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Old 2nd May 2005, 07:44 PM   #1
kpero is offline kpero  Croatia
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Thumbs down Question for box volume

Ok!
I'm new on this forum, and have question about woofer design.
I have one speaker bought from my friend. Nothing fancy, just good for my first project.

Bigest problem is in driver volume. For vented design WinISd calculate 130 l, but that is too big for my house (green line in diagram ).

For smaller box it has - 3 dB on 50 Hz which is still high for me.

Is there a way to drop frequency below that or just with biger volume i can get lover frequency.
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Old 2nd May 2005, 07:59 PM   #2
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Electronic correction...

T/S-parameters would be welcome at any time

Mvg Johan
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Old 3rd May 2005, 05:11 AM   #3
simon5 is offline simon5  Canada
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You have to understand that the room will lift up the frequency response in the low end. You gain about 4 dB at 20 Hz and 2 dB at 40 Hz.

You can tune your box lower than that.

To have a lower tuning point, you can have a larger box, a box with two drivers in a isobaric enclosure so the box is 2 times smaller for the same tuning frequency, or use electronic correction.

You can't use electronic correction much because you have only 5 mm of Xmax to work with. I suggest isobaric if you have another driver like this one.

Final solution is to use the largest box you can tolerate, if it's 60 liters, try tuning it to 25-30 Hz...
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Old 3rd May 2005, 10:36 AM   #4
kpero is offline kpero  Croatia
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Simon5

That Xmax isn't so right. Woofer has much more cone excursion than that. Which electronic you have in mind. EAS or something diferent?

Rademakers
T/S parameters are in atached file ,where is winisd graph
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Old 3rd May 2005, 12:36 PM   #5
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My bad,

Anyway your T/S-parameters don't go along.

Qts:0,36 / Qes: 0,7 / Qms: 6,33 Now what's wrong here??

Your Qes doesn't look exactly right but your Qts just looks plain wrong.

Quote:
Woofer has much more cone excursion than that
How do you know? (Your not talking about Xmech right?)

Xmax going to be enough or not largely depends on the place your going to put the cab and your desired output.

Remember you can increase the internal volume by (about) 20% if you stuff it correct.

BTW: You're using WinISD 0.44 Don't do that!! Use WinISD Pro a7 (or a6) to see some of the more important things (like cone-excursion and applying filters).

Mvg Johan
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Old 3rd May 2005, 12:49 PM   #6
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If the quoted Qes and Qms are correct, Qts shopuld be 0.63. If it's that high it will be no good in a vented box. Even in a sealed box it will need a big box and/or be quite peaky. I'll bet this is a cheap woofer?
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Old 3rd May 2005, 04:50 PM   #7
simon5 is offline simon5  Canada
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Quote:
Originally posted by kpero
Which electronic you have in mind. EAS or something diferent?
A Linkwitz Transform circuit.
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Old 3rd May 2005, 05:08 PM   #8
kpero is offline kpero  Croatia
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whell i don't know is that right or not. I copy pasted from web. On which formula you calculate that Q parametar.
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Old 3rd May 2005, 05:48 PM   #9
Mikey p is offline Mikey p  Canada
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Quote:
Originally posted by simon5
You have to understand that the room will lift up the frequency response in the low end. You gain about 4 dB at 20 Hz and 2 dB at 40 Hz.
Room gain is alot more than that. From the graphs I've seen from Adire Audio, typical room gain is 10db at 20hz and 7db at 40hz.
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Old 3rd May 2005, 07:37 PM   #10
kpero is offline kpero  Croatia
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Will that room gain also have impact on cone movement?

By the way this woofer is peace of junk ). That t/s parameter are all but true.
Tomorow i'll buy some other speaker. Hope it will be better than this one.

Here are some t/s parameter of that driver.
Qts= 0.370
Qms=1.75
Qes=0.47
Prms=150 W
d=250 mm
Spl= 92 dB

Can't find it's Xmax. How can I measure that parameter?

I think that box of 50 liters will do good for this one. Vented of course
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