Transmission Line Question

[Tubamark]

Originally posted by mclsound
thank you Mark,
it will be put behind the woofer only for tuning,not throughout ...
have you tried this product??
john

Yes, have tried . . . but only for sleeping on!
'Not tested for speaker damping. Likely reflective at some frequencies due to closed-cell construction.

-- Mark

[bjorno]

Hi John,

Sorry for delaying the thread …Here is an attempt to model your speaker that I think is quite close: Check the numbers given in the following pictures: 3(3).

b

1(3)

[bjorno]

2(3)

[bjorno]

3(3)

[mclsound]

hi B,thanks for getting back,i have drew up some more accurate #'s.......the exit line slopes...here we go
a-1---9.25 s-11---8.50 s-0---1
2------4.25 12---11.875 1---24.50
3------8 13---4.25 2---9
4------11.75 14---4.125 3---20.625
5------8 15---3.875 4---7.625
6------10.25 16---3.625 5---28.75
7------7.5 17---13.625 6---21.625
8------6.75 18---3.50
9------9.25 19---3.25
10-----6.75 20---3.25
11----9.75 21---3.50
12----6.75 22---25.75
13----6.75 23---3
14----8.75 24---3.25
15----6 25---18.375
16----5

i left .5"around the exit opening for some foam cover(??),some where to glue to. these should be closer,thanks again for your help,i learn more every day

john

[bjorno]

Hi John,

Be sure to use the open type of cell foam.
If ½” thick and of medium porosity , you loose less than a half dB globally with respect to the stuffing scaling factor (s>0.5).

More updated simulations: 4(4).

b

1(4)

[bjorno]

2(4)

[bjorno]

3(4)

[bjorno]

4(4)

[mclsound]

hi b ,thank you for this help. but i am not sure what all that means???????????
is there room for improvements,the graphs need a little explanation for me if you can please,

my prototype does not go as low as the PMC IB1,i do know it all takes time ...one step at a time i say. look forward to your response as always.....i may have been off by a tiny bit here and there but they are very very close.
i chose a bigger box design because i know the volt 3143 is not a modified pmc version,may be i should have stuck with the pmc dimensions????
do you think i can get this design i created to dig down low(20-25hz at 100 db) and still be accurate.????

thanks john