In Bass reflex box (vented)-If I make smaller box than what consequences will I have? - diyAudio
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Old 31st December 2010, 07:00 PM   #1
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Default In Bass reflex box (vented)-If I make smaller box than what consequences will I have?

I found this little woofer:
https: / / www.madisound.com/store/manuals/seas/H1217.pdf
I like the features but the manufacturer suggests 56 liters box bass reflex for f3 32Hz.
I want a smaller box.
If I make less than what consequences will I have?
It will suit me box 30 liters.
I will have impact only on f3 or elsewhere?
There is an algorithm that shows the consequences?
Thank you!
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Old 31st December 2010, 07:13 PM   #2
AndrewT is offline AndrewT  Scotland
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Join Date: Jul 2004
Location: Scottish Borders
download WINisd pro.
try different volumes and different vent lengths.
You will find that too small a box creates a "hump" in the frequency response. Great if you are using a driver/box that has a very high F3 and you want to create a bass effect by exaggerating the 2nd harmonic. This is very intolerant of room variations and can sound bad on male voice.

A slightly drooping response avoids the bass exaggeration and helps reduce that male voice sensitivity. It is easier to place in the room.

A true "Butterworth" rolloff (Q=1/sqrt(2)) looks nice, but in a room it falls between the two examples above.
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Old 31st December 2010, 07:31 PM   #3
sreten is offline sreten  United Kingdom
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Join Date: Nov 2003
Location: Brighton UK
Hi,

That driver is intended for sealed boxes not vented, ~13L stuffed.

But 30L tuned to 33Hz looks good to me, but a big box for a 6.5".
Good bass but limited bass power handing, well suited to valves.

Other options may work better, 30L can take 2 vented 6.5"ers.

rgds, sreten.
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Old 31st December 2010, 07:37 PM   #4
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I am thinking to use it in a 3-way as woofer 33Hz to 250Hz.
Is it possible this?

Last edited by eliaselias_0; 31st December 2010 at 07:48 PM.
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Old 31st December 2010, 08:46 PM   #5
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Join Date: Feb 2009
Quote:
Originally Posted by AndrewT View Post
download WINisd pro.
try different volumes and different vent lengths.
You will find that too small a box creates a "hump" in the frequency response. Great if you are using a driver/box that has a very high F3 and you want to create a bass effect by exaggerating the 2nd harmonic. This is very intolerant of room variations and can sound bad on male voice.

A slightly drooping response avoids the bass exaggeration and helps reduce that male voice sensitivity. It is easier to place in the room.

A true "Butterworth" rolloff (Q=1/sqrt(2)) looks nice, but in a room it falls between the two examples above.
Thank you for WINisd pro.
Very usefull program.
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Old 31st December 2010, 09:18 PM   #6
sreten is offline sreten  United Kingdom
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Join Date: Nov 2003
Location: Brighton UK
Quote:
Originally Posted by eliaselias_0 View Post
I am thinking to use it in a 3-way as woofer 33Hz to 250Hz.
Is it possible this?
Hi, its certainly possible, but it is designed for sealed 2 ways, rgds, sreten.

3 ways are very difficult to design - check out these sites/designs.

Use WinISDPro to model bass max SPL and max bass power handling.

undefinition
Zaph|Audio
FRD Consortium tools guide
RJB Audio Projects
Speaker Design Works
HTGuide Forum - A Guide to HTguide.com Completed Speaker Designs.
Humble Homemade Hifi
DIY Loudspeaker Projects Troels Gravesen
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

Last edited by sreten; 31st December 2010 at 09:30 PM.
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Old 3rd January 2011, 03:49 PM   #7
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Join Date: Feb 2009
Quote:
Originally Posted by sreten View Post
Hi, its certainly possible, but it is designed for sealed 2 ways, rgds, sreten.

3 ways are very difficult to design - check out these sites/designs.

Use WinISDPro to model bass max SPL and max bass power handling.

undefinition
Zaph|Audio
FRD Consortium tools guide
RJB Audio Projects
Speaker Design Works
HTGuide Forum - A Guide to HTguide.com Completed Speaker Designs.
Humble Homemade Hifi
DIY Loudspeaker Projects Troels Gravesen
Very helpfull.
Thx
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