BASS REFLEX ENCLOSURE/TUNING

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Hi folks,
I have a pair of 15 inch Dayton ST385 and plan to build a enclosure for it.

I listen to all kinds of music, specially classical and jazz, so it needs to get a low bass and without boomyness, a tight bass that get low to 20Hz is all I want.

I will use active crossover with a scan speak 8545 crossed at 300Hz and a SS Ilumminator 6600 TW crossed at 2Khz

So I;m planning to build an bass reflex enclosure. The programs I'm working, winISD and the german site (forgot the link), troelsgravensen, all give me different volumes and port sizes, what is the most accurate?
Fs - 18.8Hz
Vas - 301
Qts - 0.32

WinISD
Vb 140,4
Fb 23.82

German site:
Vb 171.57
Fb 22.02Hz

troelsgravensen does not gives me a result but in his projects he uses a number between this two.


in what should I trust? Does transmission Line give me better results?

Thz to all and a happy new year.

Murillo
 
re:"what is the most accurate?" - depends on what alignment the software designer has chosen, in practise there won't be much difference in the outcome. FWIW I use Unibox.
The price for getting down to 20 Hz is a huge cabinet - a smaller cabinet (say 70 - 90 L tuned to the high 20s) will get you to the low to mid 30s, which is more than is needed for good music reproduction.
 
...Does transmission Line give me better results?

Thz to all and a happy new year.

Murillo
TL it's not a good option for this driver.
BR it's a better choice.
Your alignment as to do with your options or type of use.
Let's say that a simulated ideal one it's this here,
DAYTON ST385-8, VB = 138.2 L, FB = 18.7 Hz, 86.7 dB/2.83V/m.
F-3 dB 28 Hz
F-6 dB 21 Hz
F-12 dB 15 Hz
Each one will measure it's different T/S parameters for his driver (not the standard) and will choose also different alignments.
 

Attachments

  • DAYTON ST385-8, VB = 138.2 L, FB = 18.7 Hz, 86.7 dB2.83Vm. F3=28 Hz, F6=21 Hz, F12=15 Hz.jpg
    DAYTON ST385-8, VB = 138.2 L, FB = 18.7 Hz, 86.7 dB2.83Vm. F3=28 Hz, F6=21 Hz, F12=15 Hz.jpg
    47.6 KB · Views: 354
TROELS

I think I will use a 155 liters with fb of 22Hz based in the troels project Jansen 1071 adapting it to a 15 inch version as he uses a 10 inch.
My measuring for the woofer cabinets in the unibox are of 136,4L with fb in 24Hz, but as winISD gives me 141L and mh-audio gives me 170L, 155L is in it's range.
The dimensions are external, 18mm wood.)

Woofer box:
H 87cm
W 42cm
D 52cm
155L internal

MID/TW box
H 38cm
W 25cm
D 33cm
21,5L internal

Jensen-1071
 
I think I will use a 155 liters with fb of 22Hz based in the troels project Jansen 1071 adapting it to a 15 inch version as he uses a 10 inch.
My measuring for the woofer cabinets in the unibox are of 136,4L with fb in 24Hz, but as winISD gives me 141L and mh-audio gives me 170L, 155L is in it's range.
The dimensions are external, 18mm wood.)

Woofer box:
H 87cm
W 42cm
D 52cm
155L internal

MID/TW box
H 38cm
W 25cm
D 33cm
21,5L internal

Jensen-1071

Hi,

Late post :eek: but here are some suggestions:

b:)
 

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  • Dayton-ST385-8.JPG
    Dayton-ST385-8.JPG
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  • SS-18W8545-00.JPG
    SS-18W8545-00.JPG
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  • SS8545-ST385.JPG
    SS8545-ST385.JPG
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thx Bjorno, I just finished the speaker.
I did as you suggest, the 160 liters one.
It's sounds a little strange in the frequency response, there's a huge gap in the between the 40-55Hz and 70-90Hz with almost -13dB lower with the 85Hz frequency, while the 60Hz is +6,8dB louder??? what went wrong?
I meausured some frequencies between 20 and 100Hz and came wth the following numbers:

Hz dB Variation
20 85,6 0
25 86,1 0,5
30 93,6 7,5
35 97,6 4
40 104,4 6,8
45 103,2 -1,2
50 97,9 -5,3
55 97,7 -0,2
60 104,3 6,6
65 109,9 5,6
70 100,9 -9
75 98,5 -2,4
80 95,1 -3,4
85 82,3 -12,8
90 87,1 4,8
95 91,9 4,8
100 95,5 3,6

I would like to hear some suggestion of where did I went wrong. I'm using an active crossover crossed at 200Hz to my scan speak 8545 midbass.

Thx

Murillo
 
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