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
GM,
Re is 5,2
BL has not been tested
any easy way I could calculate it?
planet10,
how big such an mass loaded transmission line would have to be? How flat, and low, do you think the response will be?
thank you both
Re is 5,2
BL has not been tested
any easy way I could calculate it?
planet10,
how big such an mass loaded transmission line would have to be? How flat, and low, do you think the response will be?
thank you both
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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