BASS REFLEX ENCLOSURE/TUNING - Page 2

murillollirum · 30th January 2013, 08:03 PM

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

wintermute · 30th January 2013, 08:13 PM

Were those measurements taken in room? It seems as though you may be seeing room effects. What do you get if you do a nearfield measurement of the cone and port (or even put the mic inside the speaker cabinet?

Tony.

murillollirum · 30th January 2013, 08:23 PM

hi Tony, the mic was inside the port. Thx for asking.

murillollirum · 31st January 2013, 01:27 PM

update, I used an FFT software and its flat.Í may have made a wrong measuring procedure.
Thx for all help.

30th January 2013, 08:13 PM	#12
wintermute just another diyAudio Moderator Join Date: Aug 2003 Location: Sydney Blog Entries: 22	Were those measurements taken in room? It seems as though you may be seeing room effects. What do you get if you do a nearfield measurement of the cone and port (or even put the mic inside the speaker cabinet? Tony. __________________ Any intelligence I may appear to have is purely artificial! Some of my photos

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30th January 2013, 08:03 PM	#11
murillollirum diyAudio Member Join Date: Nov 2012 Location: Brasil	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

30th January 2013, 08:23 PM	#13
murillollirum diyAudio Member Join Date: Nov 2012 Location: Brasil	hi Tony, the mic was inside the port. Thx for asking.

31st January 2013, 01:27 PM	#14
murillollirum diyAudio Member Join Date: Nov 2012 Location: Brasil	update, I used an FFT software and its flat.Í may have made a wrong measuring procedure. Thx for all help.