate BL so I fudged it at 506.709cm^2 for simming purposes, but it should be close enough for reasonable accuracy if it's not a really high excursion driver with a smaller than average diaphragm.
You can calculate it:
Cms = Vas/(Sd^2*rho*c^2)
where:
Vas is in m^3 (liters*0.001)
Sd is in cm^2
c is in meters/sec*0.0001 to get Cms in mm/N
then:
Mms = 1/[(2*pi*Fs)^2*Cms]
BL = [(2*Pi*Fs*Re*Mms)/Qes]^0.5
Anyway, I forgot to ask if the amp is SS or tube, if tube I'll need its output resistance (damping factor) and have to redo the ML-TL sims. Qts is too low for a reverse taper TL IMO, though if tube driven, Qts will go up, enough to tune it somewhat lower and possibly high enough to consider a TL.
I don't have any way to show you the sims, but if you have Mathcad or download the demo viewer from http://www.quarter-wave.com/ I can send you the worksheets to view/change, though you can't save any changes with the viewer.
All dims inside
'XO' = centerline of driver down from top
'rp' = radius of port
'Lp' = length of port
width/depth are golden ratio suggestions, you can make your own based on 'S0/SL (in^2)'
dims can be rounded off somewhat, I just printed out part of a spreadsheet
----------------
T/S max flat:
rp = 2"
Lp = 4.5"
density = 0.25lbs/ft^3
L (in)
20.919
S0/SL (in^2)
156.121
S0/SL (width)
15.894
S0/SL (depth)
9.823
X0 (in)
10.184
Sd (in^2)
78.54
Qts
0.2983
Vas or Vb(ft^3)
1.89
Fs or Fb (Hz)
48
-----------------
Tuned to Fs:
rp = 2"
Lp = 6"
density = 0.25lbs/ft^3
L (in)
27.510
S0/SL (in^2)
152.637
S0/SL (width)
15.716
S0/SL (depth)
9.712
S0/SL (dia)
13.941
X0 (in)
12.471
Sd (in^2)
78.54
Qts
0.2983
Vas or Vb(ft^3)
2.43
Fs or Fb (Hz)
36.5
GM
You can calculate it:
Cms = Vas/(Sd^2*rho*c^2)
where:
Vas is in m^3 (liters*0.001)
Sd is in cm^2
c is in meters/sec*0.0001 to get Cms in mm/N
then:
Mms = 1/[(2*pi*Fs)^2*Cms]
BL = [(2*Pi*Fs*Re*Mms)/Qes]^0.5
Anyway, I forgot to ask if the amp is SS or tube, if tube I'll need its output resistance (damping factor) and have to redo the ML-TL sims. Qts is too low for a reverse taper TL IMO, though if tube driven, Qts will go up, enough to tune it somewhat lower and possibly high enough to consider a TL.
I don't have any way to show you the sims, but if you have Mathcad or download the demo viewer from http://www.quarter-wave.com/ I can send you the worksheets to view/change, though you can't save any changes with the viewer.
All dims inside
'XO' = centerline of driver down from top
'rp' = radius of port
'Lp' = length of port
width/depth are golden ratio suggestions, you can make your own based on 'S0/SL (in^2)'
dims can be rounded off somewhat, I just printed out part of a spreadsheet
----------------
T/S max flat:
rp = 2"
Lp = 4.5"
density = 0.25lbs/ft^3
L (in)
20.919
S0/SL (in^2)
156.121
S0/SL (width)
15.894
S0/SL (depth)
9.823
X0 (in)
10.184
Sd (in^2)
78.54
Qts
0.2983
Vas or Vb(ft^3)
1.89
Fs or Fb (Hz)
48
-----------------
Tuned to Fs:
rp = 2"
Lp = 6"
density = 0.25lbs/ft^3
L (in)
27.510
S0/SL (in^2)
152.637
S0/SL (width)
15.716
S0/SL (depth)
9.712
S0/SL (dia)
13.941
X0 (in)
12.471
Sd (in^2)
78.54
Qts
0.2983
Vas or Vb(ft^3)
2.43
Fs or Fb (Hz)
36.5
GM
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